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The fiercest serpent may be defeated by a swarm of ants.
Admiral Isoroku Yamamoto, discussing the Yamato-class battleship.

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     General 
  • Paratroops in general. True, they are the cream of the crop in each and every army, provide a potentially unexpected avenue of attack, and jumping out of a perfectly good plane mid-air is just plain awesome. However, paratroops suffer from a number of downsides. First, unless the drop zone is secured, the jump planes are easy to shoot down and the descending paratroopers are similarly vulnerable to ground fire. Second, paratroops are generally unsupported by heavy weapons such as artillery and armored vehicles, which cannot be easily carried by planes and are very difficult, if not downright impossible, to safely drop by parachute. Third, parachute operations are heavily dependent on the element of surprise: once lost, the paratroop is at a disadvantage, as their opponent can call for more firepower and reinforcements. Fourth and finally, if the paratroop cannot link up with friendly forces in a timely manner, then it will eventually run out of supplies, at which point surrender is the only option. The experience of WWII paradrop operations was that large scale paradrops usually fail (Market Garden is an obvious example) and even successful ones (Normandy, Crete and Operation Varsity) are costly, but small scale operations (up to company level) usually succeed (an example would be the POW rescue in Los Baños). Helicopters have more or less superseded both gliders and paratroops in most armies around the world.
    • On paratroop gear, the German wartime RZ (Rückfallschirm, Zwangablösung) parachute. It was designed to open quickly, the rationale being the lower the drop, the less time on chute fall. Unfortunately, it opened extremely violently, resulting in bruises and broken ribs. Moreover, it had one single riser instead of the normal four, making controlling it in-flight impossible: the paratrooper hung on the parachute like a spider on the web, helplessly, and the only thing he could do was to try to pivot into the wind. The German jump position was a crucifix dive instead of the leaning rest, and instead of the safe parachute landing fall, the paratrooper landed on all fours, making wearing gauntlets and kneepads a must. The descent speed was faster than with Allied parachutes and thus landings were always hard, and many Fallschirmjäger broke their arms or ribs on landing. The rig itself took almost three minutes to undress and could not be unharnessed prone. The horribly unsafe RZ rigs were largely responsible for the horrendous Fallschirmjäger losses. Jumping with the RZ rig is prohibited today for safety reasons, and Fallschirmjäger re-enactors use normal four-riser Bundeswehr canopies attached on RZ harnesses on jumps. Even stranger is that the Luftwaffe at the time had and even used perfectly normal four-riser parachutes, but only as rescue rigs.
  • The Russian "Tsar" projects. After Tsar Bell and Tsar Cannon, it has become sort of Russian joke to call "tsar-something" anything impressive-looking, but unusable.
    • The Tsar Bomba was the largest nuclear weapon in history at 50 megatons. That's almost 1600 times the power of Fat Man and Little Boy. The test of the bomb was the most powerful single thing ever done by mankind.note 
  • What could be more awesome than War Elephants? Unfortunately, they tend to panic in battle, trampling friend or foe with indifference.
    • During Timur the Lame's invasion of India, his forces faced 120 armored Indian war elephants with (for even more awesomeness!) poisoned tusks. In an act of genius, insanity, or both, he ordered all his camels lit on fire and sent the screaming animals towards the advancing elephants. The massive beasts panicked and trampled over their own forces. Timur's army then easily ran down the fleeing enemy troops. Timur then picked up the Idiot Ball himself, incorporating the elephants into his own army, perhaps figuring that no one else would figure out his strategy.
    • War elephants had been made obsolete in Europe by the Roman ways (yes, ways) of dealing with them, that include such things as ox-driven chariots equipped with huge spikes to wound the elephants and pots on fire to scare them (these ultimately failed, but provoked many losses among Pyrrhus' war elephants), insane numbers of flaming arrows (scary enough to make Pyrrhus war elephants panic and stomp his own troops), extremely loud horns (that made part of Hannibal's elephants run over his own army) and simple axes. When the Romans started chopping enemy war elephants with axes, their enemies finally got the memo and stopped using them (Parthians and Sasanid still made use of war elephants, but never deployed them against the Romans).
    • Despite common depictions of the contrary, only one of Hannibal's 37 elephants survived the crossing of the Alps and the first battles in northern Italy, and did little more than parading Hannibal around.
    • During the decade-long Numantine War (sometimes nicknamed "Rome's Vietnam") the Romans themselves got desperate enough to try war elephants and hired a company from the allied African kingdom of Numidia. As they were about to charge before the walls of Numantia, however, one of the local warriors threw a stone with a sling that hit one of the elephants in the head (some versions say right in one eye). The elephant panicked, the other elephants panicked in turn, and before they knew it the entire herd was stomping the Roman lines behind. The Romans never used elephants in Spain again.
    • The only real value war elephants have is that something about the smell of elephants makes horses panic, rendering the enemy cavalry worthless near them...unless your enemy knows about this, and has trained their cavalry horses near elephants to get them used to the smell. Horses are also scared of camel smell, making them a far cheaper and more reliable alternative to war elephants; if you can field enough of them, camels even make better mounts than horses for cavalry because they're faster than horses. They can also carry troops through arid regions much better than horses, as a camel can go for much longer without needing to be watered. And all of this is without taking into account that elephants are vulnerable to the cold, require large amounts of food and water (which often puts them in direct competition for food with people), have a gestation period of two years, take many more years to grow, and people didn't even figure how to make them breed in captivity before the 20th century so every one of them had to be captured from the wild and trained to take human commands first. It is telling that elephants went completely extinct in several African and Asian countries only a few centuries after they were weaponized.
    • King Mongkut of Siam once tried to send a herd of elephants to American President James Buchanan to aid in transportation and as beasts of burden. By the time the letter ended up in America, Abraham Lincoln was the president and the American Civil War had broken out, and he obviously (but politely) turned it down on the grounds that American climate is not suitable for elephants, and that steam engines would do the job better anyways.
    • The awesome but impractical nature of elephants is exemplified in the origin of the expression "white elephant". In Thai culture white elephants are perceived as very auspicious symbols, and gifting a noble with a white elephant was one of the highest honors a king could've bestowed him with. At the same time elephants were very expensive to feed and care for, and being a King's gift it was impossible to use it as a normal working elephant to earn its own support. Thus it was a constant drain on a noble's finances, so several white elephants too many can easily bankrupt less prosperous ones. But despite all this, turning down a King's gift was not only impossible but unthinkable. So, as rumor goes, the Siamese kings sometimes used them as a hint or outright punishment for the too troublesome and/or ambitious courtiers.
  • In another attempt at weaponizing animals, the Swedes once attempted to create a unit of moose cavalry (Sweden having a limited supply of good cavalry horses but plenty of moose) in the 17th century. It turned out that 1: Moose can't just subsist on hay like horses can, 2: Once the moose are in rut, they'll attack everybody, even their handlers, 3: Moose are terribly vulnerable to a wide variety of livestock diseases, and 4: Moose are smart enough to figure out that guns and pikes are bad for their health, and once they do, they refuse to go anywhere near them. The unit was dissolved without ever fighting a single battle.
  • The nuclear survival bunkers constructed by the U.S. and the Soviet Union during the Cold War, such as Cheyenne Mountain or Mount Weather. Theoretically they can survive a near or direct impact from a single nuclear strike and have some self-reliance for food and air, but they cost a ton to build and were built in an era when accuracy for nukes was measured in miles instead of yards. Both sides stopped building them when they realized the other side could manufacture a dozen nukes to target each bunker, something which no amount of mountain will protect you from.
  • The Spartan military. A well-bred elite warrior class trained from childhood for war is undeniably awesome. However, since every male Spartan must go to war in addition to the fact that they didn't intermingle with the lower classes, any major defeat would take a significant chunk out of their future population. Since having fewer soldiers would potentially lead to even more defeats, the population went into a free fall over the centuries. The Spartan army just had fewer and fewer men until they ceased to be a relevant threat altogether. For this reason, the Peloponnesian War can be considered a pyrrhic victory for Sparta. They lost so many Spartiates despite winning the conflict that by the time of the Spartan-Theban war, they could barely fill their right flank with Spartiates, which is the most important side of an ancient Greek army. By the time of Philip and Alexander, Sparta could barely muster 1000 men, a far cry from the 10,000 that they could muster at the height of their power.
    • The Spartan training method as well, for that matter. Contrary to popular belief, the Spartan hoplite was no where near as effective as their hellish training and constant exercising would suggest. They were certainly better than the average Greek hoplite, but not by enough to offset their numerical disadvantage, population issue and sometimes just plain smart-thinking from their enemy. There have been multiple occasions in history where the Spartan army lost to enemy forces of equal size, sometimes even smaller. Not only was their fighting effectiveness not that much better, but their morale also wasn't that much greater than the average hoplite either. During the battle of Tegyra, 300 Thebans routed over one thousand Spartans by simply breaking through the middle of their line.
  • Some military thinkers in history advocated coastal fortifications as a great investment because their walls were much tougher than a ship's hull, and they were not limited in the size or number of their cannon. With superior defense, range, and firepower, in theory coastal forts were supposed to beat warships every time. The problem was that the guns (and in more modern times, their magazines, motors, etc.) were actually the most expensive part of either a warship or a fort, so it was no less expensive to arm a fort to a certain level compared to a warship. With that in mind, a country could get more bang for their buck by putting the same guns on a ship that could take its firepower anywhere and engage any target, instead of sticking them permanently in one place and probably with a limited field of fire. Because of reluctance to divert investment from ships to forts, few coastal forts were actually made as well-armed as the enemy's big warships, and with enough naval firepower it was actually possible to destroy them. Coastal fortifications could sometimes be made superior if a country cared enough about defending a strategic location—for example, Vladivostok was so heavily fortified in the Russo-Japanese War and World War II that the Japanese navy didn't even attempt to attack it—but coastal fortifications didn't have an automatic advantage over ships and they weren't a substitute for having a proper navy.
  • Old-school mass armies, at least since the end of the Cold War. Modern militaries are so equipment-intensive and have such high personnel costs that fielding millions of men is simply too expensive. Conversely, reducing equipment levels is just begging for a Curb-Stomp Battle - or at least, that was the Chinese conclusion after The Gulf War, upon which they began to furiously modernize their military along Western lines.
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    Watercraft 
  • The real life USS Enterprisenote : Eight. Nuclear. Reactors. They figured this one out before they built another one, fortunately. Why eight? Conventional large aircraft carriers have eight boilers, so logically the "Big E" should have eight nuclear boilers, right? Also, the size of the boilers matched up nicely with the reactors that the Navy had already been building for submarines, meaning it was much simpler to adapt than to create a massive new reactor (which they later did). After drastic cost overruns nixed the five sister ships she was supposed to have (and resulted in the next two carriers being conventionally-powered), engineers realized that even a ship that big only needed two reactors (though Nimitz-class reactors are much larger and more powerful).
    • The Big E was also the fastest carrier in the fleet. Which turned out to not be that useful, because few escort ships (even among the handful of nuclear-powered cruisers that the Navy used to have) were fast enough to keep up.
    • USS Enterprise also has the nickname Mobile Chernobyl for apparent reasons. She is getting old, and maintaining eight aging nuclear reactors is tedious.
    • And after her retirement, the Enterprise couldn't even be used as a museum ship like other carriers, due to the danger posed by those aging reactors. The ship literally has to be cut into pieces in order to safely decommission them. Sadly, there just won't be enough left of her to make a museum out of aside from maybe saving the distinctive cube-shaped island and placing it on shore.
  • First-rate ships of the line during the era of Wooden Ships and Iron Men were 100-120 gun monsters with 800-strong crews and which weighed in excess of two thousand tons. Whilst they were terrifyingly effective in their intended role (to stand in the line of battle and engage enemy fleets in pitched sea-battles), they were effectively useless for anything else, and could not be sent out alone, as even a pair of well-commanded frigates could outmaneuvre one. They were also fiendishly expensive to operate. When not at war, the Royal Navy generally only maintained less than ten ships of this class, usually as flagships for the various fleets. The rest were kept "in ordinary" — tied up at port with skeleton maintenance crews, and which would then be re-commissioned as the strategic situation demanded.
    • For comparison, the standard Ship-of-the-Line was a "3rd Rate" with 74 guns. They were 20-25% faster, half the cost, about two-thirds the manpower requirement, and much more seaworthy. After everyone figured this out (around 1700), the 1st and 2nd rates quit being built except as one-off trophy ships. Being able to field two 3rd rates vs one 1st rate was actually more combat effective.
  • Witness the Swedish ship Vasa launched in 1628. Armed with 64 cannons (out of 72 planned, the cannons weren't ready in time and were going to be installed later) on two decks, the Vasa was the most powerful warship in the world and in terms of naval firepower, would not be equalled for decades. She was also top heavy having little ability to naturally right herself (this is important in all but the calmest seas) and the lower gun deck was far too close to the waterline. In fact she was so ill-designed that she managed to sink on her maiden voyage, in full view of the citizens of Stockholm who had all turned out to see the maiden voyage.
  • The Spanish ship Nuestra Señora de la Santísima Trinidad, a ship larger than the already massive first-rate ship of the line. For comparison, here is HMS Victory. The Santísima Trinidad carried 140 guns, compared to HMS Victory's 104. It was so huge that it crawled at a snail's pace (and was nicknamed el Ponderoso (The Ponderous) as a result). So many men were required to man it that its supplies ran out very quickly unless it was near a friendly port. The Santísima Trinidad only saw battle twice: Cape St Vincent, where it ended up surrendering without doing any damage, but the Spanish ships Infante Don Pelayo and Príncipe de Asturias managed to reach and secure her before the British, and Trafalgar, where it was battered into surrender by the more maneuverable HMS Neptune and then later scuttled by the British in a storm due to its high center of gravity. It was Awesome, But Impractical incarnate.
    • The US Navy had the USS Pennsylvania, a four decker of 140 guns and physically larger than the Santisma Trinidad. It was authorised in 1816, laid down in 1821, and... launched and commissioned in 1837. The HMS Victory, for comparison, took only six years to complete (then spent twelve years in ordinary until finally commissioned during the Revolutionary War), while the HMS St Lawrence, of 112 guns and the only first rate in the Great Lakes, was laid down in April 1814 and completed and commissioned in September 1814.note  The Pennsylvania's only voyage was in 1837-8, from Delaware Bay to Chesapeake Bay, and was finally burned in 1861 to prevent her capture by the Confederates.
  • The Yamato-class superbattleships of the WWII Imperial Japanese Navy. Wielding the largest guns ever placed on a warship, an incredible amount of armor, and (eventually) hundreds of anti-aircraft guns, they were meant to be the superweapons that would issue the killing blow against a belligerent (likely United States) naval force — after the IJN's carrier, cruiser, destroyer, and submarine forces had softened it up with air and torpedo attacks in a single, decisive battle. Unfortunately for the IJN:
    • The rapid advance of aircraft and aircraft carrier technology during Yamato's construction eventually made it clear to the IJN that they could not risk the Yamato-class ships until US Navy airpower had been wiped out. But by the time Musashi had launched in August 1942, the USN had annihilated the core of the IJN's carrier fleet at Midway and was only a few months away from launching the first of 24 Essex-class fleet carriers. By the end of the first year of the Pacific war, it was obvious that the essential prerequisite for fielding the superbattleships — the total destruction of the US carrier fleet — was never going to be met.
    • Even if the "decisive battle" the IJN hoped for actually occurred, the superbattleships weren't necessarily the best tools for the task. Despite their massive size and armament, the superbattleships just didn't have the level of technology and survivability one would expect for a ship that required such a tremendous amount of resources to build and operate. There is evidence that the construction of these ships actually damaged the Japanese economy; the curtain woven to conceal Yamato's construction from prying eyes required so much rope it crippled the Japanese fishing industry.
      • Although the superbattleships were reasonably speedy for their incredible size, they were still slower than most carriers, and consumed massive amounts of fuel.note  As a result, in the few instances they risked leaving port, they tended to operate as a separate "Main Force" — so distant from their carrier strike force that they may as well not have left port to begin with. One key instance of the speed problem was during the Battle of Guadalcanal where the Japanese forces on the island could have benefited from extra fire support from the battleships. Unfortunately for them, the only battleships in the Japanese Navy that could operate economically were the four old battlecruisers that predated World War I. All the other battleships, including the Yamato and the Musashi, either burned up too much fuel or were too slow to effectively support their ground operations. And before long, American battleships gave a reminder of what happens when battlecruisers fight battleships; had Yamato and Musashi been built as smaller but faster and more fuel-efficient ships, the outcome could have been very different. The premature withdrawal at the Battle off Samar was influenced by concern that the Yamato was burning too much fuel in the Stern Chase of Taffy 3.
      • Both sides were reluctant to commit battleships to Guadalcanal, because the constricted waters in the Solomons meant cruisers and destroyers hiding amidst the islands could easily get within torpedo range — as proved to be the case in the first night of the Naval Battle of Guadalcanal. Both sides only committed battleships out of desperation, due to a shortage of aircraft carriers.
      • The steel armor available to Japan wasn't of the same quality as that in the United States, so despite its incredible thickness it was still vulnerable to the USN's "super-heavy" model of 16-inch armor-piercing shells. Its own 18-inch armor-piercing shells, likewise, were only about as effective as the USN's 16-inch shells, at least at long range. Thus, its guns and armor were comparable to the USN's Iowa-class, even though the Iowas were about 2/3 the displacement of the Yamatos and fast enough to operate alongside carriers.
      • Although the IJN excelled at naval gunnery at the start of the war, the accuracy of their manpower-intensive fire control systems deteriorated rapidly under actual combat conditions and had problems tracking maneuvering targets or compensating for evasive action. Since most early surface engagements were short, sharp battles that took place at short range at night, these shortcomings were neither apparent nor material for most of the war. The IJN did not develop or install new fire directors and radar as rapidly as the USN, and never developed anything close to the Mk I fire control computer that US battleships carried. So despite the massive range of the 18-inch shells, they could not match the accuracy of US guns even at the beginning of the war, let alone the radar-guided gunnery many USN ships were fielding by 1944. Yamato's poor gunnery at Samar was as much due to crew exhaustion from the repeated air and submarine attacks she'd experienced in the previous 48 hours as it was to the poor visibility which forced her to constantly switch targets, making it hard to "find the range".
      • Most problems with the IJN gunnery was because their brass completely overlooked the radar as something that will never catch on, despite Japanese researchers making several important contributions to the radar development, such as Yagi-Uda antenna. The first time the naval brass has ever seriously considered the military use of radar was after they've captured some British units at Singapore in 1942, two years after Yamato was commissioned, and they didn't even figure that the "Yagi antenna" mentioned in the documentations referred to a Japanese person at first. They did try to compensate, and by the 1944 Yamato actually carried three radars… none of which was tied into its fire control system. All the while American ships not only started mounting radars much earlier, but had actually built their fire control systems around them. Off Samar most American ships employed radar-guided gunnery, their cannons being laid automatically by the sophisticated fire-control computers, while Yamato still used traditional visual rangefinding with the (severely tired and overworked at this point) humans as main decision makers and means of communications.
      • Damage control doctrine of the IJN was lacking, which meant any damage the ships absorbed could not be repaired as rapidly, and certain types of damage had the potential to cause a cascade of failures. By using resources that could have built several capital ships to instead build one very large capital ship, the IJN compounded this issue.
    • And finally, not to put too fine a point on it, the value of the superbattleships is evident in their abysmal performance during the war. The Yamato engaged US surface ships in only one engagement, the Battle off Samar, where (despite weighing more than the entire force she opposed) she only contributed to the sinking of three small ships. The Musashi, meanwhile, was sunk by aircraftnote  in the Sibuyan Sea prior to the Battle off Samar, and never fired a single shot at an enemy surface vessel in the entire course of her career. In the end, neither ship ever came into gun range of an enemy capital ship. And those hundreds of AA guns were underpowered and obsolete even before they were installed, serving mainly to increase the number of men who went down with each ship.
    • One of the biggest flaws (and the reason for the above) is that the ships were Too Awesome to Usenote  and the allies knew it. This prevented the ships from being used as a threat to shipping and thus the allies didn't really put any effort into sinking them until they were forced to sortie in desperation.note  They ended up costing Japan a lot more money than it took for America to sink them. Contrast the careers of the German battleships, Scharnhorst, Gneisenau, and Tirpitz. These were designed for merchant raiding and even when they weren't sailing, the they threats they posed required a lot active planning from the allies like using capital ships as escorts. While Tirpitz had an even less successful career than Yamato on paper, she costs the allies more than fifteen times her total build and maintenance cost to finally sink and more if you consider the cost of escorting convoys against her. The Yamatos on the other hand were sunk without doing much of anything or any real effort expended hunting them.note  To put it in perspective, SS Lawton B. Evans and SS Stephen Hopkins both had more successful combat careers than Musashi did, and these were armed merchant ships. note 
    • Other examples of the Awesome Yet Impractical nature of the Yamato and Musashi: their guns were so powerful that the ship's boats could not be left out on deck while the guns were fired. Special hangars had to be incorporated to store all the boats, which was one more added cost and also meant they carried fewer boats than would be expected for such mammoth ships. And fewer boats to load the crew into is a problem if the ship, you know. Sinks. Likewise, the ship's crew could not be outside on deck either when the guns fired, because the concussive force would literally knock them unconscious. And potentially rip their clothes off their bodies. This proved even more problematic when it became clear that even the largest, best-armored battleship is extremely vulnerable to air attack and thus the IJN had to find a way to put lots of anti-aircraft guns on deck without them being damaged by the main guns' blast.
    • Even if they hadn't been rendered obsolete by airpower Yamato and Mushashi defined the ragged outer edge of practicality for battleships. Manufacturing their armor pushed the limits of the Japanese steel industry. The maximum range of their guns exceeded the distance that any naval gun could be aimed accurately. The sheer size of their guns required the Japanese to invent an entirely new technology in materials handling equipment just to move the projectiles around the magazines. The extreme weight of their turrets exceeded the metallurgy available for their supporting bearings. And finally their price tags were so extreme the cost to construct them actually damaged the national economy. Finally their actually performance in operation makes a pretty convincing demonstration that the even bigger battleships planned by the Japanese and the Germans simply wouldn't have worked.
  • As WWII went on, the Japanese Navy, who carefully crafted the best aircraft carriers and accompanying naval airpower the world has ever seen over the 1920s and 1930s, found themselves scrambling to make good the loss of four fleet carriers and hundreds of air crew over the course of 1942, and the substantial wartime production of US carriers.
    • The first fleet carrier the Japanese launched during the Pacific Campaign, the Taiho, was the largest carrier in the fleet, had a hurricane bow, armored flight deck, enclosed hangar deck, and effective belt armor (similar to UK designs at the time), and (like most Japanese carriers) two hangar decks. All in all, an excellent design, but with one fatal flaw. British designs went with a single hangar deck to keep the large open hangar space well above sea level; the additional armor of the Taiho forced her lower hangar to be just above the waterline and her elevator wells well below the water line.
      • During the Battle of the Philippine Sea, the USS Albacore got a single torpedo hit on the ship, which cracked her forward avgas (gasoline/petrol) fuel tank. Normally this would cause seawater to enter the tank and the gas/water mix to flow harmlessly out of the ship. Instead, due to the elevator pits being below the waterline, seawater entered the tank and carried gasoline upward into the forward elevator shaft, turning the elevator well into a massive swimming pool of flammable gasoline.
      • As gas vapors filled the hangars, damage control teams were ineffective in venting the fuel and didn't make adequate effort to cover the fuel with foam to prevent it vaporizing further. Even worse, at some point a damage control officer turned on ventilation fans that drew the explosive fuel-air mixture into not-yet-affected compartments of the ship, turning many of the habitable spaces of Taiho into a bomb. During all this time, the ship had continued to carry on normal flight operations, much of the crew oblivious to how close they were to catastrophe.
      • About six hours after the initial torpedo hit, the fumes finally located an ignition point, and Taiho popped like a balloon. The sides of the ship were blown out, the flight deck bowed upward, and (presumably) about half her crew were killed at once. With the ship beyond saving, about 500 of her crew (less than 1/4 of her complement) managed to escape before she sank 2 hours later.
    • One of the Yamato's sister ships, the Shinano, was converted into an aircraft carrier. While it seemed like a good idea - heavy armor, very torpedo-resistant, lots of protection for the magazines - the very reason carriers (even today) have very little armor is to maximize speed and hangar size. The Shinano was thus too slow and carried too few aircraft to be a fleet carrier, and instead was intended to be a nigh-unsinkable aircraft carrier tender. But by the time the ship was ready to be launched, Japanese shipyards were under constant threat of air attack, and its waters were swarming with enemy submarines. In a desperate gamble to protect from the former, the Shinano was sent into the maw of the latter, and steamed to its fitting-out base while still under construction. Its inexperienced crews were unable to save her when it took four torpedoes to the hull, with its watertight bulkheads untested (turns out they were rather leaky) and most of its damage control systems yet to be installed. It was only about a month away from completion when this happened. Regardless, even if it had entered service, it wouldn't have made much of a difference as Japan was still flying more or less the same aircraft it did at the start of the war. And had too few aircraft and even fewer qualified pilots still alive anyway.
    • After their defeat at Midway, the Japanese were desperate to put more carriers to sea to compensate for their tremendous losses. One of these measures was to change their two Ise-class Battleships into hybrid Battleship-Carriers. It turned out to be a colossal failure as they didn't have any available planes and pilots to equip the two ships after their conversion process was completed. To top off how foolish this decision was, even if they did have the pilots on hand, the only planes they would've been able to launch and recover were FLOATPLANES (slower and bulkier than a normal plane). Normal carrier-based aircraft could be launched from the converted Ise-class battleships, but couldn't land on them, meaning their only use would've been for Kamikaze attacks or close to friendly land bases where they could land. Ultimately the Ise and Hyuga had their catapults removed and the flight decks were used as a platform for anti-aircraft guns.
      • Not to mention taking out two perfectly good battleships that could have done some good in battle for extended periods of time. While something needed to be done with Hyuga (one of her rear turrets had exploded and no replacement was available), it would've surely been more practical to just remove the wrecked turret, put a steel plate over the hole and send her back into action.
      • Note also how the original plan was to convert all of their battleships except Yamato and Musashi into full-fledged carriers. Lack of both resources and time forced the IJN to adopt this decision, with the two Fuso-class battleships having been scheduled to be converted as the Ises, had them been succesful.
    • One of the great technical achievements of the Japanese was their secret development of the I-400 class submersible aircraft carrier, which at a displacement of 6,560 long tons was the largest submarine ever produced until the Cold War's ballistic missile submarines. Shortly after Admiral Yamamoto conducted the attack on Pearl Harbor, he conceived the idea of long-range submersible carriers which would be used to stage surprise attacks on American mainland cities. This fit in with his overall strategy against the much bigger United States, which amounted to a desperate gamble that Japan would be able to terrorize the military and population United States so much within a short period that they would decide the cost of opposing Japan was too high, and thus be forced to make concessions in exchange for peace without having had a chance to mobilize their full warmaking potential. Sadly for Yamamoto's ambitions, it was an issue of starting too late, lacking resources, and the result having a limited payload. If such a weapon had been available in numbers immediately following Pearl Harbor, it might have at least been able to inflict panic on American civilians. As it was, the development process was doomed to run longer than Japan's narrow window for taking the initiative, so that by the time they came out the Americans were already outproducing the Japanese by a huge margin and defeating them in one battle after another. Any such submarines would now face a steep challenge getting in and out of coastal striking distance in the face of such enemy naval and air superiority, and their construction took up scarce resources that the rest of the Japanese fleet wanted for themselves. After Yamamoto was killed in a U.S attack on his plane in April 1943, his pet project was no longer safe against cuts: initial plans to make 18 of these vessels were reduced to nine, five, and finally to the three that were actually completed (the third was finished after conversion to a tanker submarine). The ways that they solved the various technical problems was ingenious; Each sub displaced twice as much as their American contemporaries, used a crew of 144, and had enough range to circumnavigate the globe one-and-a-half times. In order to support and balance the weight of the watertight airplane hangar on top, the pressure hull had a figure-of-eight cross section. The hangar held three specially designed Aichi M6A1 Seiran floatplanes, with wings that would rotate 90 degrees and fold backward for storage, as well as floats that were detached and stored seperately. For deployment, the wings were unfolded, the floats reattached, and the motor oil piped into the engine pre-heated so that a crew of four could have it ready to take off in just seven minutes. A compressed air catapult would launch each plane into the air, and after delivering their single 850 kg torpedo or bomb load they would land on the water alongside the sub to be retrieved by a collapsible crane. In theory the sub could attack and then disappear before the enemy had a chance to strike back. The problem was that there were too few of them, and despite their size they could only hold three seaplanes each: Any damage they could have dealt would have been negligible, assuming they were able to get past any sort of alert antiaircraft defenses or fighter patrols. Towards the end of the war there was a plan to deliver a Seiran force disguised with American paint and markings to attempt a kamikaze attack on the locks of the Panama Canal, with the goal of preventing more U.S. ships from entering the Pacific; this was called off because they realized there was already too much U.S. tonnage in the Pacific for shutting down the canal at that late stage to make a difference, and that the sub carriers might yet be needed for the defense of the Home Islands. A different proposed attack that would have used a biological weapon instead was thankfully never undertaken because Japan surrendered. The I-400 class accomplished practically nothing in World War II, but significantly affected the Cold War that came next: after studying the captured subs and then scuttling them so the Soviets couldn't learn from them, the Americans developed the Greyback class missile submarine and Regulus nuclear cruise missile. The Japanese thus created the ancestor of modern nuclear ballistic missile submarines, but did so before they had a WMD payload to make it an effective strategic weapon.
  • Battleships in general, at least eventually. There's still debate over exactly when the battleship became obsolete (The rise of air power? Modern anti-ship missiles?), but it did. And when those weren't a large concern for the US Navy (e.g., off the coast of Lebanon or the first Gulf War, where the 16-inch gunnery of Iowa-class battleships proved very useful), they were still impractical for being extremely expensive to operate and manpower-intensive. However, on account of their awesomeness, all four completed Iowas are currently preserved as museum ships: Iowa at Los Angeles; New Jersey at Camden, New Jersey (right across the Delaware River from Philadelphia, where she was built); Missouri in Pearl Harbor, Hawai'i; and Wisconsin in Norfolk, Virginia.
    • Additionally, the ageing of the battleship fleet and lack of replacement meant that by the end of the 2000s, they shared literally no systems with new ships coming off the ways - steam turbines have been replaced fleetwide with diesels (most support ships), gas turbines (combat ships and some support ships) and nuclear power (aircraft carriers), the modern Tomahawk missiles are built for a different carrying system (the battleships used an armored box launcher that was phased out in the mid-90s, modern ships use a vertical launching system), their 5"/38 secondary guns used completely different shells than new destroyers' 5"/54 and 5"/62 guns; the 16" guns were completely unique. Additionally, room (and weight) would have to be found for the networking equipment required to work with other ships in the modern Navy. These old ships were struck from the Navy List in 2009, so they will likely never put to sea again.
    • The military function of battleships (killing enemy ships of all lesser capabilities without them being able to do anything about it) was taken over by the aircraft carrier pretty much as soon as it became feasible to build proper fleet carriers, presumably right at the close of WWI. It did, however, take rather a lot to convince some of the Admirals of this. A carrier can't engage a battleship under all conditions - e.g. bad weather, trapped in restricted waterways - but so long as a carrier is free to maneuver and keeping situational awareness, it can keep itself well out of range of an enemy battleship while hitting it with as many aircraft sorties as required to sink it.
    • An argument can equally be made that the battleship became obsolescent (if not necessarily useless), the moment the submarine became a viable weapons platform. The essential point remains the same - the extreme construction and operational costs of a battleship can only be justified if it is essentially invulnerable to lesser ships. The moment that a vessel or collection of vessels of significantly inferior tonnage/cost can stand a reasonable chance of crippling or destroying a battleship, then the battleship becomes too great a concentration of military resources to justify. The same can be said of aircraft carrier, too - more aircraft carriers were sunk by submarines than by any other means in WWII. Carriers, however, have become more efficient at subhunting with the development of effective hunter-killer aircraft - something battleships were and remain incapable of.
      • ANY capital ships, not just battleships, started to become obsolete as soon as the torpedo was invented. Being a powerful warhead that could damage or destroy a capital ship for a fraction of the cost made them ideal and a precursor to modern missiles and rockets. The main problem was getting a torpedo launcher within range. Battleships gained longer distance guns, recon planes, and even radar to fight long distance where torpedoes couldnt reach them. Pre-dreadnoughts began using anti-torpedo nets and many small guns to shoot any torpedo ships, while later battleships have other kinds of anti-torpedo defense but that wasn't enough. Capital ships eventually needed (and need today!) fleets to protect them from torpedoes, changing their roles to mobile artillery. When aircraft were invented that made them very effective torpedo platforms as even the longest range battleship could have attacked by torpedoes launched by squadrons of aircraft from carriers. In World War 2 most of the Italian battleships were neutralized just by a number of torpedo planes attacking in them in harbor regardless of any defenses.
      • For that matter, antiship missiles took the battleship from obsolescent to full-on obsolete. Now any ship could provide torpedo-grade antiship firepower at a range battleship guns couldn't respond to. Vessels of inferior tonnage had moved from having a reasonable chance of crippling/destroying a battleship to a near certainty, and it also provided far better means for aircraft to destroy them than torpedoes and bombs. It's not a coincidence that the last battleships began to disappear right around when viable antiship missiles began to proliferate. At the same time, antiship missiles pose a huge threat to any ship, especially aircraft carriers, which don't even have the armor plating of battleships to give them a little more survivability. It's for this reason that the Red Navy's tactics for facing US carrier battle groups to attack with a combination of submarines and a crapload of surface and air-launched missiles, while the Chinese are threatening with a long-range "carrier-killer" missile that can be fired from ships or even a mobile launcher on land.
    • One could argue with hindsight that the very concept of the battleship was inherently flawed, as it depended upon the superior range of their big guns to keep smaller ships outside of the range of their own guns and torpedoes. Unfortunately, that presumed battleships would only be employed in open water under under ideal visibility conditions, something that often didn't happen in the real world. Take for example the Battle off Samar, where poor visibility seriously hampered Japanese battleship gunnery, negating much of their range advantage, or the Naval Battle of Guadalcanal, where the battleship Hiei was smothered by a saturation bombardment from the fast-firing dual purpose guns of several US destroyers and cruisers that had managed to sneak up to point blank range in the dark in restricted waters where she couldn't maneuver. Few of the hundreds of smaller projectiles (from 8 inch down to 20mm but especially lots and lots of 5 and 6 inch) actually penetrated her armor but they did set virtually her entire superstructure on fire, rendering her all but untenable for her crew.
  • On the topic of battleships, many battleships of the Pre-Dreadnought era and the early years of the Dreadnought era had some of their guns in an off-set arrangement (for example, the en echelon arrangement used by the USS Texas and USS Maine in the 1890s, or the staggered arrangement of the HMS Neptune in the early 1900s). In theory, this allowed for maximum amount of firepower fore and aft, in addition to being able to fire the entire main battery in a broadside. In practice, the off-set guns couldn't be fired fore or aft without risking damage to the ship's structure due to the off-center force of the recoil, and if fired in broadside, the guns on the far side could damage the deck or superstructure of the ship due to the heat and force of the cannons firing. Which is exactly what happened to the USS Texas at the Battle of Santiago de Cuba.
    • Similarly, the earlier examples of superfiring main batteries (where one turret is placed to fire over the top of another turret, also seen on the HMS Neptune mentioned above) avoided the structural problems with off-set turrets, but the heat and blast (not to mention the hot gasses and such) from the upper guns firing could still damage the lower turret in some circumstances (such as the HMS Neptune's aft turrets, if the upper turret was aligned within 30 degrees of the stern of the ship.)
    • "Wing turrets" of any description proved impractical in service, as they essentially doubled the weight without doubling the firepower they provided. The extra turret was useless without separate fire control, ships almost never fired to both sides simultaneously, and being offset from the roll center along a different axis than the centerline turrets they were inherently less accurate, something easily easily demonstrated with simple geometry. Finally, their magazines were very difficult to armor and virtually impossible to provide with torpedo protection. The Captain of USS Atlanta reported that her wing turrets were not worth their weight and they were deleted from following classes. Yamato and Musashi had their secondary battery wing turrets removed early in their careers for similar reasons.
    • Perhaps the most impractical of all, though, was the superposed turret. That is, one turret with another turret mounted literally on top of it. In theory, this allowed more guns to be mounted while taking up less space. In practice, the top turret served to damage the bottom turret whenever it was fired, and to weaken the bottom turret's armor simply by existing. It also complicated the ammunition supply, as a mechanism had to be included for carrying two sizes of shells (for the main guns on bottom and secondary guns on top) through the same turret.
    • The Russian Navy attempted to avoid this problem on Gangut and Imperatritsa Mariya classes simply by setting all their main gun turrets on the centerline of the ship on deck level and rejecting superfiring turrets. This arrangement had several advantages: it reduced the stress on the ends of the ship, since the turrets were not concentrated at the end of the ship; it increased stability by leaving out elevated turrets and their barbettes; it improved the survivability of the ship because the magazines were separated from each other; and it gave the ship a lower silhouette. Disadvantages were that the magazines had to be put in the middle of all the machinery—which required steam pipes to be run through or around them—and that there was a lack of blast-free deck space. Moreover, it also meant that the arc of fire of the two middle turrets was extremely restricted, and that any secondary armament had to be installed on hull casemates below the main deck. Indeed they they were still [[Didn't Think This Through susceptible to main gun blast damage and were prone to getting hit by waves while sailing in rough weather. Combined with inverted "ram" bows, these ships were extremely wet and fared miserably in weather.
    • The Royal Navy's Nelson-class battleships, the first battleships built under the restrictions of the Washington Naval Treaty, attempted to maximize armour and firepower within the tonnage limit via an unconventional armament layout in which all three of the main gun turrets were grouped together forward of the superstructure. This resulted in a shorter ship relative to its weight and armament, and thus a smaller area that needed to be armoured. The first two turrets were superfiring, as had become universal by this point, but the third had to be placed below and behind them because making it superfiring as well would've made the ship so topheavy as to be at risk of capsizing. As a result, the third turret was of very little use due to its limited arcs of fire. It was also discovered that the third turret was placed so close to the superstructure that the blast from firing its guns would shatter the windows on the bridge. The windows were replaced with thicker tempered glass...which still shattered when the guns were fired at a high angle.
  • Battlecruisers were this when they first came out. Combining the speed of a cruiser with the firepower of a battleship, they were designed to hunt down enemy cruisers, and were effective in that role. Unfortunately, the combination of speed and firepower made it tempting to use them in place of battleships... a role which quickly exposed the light armor that enabled them to have that combination of speed and firepower. Such matchups were a case of Glass Cannon versus Lightning Bruiser. The fast battleship solved this problem, but they were spectacularly expensive, even by battleship standards.
  • The American Alaska-class "large cruisers". The idea was essentially that battlecruisers had gone wrong because they tried to match the caliber of guns battleships were carrying, which was overkill for their stated role of killing less armored ships. Thus a large cruiser fitted guns around the caliber of WWI battleships but with the catch that they could fire them more quickly due to the size reductions. The downside is these special rapid fire turrets made them cost around the same as battleships to build despite the cost savings the smaller hull allowed. Despite costing the same as a battleship, they only really had the performance capabilities of a cruiser, due to their thinner armor and lower number of AA guns. They were built specifically to hunt cruisers and kinda sucked at anything else. Only two of the ships were ever fully completed, arriving only in the last years of the war when fuel shortages severely limited the use of enemy heavy cruisers and most of them had already fallen prey to air attacks and submarines. Even if they had arrived earlier, it's speculated that their higher cost would have made the USN reluctant to use them much like battleships.
  • The Soviet Union's Kirov class cruisers. The USSR, unburdened by naval restrictions that clearly defined heavy and light cruisers, decided to build cruisers with an intermediate caliber gun 180mm, which wasn't a bad idea. Unfortunately they also did not want to spend a lot of money, and made the cruiser's as light as possible. This is idiotically accomplished by making the turrets incredibly tiny (thus meaning there didn't have to be as much ship supporting them) but this also make the Kirovs absolutely unsuitable for actual naval combat. The guns were right next to each other with no spacing at all, meaning thy would blow each other's shells off course. Nearly as bad, the tight spaces inside the turret made loading an extremely time consuming process (negating on the biggest theoretical advantages of the 180mm gun), with the Kirovs loading slower than many contemporary battleships.
  • Super Destroyer concepts generally fell into this category. Since navies began experimenting with super battleships, super cruisers, and eventually super carriers, why not make a super Destroyer too? Take in incredibly powerful compact engine, build a super stream lined hull around that, slap as many weapons as you can on the result, and finally finish it out with all the high tech bells and whistles you can fit. The resulting ship will be able to beat the crap out of any other destroyer in the world but will probably cost five to ten times as much. Unlike a super battleship however, it still only takes one well placed shell to send the whole thing to Davey Jones, much like a much cheaper destroyer. And at the end of the day your ship simply can't be five places at once.
    • To add insult to injury, the main purpose of a super destroyer is to actively hunt down and destroy enemy destroyers. However for the same cost you could build a light cruiser, (or even a heavy cruiser in extreme cases). The five normal destroyers or the cruiser are more capable for use as escorts and at the end of the day are quite capable of bagging enemy destroyers that are forced to try to engage them. And then aircraft carriers became a thing and were far better at hunting down and sinking enemy destroyer packs than destroyer hunting surface ships ever were.
    • "Super destroyers" evolved from dedicated flotilla leaders (some times just called leaders). These were either extra-light cruisers or enlarged destroyers designed to provide destroyer flotillas with both extra firepower and command facilities. However, these two roles turned out to be quite counterproductive to each other. Strapping on extra armaments meant that commanders tended to want to have leaders involved in the action, where said commanders would be at extreme risk. Navies eventually phased the concept out by adding custom but discrete command modifications to production model destroyers.
  • The People's Republic of China's Kuznetsov-class aircraft carrier Varyag, purchased from Ukraine. As one Chinese officer was quoted, "All of the great nations in the world own aircraft carriers — they are symbols of a great power." But whether China will able to operate an aircraft carrier as an effective weapon of war, as opposed to just a symbol of prestige, remains to be seen. The United States Navy has nearly a hundred years experience in carrier aviation, something that can't easily be matched overnight. China is attempting to jump straight from what amounts to a coastal-defense force (albeit a very large one, given that China has a lot of coast to defend) to super-carriers, with no prior experience in naval aviation.
    • The Liaoning (they finally settled on a name for her) is proving to be quite a drain on manpower and resources, as the Chinese had real possession of her since 2003 (when it first entered Chinese waters), yet officials continually claim that they have a "long way to go" before the carrier becomes fully seaworthy, let alone operational. And indeed, looking at up to date photos of the thing, it's highly doubtful America will be having any competition there, at least for a long while. Fortunately for China, manpower is not something they have any shortage of. Only time will tell how effective the Liaoning will prove as a blue water vessel (much more a carrier), as well as how effectively the Chinese will utilize her.
    • The Kuznetsov-class carrier in general is a fairly impractical vessel, as it was built under the Soviet doctrine of being a cruiser first and a carrier second; in fact, the line is referred to as an "aircraft carrying cruiser" in original Russian terminology. To put that in perspective, the Kuznetsov-class has more raw firepower than traditional carriers, which allows them to function as actual attack ships instead of just floating runways, but this comes at the cost of having a smaller carrying capacity than traditional carriers as well as lacking effective means of launching them (a la catapults). In turn, the aircraft carried are normally used in fleet defense rather than frontline action, which the Russians reserve for ground based aircraft. Overall, the Kuznetsov is something of a go-between for carriers and cruisers, capable of performing either type's roles but nowhere near as effectively as "real" carriers and cruisers dedicated to either role.
      • Part of the reason for this Soviet doctrine has to do with treaty limits concerning the types of ships that can cross the Bosphorus. A pure aircraft carrier cannot cross the Bosphorus under the Montreux Convention, but a cruiser that just so happens to carry aircraft can.
      • The Chinese actually realized this, and have removed the anti-ship missile tubes while completing the Liaoning, thus expanding the hangar capacity somewhat. Russia intends to do the same the next time the Kuznetsov is overhauled, whenever they get around to doing that. However, both ships are still stuck with the ski-jump for launching their aircraft, which is simpler and cheaper than a set of catapults but limits the payload of the aircraft, the type of aircraft that can be operated, and also requires them to expend more fuel in takeoff. Converting them to use catapults would be such an extensive modification that building a better carrier from scratch would be a more cost-effective choice. In the long run, the latter is exactly what China intends to do. Russia, operating with half of China's military budget and being geographically in a worse location for operating a large blue-water navy, will likely just stick with Kuznetsov for as long as she floats.
  • The Tessarakonteres is an ancient example from the Hellenistic period. The largest human-powered vessel ever built, it had 4,000 rowers... and roughly the maneuverability of the Parthenon. A 2011 study suggests that it was never meant to be used in ship-to-ship battles, but was intended as a siege platform against harbours. This fits the style of warfare of that time, which consisted of campaigns along the eastern Mediterranean coast and the Greek isles to conquer the coastal cities.
  • The submarine aircraft carrier - such an awesome idea that the Germans, British, French, Americans, Italian and Japanese all pursued the idea. Only the Japanese ever actually built one, though. The Japanese actually built 47 submarines with the capability to carry seaplanes (between one and three, depending on the model). But the aircraft carried were limited in capabilities (with potential strike damage essentially limited to propaganda value), the process of surfacing, launching, recovery and submerging took a lot of time, and the submarine itself was vulnerable to attack while doing so. They were also very large — the I-400 class boats were among the largest non-nuclear submarines ever built. It's still an awesome idea, though... and one which just might have a shot at becoming practical in the 21st century, in the form of submarine-launched UAVs.
    • France built an equally impractical submarine cruiser, the Surcouf. It weighed in at over 4000 tons, larger than destroyers of the day, and was armed with a pair of 8-inch (203mm) guns in a forward turret, and a single small seaplane for reconnaissance and spotting for main guns. Its more conventional armament was a dozen torpedo tubes. Surcouf had a rather unsuccessful career until it was sunk under controversial circumstances during World War II.
    • Britain had already done one better than the French in 1917 with the M-class Submarines. Originally designed for shore bombardment, the M-class was equipped with a 12-inch gun that allowed the submarine to attack from a range of 15,000 yards. Unfortunately, the 12-inch gun could only be reloaded when the sub was surfaced and also represented a weak point in the hull which was well illustrated by the accident that sunk the M1: A Swedish ship collided with the M1 which caused her gun to be torn off and created a gaping hole that allowed seawater to gush through. After the accident, M2 was converted into an impractical Carrier Sub and M3 was converted into a Minelayer Sub, meaning it was the only one of the three to have any useful purpose.
  • The USSR's "Alfa" class submarine. It set and to this day still holds the record for the fastest and deepest-diving non-prototype military submarine in the world,note  and knowledge of its production greatly alarmed the West, to the point that the US and Britain both designed torpedoes for the specific purpose of hunting down Alfas.note  Unfortunately the Alfa had small and powerful but very maintenance-intensive lead-bismuth-cooled nuclear reactors that couldn't normally be turned off, as doing so would let the metal solidify and essentially turn the whole thing into a solid inert lump. Entire maintenance facilities had to be constructed at Alfa homeports simply to keep the reactors hot when they weren't being used - but, in typical Soviet fashion, the facilities themselves weren't properly maintained and often didn't work. As a result Alfa reactors had to be kept running at all times, which they hadn't been designed for and which resulted in several expensive failures. While the reactors could remain active for 15 years, they also could never be refueled and were intended to be replaced at the end of their life, like a battery is; despite this, the Alfa hadn't been designed with quick reactor replacement in mind, so the process would have been expensive and slow, potentially more than refueling a traditional submarine. In addition, while the Alfa reportedly had a crush depth of over 1300 meters, deep dives did permanent damage to the submarine's onboard equipment, so that impressive diving ability was largely wasted in practice. The Alfas were also louder than other nuclear attack subs of their era, which is a problem since stealth is the main weapon of a submarine. On the other hand, all this loudness was mainly during the top speed runs; at cruising speeds, Alfas weren't any louder than other Soviet subs of that generation.
    • It should be noted that the Alfa was designed and operated as a "defensive" submarine; rather than deploying in combat patrols or collecting intelligence (the Soviets had other submarine classes for this, rather than relying on the one-size-fits-all "fleet boat" approach the Americans and British used), their mission was solely to intercept and destroy enemy submarines. A higher top speed and better deep-diving capability than the submarines (and their torpedoes) it would hunt were crucial; noise and maintenance concerns were secondary, until near the end of the Alfa's life when they affected availability.
  • The Triton one-off radar picket submarine. Intended to extend the radar range of sea-based air wings; it was the largest submarine produced at the time, with two nuclear reactors and a traditional "knife" submarine hull made it stable on the surface but severely impeded speed underwater. The radar picket role would become obsolete with the rise of carrier-based AWACS aircraft (the first, the E-1 Tracer, was already flying when the Triton launched), and the Triton ended its career as a conventional attack submarine.
  • The Seawolf-class submarine, which was the last Attack Submarine of the Cold War era, was designed to combat the advanced Akula-class and Typhoon-class submarines of the Soviet Navy. Cue the fall of the Soviet Union which led to the Seawolf becoming so unnecessary (and more importantly, expensive; in today's dollars they'd cost over $3 billion apiece, comparable to the cost of a new supercarrier) that only 3 out of an intended 29 of them were built. The class was an example of a costly political boondoggle, as Bill Clinton's promise to keep the program afloat in 1992 enabled him to carry the state of Connecticut (Electric Boat, the USA's submarine contractor, is a huge employer in the state) over New Englander Paul Tsongas in the Democratic primaries and ultimately become President. The Seawolf was succeeded by the Virginia-class attack submarine, which was a less capable blue-water sub, but less costly to build due to using commercial-off-the-shelf electronics and lower-grade material.
  • The German electronic industry of the 1930s was a pioneer of the radar and Kriegsmarine battleships had very advanced radar systems, more accurate than ever battleship guns when ranging a ship-sized target, yet none of them had a plotting grid or means to broadcast the radar data to the fire control directors, so each radar range had to be corrected by optics to get a firing solution. It had over 40,000 kilometres of electric wire and was very prone to shatter and vibration damage. Moreover its Unusual User Interface - the fire control officer fired the guns by blowing into a mouthpiece fitted with a pressure switch which closed the firing circuit instead of an ordinary pistol firing key - meant it was an embodiment of this trope. Pneumatics fare badly at sea, and the British estimated the German gunnery was efficient only for the first ten minutes, after which it deteriorated sharply.
    • As this article demonstrates, this was something of a persistent problem for the Kriegsmarine. The company that built the AA fire control system, for instance, bragged that only twelve employees (out of 20,000!) could assemble the damn thing.
  • The Italian Littorio-class battleships of World War II had greater firepower of anything that wasn't American or the Yamato (yes, even the famous Bismarck was badly outgunned by the Italian ships) with the longest-ranged guns of any battleship ever (and a piercing capability comparable to the much bigger 406mm-caliber guns of the American battleships and the 460mm guns of the Yamato), had an awesome point defense, were 30 knots fast (enough to qualify as fast battleships, and faster than most), and were awesomely armored. Also, the guns were tremendously inaccurate at the long range they were used at (not just due a lack of radar: they remained inaccurate even after the Italians managed to develop and install it, because one of the biggest issue lies with their ammunition: the quality is extremely uneven) and had short barrel life (due to the excessive velocity) and low rate of fire, the torpedo defense used an ineffective design more expensive than the conventional (it would have been superior to normal, had the right construction techniques been available and not been compromised by speed-optimized hullforms), and the combination of high speed and thick armor made them fuel hogs, with the fuel shortage suffered by Italy during the war forcing them to stay in harbor for most of the war. Note that this is the less impractical version: the ships had been originally built with bulbous bows for higher speeds but had been modified due to excessive vibrations, and the original design was supposed to use 406mm-caliber guns, but opted for smaller 381mm guns because they would have to be designed from the ground up while 381 designs to improve were already available.
    • Italian ships from the war in general: as Italian doctrine of the time was geared to fight the French Navy, ships other than battleships were built with high reliability, ludicrous speed and thin armour in mind, so that their light cruisers would chase down and sink enemy destroyers and lure enemy light cruisers towards where heavier firepower was available, their heavy cruisers would chase down enemy light cruisers and lure enemy heavy cruisers into the guns of the battleships (that would have been able to sink enemy battleships from range and avoid counterfire at smaller ranges thanks to superior speed), and their destroyers would simply avoid enemy battleship fire and torpedo them with impunity. While arguably effective against the intended opponent, the Italians never fought the French Navy - they fought the Royal Navy, whose more aggressive combat doctrine, combined with higher initiative allowed to British commanders, the presence of carriers, the British ability to consistently break Italian and German codes, and the usage of superior radars (which Italy lacked, having incorrectly figured radar was a passing fad) ended up causing Italian ships to fight with similar-sized opponents again and again, where speed was less a factor than thick armour.
  • Similar to the above, the Italian Zara-class cruisers were one of the finest cruiser designs of the second World War: A unique armor layout made them the best protected cruisers until the introduction of the Des Moines-class by the USN after the war, an innovative scheme of secondary weapon placement that made their anti-aircraft defenses extremely formidable, and saved weight meant they were only 2kts slower than the preceding Trento-class, whose Glass Cannon tendencies they were designed to address. Indeed, there were no better ships for their intended mission - zooming up and down the Italian coast defending it from French attack. In the Battles of Calabria and Cape Spartivento, they gave the British serious difficulty. However, all that weight reduction meant cutting down the superstructure, meaning it was very difficult to mount radar, which in turn meant the Regia Marina didn't bother (which did not even matter because, as mentioned above, Italy didn't even have access to radar technology when the ships were being designed). The folly of this decision was demonstrated at the midnight Battle of Cape Matapan: three (radar-equipped) British battleships, the Warspite, the Valiant, and the Queen Elizabeth, were able to close to within 3 kilometres of a flotilla of three Zaras - point-blank range in naval terms - and opened fire, illuminating the Italian ships with their searchlights (the Valiant's searchlights were commanded by Prince Phillip). Within minutes the Zaras were out of action. They had not even managed to fire a single shot in reply.
  • Meanwhile, the Imperial Japanese Navy's post-Washington Treaty light cruisers showed that they were all about this trope. While they pioneered the idea of circumventing the treaty by abusing its loophole of defining light cruisers only by gun caliber and building what were effectively heavy cruisers with light cruiser guns in huge numbers (the US Navy and Royal Navy promptly copied this idea, in the form of the respective Brooklyn- and Town-class cruisers, which were far more balanced) in the form of the Mogami class, they also insisted on using 6.1-inch (155mm) guns even though the IJN already had ships in service with 6-inch (152mm) guns of nearly identical capability to the new slightly larger guns. Why? Because they were so offended by their government agreeing to the treaty that they required that every treaty-compliant ship have the absolute maximum allowable capabilities - even when it resulted in complicating the fleet's logistics for no discernible gain.
    • The resulting Mogami class was supposed to come in under the treaty limit at 9,000 tons (treaty allowed for 10,000), but the resulting ship turned out to be badly flawed structurally (the hull buckled during the gunnery testing). The resulting fixes not only cost heaps of money, but wound up adding 4,000 extra tons to their displacements.
  • There are modern schools of thought that suggest the modern concept of the supercarrier (massive floating airfields with dozens or over a hundred aircraft and thousands of sailors and airmen) is, itself, awesome but impractical for the purposes of naval engagement. While they are powerful political tools and amazing resources for fighting asymmetrical wars (being essentially unreachable by "boots on the ground"), antiship missile technology has matured to the point where even relatively lower-tech countries can afford to just spam effective anti-ship missiles in such numbers that getting through to such a massive target is virtually certain. Additionally, supercarriers and their escort fleets can be easily spotted even from space by their massive wakes and by surface radar.
    • Basically, the theory goes that they're already outdated, and there just hasn't been a symmetrical naval war large enough to make this fact apparent. Not to mention the extreme expense that goes into building and operating what is effectively an entire floating city compared to more Boring, but Practical measures like simply basing aircraft out of ground-based airfields in friendly territory.
    • Much of this has always been true (and has been argued since before WWII), but the problem has been magnified by procurement decisions of the United States Navy over the last 50 years. Most specialized strike aircraft, anti-radar aircraft, anti-submarine aircraft, and everything else that isn't a COD or a helicopter have been folded into the Hornet and Super Hornet programs, sacrificing operating range in order to maintain the two aircraft as supersonic-capable air superiority fighters. The lack of long-range interdiction capability requires carriers to operate closer to land, and within anti-ship missile range. The problem will be magnified in the future, as fifth-generation stealth aircraft are expected to complete the vast majority of their missions on internal fuel, as to not compromise their stealthiness.
      • However, one potential solution is the use of drones, which have over double the effective range of manned aircraft. This is why the Navy is now investing heavily in Northrop Grumman's X-47B, which has been able to autonomously land and take off from carriers.
    • Conversely, proponents of the aircraft carrier argue that a sea denial network capable of doing all of the above qualifies for this trope as well. The arguments hinge around carriers being actually very hard to find when they don't want to be; satellites have known tracks, surface radar still needs to cover enormous swathes of oceannote , and without the carrier and its escorts blaring out radio emissions there's no easy way to home in. The sheer array of assets the Soviets dedicated to the problem backs this up: hundreds of Backfire bombers, dozens of nuclear-powered guided missile submarines, surface ships, and reconnaissance aircraft, and a lot of big, sophisticated, and thus rather expensive missiles.
    • Also, conversely, using a system of many smaller aircraft carriers rather than fewer super carriers, though a bright spark always seems to suggest it every few years. In theory, it's less expensive and you have a lot more ships that can be in different places at once. In practice, it's actually significantly more expensive, especially over time. See, building more ships with the same capability as fewer good ones is actually more expensive thanks to the Square-Cube Law making larger ships (to a point) just more efficient in everything from combat capability to operating costs. And in a quantity over quality model, build quality is always going to be sacrificed at some point to try to compensate the previous law. This in turn causes the ships to wear out and or become obsolete faster, and thus need replacement more often. And as for the whole "put your eggs in more baskets" argument, most modern navies haven't fought another navy since the second World War and if two that could realistically sink aircraft carriers went to war, how a conventional naval war would actually turn out would be the least of everyone’s concerns.
  • The submarine itself was like this for many years. It was slow and often more dangerous to its operator than to an enemy ship - the first successful sinking of a surface warship (the USS Housatonic) by a submarine (the H. L. Hunley, armed with a spar torpedo), during The American Civil War, was followed soon after by the third sinking of that same submarine in only half a year since its completion. Germany - ironically the last Great Power to build a submarine - was able to demonstrate its capabilities once and for all when, in the opening weeks of World War I, a single U-boat sank three British cruisers in under an hour. Having a submarine with 24 men take down three cruisers and 1500 enemy sailors proved hard to resist, and the Germans quickly capitalized on their success... only to ultimately use that weapon in such a way that it neither weakened Britain in any significant extent (which, given that Britain is both an island nation and a net importer of food could have been devastating if enough transports had been disrupted) nor did them much good in the diplomatic arena, and ultimately brought the US into the war.
  • Lattice, or cage masts, as used on many American WWI-era battleships. They were lighter than the British-preferred tripod masts, which was thought to make them more survivable, since shells striking light wire were less likely to detonate, and would only take out a few wires at a time, allowing the structure to remain standing. In practice, however, their light weight and flexibility made them vulnerable to bending and buckling, as seen when USS Michigan's mast collapsed in a storm, and the thin wire was more vulnerable to corrosion. Most battleships with cage masts were either scrapped or refitted with tripod masts after the war.

    Land Vehicles 
  • Multi-turreted tanks.
    • A class of large, multi-turreted tank called the "land battleship" was investigated by various countries during the vacuum between the two world wars, when there was a train of military thought that believed battles between tanks would be like battles on the seas. Hence "cruiser tanks", "battleship tanks" etc. Examples built included the German Grosstraktor and Neubaufahrzeug, and the British A1E1 Independent, and there were also numerous development projects by various nations that never left the drawing board. Needless to say, in reality the battles were nothing like that, and all these designs quickly fell out of favour and were replaced by more practical ones. The idea of sticking guns poking out everywhere on a tank may have seemed like a neat and effective idea, but the difficulty a commander faced in coordinating all the guns, the increased crew requirement to man each gun, problems in ammunition management and supply for varying calibres of weapons, and the complexity and cost that multiple turrets and sponsons added to production were ultimately the undoing of the Multi-turret concept. By the latter half of the 1930s, it occured to everyone that maybe the French had already gotten it right back in 1917 when they just stuck all the guns onto a single rotating turret for the granddaddy of modern tanks, the Renault FT.
    • The Soviet T-28 tank, with Finnish nickname Postivaunu (Stagecoach). Three turrets, one cannon, and up to five machine guns, but horribly unmaneuverable, poorly-armoured, and a huge target. Finnish troops captured seven of these monsters during the war. In the vehicle's defense, it had first been deployed in 1931, at which time it totally out-classed any other extant design. It was simply kept in service well-beyond its effective life.
    • The American M2A2 light tank accepted in 1935 had twin turrets, one with a .50 cal machine gun and one with a .30 cal. The two side-by-side turrets limited each other's field of fire, and like most countries the U.S. concluded from the Spanish Civil War that a tank armed only with machine guns was useless against other tanks. The M2A2 and its slightly upgraded A3 version were superseded by the stopgap M2A4 in 1940, with improvements including more armor and one turret mounting a 37 mm main gun.
    • The Soviet T-35 heavy tank deserves special mention here; it looked impossibly cool, had 5 turrets and 6 machine guns, weighed 45 tonnes and took 11 crew members to operate. It was also slow, incredibly expensive, and far too mechanically complex for the rigors of war. The excessive length made it difficult to turn, and it was top-heavy enough to tip over. Only 61 were built, and most of them were lost due to mechanical failure rather then German Panzers. By comparison, the much more successful T-34 was half as big as the T-35, and only had one turret. Worst of all, the T-35's turrets, when aligned a certain way, actually blocked the escape hatches. So, if the tank was hit, the poor bugger crewing it had to hand-crank his turret out the way before he could bail out - or, if the turret was damaged and unturnable, presumably use his sidearm to shoot himself rather than burn to death.
    • The British A15 Crusader had a front-mounted machine gun turret which, despite having a wider field of fire than a hull-mounted machine gun, was both an uncomfortable position to man and an easy weak point for an enemy soldier with an Anti-Tank rifle. It was left empty and eventually deleted in the Mark 3 variant. The Cruiser, Mark I (A9) had two machine gun turrets on the front, which were similarly unpopular as the men inside them would cook in the heat of the North African desert.
    • The M3 Lee Medium Tank was developed as a stopgap so the U.S. would have a medium tank with a 75 mm gun while they waited for the M4 Sherman to arrive; this meant putting the 75 in a limited traverse sponson in the hull. Major General Gladeon Barnes of Ordinance Department was okay with the idea of a turretless tank, but the Infantry arm which still held sway demanded that the 37 mm also be retained, apparently because of its ability to fire canister shot. So in addition to the hull 75 there was also a turret with the 37... and on top of the turret was a rotating commander's cuppola with a .30 cal machine gun that he could fire. Basically, a mini superimposed turret. The machine gun cuppola was replaced with a simple hatch in the M3 Grant variant made for the British because they thought it was silly.
    • While not a turret as such, the hull-mounted auxiliary machinegun managed to linger on through World War II because of the belief that it was more stable and accurate than the turret-mounted coaxial, but eventually by the end of the Korean War it was realized that stabilized turret armament had fixed this perceived issue, and it was better to not have to cut a hole into the hull's front armor to stick a machine gun through.
  • Overlapping somewhat with the multi-turret dead end was the idea of tanks with loads of machine guns. Since tanks were mostly controlled by the infantry arm in most countries during the interwar period, they wanted tanks that could kill a lot of enemy infantry. The United States in particular had what Harry Yeide has called the "cult of the machine gun". The M2 Medium tank had a turret with a 37 mm gun in case it had to fight an enemy tank, but primarily it was designed to be a mobile machine gun nest. It had nine .30 cal machine guns: one coaxial, two fixed-traverse machine guns in the glacis to be fired electronically by the driver, one sponson mounted MG on each corner of the hull, and two more stuck on the outside of the turret as spares. As the tank drove over an enemy trench, the rear sponson machine guns could aim at bullet deflectors on the rear fenders to ricochet the rounds down into the trench. The tank started production in 1939, just in time for World War 2 to begin in Europe and show that it was already obsolete. Trench warfare gave way to war of movement, it was really inefficient to have four out of six crew members just be machine gunners, and the inability of the Germans' 37 mm guns to reliably defeat French and British armor proved that a bigger gun was required moving forward. The U.S. Army also determined from tests that a 75 mm high explosive shell was actually more effective against infantry than machine guns, so they experimented with putting a 75 in the hull of the M2 as a prelude to producing the M3 Lee. Equipping the 75 was a step in the right direction, but the M3 Lee and some very early M4 Shermans retained the glacis-mounted driver's machine guns as a last gasp of machine gun fever.
  • Heavily sloped side hull armor.
    • The benefits of sloped armor in general are well-established. A plate that is sloped instead of vertical presents a greater effective thickness of metal towards a round that's coming in horizontally. Furthermore, World War II era armor-piercing shells were relatively short and thick compared to the long rod penetrators of today, so they were more easily made to ricochet off of a sufficiently thick and sloped plate without penetrating. Making the front of the hull a sloped glacis was a pretty straightforward improvement.
    • Now, often the main benefit of sloped sides was actually to give the upper hull a smaller profile and make the front a smaller target. Since side armor is normally thinner, and it can't be as dramatically sloped without reducing crew space, the protective benefit is not as great. However, depending on the weapon and the position of the hull, it might give you a lucky bounce. The T-34 was a notable exception, since like the KV it had the same or almost the same plate thickness on the hull sides and rear as on the front.
    • Unfortunately, as already implied, sloped sides are way more inconvenient from an internal space perspective than a sloped front or even rear. To begin with, it makes sense for a variety of reasons for tanks to be longer than they are wide, thus giving more room to work with on the front or rear slope. With the front slope you can put the driver(s) in reclining seats so that they fill up the space nicely, and if it's a front sprocket drive vehicle that awkward space at the bottom of the glacis is the ideal place to put the transmission. Depending on the shape of the engine and whether or not there's a turret, sloping the engine deck or the rear plate is similarly feasible. In comparison, inward sloped sides reduce headroom along the whole length of the hull and crowd in the crew. There's less space for roof hatches, making escape more difficult, and the size of the turret ring is constrained. The French FCM-36 had the problem of the driver getting a glacis hatch instead of a roof hatch, but it was a two-man tank with a one-man turret, so not much worse than it would have been anyway. The Soviet T-34, with sides sloped at 40 degrees from the vertical, had the additional problem of the springs for the Christie suspension taking up space in the hull, making it doubly cramped. Perhaps the most wretched of all was the Jagdpanzer 38(t), an ambush-focused German casemate tank destroyer designed to be easily concealed and hard to kill from the front. In order to fit both the main gun and crew members into a tight casemate whose sides sloped inward 40 degrees, the gun needed to be shoved all the way to the right. The commander sat on the right, behind the gun; the driver, gunner, and loader sat all in a row to the left of the gun, which sucked for the loader because the 7.5 cm Pak 39 had the breech controls on the right. The gun had about 11 degrees of traverse to the right and just 5 degrees to the left because the breech would run into the right wall of the hull. Vision from inside the vehicle was atrocious, and in case of fire there were just two roof hatches and one tiny floor hatch for four crew members to escape through.
  • The Soviet KV-1 heavy tank and KV-2 heavy artillery tanks, named after the Soviet defense commissar and politician Kliment Voroshilov. They were first used against the Finns in the Winter War, and then against the Germans in the face of Operation Barbarossa.
    • They were so heavily armored, with 75 mm of steel on all sides, that they were almost completely immune to Finnish and German antitank fire. The KV-1's L-11 could punch through the thin armour of early German tanks from a thousand meters away, while the 152 mm howitzer of the KV-2 could blast apart concrete pillboxes. There were some cases in Barbarossa where KV tanks managed to face off against foes several times their number: a single KV—accounts differ on whether it was a KV-1 or KV-2—held off the whole 6th Panzer Division for 48 hours during the Battle of Raseiniai. The problem is that they also happened to be too heavy for most bridges to support, and lacked the snorkeling equipment necessary to ford rivers. It also made them very slow and resulted in far more breakdowns than the famous (and far more effective) T-34 tank. And of course, being immune to German antitank guns is one thing. Being immune to German aerial bombardment is something else. The large, slow KV-1 and KV-2 were easy targets for Stukas.
    • The KV's reliability problems were legendary. They were flawed from the drawing board, as the Soviets attempted to build a heavy tank the size of a Panther... with the same technical components used for pre-WWII medium tanks. The engine, which gave superb performance in lighter T-34s, struggled to move a mass nearly twice as great as a T-34 Model 1940. Through a transmission which had been poorly built even for the light tracked vehicles of the 1930s and shredded itself to pieces under the weight. While steering by clutch-and-brake, a steering method which was harsh even on a tank the size of a Pz IV, let alone the KV which was twice as heavy. The joke was that KV drivers had to change gears with a sledgehammer, which was not far from the truth. Out of 600 KVs the Soviets had at the beginning of the war, 200 broke down without enemy contact at all, and another 200 were incapacitated by non-perforating hits. Other nations, when facing a similar weight problem, developed things like the complex semi-automatic transmission-steering of the Tiger I, or limited the tank to roughly M4 Sherman size. Later in WWII the IS-2 tank came with a planetary steering-transmission unit.
    • The vast turret of the KV-2 deserves its own mention. In order to equip the huge bunker-busting 152 mm howitzer, the Soviets built a very tall turret for it. Unfortunately, that made it a giant, impossible-to-conceal target. So, to protect the poor bastards who had to lay, load, and fire the massive gun, the Soviets made the turret armor a whopping 110 mm thick on the front and 75 mm on the sides, hoping to compensate for its huge profile and lack of sloping. With all this stuff the turret weighed 12.9 tonnes, so the traverse motors couldn't turn it against gravity. The tank couldn't operate at even a slight angle, or the turret would seize, and on a more pronounced lateral slope the topheavy turret put the whole tank in danger of toppling over. Production was discontinued after only 203 were built. With hindsight we can say they should have never bothered with the turret at all, and instead made it an unturreted casemate SPG like the later SU-152 would be.
  • Even the famous Soviet T-34 medium tank was a bit of a fixer-upper when it first saw combat. It began in 1937 when the automotive and antitank directorate, recognizing the inadequacy of the T-26 infantry tanks and the BT series cruiser tanks, put out specifications for a universal tank that would combine their roles and feature improved armor and firepower. Engineer Mikhail Koshkin responded by submitting a design that was developed into the T-34 1940: It had a powerful engine, wide tracks and Christie suspension for cross-country mobility, 40-45 mm of sloped armor on all sides of the hull, and an impressive 76.2 mm gun. German intelligence failed to discover this new model during the planning of Operation Barbarossa, and it was a nasty shock to German vanguard forces in the summer of 1941 when they started running into a surprise Soviet supertank. However the initial version had a very narrow and cramped two-man turret (the idea was to make the turret as small a frontal target as possible) where the commander also had to serve as the gunner. He had very bad vision and situational awareness because he had no cupola, and the enormous front-hinged hatch was no good for commanding unbuttoned because it would totally block his view when open; all he could see out of was a single traversible periscope. He was distracted from gunning by the need to command the tank (and vice versa), and if he was also a platoon commander he had yet another thing to worry about. The Germans estimated that one of their tanks could get off about three accurate shots for every one that a T-34 could, and the Soviets started with such low stores of 76.2 mm shells that T-34s would run out of ammo and resort to ramming the enemy! Only the platoon commanders' tanks had radios, leaving signal flags as the only way to attempt communication, so they tended to clump together "like a hen with its chicks" when they attempted any coordination at all. Primitive metallurgy was evident in defective armor, and badly manufactured parts such as clutches and transmissions caused frequent mechanical breakdowns. The Christie suspension, despite enabling high speed and obstacle crossing, had huge springs contained inside the hull which reduced crew space and were a pain to access for repairs. What's more, because it was a new model there were only 967 of them at the start of hostilities. At this early stage most of the tanks standing in the way of the Germans were old models like the T-26, BT series, and T-28. The T-34's reputation with the Germans for being unkillable partly came about because they would mistake KVs for T-34s, and although T-34s could reliably bounce the 3.7 cm round fired by the Pak 36 antitank gun they were still vulnerable to 8.8 cm Flak guns or to the Pak 38 firing 5 cm armor-piercing at close range. The bad state of Soviet logistics and leadership led to many unsupported tank attacks that got chewed up by the Germans. It took a lot of hard lessons in tactics as well as heroic efforts of manufacturing and logistics to remake the T-34 into the war-winning tank we all know and respect; radios were installed as they became available, and later models came with a less cramped hexagonal turret, proper turret roof hatches, a commander's cupola, and eventually a cast three-man turret with the more powerful 85 mm gun. Over the course of the war the armor and firepower doubled while the cost was cut in half. The latter was done through vast economies of scale, removing all non-essential features, accepting crude workmanship wherever it wouldn't unacceptably hurt performance, and intentionally not building any part to last much longer than the life expectancy of the entire tank before it would be destroyed in action, which during heavy combat operations could be less than two weeks. We Have Reserves was key to its success: it was the most produced tank family of the war and the second most of all time—80,000 including all variants and postwar production—while also being the most destroyed tank of all time at 44,900 losses throughout the 20th century.
  • The A7V was the first and only German-made tank to see combat during World War I. The German military had ignored earlier proposals to build armored breakthrough vehicles, but then the British used tanks against them in September of 1916, causing them to change their tune. Joseph Vollmer, famous automobile pioneer and chief designer of the War Department's motor vehicles section, got the job of designing one and thought he could make a machine both more fearsome and mechanically sophisticated than the British ones. In a couple of ways, he succeeded. It was shaped like a huge metal box—7.34 meters (24.1 ft) long, 3 meters (9.8 ft) wide, and 3.3 meters (11 ft) tall—and weighed 33t. It could reach higher speeds than the British Mark IV—15kph/9.3mph on road or 6.4kph/4mph cross-country—thanks to a powertrain that was fancy for its time: Unlike the British tanks, which had no suspension at all, the A7V's suspension was based on the American Holt Tractor, with 24 wheels that were individually sprung to dampen the bumps. There were two Daimler 4-cylinder engines producing 101 hp each mounted in the center, and it had a remarkable three-speed gearbox that could switch to move the tank equally fast in forward or reverse; the driver sitting in the top center could just swivel his seat around to face the way he intended to move the tank, and the only real distinction between "front" or "back" was that the front had a 57mm cannon, and the rear had two of the six machine guns. The armor was 30mm in front, 20 mm on the sides, and 10 mm on top, which was thicker than on British tanks. It must have seemed to them like they'd just created an unstoppable death machine bristling with weapons, but in practice it was an overengineered flop during its brief use from March to October of 1918. Firstly they only ever managed to make 20 out of a proposed 100 chassis, a pathetic number compared to the 3,600 FT tanks made by France and the 2,500 Mark I through V tanks made by Britain during the war. Secondly, the armor wasn't hardened, reducing its effectiveness so that despite its thickness it was still little more than machinegun proof. Thirdly, the minimum crew of 18 required both to make it run and to man all the weapons was excessive compared to the minimum of 8 in a British heavy tank. But worst of all, it just wasn't a good vehicle. The driver's vision was partially obscured by the hull, its low ground clearance and overhangs in both front and back caused it to get stuck on rough terrain, and its topheavy design made it prone to toppling over on its side. In the end, it was too little, too late. It says a lot about its impracticality that Germany's small WWI tank force used up to twice as many captured British tanks as it did A7Vs.
  • The German army fielded some of the most dangerous and terrifying tanks during WWII. However due to a mix of poor maintenance, needless complicated design, and high production costs, these tanks were considered to be failures. To wit:
    • In general the Germans over-engineered their designs, which meant that they were generally built far more complicated than they needed to be. They spent far too much time and resources trying to make their machines meet 100% of all design specifications, when simply meeting only most of them would have meant that they could come up with a finished product in half the time. The German style was to make a large number of successive iterations of the same vehicle with short production runs, updating the design every time any kind of little improvement became available: for example, the Panzer Mk. III started in 1937 with Ausf. A and ultimately got to the letter N in 1943 (the letter I was skipped). This increased costs and slowed production down for the sake of tweaks which, individually, didn't make much of a difference. The Americans in contrast produced vehicles in long runs and wouldn't stop producing an older subtype until enough important upgrades had accumulated to justify a new one.
    • German tanks were also harder to repair. In the U.S., parts were required to fit from the factory and be 100% interchangeable. G. McCloud Ross from the British tank mission to the U.S. noted that he never saw a vise on an engineer's workbench in American tank factories, because the only thing you'd need one of those for is to hold a part that you're modifying to fit. German tanks, however, were full of individual quirks and replacement parts needed to have bits shaved off or welded onto them to fit a particular tank. It didn't help that there were so many different models out at the same time, for which various parts were made differently. Lastly, these tanks were not designed for easy removal of individual parts: whereas the American M4 had the transmission and final drives contained in a bolted-on front section so you could simply take off the old module and stick on a new one, replacing the transmission on the Panzer III required removing the turret and everything behind the transmission—including the positions of the driver and radio operator/machine gunner—so you could lift it out through the turret ring with a crane.
    • Before going into the rest, it's worth pointing out that the broad shift of the Germans towards heavy armor and armament at the expense of mobility and numbers made sense in their situation. They could not realistically have beaten the Soviets and Americans at their own numbers game, and in any case producing more vehicles would have only exacerbated their increasing shortages of manpower and fuel. Unlike the Americans they did not have to worry about making their tanks too heavy to ship overseas, and if they really had to they could put a tank on a train back to the factory for a complete overhaul. And finally they were fighting a defensive war from 1943, in which quality was perhaps more useful than quantity. HOWEVER, their manufacturing process was still wasteful and inefficient even at producing fewer vehicles, and the lack of mechanical reliability and repair capacity rather defeated the idea of going for quality over quantity.
    • The Panzerkampfwagen VI heavy tank, aka the Tiger I:
      • This tank was infamous for its combination of firepower and protection. The Tiger could kill a T-34/76 from 1500 meters away using its great big 88 mm KwK 36 L/56 gun. With armor 100mm thick on the front and 80 mm on the sides and rear, it was practically immune to the weaker enemy guns of the time as long as it maintained a standoff distance of 1000 meters. It also drove pretty well for such a heavy tank: it was by no means slow, the wide tracks provided flotation on soft ground, and the Schachtellaufwerk suspension with interleaved and overlapping road wheels made the ride nice and smooth. Beyond the stats the Tiger's reputation took on a life of its own, such that merest mention of a Tiger would be enough to send Allied tank crews into a panic, and in their paranoia they would often misidentify the similar-looking-at-a-distance and much more common Panzer IV as The Dreaded Tiger. However, the Tiger was actually something of a white elephant: it was difficult to manufacture, difficult to transport, and very difficult to maintain. Despite its vaunted reputation, the Tiger was actually something of a rush job pushed out in response to experience with heavier French, British, and eventually Soviet tank designs. It broke down a lot because of the wear and tear that its weight placed on the components and required a full maintenance overhaul every few hundred miles, something which often meant sending the tank back to the factory that made it. At 57 tonnes combat loaded, this big boy was too heavy to cross most bridges, and was difficult to recover if knocked out. The intricate suspension created its own problems, as detailed in a bullet entry further below. Furthermore, Germany's deteriorating military situation later on meant that crucial supplies of nickel, molybdenum, tungsten, and manganese for armor plate were cut off; so the previously excellent German alloy steel was replaced with weakened variants to save on vital materials. This in turn meant that the Tiger's thick armour had an embarrassing habit of shattering on impact. The German tendency to overstuff their guns with propellant, thereby increasing muzzle velocity for better long-range accuracy and penetration, meant that the tank's mighty 88mm gun wore out barrels quickly and had a muzzle-flare that could be seen from miles away. It was also very expensive to manufacture because of its weight, complexity, and the small scale of production: a Tiger cost around twice as much as a Panzer Mark IV and over four times as much as a StuG IV assault gun.
      • Now, there's no question that there were some faults with the design itself, but Nicholas Moran notes that on the whole it was actually a pretty excellent tank; the problem is that it was designed to perform a specific role, and then it was yanked out of that role by circumstance. The Tiger was an elite heavy breakthrough tank meant to punch a hole in the enemy's line, which exploitation forces with cheaper tanks would then flood into. At that point the Tiger's job would already be done, and it could be withdrawn for maintenance and repairs to await its next mission. It wouldn't have been such a problem that it took more logistics and planning to transport, or that it took more man-hours to maintain, because that kind of breakthrough task wouldn't be demanded very often and there should have been plenty of time between missions to take care of those matters. The Tiger's high cost and low numbers were also acceptable to the Wermacht because it was never intended to replace standard medium tanks, but rather to support the military's panzer forces in an important specialized role. Unfortunately, when the invasion of Russia turned into a fiasco, desperate German commanders who were often ignorant of the Tiger's limitations turned it into what Moran calls "The Fireman of the Eastern Front": wherever the Soviets attacked the Tiger would be rushed over there to put out the fire, and no sooner had it done that then it would immediately be needed to fight somewhere else. This meant they couldn't take the the proper time for repairs or maintenance, and with more breakdowns the operational readiness rate of Tigers went way down. Despite its strengths the Tiger was impractical in the reactive role it got forced into.
    • The Panzerkampfwagen V Panther tank was the Germans' next generation successor to the Mark III and IV models, having been redesigned after Operation Barbarossa to serve as Germany's answer to the Soviet T-34. On paper it looks like the best fighting tank in the war: it was better than the Tiger I in its nimbleness, front armor effectiveness, and antitank firepower, yet it was far cheaper and produced in quantity second only to that of the Panzer IV. On the other hand, the Panther suffered from a very short development period, came out with severe mechanical reliability issues, and was still quite complicated and time-consuming to manufacture compared to the M4 or T-34. Despite being lighter than the Tiger and classified as a medium tank by the Germans, it still weighed 45 tonnes and had to beware of crossing bridges or breaking the final drive by performing high-torque maneuvers such as pivot turning. There were also weaknesses in protection: the constraint of weight required thin side armor which could be perforated easily, and the ammo racks were in the hull sponsons where they could get hit and catch fire. The original gun mantlet was a shot trap, since the curved underside would deflect an incoming shell downwards into the thinly-armored front hull roof. The suspension, like the Tiger's, was a pain in the butt to repair. There were also serious engine problems early on. And then we get to the most infamous issue of the Panther, one which came from the opposite of the German tendency to overengineer and overinvest: In order to mass produce the Panther despite a shortage of crucial gear-cutting machinery, they cancelled their plan to use a planetary system for the final drive and instead changed it to a double spur system. Spur gears were much simpler to produce than helical or herringbone gears but more prone to failure due to the greater stress it places on one tooth at a time. The final drive system was notoriously weak and broke after 150 km on average. Most of the technical issues were more or less fixed eventually, but by then it was too late: fuel shortages, lack of alloys for good armor, lack of spare parts, and insufficiently trained crews reduced their combat effectiveness so much it hardly mattered how good the design was. The French army used Panthers after the war and managed to operate them more effectively.
    • Meanwhile, the Tiger II was a Tiger I doping on bull shark testosterone. It was a bigger, badder version of the already big and bad Tiger I, with improvements including thicker, sloped armor and the long-barreled 8.8 cm Kw K 43 L/71 cannon, the most powerful ever mounted by a World War II tank turret. It could perforate Allied tanks from up to 3km away, and there is no record of a Tiger II ever having been perforated through the front during the war. However, much like anyone else doping on bull shark testosterone, the Tiger II had some serious performance issues. Because of production limitations due to the Allied bombing campaign targeting German industrial production, the Tiger II's initial drivetrain was from a tank twenty tons lighter, resulting in broken transmissions and destroyed engines. It required 300,000 man-hours to build, cost as much as two Tiger I tanks or nine M4 Shermans, and guzzled large amounts of fuel which the Third Reich was dangerously short on. The biggest liability however was the Tiger II's sheer size. Try to imagine just how much of a panic attack a logistics officer had when trying to figure out how to pull a 70-tonne tank out of a crater in a bog in the middle of a battle, or out of a stream after the bridge beneath it collapsed. More Tiger II's were rendered unrecoverable due to mechanical failure and getting stuck in terrain than those that were destroyed. When they were destroyed, it was usually due to being in terrain "lesser tanks" had an easier time negotiating and liberal use of the air superiority that the Allies so enjoyed at that point of the war.
    • Nicholas "The Chieftain" Moran has described the complex Schachtellaufwerk suspension used on the Tiger I and Panther as both an engineer's dream and an end user's nightmare. The Tiger had sixteen torsion bars in the hull, with eight suspension arms on each side and three road wheels on each arm. Normally you can either have big wheels for an easier time rolling over obstacles, or a lot of smaller wheels to produce more even ground pressure. The Tiger does both by arranging the large 80 cm wheels in an overlapped and interleaved pattern on wide tracks, while torsion bar suspension allows a lot of vertical travel for each set of wheels. The overlapping wheels even act as additional armor for the lower hull! The obstacle-crossing capability and smoothness of the ride are unmatched, but if you damage just one inner road wheel, you'll have to take off as many as nine other wheels in order to get at it. The Tiger's combat tracks and wheels were also too wide for rail cars: First, to get it on the rail car they had to remove the outer road wheels and put it on narrower transport tracks, and then at its destination they had put the outer wheels and combat tracks back on. As if all that wasn't enough, there's an unconfirmed but plausible-sounding anecdote about how in Russian winter conditions, mud could get between the wheels and then freeze them together overnight, so that a tank crew would wake up and find themselves stuck when they tried to start the tank. While torsion bar suspension is universal nowadays, nobody but Nazi Germany has ever made tanks with interleaved, overlapping wheels because the maintenance is more trouble than it's worth. The Germans tried to mitigate the problems later by replacing rubber-rimmed wheels with steel-rimmed ones, and by producing the Tiger II and some later Panthers with overlapped, but not interleaved wheels.
    • Pull up a chair and read the saga of the Tiger that didn't get made, and instead became Germany's worst AFV of World War II:
      • Back when the authorities were holding trials to decide whose version of the Tiger I would get produced, Ferdinand Porsche submitted a prototype that used a novel petrol electric generator drive: instead of the usual tank setup of having one internal combustion engine provide power through a drivetrain to a transmission connected to the drive sprockets, this design had two gasoline or diesel engines that charged two electric generators, which fed two electric motors connected to the drive sprockets. The idea was to avoid the reliability problems that come with having a mechanical gearbox, and deal more easily with the fluctuating torque requirements of a tracked vehicle going over rough terrain. This kind of petrol electric drive had already been successful in other applications such as cars and trains, and Porsche wasn't the first—nor would he be the last—to try putting it in a tank.
      • Sadly, despite the generators and electric drive working just as they were supposed to, the problem was with the engines and how they were affected by the overall layout. Porsche was a talented engineer, famous for his racecars and the original Volkswagen Beetle, but he increasingly suffered from Complexity Addiction and felt compelled to use only the latest cutting edge technology in his machines. In this case he wanted to design his own state-of-the-art engine rather than using an existing model, and his instistence on starting from scratch on a tight deadline was ill-advised considering that high horsepower engines in those days required years of refinement in order to make them reliable. On top of that, an inevitable problem with petrol electric was the amount of space it took up inside the vehicle compared to regular internal combustion. Having to cram so much extra machinery into a hull of the specification size didn't leave enough room for proper engine cooling, and the powerplant was inadequate for the huge 60 tonne mass of the vehicle. As a result the twin engines were prone to overheating, breaking down, and even bursting into flame.
      • The Henschel and Porsche prototypes were tested against each other in front of Hitler on his 53rd birthday, 20 April 1942, and the people running the trials quickly realized that they'd be better off choosing the simpler Henschel model: the Porsche prototype demonstrated its unreliability with an embarassing breakdown, and they balked at the idea of mass producing a vehicle whose electrical machinery would have required so much strategic copper.
      • That would have been the end of Porsche's folly if not for one big problem: he'd had been so confident that his version would be selected that he'd already gone and had the Nibelungenwerk factory in Sankt Valentin, Austria produce 100 hulls for his tank that didn't work, and all the money, time, and material that Germany had poured into them would go to waste if something wasn't done. Armament Minister Speer decided that the Porsche Tiger should be used as the basis for a new heavy Jagdpanzer ("hunting tank", i.e. tank destroyer) that could mount Krupp's new 8.8 cm L-71 antitank gun, which attained higher muzzle velocity than the L-56 used on the Tiger I by having a substantially longer barrel and using ammo with the same caliber projectile but an enlarged propellant case. This decision was influenced by the fact that, after the initial debacle, the 100 turrets originally ordered from Krupp to put on the Tiger(p) hulls had been reallocated for installation on the first series of Henschel Tigers. German engineers welded a large superstructure onto the back of the Porsche vehicle's hull to accomodate the larger gun and a second loader, increased the frontal armor to 200 mm, and moved the engines—now a pair of the same reliable Maybach HL120 model engines used in the Panzer III and IV—forward to the middle of the hull since there was no longer room in the back. The now 65-ton vehicle was named the Ferdinand after its inventor: 91 Ferdinand tank destroyers were hurriedly put together from March to May 1943, and they were sent in two groups to the Eastern Front.
      • Despite the reconfigured design, the Ferdinand continued to be plagued with problems related to lack of space for proper cooling and access to the engines, as well as its longitudinal torsion bar suspension (another of Porsche's bright ideas) which helped save much-needed space in the hull but was more failure-prone and complicated to maintain than regular horizontal torsion bar suspension. These machines broke down with alarming frequency: one crewman recounts an incident during Operation Citadel where the engines of multiple Ferdinands caught fire one after another from the strain of climbing a hill, which initially made the crews think they were being hit by artillery! In the Battle of Kursk in July and August of 1943, the Ferdinands were effective at sniping Soviet tanks from ranges of up to 2 km, where their heavy armor and long-range firepower gave them a strong advantage. However, once they advanced further into the deep defenses the Soviets had set and got isolated from their infantry, their lack of a turret, peripheral vision periscopes, or even machine guns meant that Soviet troops could hide in trenches until the tank destroyer passed, and then swarm it with Molotov cocktails and demolition charges. Perhaps too much has been made of the lack of machine guns, since Kursk was a wierd kind of chaotic situation and they would have normally been shooting from a safe distance away, but the more serious problems for them were mines, artillery, and mechanical failures: any damage to the suspension made the armor moot by forcing the crew to get out in the open to perform repairs. The super-heavy vehicles were also horribly difficult to tow, requiring five of the standard armored recovery vehicles based on the Panzer IV chassis to drag one off the battlefield if disabled.
      • Between January and April of 1944, 48 of the 50 surviving Ferdinands were called back to the factory and given a modification package based on the lessons of Kursk. This included a ball-mounted MG 34 on the hull front, redesigned armored engine grates, a commander's cuppola with seven periscopes, Zimmerit anti-magnetic mine coating, and additional armor in some places, which brought up the weight of the vehicle—now renamed Elefant—to 70 tonnes. Again, with no increase in engine power. Elefants were then deployed to try and hold back the Allied landings at Anzio, Italy, where the mountainous terrain both negated their advantage in long range combat and exacerbated their deficits in mobility and reliability.
      • Despite an impressive kill/loss ratio—crews reported about 10:1, though claimed kill numbers have to be taken with a grain of salt—far too much precious time and resources had to be spent trying to recover and repair immobilized vehicles, and many of them had to be abandoned or destroyed by their crews. In his analysis of the Ferdinand/Elefant, Potential History judges that this whole project was an example of the Sunk Cost Fallacy, and that the Germans should have cut their losses by letting the misbegotten things die early on.
    • Also awesome but impractical was the colossal 71.7 tonne Jagdtiger, the heaviest armored vehicle used in WWII, which was essentially a Tiger II with a gigantic 128mm Krupp gun mounted in a fixed casemate instead of a turret. On one hand, its frontal armor was nigh impenetrable at up to 250 mm thick, while its gun could be accurate out to about 3.5 km away and was guaranteed to destroy any kind of Allied tank it hit. On the other hand...everything else about it. Speed was about 12 miles an hour since it was so overweight and underpowered: it was heavily dependent on the increasingly strafed and bombed-out railroads for transport, so it could hardly ever get to the battlefield in time. It had a piss-poor rate of fire due to its unique loading method (which required two men instead of one - the ammunition was, obviously, quite heavy, so projectile and propellant were loaded separately). The gun could only be moved 10° to the left and the right each, so it was usually necessary to turn the whole tank to aim at a target. Turning the heaviest armored vehicle of any type to achieve series production on the spot did put quite a bit of stress of the drive system, which therefore often broke down when it was needed most. Did we mention that in order to fix the transmission they had to remove that giant main armament to get it out? Without the ability to turn the tank, it could not defend itself against anything outside the 20° sector; its MG34 machine gun was also front-facing with limited traverse. By the time it was employed it was easy prey to air attacks, and since all the good tank crews had been killed earlier in the war, the green soldiers who operated this monster vehicle just weren't skilled enough to handle it. Only about 20% of the Jagdtiger vehicles were lost in combat, and most were destroyed by their own crews when abandoned due to breakdown or lack of fuel.
    • The Germans also built the Sturmmörser Tiger or Sturmtiger, consisting of a heavily armored casemate installed on a Tiger I surplus hull and armed with a colossal 38cm rocket mortar for destroying buildings; oddly enough, this weapon had originally been developed by the Kriegsmarine as a coastal antisubmarine weapon. The huge 350 kg/770 lbs. projectile was capable of crashing through about eight feet of concrete and blasting most hardened defenses to rubble. There would also an unconfirmed report of a single one of these shells taking out three M4 Shermans somewhere on the Western front. Alkett produced 19 vehicles—each one slightly different from the others in minor construction details—and they were distributed to three armored assault mortar companies.
      • Mortar Company 1000 saw action in the Warsaw Uprising: the unit commander reported that the 38cm rocketgun was extremely effective. So effective, in fact, that the Sturmtiger risked damaging friendly forces or even itself if either got too close to the projectile's roughly 500 meter blast. The circumstances of urban combat were forcing them to use one Assault Mortar at a time in the direct fire role, using a naval antitank sight to aim down city streets. Apart from the risk of collateral damage, there was also the problem that the massive blast of the mortar shell usually had the effect of replacing an impassable enemy fortification with an equally impassable chaos of rubble and craters, which sucked for the troops who actually had to follow through.
      • The February 1945 manual, written by the Artillery after they took over control of the assault mortars from the Panzer arm, stated that such use was to be an exception, and that otherwise they should always operate in batteries of four, laying indirect fire on targets up to 5500 meters away. Having four of them all firing at the same thing compensated for the large dispersion of hits at long range, as well as each crew only being able to load and fire about four rounds per hour. Still, the target would have to be something really big like a building or a huge concentration of troops and supplies in order to have a chance of hitting it and make using the high-value weapon worthwhile. The vehicle could carry 12 to 14 rounds, and only 317 rounds were ever issued, leaving an average of 17.6 shots per mortar. Despite being heavily armored and hopefully very far away from return fire, the assault mortars were advised to seek concealment because the enemy would try to take them out. The large amount of gas that they vented out the holes in the barrel to reduce recoil tended to give their position away, and they had to be covered by the company's organic antiaircraft assets. Finally, they were at the end of the day Tigers with the expected maintainence and fuel requirements, more so because they were eight tonnes heavier.
      • The other two Sturmtiger companies saw action on the Western front at the Ardennes offensive and at Remagen, with disappointing results. Most of the Sturmtigers ended up abandoned by their crews after they could no longer obtain ammunition or fuel. Much like the Ferdinand, it looks like a case of thinking they'd found a good use for valuable hardware that would otherwise go to waste, except that the resulting white elephant required a lot of maintainence and protection and had to take out really high value targets in order to be worth it, something which didn't reliably happen. It was weapon suited to a purely offensive role, yet it was coming out after the failure of Operation Citadel permanently changed the German position from invading to being invaded. Perhaps some kind of tank destroyer would have been a better strategic use of those chassis.
    • Most of the problems the Germans had with the above designs could have been averted if Hitler had diverted as much resources to logistics as he did to the sharp end. One critical failure in this regard was the Nazis neglect of armored recovery vehicles. Most modern armies base their ARVs on the principle that "1 pulls 1": ie, 1 ARV is sufficient to recover 1 main battle tank. The Germans, due to a failure to update their designs, maintained recovery vehicles based on the Panzer IV chassis even as the Heer switched to Panthers, Tigers, and then on to Tiger IIs. It took five Bergepanzer IVs or three halftracks to pull a Tiger or Elefant out of action, even more for a Tiger II. In some senses, Hitler's neglect of logistics made the entire Wehrmacht Awesome, But Impractical.
    • Dr. Roman Töppel says that Germany did not lose the war because they didn't have enough tanks; they lost because they didn't produce enough spare parts to keep them running! Because German tank production was fairly inefficient at the outset of the war and could barely meet demand to begin with, they weren't willing to slow production down in order to produce generous numbers of spare parts. This didn't turn out to be such a big deal in their invasions of Poland and France, which involved relatively short distances and which they accomplished in such a short time that mechanical wear was minimal. However the distances in Russia were a lot greater and the roads were rougher, consisting of dirt that tended to billow up in huge clouds when the panzers drove over them. This dust got sucked into the engine intakes and wore out the engines so that they needed to be replaced after a certain distance, but there simply weren't enough spares to go around and many otherwise perfectly good tanks were disabled. Also, because Germany alone didn't have enough fighting vehicles or trucks for Operation Barbarossa, they had commandeered basically everything with either tracks or wheels throughout all their captured territory, going into Russia with a chaotic menagerie of models from different countries with as few parts in common as you can imagine. The further they pressed into the USSR, and the longer the campaign dragged on, the worse it got. When Albert Speer became Germany's armaments minister, he made a big show of increasing all kinds of war production, including tanks. However, because he was so focused on achieving big vehicle production numbers in order to please Hitler and make himself look good, he pursued this at the expense of spare parts production. For example, despite the frequent breakdowns of Tiger I tanks, the factories would make just one extra engine and transmission for every ten Tigers they produced. Therefore, unlike the Americans who sent large numbers of spare parts to Europe so their tanks could be maintained, German tank crews had to wait for months to get a requisition filled. When spares came in on the trains, crews would literally fight each other at the station to get their hands on them. Since it was forbidden to cannibalize any of their tanks for parts, the units would do things like falsely report a damaged but recoverable tank as a total loss so they could get away with stripping it. So however many tigers and panthers Germany had on paper at any given time, in reality a large portion of them were broken down waiting for parts.
    • For context, loss-rates for armoured vehicles during offensive operations in WWII average 50-300%, but irrecoverable losses were typically only 20-50% (no new vehicles being added). It is extremely easy to put a vehicle out of action (usually by a 'mobility kill' i.e. damaging the track and road wheels with mines, grenades, or shells fired at the flank), and thus immeasurably important to have an effective vehicle-repair institution in place. Not losing the ground you fight on is also extremely important, as it means you don't have to destroy your immobilised vehicles to prevent the enemy from capturing them.
  • The famous German half-tracks for used for supply and as infantry armored cars all used the same Schachtellaufwerk type of chassis and track, only scaled up or down to their respective size. Unlike tank tracks, which were classic links held together by pins, in Schachtellaufwerk tracks designed to allow high road speeds all track links were fitted on needle bearings with individual sealing and lubrication. That makes a few hundred lubricated bearings for each vehicle, with expected costs and hardships when building them in large numbers. And all for no useful purpose, since there were strict orders to drive them at lesser speeds than possible anyway. The interleaving and overlapping wheels were also a big maintenance issue, namely that one would have to disassemble the running gear assembly just to replace ONE wheel.
  • The whole German approach to half-tracks was of questionable net value. While the Americans, inspired by French designs, basically took the existing M3 Scout Car and replaced the rear wheels with sprockets to drive a short bogey suspension track unit, the Germans came at it from the opposite direction by making an almost fully-tracked caterpillar chassis with a wheeled steering axle added to the front. American developers sometimes called what the Germans made a "three-quarter track". Unlike the American M2 and M3 half-tracks which relied entirely on the front wheels for steering, and used the rear tracks only as a means of reducing ground pressure, the German Sd.Kfz. 250 and 251 had a more complicated steering system where the wheels would take care of slight turns to preserve momentum, and when the steering wheel was turned more sharply the differential steering of the tracks would kick in to assist with the turn. This did meet the criterion of the vehicle handling more like a truck and being easier to drive than a tank, but the expense of producing it and the complexity of maintainence was comparable to that of a fully tracked vehicle. At the same time, while it had better cross-country mobility than American versions and wasn't as crippled if the front axle got taken out, the front wheels reduced its obstacle climbing ability compared to a fully tracked vehicle which wouldn't have cost any more to produce.
  • The early Cold War saw the final development of the heavy tank concept: the Soviets continued to develop the IS series to maintain the lead they had gained by the end of World War II, while the US and allies such as Britain and France created their own heavy tank programs to counter them. Gigantic guns meant to kill enemy tanks at extremely long range were combined with thick steel armor, so they could either perform overwatch support for the lighter tanks or lead in a breakthrough. There were several problems with them: weight was increasing to the point where the powertrain technology of the time couldn't keep up, causing low speed and reliability; the size of the shells they fired reduced ammo stowage and required two-piece ammunition, hence a slow rate of fire; and they were too heavy to cross most briges. By the 1960s they'd been rendered obsolete by improved HEAT rounds and Anti-Tank Guided Missiles which no practical thickness of homogeneous steel armor could protect against, and against which they were sitting ducks with their low speeds and large profiles. They were rare and extensive, yet still just as likely to be taken out by mines, tank destroyers, artillery, and aircraft. Therefore they were abandoned while all focus went towards improving balanced and increasingly capable Main Battle Tanks such as the Centurion, M60, and T-64.
  • To give an example of the above, the last Western heavy tanks, the American M103 and British Conqueror, somehow repeated many of the mistakes the Germans and Soviets made with their WWII tanks. They used the same extremely powerful 120mm rifled gun designed to counter the Soviet IS series, and with elephantine armor they reached the monstrous mass of 59 t for the M103 and 64 t for Conqueror. The M103 suffered from originally using the same powertrain as the much lighter Patton series, leading to criminally low speed, high fuel consumption, and serious maintenance issues. The Conqueror had many of the same problems, but at least it had excellent cross-country mobility. With the new M60 and the Centurion up-gunned to 105mm on the horizon, the US Army operated a single battalion of M103s for five years before shoving them onto the Marines, who had a use for them in their landing doctrine and modified them for better performance, though they were still never used in combat. As for the British, they parked all the Conquerors in West Germany until 1966, when they dumped them in favor of the new Chieftain MBT which was smaller and more mobile, yet had as powerful a gun and equal or better armor. As some final trivia, there was also a Conqueror variant with a 183mm gun that never got off the drawing board.
  • British tank doctrine and production for most of the Second World War. Either they'd make the right tanks for the wrong doctrine, or they'd have a great design that got let down by the limitations of their military industries, or the tank would have practically everything going for it except for maybe one important part of the design that wasn't quite right and dragged it down from fantastic to just mediocre.
    • When the Second World War began, Britain—like most countries—still considered the infantry/cruiser concept to be basically sound. The well-armored but slow-moving infantry tanks such as the Matilda II and Churchill were supposed help the infantry create a breakthrough at some point in the enemy line, and then the lightly armored cruiser tanks such as the Cruiser Mk. I and Crusader would use their greater speed and operational range to rush through the gap and wreak havok deep inside enemy lines. While many of the tanks they made were well-suited for their intended use, the problem was that the British planners had based their machines on what turned out to be a mistaken prediction about how the next war would be fought. Instead of the slowly moving front of World War I, where flexible deployment wasn't as much of an issue, the more dynamic and maneuver-based operational picture of World War II tended to favor Jack-of-All-Stats medium tanks such as the U.S. M4 Sherman and the Soviet T-34, which could be produced in large numbers and perform adequately in whatever role the circumstances required. After all, if the tanks were too specialized, one could not always ensure that the right tank would be in the right place at the right time. The Britons' assumption had been that infantry tanks wouldn't have to move very fast because they'd be supporting riflemen on foot, and great speed would be counterproductive anyway since the tanks would also be vulnerable if they left behind their infantry. And since the Infantry tanks would take care of the breakthrough role, the cruisers would help themselves to soft targets while avoiding anything they couldn't handle. However the infantry tanks lost a certain amount of tactical and operational flexibility because of their low speed, and the thinly-armored early cruisers inevitably had bad encounters with German AFVs which weren't quite as fast but had more firepower and protection. In general the infantry tanks were more effective, although the cruisers also had their moments.
    • Having said all this, Tom Schwallie of Tank and AFV News points out that the mediocrity of British tanks wasn't so much caused by their designs' adherence to the infantry/cruiser doctrine per se, as it was that military bureaucracy and industrial problems slowed the development process to the point they'd be obsolete by the time they came out. For example, the development of what would lead to the Cromwell began in 1940. If something like the Cromwell could have been in North Africa by 1942 it would have been fantastic because of its more powerful and reliable engine, high mobility, 75 mm gun, and improved armor; instead it took until 1944, by which time the Cromwell's firepower and armor were far from impressive. British tanks tended to lag behind other countries in firepower and engine development through most of the war. Furthermore, the production rate was hampered by lack of efficiency and standardization, which is odd considering the high standardization of parts and production for the Royal Air Force. Thus, both for combat effectiveness and for sheer numbers the British had to rely heavily on American Lend-Lease tanks such as the Sherman.
    • The need for a "universal tank" was recognized early in the war, with Bernard Law Montgomery its biggest advocate, but the idea didn't get very far until the Rolls-Royce Meteor engine became available as the basis for a Lightning Bruiser; they were then able to up-armor and up-gun the next generation of cruisers to the point where infantry tanks became unnecessary. Britain finally struck gold with the Comet towards the end of the war, an improvement on the Cromwell design that was not only fast, but also armed and armored well enough to be considered a match for the Panther. Immediately after came the Centurion, a hugely successful and groundbreaking design widely considered the first Main Battle Tank to have been designed as such.
  • The idea of the U.S. adopting the Sherman VC Firefly.
    • The British managed to squeeze the huge 17 pounder anti-tank gun into the small turret of the M4 Sherman—designed for the much smaller 75 mm gun M3—by changing the orientation of the breech, modifying the recoil mechanism, adding a turret bustle to get the radio out of the way while turning it into a counterweight for the gun, and eliminating the bow gunner's position to put in more ammo racks. The 17 pounder was one of the only guns at the time which could potentially pierce the frontal armour of a Tiger or Panther, and the Sherman chassis was both mechanically reliable and more protective for the crew than the Archer or Achilles tank destroyers. However, the confines of the turret made it difficult to manhandle the long, heavy rounds into the breech, and the gunner had to really contort himself to reach down to the awkwardly-placed elevation wheel while also looking through the sight. The Firefly got its name because of the huge muzzle flash of the 17 pounder, and sometimes there was flashback through the breech; it was said that you could tell a Firefly crewman because his eyebrows had been singed off. The dust kicked up by the shot obscured vision for several moments, making follow-up shots difficult. By reducing the rate of fire, exchanging the anti-infantry effect of the 75 mm HE shell for the 17 pounder's better armor penetration, and removing the bow gun, it was basically turned into a lousy tank but a pretty good tank destroyer. For the British it was still a useful stopgap until they could produce a proper 17 pounder tank like the Comet; they were the producers of both the gun and the ammo, and they were able to start producing Fireflies in January 1944, in time to assign one to each Sherman platoon for D-Day.
    • The American Ordinance Department was interested in the capability of the 17 pounder, and used it in comparative tests of different gun tanks both during and after the war. Since 1942 the US had been testing the 76 mm gun M1, a smaller and lighter version of the 3 inch gun. The initial "quick fix" turret with the 76 mm in the standard Sherman turret had already been rejected as impractically cramped, so Army Ground Forces would have been unlikely to accept the even bigger 17 pounder in the same turret. Ordinance ended up putting the turret of the cancelled T23 tank onto the Sherman to create the eventually accepted E6; ironically, the 17 pounder could not be installed in this larger turret because of how the trunnions fit. In testing between the 17 pounder and the 76 mm, what they found was basically that the 17-pounder would have amazing penetration using the British-developed Armor Piercing Discarding Sabot round, but the problem was that this round couldn't hit the broad side of a barn from more than 500 yards. For one test they basically gave up because they couldn't hit the target even once. The regular Armor Piercing Capped Ballistic Capped round worked properly and penetrated farther than the 76, but still not enough to reliably defeat Panther front armor; whatever the 17 pounder could kill with APCBC ammo the 76 mm usually could, and whatever the 76 mm couldn't kill, the 17 pounder's APCBC round usually couldn't either. Since the U.S. had the 76 mm, would soon be getting the 90 mm gun, and would have to rely on the British to get converted Shermans and ammo, they decided the Firefly wasn't worth it.
    • So if that was the right decision, why does the Firefly get such hype today? Well, despite the fact that one hundred 76 mm shermans were sent to England to take part in the invasion of Normandy, the U.S. unit commanders for D-Day didn't realize how serious the Panther threat was, and they were more concerned with the fact that the 76 was unfamiliar equipment and didn't have as good an HE shell as the 75. Therefore they left the new tanks behind when they crossed the Channel, and got a rude shock when the terrain of Normandy changed the situation from maneuver warfare to straight-up gun duels in which the 75 was at a huge disadvantage. At the same time the U.S. military dropped the ball on producing and issuing sufficient quantities of High Velocity Armor Piercing ammo which would have been needed for U.S. guns to achieve best results against armor, making the 76 a big disappointment even when it arrived. Meanwhile, the British Fireflies gained a glorious reputation simply because they'd brought them from the start, and there was a big morale boost from having something that could knock out a Panther even in limited circumstances. Those mistakes reflect poorly on the U.S. in hindsight, but they were unrelated to the decision not to use the Firefly, which in and of itself was a sensible one.
  • French tanks in the Battle of France, 1940.
    • France's military policy was shaped by its perception of what had worked in World War I, as well as the limitations imposed by the war's lasting damage to population and economy: The fighting of the Western Front had largely taken place on her soil, with over a million men killed or missing in action, and more than four million wounded. The Great Depression hit in the 30s, reducing the amount of money for defense, and all the men who didn't come home from the war to start families led to a significant dearth of young men for the army 20 years down the road. French politics was unstable, with Prime Ministers changing frequently, and the left wing government was suspicious of letting the traditionally right wing professional military grow too large and powerful for fear of a reactionary coup. With all of this in mind, the French came up with the defensive strategy they would use in case of invasion by Germany: a small but elite professional military would be used in peacetime to train reservists, who would be summoned for refresher training from time to time, and in wartime the professionals would hold back the Germans to prevent France's industrial areas from falling, thus buying time for the massive reserves to be brought up. Armored fighting vehicles were divided into chars (tanks), which by law were exclusively attached to the infantry arm, and automitrailleuses de combat (combat cars), which was what the cavalry named their tanks in order to get around the law. Since the professional military's reservist teaching duties didn't leave them with much time for new courses or exercises, and reservists coming for refresher training would have a hard enough time shaking the rust off of what they'd learned before, most tactics including those for tanks would have to stay relatively simple and unchanging.
    • Towards the end of World War I the French had come up with their first good tank design, the little two-man, 6.5 tonne Renault FT. The FT was the Ur-Example of the modern tank layout: tracks that extended the whole length of the vehicle, the driver in front, the fighting compartment in the middle with a 360 degree revolving gun turret, and the engine in back. The French decided on a strategy of using a "swarm" of light tanks to overwhelm the Germans, ordering 3,530. This seemed to work well with their overall strategy in 1918, and after the war they continued to favor relatively small two-man tanks. After all, if they wanted to swarm the Germans with a huge number of tanks despite lack of money and recruits, they'd need tanks that were cheaper to produce and required fewer men to operate. At the same time, the need for breakthrough tanks to spearhead the counterattack led to the development of some heavies such as the Char 2C and the Char B1 bis.
    • The French designs had some good points. Their factories became skilled at casting, with the SOMUA S35 being the first tank with a hull made entirely from castings, and the FCM 36 was among the earliest to be made with welded armor. The tanks the French made in the leadup to World War II had substantial, often rounded or sloped armor which the standard German 37 mm antitank gun would often fail to penetrate, and considering that more than half of the German tank inventory in 1940 was still small, barely-armored Panzer mark I and IIs armed with machine guns and a 20 mm cannon, respectively, the French tanks were better armed and armored on average, as well as more numerous. On paper the SOMUA was superior to 1940 German models in every way except for the one-man turret, and the big, heavily-armored B1 bis looked like a monster that could eat panzers for breakfast.
    • However, the R35 and H35 which were the most numerous models had painfully low horsepower, and were armed with short-barreled 37 mm cannons (often SA 18 cannons taken straight off of old World War I FTs) that had very anemic armor-piercing capability. The R35 showed the teething problems of early hull casting technology, as the steel came out much weaker than its thickness would imply. Tests proved it was vulnerable not only to 25 mm antitank rounds, but even in some places to 8 mm armor piercing bullets.
    • As for the welded, angular FCM 36, it was produced by a shipbuilding company using welders whose skill was rare at the time, and while this construction method was quicker it also cost more. Only 100 of them were ordered early enough to be built in time for the German invasion. They may have been the best of France's two man tanks on the whole, since they had sloped armor, the turret wasn't as cramped as the APX, and it had a reliable diesel powertrain, but the welds tended to act as weak points and it just wasn't better enough to be considered good.
    • In addition to relying on primitive vision slits that were hard to see out of and didn't protect against bullet splatter, the French lineup also demonstrated why a one-man turret can be a major disadvantage. When France was rearming between the world wars, it was a lot cheaper for the cash-strapped French to make just one standard model of turret that would fit all of their tanks, so they decided to make a cast, one-man turret. Compared to a two- or three-man turret, a one-man turret would make a smaller target, use less metal and add less weight, be more heavily armored for the weight, and be backwards compatible with the small turret rings of their old tanks such as the FT and D1. However, the drawbacks were so horrible that in hindsight it seems unbelievably boneheaded. The ideal, codified by the German Panzer III, is to have a three man turret in which the gunner aims and fires the main gun, the loader loads the shells and perhaps shoots the coaxial machine gun, and the commander looks out the roof hatch with his binoculars, guiding the gunner onto the target and feeding him range adjustments. In contrast, the commander in a French tank had to do all the work of loading and operating the gun himself, in addition to having to actually command the tank or—god forbid—several tanks if he was the platoon leader. Rate of targeting and fire was rock bottom, and try as he might to juggle his different tasks, he could only do everything poorly. As for situational awareness, the standard APX turret didn't even have a commander's hatch in the roof above him, just a dome-shaped rotating cupola which on early versions had only one vision slit, making it a sort of poor man's periscope. The only way for the commander to stick his head out was a door on the back of the turret, and in order to see forward over the turret he'd have to leave the gun unmanned and sit on the opened turret door with most of his body outside the tank. Okay for a road march, but not so much for battle. As you could imagine, there wasn't much room in the turret for ammunition and most of it was down in the hull. The SOMUA and the B1 bis were only slightly better for the commander in that regard because they had a version of the APX with a bigger turret ring, so that the radio man—who usually had no radio and thus had nothing better to do—could pass 47 mm shells from the ammo racks up into the turret. German commanders noted that the French tanks would usually roll into battle and then stop in one place as soon as they began firing, not moving at all because the poor commander couldn't handle the demands of scoot-and-shoot all by himself. When the Germans captured large numbers of French tanks in the Fall of France, they did the best they could by installing turret roof hatches in place of the dome cupola.
    • Only the platoon leaders had radios, forcing the others to signal to each other using flags. Good luck noticing or reading those flag signals while buttoned up, since the vision from inside these tanks was so poor! The radios that were issued weren't very good—they tended to be of the morse code only type which was impractical to use in the heat of combat—and furthermore the tankers might be ordered not to use them because the generals were worried that the Germans might eavesdrop or attempt to confuse the tanks by transmitting fake orders. That fear was the reason for the whole French army's ill-fated reliance on telephone lines and message couriers for communication instead of radio. The whole French system of using its forces, "Methodical Battle", assumed that fighting units would have to follow precise, predetermined orders in order to act in sync with artillery barrages, and made no real allowance for local initiative in response to unexpected opportunities or threats.
    • On top of all this, the crews weren't adequately trained on even the basics of operating their tanks, owing to the shortening of reservist training periods and the fact that many of these tank models—which had been stuck in Development Hell and held back by inefficient manufacturing—were just beginning to be produced and delivered to the units by this time. A lot of tanks weren't even finished when they were sent from the factory almost directly into combat, leading to examples such as B1 bis tanks with no turret installed. The crews had little or no time to train on their vehicles before going into action: one famous issue was the complaint that the SOMUA had a ridiculously short range. This actually happened because it had two fuel tanks, both equipped with overfill valves for safety: a small one holding 110 liters which the engine drew fuel from, and a large 410 liter tank which replentished the small one. Crews who didn't understand how the overfill valves worked would pour fuel in until it looked like everything was full, and then afterwards they'd wonder why the tank ran out of gas so quickly, not realizing that they had actually filled up only the small tank. Another issue was that the B1 bis used large amounts of castor oil as lubricant, but not the type available in pharmacies because that kind stops working above a certain temperature. Crews didn't understand the difference and assumed any kind of castor oil would do, which led to friction problems and gave them the idea that the system was a piece of crap.
    • Despite their flaws, there were a few places where the French tank forces gave the Germans a black eye, and it's likely that they could have stopped the Germans' very risky and vulnerable lightning offensives if not for the fact that the French high command assumed that Belgium was the real German thrust and the Ardennes a diversion (it was the other way around), combined with the fatal lack of radio at all levels which made it impossible to coordinate and react at the speed the Germans were maneuvering. As it was, though, the Germans ran rings around and defeated what was supposed to be the strongest army in the world.
  • The Tank Destroyer doctrine of the U.S. Army, and the related choices of what kinds of vehicles got produced during world War II.
    • Before the fall of Poland and France, the conventional anti-tank policy was to have towed anti-tank guns spread out across a battle line, ready to take out any enemy tanks that attacked. Then the U.S. observed the German use of highly mobile, concentrated armored formations in those campaigns and concluded that as long as the Germans concentrated their tanks to attack a narrow front and used terrain to keep out of the flanking anti-tank guns' fields of fire, the defense would never have a high enough concentration of anti-tank firepower to counter them and would be overrun. Therefore, the U.S. thought it needed more concentrated units consisting of self-propelled guns that could move quickly to react to a tank attack at any point. While tanks could be effective at fighting other tanks, and were fully expected to do so when they encountered enemy tanks during offensive actions, the U.S. Army believed it would be a waste to use tanks in a reserve or defensive capacity when their greatest use was on the offense. Besides, tanks were expensive to manufacture and it would be better if cheaper weapons could do the job instead. Therefore, tank destroyer battalions were formed whose mission was purely defensive; they would wait in reserve until the Germans attempted to attack in a certain place using massed armor, at which time they would spring into action and thwart the attempted breakthrough.
    • From humble beginnings where they were just sticking antitank guns onto half-tracks and trucks, the Tank Destroyer program progressed to using fully tracked vehicles (M10, M18, M36) with relatively light armor and a powerful gun mounted in an open-topped, revolving turret. It's important to understand that these vehicles were not automatically considered Tank Destroyers in US terminology; unless a particular vehicle was actually assigned to Tank Destroyer force, it was merely a self-propelled antitank gun. Since the vehicles were designed to rush to where they were needed and then ambush the enemy from an advantageous position—using their superior vision to see first and shoot first—speed and firepower were prioritized over protection.
    • In reality, the Germans practiced effective combined arms warfare without ever mounting the kind of clumped-together tank onslaught the Americans expected to need the Tank Destroyer battalions for, and as German combat losses mounted late in the war the American TDs started running out of German tanks to destroy. Meanwhile, tank support wasn't available to all infantry units at all times, and they desperately wanted help from anything that had tracks and a gun on it. Almost as soon as the US began ground combat in the European Theatre, the TD doctrine was basically thrown out the window: the battalions were split up into companies or platoons and sent to support the infantry on the attack. Thus, contrary to what the doctrine prescribed, they were now being used as pillbox destroyers, indirect fire artillery, and sometimes even as substitutes for tanks in close infantry support. This kind of combat didn't always play to their strengths: their armor was relatively thin, and their open tops made their crews vulnerable to infantry assault and shrapnel. They also lacked hull or coaxial machine guns for defense against infantry.
    • Thus, these self-propelled antitank guns weren't as versatile as tanks and weren't appropriately designed for a lot of what they actually ended up being used for; in North Africa, General Patton went so far as to opine that the M10 should stop being produced, and that the existing ones should be turned into tanks by welding on more front armor and a turret roof. The Tank Destroyers were a success in the sense that they got superior kill ratios against enemy tanks, but this can partly be attributed to the fact that unlike tank crews, which were trained as generalists, these guys were specifically trained to destroy tanks. In other words, it wasn't so much the hardware as it was the training. The idea that the TDs would have enough punch to take out anything the tanks couldn't handle also contributed to the Army's general lack of urgency about upgunning the medium M4 Sherman and introducing the heavier M26 Pershing, which were not recognized as necessary until the Normandy campaign starkly highlighted the inadequacy of US guns and armor vis a vis the Germans. There was also an increasing duplication of capacity once the Sherman got the same gun as the Hellcat, and the Pershing the same one as the Jackson.
    • After the war's end it was no longer as difficult to produce tank turrets which could mount guns as big as any tank destroyer's, and it became accepted policy that the best counter to a tank was another tank. While the development of smaller, usually missile-armed tank-killing vehicles continued, the existence of a seperate, independent Tank Destroyer branch was abolished.
  • The United States M6 heavy tank began development in May 1940 with a recommendation from the Chief of Infantry to the US Army Ordinance Corps. Originally conceived as a 1930s-style multi-turreted monster with cannons and machine guns sticking out of everywhere, it was revised to a one-turret design. It had a combat loaded mass of 57.4 tonnes, with armor up to 10 cm on parts of the front, and since it came before the Tiger it would have been the most heavily armed and armored tank in the world if introduced. The three-man turret housed a commander, gunner, and loader; toys included a three inch gun M7 and a coaxial 37 mm gun M6. In the hull were a driver, assistant driver, and an assistant loader whose job was to get ammo from the hull racks and pass them up to the turret. Also, the tank had loads of machine guns: a twin .50 cal hull mount for the assistant driver, two .30 cals in the front plate fired electronically by the driver, a .30 on the commanders cupola, and a .50 antiaircraft mount to be used by the loader. The US didn't have any high-horsepower tank engines at this point, so they put in the G200 variant of the large Wright R-1820 Cyclone radial aircraft engine. This produced too much torque for any existing transmission, so variants using torque converter and electric transmission were both produced. The tall engine gave the tank an excessively high silhouette, while the transmission type contributed to the large volume and length. By the time it was finished the Army said they didn't want it: they had no doctrinal use for a heavy tank; the crew layout was inefficient; it was too big for bridges, flatcars, and ship cranes; it wasn't reliable enough; and for the same weight of shipping they would rather send two M4 Shermans overseas than one M6. The 3 inch gun was more powerful than the Sherman's 75 but not big enough to justify such a huge vehicle—they put that on the much lighter and less expensive gun motor carriage M10—while the 37 mm and its ammunition were pretty much a redundant waste of space. In terms of combat potential, it would have been a big target because it was so tall and large in volume, and the amount of space that had to be surrounded by armor meant it wasn't much more well armored than a medium tank. The M4 could get away with using a last-generation powertrain because it was light, but for a heavy tank that sort of thing just didn't cut the mustard. Forty M6 tanks were built, all of which stayed in the US and never saw any use except for testing and propaganda purposes. Ordinance Department attempts to make it relevant again by installing various bigger guns were turned down. Ultimately, the Army saved one as a museum piece and broke down the rest for scrap.
  • Tankettes during World War II. The idea of miniature tanks sounds awesome: you can make a bunch of your infantry more mobile and give them more firepower against other infantry at a relatively low cost. Italy was particularly keen on tankettes because they were small enough to navigate narrow mountain paths that were all but impassable to full size tanks, and for a country without much heavy industry they were a lot cheaper to buy or produce than real tanks were. Similarly, Japan liked its tankettes, all of which had great mobility in non-ideal terrain (such as supposedly "impassible" jungles) and could easily cross improvised bridges. While they performed well during the early days of armored warfare and against poorly-equipped infantry, they quickly became outclassed due to the fast pace of armored vehicle development. Their disadvantages were their very thin armour (vulnerable to most heavy weapons and even small arms fire), light armament (most couldn't mount any weapon larger than a machine gun or autocannon, meaning they were useless against most heavy armoured vehicles), their cramped interiors, and a general lack of versatility and mobility in rough terrain depending on the design of the tracks with respect to ground clearance. Most tankettes were phased out of frontline service, or relegated to non-combat or low-intensity duties. Luckily, the advent of better alloys and weapon technology has made miniature armored vehicles more practical in the form of the Wiesel, which can be airdropped from a helicopter, is protected against rifle fire, and can use an autocannon or TOW antitank missiles.

     Aircraft 
  • The heavy fighter concept. Compared to smaller fighters, the usually twin-engined heavy fighters packed much more firepower, and had much longer range, designed to escort heavier bombers and escape using their high speed. In practice, however, the concept failed; they couldn't maintain their top speed for very long, and they just couldn't match lighter fighters in terms of maneuverability. That, and the proliferation of drop-tank equipped light fighters removed their range advantage. Many were converted to night fighters (where they were more successful, since maneuverability wasn't as much of a concern in darkness) or bomber destroyers (where they were initially successful against unescorted bombers, but ultimately fell victim to the aforementioned lighter fighters).
  • It's 1949, and the US Navy high command is pissed. For nearly two centuries, the Navy has been the lynchpin of US strategic defense, but now everyone is talking about the Air Force, nuclear bombing, and Strategic Air Command. The USS United States, supposed to be the largest and finest (and most expensive) American warship ever launched, has been cancelled only 5 days after being laid down. So what do you do? Well, if we can't launch strategic nuclear aircraft from ships, we'll just launch them straight off the damn sea! And so was the Martin P6M SeaMaster born. A transonic flying boat to be used as a strategic nuclear bomber. This was in many respects a cutting-edge, extremely advanced aircraft, designed to float on open water, supported by seaplane tenders or special submarines, hopping from place to place and making it hard for the Soviets to find and destroy them. Trouble is, all this brilliant innovation was dedicated to solving a problem that could more easily be circumvented entirely, and it was, with the fleet ballistic missile submarine and the aircraft carrier - suddenly back on the agenda following the Revolt of the Admirals - eventually beating out the SeaMaster for funding. The program was cancelled as Navy pilots began conversion training to use the new bomber.
    • The SeaMaster as originally designed was even more impractical: it was supposed to be ramjet-powered.
  • The B-1 "Lancer" was originally conceived as a nuclear bomber that would roar in at supersonic speeds to defend itself against missiles and enemy aircraft, and would, if hit, eject the entire cockpit as a survival capsule that would parachute to earth. By the time its production version, the B-1B, ended its operational life it was used as a conventional bomber operating almost all the time at subsonic speeds. And no capsule. Ironically, despite its less glamorous mission, the B-1B has become quite effective in its new role, the "Roving Linebacker" for urgent-need air support.
  • Some awesome Atomic Age aircraft were rendered impractical not so much by inherent design problems as by advances in missile technologies:
    • The XB-70 Valkyrie was a six-engined high-altitude strategic bomber designed to travel at Mach 3 (which would allow it to outrun Soviet interceptors). All very impressive — before the development of surface-to-air missiles that could effectively target and destroy high-altitude supersonic bombers. Furthermore, bomber designs like the XB-70 were made obsolescent by advances in intercontinental ballistic missile technology. An ICBM that could accurately hit a target half way around the world in 45 minutes increasingly marginalized the role of strategic bombers. There was also the huge per-unit costs. To get those impressive Mach 3 speeds, the airframes had to be made of titanium and other expensive metal alloys, making it economically unattractive to mass produce them.
    • The MiG-25 Foxbat was a blisteringly-fast high-altitude interceptor designed to intercept bombers like the XB-70. Despite its short range and primitive but rugged avionics, it might have been effective in that role. But it also had terrible maneuverability and a limited payload (four missiles, no cannon) which made it rather useless when its intended mission disappeared. While useful in a reconnaissance role, its combat record (in the service of Egypt, Syria, and Iraq) is poor. And its engines would melt if it pushed to around Mach 3 (what it was designed to do in the first place)note , eliminating its cost effectiveness as well.
      • The Foxbat did get a limited, short-term use as a propaganda item as it was by far the fastest and highest flying jet fighter at the time (one incident had a Soviet Foxbat in Syrian colors saunter up to an Israeli F-4 running flat out at operational ceiling altitude, let the F-4 crew get a good look, and then accelerate and climb away), but even this backfired when the US developed jet fighters designed to defeat the plane that they thought the Foxbat was, namely the uber-successful F-15 Eagle. Then, the US got hold of one through Viktor Belenko's defection in 1976, and discovered all the shortcomings.
      • Its successor, the MiG-31 Foxhound, is also a pure interceptor, and at first glance looks like a two-seat Foxbat. In reality, it's only loosely based on the MiG-25, and has a stronger fuselage that allows it to go supersonic even at low altitude. The top speed was dialed back to Mach 2.8 (still very fast, and what turned out to be the top safe speed of the MiG-25). The MiG-31 turned out, despite its limited role, to be far more practical, due to its far superior radar and missiles making it effective against terrain-hugging cruise missiles, not just high-flying bombers.
      • The Foxhound is also seeing a new use in Russian weapons testing, apparently - with their speed, they're perfect chase planes for the Russian military's new planes.
      • Its incredible speed gets another good use when armed with a new Kinzhal SRBM/IRBMnote , an air-launched version of the already pretty impressive Iskander land-based one. Launching it during the top speed dash adds as much as 2 Machs to the 8M terminal velocity of the baseline missile, making it about as difficult to intercept as a full-on ICBM.
    • The B-47 Stratojet had been a Cool Plane, but just the features that made it cool blew the efficiency to hell: the graceful almost Sci-Fi airframe barely had space for a crew of 3 and the wings were thin enough to be flexible in flight, the aerodynamics were so efficient that the plane would float over the runway instead of touching down, the superior maneuverability mandated the nuclear bomb had to be tossed in a wide looping like a fighter would do in a ground attack flight (less fun when the B-47 weighed almost 100 tonnes at takeoff with full load and maybe 60 tonnes at the point where the ordnance would be released) and the combat range was too short, only 2000 miles or so, shorter than a regular commercial airliner.
    • The B-58 Hustler was an awesome aircraft for the mid-1950s (it could climb like a rocket and cruise at Mach 2.2 for hours years before the parents of most Tropers were born), yet it was so breathtakingly expensive to build and maintain (it needed a gigantic belly tank to carry its fuel and just changing a fuselage panel in the field required the specialized jig from the factory to be brought at the airbase) that it was dropped after 10 years in service to be replaced by ICBMs.
      There were people daring enough at Convair back into The '60s to propose a supersonic transport version, either for paying passengers or as a VIP transport for the military. It proved so madly expensive there was no funding even for a prototype.
      • That tank also was the only place to put the single atomic bomb it could carry, which had to be literally built into it. As it then, naturally, had to be jettisoned at the target together with the bomb, the plane had to rely just on the internal fuel reserves to get back. It also constantly leaked fuel into the bomb compartment, requiring the eventual replacement with the two-piece pod, where the tank and the bomb could be jettisoned separately.
  • The Messerschmitt Me 321. It began its life as a glider, the biggest glider ever made. The mission for this glider was to rapidly transport large amounts of troops and medium or light tanks into the battlefield. The first problem was how to make something that big glide. Thus, it was made largely of hollow steel tubing, doped fabric and wooden spars. Then came actually getting it up into the sky. Normally, a tow aircraft would be used to drag it up into the air, but two towing aircraft would have to do the job, which would be impossible to synchronize safely. The solution? They just stuck two Heinkel He-111's together with a fifth engine between. Originally it was intended to be used for the scrapped invasion of Britain, but then was used for Operation Barbarossa. After that, feedback from the people who "flew" them led to a big design change. Sticking six powerful engines on it, they turned it from a glider into the Me 323 transport plane, and it still needed the damn Franken-Heinkel to take off (or RATO or three airplanes working in sync) if it was fully loaded. It arrived just in time to support Rommel in his collapsing North African campaign. Where they were shot down in droves, because they were slow, ungainly and massive targets loaded with fuel, ammo and other things that went boom. In one famous incident, 22 were shot down in just one flight. It saw service for little under a year before being retired.
    • An escort gunship version of the Me 323 was prototyped, with 20mm gun turrets and additional gun positions, intended to escort loaded Me 323s. However, with only two prototypes produced, it was determined that single-engine fighters would provide better cover than the Me 323 E-2 WT, and the design was cancelled.
  • The Convair B-36 "Peacemaker" long-range atomic bomber, which kept the balance of power during the cold war and looked positively badass. When everyone was switching to jets Convair used six huge radial enginesnote  - which turned out to be maintenance nightmares, both for their inherent complexity (the ground crews hated having to replace all fifty-six spark plugs in each engine) and because they were never meant to be mounted in a pusher configuration, resulting in many failures (when your plane losing an engine is considered so routine that the mission is allowed to continue as if nothing happened, you know you have a problem). And for all that the plane was still underpowered, so they eventually fitted four additional jet engines to compensate, though they were normally only used for takeoff and shut down while cruising to conserve fuel. The B-36 also featured an innovative control-by-wire system for the engines... but no mechanical backups, so if the electronics failed you were screwed. And the electronics were mounted in delicate housings that would shake themselves apart under the vibrations caused by the turret guns. Even after the design was tweaked and bludgeoned into some kind of functionality, it still had a tendency to spring oil and fuel leaks all over the place or abruptly catch fire. It got retired ten years after its creation, while its Soviet counterpart the Tu-95 "Bear" is still in use today and is predicted to stay in production for several more decades. Then again, it could carry ten times the payload of the famous B-17 Flying Fortress, and its morale and propaganda value was enormous.
    • Then again, engine failures were less of a problem for the B-36 because its wings were so enormous that the aircrew could actually crawl around inside them and fix the engines in flight if necessary.
    • The B-36 was so very prone to engine fires (mostly caused by excess fuel from air intake icing) and failures that the aircrew soon turned the typical phrase "six turning and four burning", indicating all engines were running properly, into "two turning, two burning, two smoking, two joking and two unaccounted for".
  • During World War II, the US Military subscribed to the "Bomber beats Fighter" philosophy by arming their bombers with multiple gun turrets for defense against enemy fighters, the iconic B-17 and B-29 bombers sporting anywhere from from 8 to 13 machine guns. In theory, long-ranged bombers could only rely on themselves for protection as then-existing fighters lacked the range necessary for escort missions. In practice, the defensive armaments turned out to disappointment despite initial successes following advancements in air combat. Although the guns were initially useful against the BF-109 used by the German Luftwaffe, these proved inadequate against newer tactics and lightning-fast jet and rocket fighters that could evade the gunfire, while also being useless against ground-based anti-air. Improvements in fighter speed and range gave bombers adequate long-range fighter escorts that proved to be much more effective at reducing losses. Yet what ultimately shot down this doctrine was the development of beyond-visual-range missiles that gave fighters the ability to safely shoot down bombers from beyond the guns' maximum firing range. Subsequently, most post-WWII bomber models have had few if any defensive weapons, which would function as little more than deadweight at the cost of plane mobility and payload.
    • The concept was briefly resurrected with the YB-40 project, which took the basic B-17E design and removed the bombload, replacing it with a second upper turret, doubling the waist guns, and adding a chin turret, with increased ammunition supply, as a means of augmenting the ability of B-17 formations to defend themselves when carrying out missions beyond the range of fighter escort. However, the additional weight of the armor and weapons meant that it could not keep up with the returning bombers that no longer had the weight of their bomb load to slow them down, and the introduction of the long-range P-51 Mustang that could escort the bombers through the entire missions eliminated the need for gunships. The chin turret from the YB-40 program was, however, added to late B-17F aircraft and all B-17G aircraft, so the resources put into the program were not entirely wasted.
  • In World War 2, Japan actually deployed balloons to drop bombs. They tied bombs to high altitude balloons that would ride the natural air currents across the Pacific, at which point a built-in timer would release the payload and bomb whatever happened to be below. In a sense, they were successful, being the only attempt by an Axis power in WWII to directly bomb the Continental US that actually hitnote . On the other hand, the carried bombs were too small and too widely-dispersed to reliably hit anything of strategic value, making them useless as anything other than a terror weapon, although the Japanese did also develop incendiary bombs, with the aim to start forest fires. A family of six in Oregon killed by one of the bombs was the only known civilian death case in the US during the war directly caused by enemy action.
    • The notorious Unit 731 of the Japanese Army perfected a system to drop plague-carrying fleas via the same balloons, but the US managed to locate and bomb the launch facilities before it was ready. It wouldn't have really done much damage in the scale of the carnage occurring at the time, but would have been awkward and messy to contain had a plague outbreak started in a major west-coast city.
    • Also, thanks to gag orders and censorship, the US government was able to keep any news of the balloon bombs out of the press. The Japanese then believed the project was a total failure and scrapped it.
  • The Northrop Grumman B-2 Spirit heavy strategic bomber was the culmination of decades of research into stealth and precision bombing: It's a flying wing with no tail or fuselage, the engines and armament are hidden inside the wing/body, and every angle and curve was designed with the help of computers to deflect radio waves away from radar receivers below the bomber. The skin is made of materials that absorb radio waves and convert them into heat, and the engines have a low thermal signature. The intended capability was to slip through dense anti-aircraft defenses to deliver nuclear weapons. Then it suddenly lost much of its value as a strategic stealth bomber when the Soviet Union collapsed in 1991. It has since been relegated to rear echelon status and has seen action as a conventional bomber in only four conflicts: Kosovo, Afghanistan, the 2nd Gulf War, and the Libyan Civil War. On the plus side it performs conventional bombing very well, with an absolutely absurd bomb capacity, a varied arsenal of smart munitions that it can pick out of a revolver-like bomb bay carousel, and fantastic range thanks to its flying wing design. In particular, its ability to get very close before it shows up on radar helps it to slip through gaps in ground-based anti-air radar networks and bomb them, in order to clear the way for non-stealthy aircraft to come in and wreak havok. However, there's still the problem that it's incredibly expensive to maintain. It also requires a computer-controlled fly-by-wire system to safely operate the complex system of split-brake rudders, differential engine thrust, and "elevons" that control the inherently unstable flying wing aircraft, and if those computers fail the damn thing will crash.
  • Stealth aircraft in general fall into this trope. They're hard to detect with standard engagement (X-band) radar, allowing them avoid anti-air and launch surprise attacks. However, their advantages are offset by higher costs and performance penalties. Most stealth aircraft are more expensive to build and maintain than conventional aircraft, often requiring separate factories and hangars. They also have reduced combat capabilities as they carry their weapons and fuel internally to avoid detection. They would also be detected if they use conventional radar or radio (or outgoing datalinks), and can be detected with IRST or VHF radar (latter of which however can only be ground-based). While ideal for niche roles like attacking heavily defended command centers, they aren't versatile or practical enough to completely replace conventional planes.
    • Case in point, the Serbians managed to shoot down an F-117 during the Kosovo War by increasing the wavelength their radar operated on, catching a glimpse of the F-117 while its bomb bay was open. This was done with an 'obsolete' S-125 SAM launcher of old Soviet design from the early 1960s.
  • The Messerschmitt Me-262 Schwalbe, the world's first operational jet fighter. While fast enough to leave any Allied plane in its contrails and an excellent bomber interceptor, its engines were prone to mechanical problems and required high temperature alloys that Germany didn't have enough of. It also required more fuel than the Germans could afford to ration to it. Many armchair historians have cited Adolf Hitler's decision to make the 262 a fighter-bomber as a boneheaded move that delayed the introduction of a potentially war-winning weapon, but this view is mistaken and unrealistic: Hitler was right in believing that the 262 would be the only aircraft capable of penetrating the air umbrella over an Allied invasion fleet, though it wasn't ready in time, and the fighter-bomber issues only delayed production by about a month. And by that point in the war all fighters were effectively fighter bombers, as the Allies realized that fighters made effective ground attack aircraft and used them to replace dead-end types like dive bombers. Anyway, cutting out that extra month wouldn't have changed the fact that the project was very rushed, such that it really could have benefited from more time in development. And even if the Me 262 had gone straight to fighter units, their primary opponents - the P-51 Mustang and the Supermarine Spitfire - still would have outnumbered them 60 to 1.
  • The Messerschmitt Me-163 Komet, designed by Alexander Lippisch and introduced in 1944, is the only rocket-powered fighter aircraft to have ever seen operational use. Its role was to be an interceptor which could rapidly engage enemy bombers by climbing to 12,000 meters (39,000 ft) in an unheard-of three minutes, and it could reach more than 1000 kph (621 mph) in level flight, the first piloted aircraft to ever do so. However, there were a bunch of problems. First, the sheer speed and altitude. It flew so high that pilots were required to eat a special diet to reduce intestinal gas, and so fast that they couldn't accurately hit bombers with their low-velocity, short-ranged cannons. No pilot ever scored more than one victory with it. A promising solution to the high-speed targeting problem was a bank of ten single-shot, upwards-pointing cannons that would fire automatically when a photocell detected the silhouette of the bomber above it, but this was seemingly only used in combat once. Secondly, it burned up all its fuel in just seven and a half minutes. It could only be used for point defense, and it was defenseless while returning to land since it turned into an unpowered glider after the fuel was gone. Thirdly, it was extremely unsafe for both pilots and ground crews. The rocket engine used two highly-corrosive fuels called C-Stoff and T-Stoff that violently combusted upon mixing, and since they were both clear fluids that couldn't be easily distinguished from one anther, there were separate refueling teams for each fuel who were never allowed to be near the aircraft at the same time. The fuel tanks and other systems would be regularly flushed out with water to prevent accidental explosions. However, even these measures didn't prevent occasional detonations on the tarmac. Moreover, the Komet had a habit of spontaneously exploding if jarred too much by, say, a rough landing. The plane was made of wood to keep the weight and costs down, and while it had wheels when it was going up, they broke away from the aircraft as it took off. What did you land with? A single skid. The "best" part was that at this stage of the war, even flat runways were in short supply, so the pilots had to land them in bumpy, rocky fields. The whole idea was so poorly worked out that there were multiple incidents of these aircraft destroying themselves on takeoff with their own launch wheels. Because of the poor fields they were taking off from, it was entirely possible for the rubber-tired take-off wheel assembly to bounce higher than the altitude it was dropped from...and smash into the plane, often resulting in a catastrophic explosion. More pilots died trying to fly/land these things than in combat. Oh, and the engines were considered more valuable than the pilots. What does that tell you?
  • Around the end of World War II many rather impressive prototypes of fighter and bomber aircraft had been designed by various American and Russian manufacturers. Innovative uses of old technology (for instance, contra-rotating propellers) made them fast and powerful; sadly, the innovative use of new technology - namely the jet engine - resulted in aircraft that were even faster and more powerful, but also more efficient and less maintenance intensive. Needless to say, this doomed all the new piston-engine planes into never leaving the prototype stage.
    • Related to the above is the turbo-compound engine. It was a late development that used a turbine placed at the end of the exhaust that would recycle power wasted by the piston engine and add it directly to the driveshaft. The engines thus obtained were very powerful and efficient, but were both maintenance-intensive and impractical: the bigger the turbine was the more efficient the engine became, until someone eventually figured out that you might as well leave the piston engine out altogether and simply use the turbine as a turboshaft.
      • The turbo-compound could make a comeback. The problem was it put a lot of stress on exhaust valves which would fail and their shards would take out the turbine. A lot of the power that could potentially go to the turbine was also absorbed by those valves. However, if used on a Wankel rotary engine, which has no exhaust valves, turbo-compounding could potentially make a Wankel engine that runs on automotive unleaded gasoline provide fuel economy and horsepower competitive with turboshaft engines, but without the turbo-lag.
  • The jetpack, sadly, turned out to be this. Starting with the Germans in the later years of WWII, several nations attempted to build a practical jetpack for military purposes (though contrary to popular belief, the earliest designs were intended for short jumps rather than sustained flight - just enough to bounce over a minefield or quickly cross a river). And sure enough, many of the designs did work, they were just too impractical. The engines were incredibly loud, they could only fly for a short time (20-30 seconds), and the pilot could get a nasty burn on his legs if he wasn't careful (not to mention he could break his legs if he wasn't careful coming down). Ultimately all the military applications jetpacks might have had could be done using easier, cheaper, and safer (though sometimes slower) methods. So while working jetpacks do exist, barring a revolutionary new discovery in small-scale rocket propulsion they are doomed to an eternity as scientific curiosities.
    • Perhaps, however the worst part of this all is, towards the end of its testing life, improvements were starting to be made that could have made it practical enough to regain the Army's interest. Unfortunately, the mind behind it all, Wendell Moore, died due to complications from a heart attack, and the concept died with him.
    • The '50s and '60s also saw the US military experiment with one-man helicopter-like flying platforms, which likewise proved possible but not practical. They could stay aloft longer than a jetpack, but only introduced a new problem: soldiers floating above a battlefield are little more than horribly exposed targets begging for someone to shoot them. Old-fashioned ground based infantry at least have the luxury of taking cover behind something.
  • This was the US Army's evaluation of the Sopwith Camel during World War I. While very agile, the Camel was unforgiving to inexperienced pilots, and the Gnome Monosoupape rotary engine had a variety of quirks and shortcomings of its own (which the Americans were very aware of from operating the Gnome-engined Nieuport 28). If not properly handled, the Gnome could burst into flames. Instead, the US Army Air Service opted to adopt the SPAD S.XIII, a less agile but faster French fighter plane, for most of their front-line units.
  • The FIAT CR.42. The best biplane fighter ever built, it was very manouverable (even for a biplane), and was remarkably fast and tough, for a biplane. It entered service in 1939, when monoplane fighters had got much faster, tougher and better armed, and once their RAF opponents adapted to them all they could was to fight on as a monoplane replacement was put into production.
    • The experimental CR.42DB variant, fitted with a Daimler-Benz DB 601A 1,200 hp engine, could reach the speed of 525 kph, making it the fastest biplane ever flown to this day. It was still an open-cockpit biplane, and still slower, frailer, and less armed than its monoplane opponents, resulting in it remaining a one-shot prototype.
  • The Yokosuka MXY-7 Ohka, whose name means "Cherry Blossom", was a rocket-powered suicide aircraft developed by the Imperial Japanese Navy later in World War II. On paper, it could carry three times the bomb load of a conventional kamikaze or conventional light bomber aircraft, and could very well sink a US aircraft carrier or destroyer in one hit,note  as well as evade American Anti-Air fire and enemy fighters once its rockets had been switched on. However, because its solid fuel rockets burned up so quickly, it had to be carried within 37 km (23 mi) of its target by a G4M "Betty" bomber specifically modified to carry it. This bomber, already lacking in armor and protection for its crew, was vulnerable to American fighters patrolling the skies, and these bombers were usually shot down miles from the US fleet as a result, usually with the Ohkas still in the bomb bay. Only seven ships were successfully sunk or damaged by Ohkas.
  • The F-14 Tomcat. Though undeniably an incredible interceptor and quite solid in the air superiority role, the early-model Tomcats were plagued by the craptastic TF30 engines salvaged from the failed F-111B project, which flamed out for any reason at all, and were also big and expensive. The vaunted Phoenix missiles also had weight issues, and were not of much use against maneuvering targets. Worse, as the years went on, the effort of keeping them running rose to unreasonable levels; according to former Navy veterans, Tomcats would frequently fly without a functioning radar, just because it was such a pain to keep running. Add in a lack of upgrades (the best it got were better engines and then new avionics), and the Navy was probably not sorry to see it go in 2006. In addition, the Tomcat has the dubious honor of being the last major warplane deployed before digital fly-by-wire controls revolutionized the entire fighter concept; new planes such as the F-16 and F/A-18 blew away the Tomcat in the maneuverability department. Also, the AEGIS radar present on all new American destroyers and cruisers has rendered the "fleet defense interceptor" concept obsolete.
  • The Mi-24 "Hind" is one of the most iconic military helicopters of all-time. It was designed to have the weaponry of a gunship, the armor of a tank, and on top of all of that the ability to transport a squad into battle. In practice, the latter feature isn't as versatile as it sounds. Carrying infantry means having a large amount of extra weight, which limits its maneuverability, along with adding an extra distraction when maneuvering or taking fire, while its capacity of eight soldiers is on the low end of transport helicopters. It isn't too surprising that its successor, the Mi-28 "Havoc", drops the troop transport ability entirely in favor of a streamlined attack helicopter design.

    Artillery, Missiles, and Small Arms 
  • Dragon's Breath shotgun shells. Imagine a shotgun that shoots fire. That's what a dragon's breath shot is. It's also incredibly expensive, costing anywhere from one to five US dollars per shell, and that's if it isn't banned outright, due to the inherent fire hazard of the rounds. Dragon's Breath rounds can also only be used in pump-action shotguns, since the recoil on the shells isn't sufficient enough to auto-load the next shell in an automatic shotgun. There's no record of them being used in actual combat, because regular shotgun shells would do just fine for lethality, and there's less chance of setting the whole room on fire. But most importantly of all, it fouls your shotgun's barrel after just a few shots.
  • Flamethrowers. It was an ideal weapon for WWI and WWII that could quickly torch infantry, bunkers, and vehicles while also having the psychological effect of producing the hellish images of burning people screaming in pain. However, the weapon was eventually phased out since the Vietnam War for several reasons. First, it was a heavy weapon that weighed down the user and turned them into a highly visible target. Second, while its range isn't as atrociously short as depicted in the media, it still wasn't effective for long range engagements. Third, the weapon couldn't be safely stored in such a way that it would not explode if hit by an explosive or incendiary projectile. Finally, even its psychological advantage has its own downside; since flamethrowers were so terrifying, their users were always the first to get targeted. Incendiary rockets and grenades have since been tried as more practical alternatives, although some of these have their own problems.
  • Machine pistols in general. A machine pistol is a small submachine gun using a small-size pistol cartridge and capable of being fired using only one hand. Unfortunately their lightness and handiness is at the same time their undoing. They are usually horribly inaccurate and their rate of fire is so great that they easily spray the whole magazine empty with just one squeeze of trigger (assuming the user is stupid enough to yank hard first). One of the most famous failures is Ingram MAC-10, whose immense rate of fire (1200 rounds per minute) and flimsy stock made the weapon so inaccurate it was nicknamed as "bullet sprayer". But, hey, they can be fun! Just look at the Trejo machine pistol, a Mexican Colt 1911 look-alike with a 7-shot magazine of 22lr. Just good enough for giggle-factor...
  • The Nock Volley Gun, a smoothbore flintlock small arm with seven barrels, designed to be fired from the rigging of Royal Navy warships during The Napoleonic Wars. Unfortunately, it turned out most men weren't big or strong enough to fire it without a) being thrown violently backwards by the recoil, b) falling off whatever high place they were firing it from, c) having their shoulder shattered, or d) all of the above. It also took freaking ages to reload, even by the standards of the period. Moreover, because of its enormous muzzle blast, it also had a tendency to set nearby ropes and sails aflame.
  • The Imperial Japanese Type 97 20mm automatic anti-tank cannon, despite its name, was actually a semi-automatic anti-tank rifle. Relatively powerful for a weapon of its class and possessing a high rate of fire to boot, it was also one of the heaviest anti-tank rifles ever made, weighing an unwieldy 50 kilograms unloaded, requiring at least two people to carry it around. This went up to as much as 68 kilos when fully loaded and equipped with accessories.
  • The rubber-band Gatling gun. The ultimate in rubber band small arms technology, it can fire over a hundred bands in a matter of seconds. Unfortunately it costs $500.00 (not including shipping), takes around half an hour to load, has a tendency to jam if not loaded very carefully, and is horribly inaccurate.
  • Ironically, the actual Gatling Gun was viewed as being this when it was first developed, although it has since been Vindicated by History. With the American Civil War underway, military quartermasters already had their hands full trying to develop logistical standards for weapons and ordinance. They simply did not want to deal with another weapon with its own unique set of ammunition and upkeep needs.
    • One of the more notable people to hold this viewpoint of Gatling Guns was General Custer. Custer in general, valued mobility highly, and when given the option to have them present at what would become known as his last stand, he rejected not just Gatling Guns, but artillery in general as they could not fight on the move. It's debated on how much of a difference they would've made in the Battle of Little Bighorn (AKA Custer's Last Stand), with one side saying that they would've saved the day, while the other side saying that they wouldn't have made a difference fighting Indians. That the Gatling Gun in Custer's unit was really heavy and required a minimum of two people to operate it didn't help him, as it would have become a stationary target for Sitting Bull's men.
  • The Gyrojet gun fired tiny rocket-propelled bullets and was cool enough to showcase in the Bond film You Only Live Twice, but rocket propulsion caused problems. Rather than starting fast and slowing down, it started slow and built up speed. This meant that within a certain range, the bullet would not be moving fast enough to do any significant damage to anyone with body armor, and it was allegedly possible to prevent the fired projectile from leaving the barrel just by covering the end of it with your bare thumb, but this was debunked when a test showed that the projectile left the barrel with enough momentum to puncture a plastic bucket at the muzzle of the tube (and even then, the projectile is red-hot by that point, meaning you'd burn your thumb to a crisp if you attempted to stop the rocket). They were also both more difficult to manufacture and much more expensive than conventional bullets, costing several dollars per round. Finally, air turbulence resulting from the transition from subsonic to supersonic speed effectively destroyed its accuracy. So, lack of power at short range, and lack of accuracy at long range. While later designs have ameliorated some of these problems, they remain more curiosities than practical weapons.
  • Other types of WMDs fall victim to this as well. If you use chemical weapons on the battlefield, you automatically allow counter use... and there are a LOT of countries with covert or open stocks of chemical weapons. The standing policy of the United States (which no longer has chemical weapons in its arsenal) is that any WMD attack will be responded to in kind - i.e., with nuclear weapons, the only WMDs America still has.
    • Of course, that doesn't mean the US isn't willing to allow their allies to use chemical weapons themselves. During the Iraq-Iran war, the US supplied Iraq with the technology to make chemical weapons.
    • Hitler specifically forbade the use of chemical weapons in WWII (despite having a very large stockpile of the chemicals) because he himself was the survivor of chlorine and mustard gas attacks, and if the Germans used them then the enemy would be used in kind, and Hitler didn't want that kind of horror to be inflicted upon a human being. Didn't stop him from using it on the Holocaust victims as he didn't see them as human.
    • Sure, it's possible that Hitler's reluctance to use chemical weapons was a rare, self-centered mercy based on his own war experience. It's more likely, however, that Germany avoided combat use of chemicals because their logistical transportation was still heavily reliant on horses, compared to other belligerent nations with much greater production and/or imports of trucks. German supply lines would have been terribly vulnerable to any kind of chemical retaliation.
  • The third type of WMD that has been developed, biological weapons. All sides had operational weapons before the end of WWII (anthrax for the US weapon, and Plague-bearing fleas that could be dropped from a bomb casing for the Japanese one). These theoretically might have been more devastating, and certainly anthrax could have been more persistent, than the nukes actually used. However, in practice they proved to be absolutely unreliable, as the stresses and conditions of deploying them tended to kill both the vectors (such as infected fleas) and the disease microbes themselves. And even in the cases when the weapons were successfully deployed (like Unit 731 did in China), they usually managed to devastate a couple of villages at most. And the strict wartime quarantine measures, available under martial law, were later shown to be very effective in successfully stopping the epidemic, negating the very reason of the weapon's existence. US learned this from captured Unit 731 members after the war, and quickly abandoned the concept. The Soviet Union toyed with the idea much longer, up to the very end of the Cold War and tried to overcome these shortcomings, but without much success.
    • Also, unlike conventional weapons, there's often going to be a chance that the disease will spread to your own soldiers or some neighboring allied countrynote .
    • Developing and testing these weapon can also be an own goal. Even into the 2000s, one remote island in the Western Hebrides of Scotland was still too dangerous for humans to even briefly visit, because of its use in WWII as a test-site for biological weapons such as anthrax. The issue of cleaning it up still persists nearly eighty years on.
  • Among nuclear weapons, atomic bazookas are the least useful and most hazardous. During the 1950s the United States developed the Davy Crockett recoilless rifle which can fire low-yield nukes (think the Fat Man launcher from Fallout and you get the picture). As cool as the idea of a man-portable nuke may seem, it was rendered useless by the fact that the weapon's fallout was wider than its optimum firing range. So if it were ever fired, the users would almost certainly die from cancer caused by the weapon's fallout, making it effectively a suicide weapon. Fortunately, it was never used in combat since it would probably inflict more harm on its users than its target.
  • Going cyclic. Dumping your magazine with fully automatic fire is seldom good for anything other than making a lot of noise. It's useful in some situations for suppressive fire, such as when the unit is at risk of being overrun, necessitating dumping as many rounds as possible downrange. With weapons not placed on some sort of mount or chassis, it's a great way to waste most shots after the fourth into the wild blue yonder at anything beyond short range. Not to mention overheating and jamming your weapon which can potentially lead to a catastrophic failure.
    • Standard NATO practice is to almost always use only semiautomatic fire. Makes one wonder why they bother with installing the burst fire and full auto capabilities to begin with.
      • Because while often inefficient, when it gets down to it, full auto cyclic fire is often effective, especially when used judiciously - a "mad minute" can have longer lasting suppressive effects, and enhance sustained fire later. Burst fire settings may actually be more correct - while trying to find a good compromise between full auto suppression and semi-auto accuracy, they end up not giving enough rounds to properly suppress, and ruining the accuracy of a single shot.
  • Project Thor, aka "Rods From God". A platform in orbit firing kinetic-energy projectiles at targets on Earth. Sounds awesome, right? Well, not so much:
    • It takes about 15 minutes from firing to impact, but about 50 minutes (on average) to target.
    • Everyone would know exactly where a launch platform is at any instant, what it could possibly hit, when it fires, and once it fires determine very quickly what it's firing at.
    • Due to the plasma sheath that forms around a projectile entering the atmosphere, the projectile can't use sensors to retarget itself.
    • Finally, the dealkiller: the amount it would cost in money, energy and resources to put enough weapons platforms and projectiles in orbit to make Project Thor effective as a weapon system would buy more than enough existing and conventional weapon systems and launch platforms (which have more flexibility) to make project Thor utterly pointless to have, except when conventional weapons can be easily shot down or fooled by countermeasures.
  • The AN-94 assault rifle, originally intended to replace the AK-74 as Russia's general issue rifle. It is extremely accurate even in burst-fire mode thanks to a system that puts out both bullets before the recoil even affects the shooter's aim. However, it is prohibitively expensive and its internals are much more sophisticated than the AK-74, relegating it to Special Forces use. The complexity also meant that certain jams are extremely difficult to clear, not what you want in combat. A great example of such a jam can be seen here.
  • The German Schwerer Gustav and Dora Gun were railway siege guns, and the two biggest artillery weapons ever. Designed specifically to destroy France's Maginot Line forts, the guns weren't ready at the time of the Battle of France, which at any rate ended up completely bypassing the fortifications altogether thus eliminating the need for the guns in that campaign. The Schwerer Gustav was used to very good effect in the siege of Sevastopol, but only fired 48 rounds before wearing out its barrel. The Dora was only deployed briefly against Stalingrad, but quickly withdrawn when Soviet encirclement threatened. These guns were also awesomely impractical when it came to manpower. It took the equivalent of an entire regiment just to man, move, fire and maintain one single gun.
    • In a sense though, Gustav and Dora were actually practical in that they were in effect the only weapons ever created that could breach some of the targets they were used against, in the case of the siege of Sevastopol. Many targets within the city such as the White Cliff ammunition magazine underneath Severnaya Bay were literally immune to any other weapon, and had those targets not been destroyed the siege of the city might have taken even longer then it had, tying up the Germans for a greater period of time and contributing to a hastier collapse. Think of it like this, what's more helpful to you when you need to tighten a bolt: A big expensive wrench that fits the bolt, or a bunch of small inexpensive ones that don't? While the situations where the 80cm guns were of use were limited, they did exist and there was a military requirement for a gun that could penetrate such massively hardened targets, and while Gustav and Dora were expensive and required a great deal of time and manpower to manage, they did ultimately do those jobs adequately.
    • The Dora is vindicated in the first Worldwar novel by Harry Turtledove, where it's used to take out two Lizard Folk starships parked in Ukraine (one of which just happens to hold most of their nukes). The thing only manages to fire two shots, though, before being blasted by the lizards' air force. It doesn't help that it takes about 30 minutes to reload.
    • The railway guns were also so large they couldn't use existing rail lines when emplaced, unlike normal railway artillery which could either pivot on its carriage or would simply use an area where the rails curved and move forward or backwards to adjust the aim horizontally. Custom rails had to be built wherever the guns had to be set up, using dual sets of tracks in a curve. When broken down for transport, the gun was moved in a train of 25 cars length on conventional tracks.
  • The V-2 rocket, a single-use weapon that cost a fantastic amount of resources per shot, and, thanks to careless use of slave labor, still the only weapon that killed more people on its own side than enemies. But since the slave laborers were also considered enemies, it still sorta worked from the Nazis' perspective.
    • The main problem was the guidance system, which often failed to hit any of the Britain Isles, if it didn't crash into a German town first.
      • Later it turned out that the guidance system design was basically pretty sound — the missiles' lack of accuracy were largely the result of the deliberate sabotage of the concentration camp prisoners that built them. Boris Chertok, a Soviet rocket scientist and influential chronicler of The Space Race, who worked at their Mittelwerke production site shortly after the war, noted that the workers learned to make unreliable solder joints and similarly cripple other parts so that they looked and worked fine on the initial inspection, but basically shook themselves apart due to stresses and vibrations during the flight. Another issue was that the German spy network in Britain used to report the missiles' accuracy had all been converted to double agents by the British, so when V-2s would land accurately, they would send back false reports to Germany that the missiles weren't aimed far enough, causing the Germans to "correct" the problem and end up overshooting.
      • Another problem was the decision to steer the missile by the "gas rudders" — graphite vanes placed into the nozzle that directed the exhaust flow. These were fragile and unreliable all by themselves, and were quickly replaced by vernier engines of pivoting (gimballing in the engineering parlance) the whole combustion chamber and nozzle assembly together both on the Soviet and the American designs.
      • As if all this wasn't enough, the V-2 was intended as "Vengeance" for Allied bombing, and so it was fired primarily at London, rather than at the Western Allied beachheads in France, which were often chock-full of vulnerable supplies.
    • The V-2's big brother, the A9 - which, fortunately, never left the planning stage, though it did come worryingly close to actually being prototyped - was much bigger, and intended to strike the US after an intercontinental flight. It would have been so expensive as to make the V-2 look like a bottle rocket in comparison, especially as it would have required an even more massive booster stage to get the required range. Such a booster, the A10, would have used six V-2 engines. The engineers realized that if they couldn't get precise targeting from V-2s there was no way it could be achieved over such long distances, so it was decided that the second stage would be manned. The pilot, had he managed to eject, wouldn't have had much of a chance, as he'd be parachuting into enemy territory. The Nazis even built test sites for this behemoth, but none were ever produced.
    • And then there was the A11, which was intended as yet another stage for the A9/A10 combo, and would have used thirty-six V-2 engines. This three-stage monster was intended to target Japan, but the technology of the time would have limited the payload to... 300 Kg. For comparison, WWII-era general-purpose aircraft bombs - certainly capable of causing serious damage, but of little threat singularly - commonly had a weight of 500Kg, and often more. So Germany would have expended huge amounts of fuel, metal and man-power to deliver a payload that would have, possibly, destroyed one or two buildings. Nor did Germany, which was at the time allied with Japan, have any actual desire to attack them. Not surprisingly, this one didn't even leave the drawing stage.
  • The V-3 artillery cannon, which was a massive 130 meter long cannon originally designed to bombard London from across the English Channel. While the gun could actually be fired, it was horribly unreliable since it used a series of controlled explosions to propel the projectile instead of a single explosion. This also made the gun prone to exploding, which is what destroyed the prototype. The guns also could not be turned or moved in any way, though given that they were intended to fire at cities (which by definition also cannot be moved) this was considered unimportant, but it meant that the V-3 guns were incredibly vulnerable to air attack. The intention was that the V-3s would fire 24/7, each one landing a 140kg shell in London every 12 seconds. While each individual shell wouldn't do much damage, an actual sustained bombardment would have completely shut the city down since it would never be safe to leave the bomb shelters. In practice, they never achieved such a sustained bombardment and the V-3 guns aimed at London were destroyed by Allied bombers before they could even be fired. A second set of two V-3 guns managed to shell Luxembourg during the Battle of the Bulge, but failed to do any significant damage and amply demonstrated why the original plan never would've worked even without the Allied bombers destroying the guns. Over five and a half weeks, they managed only 183 rounds fired (a far cry from the intended rate of fire) and only 44 of them were confirmed to actually hit the city, killing only 10 people and injuring 35. In addition to the inherent technical problems with the design, the Luxembourg bombardment was impaired by severe ammunition shortages due to the German railways being under constant air attack. This resulted in the gun crews improvising a much smaller 95kg sabot round containing only 9kg of explosives.
  • The Karl Device. Have a look. The second largest calibre weapon ever fired in war, one shell weighed two tons, and each launching platform weighed 124 tonnes. Could only be effectively moved by rail, and was almost useless as tactical weapon. But two tonnes of explosives.
    • Here is what it looked like when it hit the old offices of the Prudential Insurance Company in Warsaw. Here is a picture of a dud shell. One was also used during the Siege of Brest Fortress, where the shockwaves from the impact could travel through metres of concrete and still be lethal.
  • One of the weapons the Ottomans brought with them during their siege (and eventual conquest) of Constantinople was Basilica, a 27-foot long cannon that could launch cannonballs as heavy as 600 pounds up to a mile away. It probably didn't see much action due to a lack of effective ammo to get the desired results and required 60 oxen to drag it from place to place. It also took three hours on average to reload, giving the Byzantines a chance to repair the damage between each shot.
  • The XM29 OICW. It was a standard 5.56mm assault rifle with a 20mm grenade launcher that had programmable airburst grenades. Issues came about due to weight,note  cost,note  and the ineffectiveness of both the 20mm grenadenote  and the rifle itself compared to the M16A2note . The grenade launcher part did manage to spawn the XM25, using a larger and more effective 25mm grenade, which saw continued testing and some actual service, before reliability issues and lawsuits between the people who were supposed to produce the weapons saw the project finally die in 2018.
    • The South Koreans actually managed to salvage the design in the form of the Daewoo K11, a combination of a 5.56mm assault rifle and a 20mm bolt action grenade launcher, with such features as a ballistic computer, thermal viewing capabilities and an effective engagement range of 300 meters, all while weighing 6.2 kilograms while unloaded. It was apparently tested in Afghanistan and while initially showing some serious defects (most notable defects with the striking mechanism and the barrel moving during firing) DAPA managed to repair these and the weapon is now fully functional. It has actually been successful enough to get export requests from several other countries, most notably the UAE and Saudi Arabia. Not so impractical after all. But South Korea makes no pretense that the K11 is suitable for replacing standard infantry rifles, as the US tried to do with the OICW program; it's a specialist's weapon, issued to a couple of grenadiers per squad. What's impractical in one role can be quite practical in a much smaller one.
  • Arguably, a lot of the weapons in the US Army's Advanced Combat Rifle program could fall into this by the sound of it. Varieties include stuffing two bullets in a single cartridgenote , making cartridges shorter by packing the gunpowder on the side, flechette riflesnote , and caseless ammunition weaponsnote . Unfortunately, none of these weapons produced results that were significantly better than what was available at the time. It didn't help that this program was obsessed with smaller ammunition that didn't perform any better all for the sake of More Dakka (though many rounds, such as the 4.7mm round, were also designed with armor penetration in mind, and the thinking was that even if the bullets were individually less lethal the sheer number would make up for that). Oh, did we mention that the program wasted over half a billion dollars in the process of proving that US Army Ordnance couldn't properly design a rifle?
  • The XM214 Microgun. Intended to be a man-portable version of the M134 Minigun, it was scrapped when someone figured out two simple facts: 1) the combined weight of the gun, battery and ammo pack were still too much for any soldier to carry, and 2) such a huge amount of firepower is rarely actually needed - normal machine guns provide more than enough for the vast majority of purposes.
  • In the great Soviet tradition of moar firepower, the Soviet army designed their rotary cannons (the GSh-6-23 and GSh-6-30) differently than the US: instead of being powered by electric motors, they ran on the gas they themselves generated, which made them very fast to spool up and ridiculously dakka-capable. It did, however, come with a few slight issues: because they were adapted from the naval CIWS guns, the massive recoil and vibration, while quite acceptable for the much more massive ship installations, were putting so much stress on airframes that stress fractures and breakage of minor systems was practically a given (they had to install powerful lights near the landing strips, because the aircraft's own landing lights would almost invariably break upon firing of the gun), and not-so-minor ones like the landing gear or, in one case, the entire control panel would sometimes break as well. Oh, and a full magazine would be exhausted in less than two seconds of fire. And shells would occasionally rupture prematurely and damage the firing aircraft. And the cannon could be fired no more than ten times, because it was ignited by pyrotechnic charges. As a result, the final generation of Soviet fighters (and the post-Soviet Russian designs to date) have reverted to a single-barrel cannon (and repurposing the pyrotechnic charges of their rotary cannon to give the GSh-301 the unique ability to unjam itself in the event of a dud round).
  • In general, automatic combat shotguns. Weapons like the H&K CAWS, USAS-12 and the AA-12 are typically designed for close-quarters engagements in built-up urban or thick jungle/forest areas. However, where they have raw firepower, they lack versatility. With the military, shotguns are largely relegated to the role of door breaching and lack the versatility to quickly adapt from a close-range to medium-range threat like a rifle or carbine (requiring unloading and reloading with a different shell type for the new purpose - the CAWS program was actually brought to a halt partly because someone asked what exactly a soldier was supposed to do if they encountered an enemy further away than the 100-meter maximum range intended for the weapon). For the police, that much firepower is simply overkill, and private citizens who want to own one have to go through a mountain of expensive paperwork.
    • The Mk3 Jackhammer never even got as far as most of the others (which are available for purchase): designed as one of the very first automatic shotguns, the Jackhammer was weighty, inaccurate (which is saying something when you're talking about a shotgun, which with normal buckshot is supposed to use less-than-perfect accuracy as an advantage), and most damning of all, could not be actually be fired in full-auto. The weapon was very quickly scrapped, and only a dozen or so prototype versions were ever made, maybe two of which were actually capable of full-auto fire (and even then they'd immediately jam after one or two shells). There were also plans to make the magazines work as an anti-personnel mine with the addition of a detonator, but that too never got further than a mock-up of a slightly-modified magazine. But that being said, the Jackhammer had a devastating rate of fire and a surprising range when it did work.
  • The Heckler and Koch Mk 23 pistol. It's a match-grade-accurate, very reliable and durable handgun developed for Special Forces use. It is capable of making a 2-inch group at 27 yards and has exceptional durability in harsh environments, being waterproof and corrosion-resistant as well as being capable of firing tens of thousands of rounds without a barrel change. The .45 ACP round has considerable stopping power and yet is subsonic, making it suitable for use with a suppressor. However, since the design priority was using the pistol as a primary weapon instead of as a secondary or fall-back weapon, the thing is five pounds and sixteen inches long when loaded and outfitted with all the trimmings (specially designed suppressor and laser aiming module). To compare, the Desert Eagle, the king of Awesome, But Impractical handguns, is almost four and a half pounds loaded, and almost eleven inches long. No operator wants to carry a sidearm that weighs as much loaded as an unloaded MP5, and so H&K quickly designed and released the USP series of handgunsnote  which retain most of the good qualities of the Mk 23, but with less weight and bulk; the USP Tactical in particular does pretty much everything the Mk 23 does at two-thirds of the weight or cost and in three different calibers, thus leaving the Mk 23's civilian version to end production.
  • The M16, when first used in Vietnam, was supposed to represent the pinnacle of the modern assault rifle. It was made of lightweight polymers which reduced the rifle's weight tremendously while still giving the user the option of automatic or single shot fire, decent penetration for its weight, and a number of other features which are now standard design elements. However, cost-cutting measures (particular removal of chrome-plating in the bore) and a supply issue with the powder used with the ammunition it was tested with and designed for lead to a switch late in the game that led to corrosion and jamming issues in the field. While quickly fixed (as in by 1968) by the improved M16A1, and evolving into a top-class assault rifle in the M16A4, the reputation lingers, particularly among those that have never used one.
  • The immediate predecessor and the rifle the M16 replaced, the M14, was also an example of this. The M14 was a far more traditional rifle than the M16, with a body made of wood, mechanisms based on the M1 Garand rifle and firing a full-sized rifle round (the NATO-standard 7.62x51mm round). Unlike the Garand, it was selective-fire and could fire on full auto as well as semi-auto. The idea of the rifle was to replace several semi- and fully automatic weapons systems with a single do-all weapon that could reliably engage a target at any possible range. The fact that it was a more "traditional" rifle compared to the M16 also meant it was more widely accepted by the old guard of the U.S Military. However, it proved to be very flawed as a general infantry weapon. For starters, the M14 is two pounds heavier than an M16. Its ammunition was also heavier than an M16's, with the same amount of ammo becoming a much greater burden for a soldier trudging through Southeast Asia. The heavier round also resulted in heavier recoil, which made the M14 extremely inaccurate in sustained automatic fire. Finally, in attempting to be a do-all weapon system, it had failed to surpass any of them. It was too light to be a squad automatic weapon, too heavy to be comparable to a submachine gun and one Department of Defense report went so far as to call it "completely inferior" to the M1 Garand. The only real improvement was that it used a detachable 20-round magazine instead of feeding from 8-round clips like the M1... and John Garand had already designed a modified M1 using BAR magazines of that capacity before anybody thought of the M14. Most damning, the Springfield Armory could not produce it in the numbers needed for mass adoption (breaking a promise that had effectively sold the weapon over the FN FAL and thus gave the Pentagon the excuse it needed to not buy a foreign rifle; units in Vietnam were still equipping the M1 at the time of the M14's replacement). Eventually, the M14 was completely replaced as a frontline general-issue infantry weapon. It was however later modified into several designated marksman's rifles like the M21, a role it has proved to be much more capable in.
  • In general, drum magazines tend to be this when compared to either traditional rifle magazines or a belt feed system. While they hold more rounds than a standard rifle or submachine gun magazine, and load faster than a belt feed system, they are also heavier than the former and a lot more finicky than the later. Because of the weight, a soldier could only potentially carry one or two. They can be reloaded by hand, but as you can imagine, reloading a 50-, 70- or 100-round drum magazine by hand takes a pretty long time. Finally, they have a tendency to jam. That's why almost every firearm originally made with a drum magazine either had a traditional magazine made for it later or was adapted for a belt-feeding system, and why the G.I. issue version of the Thompson submachine gun cannot load drum magazines at all.
    • In a subversion, there is one place where drum magazines were better than either detachable box magazines or belt-fed ammunition systems. That would be the magazines for the single barrel 20mm+ wing mounted cannons of WWII fighter and ground attack aircraft. Box magazines couldn't carry enough ammunition and belt-fed ammunition systems often required a complete wing redesign that would have taken several years.
  • The Urumi is an extremely flexible Indian sword, more like a whip that has a sharp edge to it. In the hands of a master, almost no one can get near the user and no parry would be able to successfully block it. In the hands of anyone else, they are as likely to slice their own leg off as kill the enemy. Another downside is that it requires a lot of stamina as swinging it around, even with two hands, is very tiring. There is a reason it considered one of the most difficult weapons in the world to master.
  • Every military weapon made by Italian gun designer Abiel Bethel Revelli di Beaumont, due to different reasons every time. Here's a quick breakdown:
    • Glisenti Modello 1910: the first semiautomatic handgun of Italian make produced first by Glisenti and then by Metallurgica Bresciana già Tempini, it was a cheap and reliable handgun (compared to the Luger P08) firing an adequate proprietary 7.65mm round. When it came the time for the Royal Italian Army to adopt a semiauto, this was the chosen weapon, but at one condition: it would have to fire a 9mm round. Thus MBT redesigned the weapon to fire the proprietary 9mm Glisenti... And that's when the gun becomes impractical: the 9mm Glisenti is a 9mm Parabellum weakened enough to be fired in the more fragile Italian pistol, but aside for that the two rounds were identical, and during World War I Italian troops would occasionally capture Parabellum rounds and, unable to notice any difference, load their handguns with those, with explosive results.
    • Fiat-Revelli Modello 1914: a machine gun, it was a sound design, had an indexing multiple-column magazine that was more reliable than a belt (even if hellishly complex and slow to load without special tools), and, most important, was Italian, thus freeing the Royal Italian Army from foreign supplies that would come either from Britain (at the time an enemy), Austria-Hungary (technically an ally, but a very unliked one that the Italian government planned to betray at the first chance) or Germany (an ally. This one Italy liked, but also knew they'd stay loyal to Austria-Hungary). Less awesome were the many troubles that earned this weapon a place in the Reliably Unreliable Guns page on This Very Wiki and the fact it was adopted over a better Italian design only due the Fiat company political power and bureaucrats screwing up hard while buying Maxims. Its successor, the Modello 1935, was even worse as it frequently overheated and jammed if not oiled.
    • Fiat Modello 1915: AKA the Villar Perosa or, to the soldiers, the Raspberry, Trope Codifier of the submachine gun (and the Trope Maker alongside the German MP18). It was awesome also for other reasons: it was a combination of two independent submachineguns, each gun had an awesome rate of fire of 1,500 rounds per minute (enough it was also used as an aircraft gun), and, firing the underpowered 9mm Glisenti, the recoil was easily manageable. On the impractical side, the magazine for each gun contained a measly 25 rounds (AKA less than one second of fire. That's why the soldiers called it Raspberry), the weak round made it ineffective as an aircraft weapon, and the ergonomy was so bad that you have to wonder how the soldiers managed to fire it while moving (Italian soldiers were very good at improvising).
    • Cannoncino Semiautomatic Fiat Modello 1916: a portable automatic cannon for infantry and aircraft use, firing 25.4mm-caliber high-explosive or AP rounds, with an higher rate of fire than its counterparts from Austria-Hungary and France. As an aircraft gun it failed due excessive weight and the rounds being too slow to hit late war airplanes, and production ended up being cut short when the British (by now allies) noticed it was suspiciously similar to their Pom-pom and threatened to sue.
    • Villar Perosa Modello 1918: AKA the OVP and the Half Raspberry, it's a derivate of the Villar Perosa, taking one of the Villar Perosa's two guns, modifying it to fire slower (900 rpm, still fast but on the high end of current service submachine guns), and mounting it on a spare rifle buttstock. It was a good weapon, apparently pure awesome... Except the young military officer Tullio Marengoni came up with a less expensive way to do the same thing and attach a bayonet to the gun, resulting in the Moschetto Automatico Beretta Modello 1918.
  • Yet another example of the Soviet love of More Dakka, the ShKAS aircraft machine gun. Quite unusually for a 7.62mm machine gun, it functions like much larger revolver cannons to ensure smooth feeding. It also has an unusually light recoiling section, allowing for an incredible rate of fire of 1,800 to 2,000 rounds per minute in the standard model and up to 3,000 RPM in the rare "Ultra-ShKAS" version. That's at the lowest level the M134 Minigun can reach, and with a single barrel. While (like any rifle-caliber machine gun) the ShKAS was shorter-ranged than a .50-caliber one, the ability to put up a veritable wall of lead greatly increased hit probability once the target did pass within its range. The problem was, the ShKAS was described as having 48 ways of jamming, some of which were difficult to clear even on the ground, and the Ultra-ShKAS was even less reliable. It was also very manpower-intensive to manufacture, a flaw that carried over to the otherwise much superior 20mm ShVAK autocannon that was developed from it.
    • Much of its reliability problems stemmed from the very rate of fire it was designed for. Just as an example, the rimmed Russian round required two-phase feeding, first pulling it out of the belt to the back of a weapon, and then pushing it forward into the action. Because of the insane rate of fire, the round was jerked out of the belt with such a force that the bullet would often fall out of it. They had to design a special kind of ammunition with much heavier crimping to fight this problem, but this increased the barrel pressure, leading to a whole new host of reliability issues. On top of this, these special rounds would often mix with the normal ones in the supply chain, causing issues for other guns if they accidentally loaded the ShKAS bullets - but this wasn't so much of an issue because the ShKAS-specific bullets were quite rare, tempting the armorers to load the guns with the normal ones when they weren't available.
  • The Luger P08 is absolutely gorgeous for a handgun, and is superbly machined and precisely fitted. That's why it was a terrible combat pistol for anyone not well drilled on its usage. The toggle action is notoriously finicky if not racked properly (and will injure a person who attempts a rack on the draw), prone to corrosion at sea if not well-maintained, fails to cycle if fed "civilian-self-defense-grade" low-pressure ammunition, and the degree of hand-fitting meant that interchanging parts was practically impossible without the expertise of a proper gunsmith. Additionally, while the Luger was extremely reliable and mud-resistant in the trenches, it was very expensive to produce in large numbers. In both World Wars, the Luger worked fine as an officer's sidearm for shooting prisoners and deserters or as the weapon for specialized soldiers who raided enemy trenches, but it didn't take long for the German army to notice how poorly suited the gun was as a backup sidearm for regular infantrymen, and it was eventually replaced as standard issue by the boxier-looking and less costly Walther P38, which was also quickly adopted by officers as a replacement for the Luger, as the P38 could interchange parts more easily.
  • The Canet 12.6" naval cannon, as mounted on the Japanese Itsukushima-class protected cruisers. Intended to give the ships a gun that could actually tackle battleship armor, it proved not only far too large for the ships, but also abominably slow at reloading, even for the era. In their only battle, it took an hour to reload the gun. Unsurprisingly, the Japanese bit the bullet and bought proper battleships shortly thereafter.
  • The 46cm/45 Type 94, the gun mounted on the Yamato-class battleships, is the largest gun ever put to sea, and the problems mounting it caused the ships is documented above. The gun itself, though, had two major flaws that made them even less practical. Their armor-piercing shells were designed to dive underwater and strike below the armor belt, with the result they had less penetration under normal conditions, which is one reason the American Mk. 7 16"/50 matches it at longer ranges. Further, the Japanese could only reline the guns at such colossal expense that they simply planned to replace the guns entirely when they wore out.
  • Most high-velocity naval guns fall into this category. High muzzle velocity has its benefits - increased range, greater belt penetration, and against lighter ships greater accuracy - but the drawbacks made them very situational based on the navy in question's operational doctrine. That high velocity wore out the guns at alarming speeds, often suffered from decreased accuracy due to the incredible firing pressures, stressed breech mechanisms, and early in the 20th century the guns themselves were too long to hold up, structurally. But above all, high-velocity guns traded in reduced deck penetration at long ranges due to their flatter trajectories. Most of the navies that opted for high-velocity guns expected to fight close to their bases, while Japan, the US, and Britain went for more modest ballistics and sought other ways to improve their guns. See the Italian 15" gun mounted on the Vittorio Veneto classes and mentioned below for a good example.
  • The big Cold War-era Soviet antiship missiles. You know, the ones that are mounted in massive canisters that seem to take up half the ship they're on. Often supersonic and long-ranged with big warheads, they were a constant headache for the US Navy and drove their development of ever-better air defense systems, but... well, look at that description again. These missiles were enormous, and required either equally enormous ships to carry them, or serious compromises in numbers and stability. Now that technology has made smaller missiles with similar capabilities viable, the Russians are replacing these big old missiles as fast as they can.
  • The American RIM-8 Talos Surface-to-Air missile, one of the "Three Ts" that equipped early American missile ships. The Talos had, by an enormous margin, the greatest range of any missile of its era, with equally excellent altitude performance, an 80% accuracy rate, and the ability to carry a nuclear warhead. Unfortunately, they came with a laundry list of issues that drastically reduced system effectiveness. The 7800-lb, 32-foot missiles had to be carried horizontally in massive magazines that ate up so much space that only a handful of cruisers could carry it. The beam-riding guidance system required two massive guidance radars high up in the ship per launcher, and meant only two targets could be engaged at once. And finally, they had a battery that required monthly replacement, and the missiles themselves needed to be tested every two months. And as the final nail in the coffin, unlike the smaller Terrier and Tartar systems, the launchers were incompatible with the later Standard missiles, which meant the ships were obsolete as soon as the Talos was.
  • In World War II, the British and the Germans tried out sticky bombs on the field as anti-tank weapons. They suffered from a variety of drawbacks. Both versions were infantry weapons that required the troops to get within throwing distance of a tank. Whereas the German magnetic version was unable to reliably stick to its target, the British glue version was actually too sticky and could easily attach to the user instead of the tank.

    Experimental Weapons 
  • The book My Tank is Fight! is all about impractical inventions of World War II.
  • Before the first A7V tanks were even completed, Imperial Germany decided it needed to go bigger and ordered the super-heavy K-Wagen, also designed by Joseph Vollmer. This was going to be a true landship: 13 m (42 ft. 8 in.) long and 120 t in weight, with four 77 mm cannons, 7 machine guns, 30 mm of armor, and a crew of 27! It was so gigantic that it was designed to be shipped by rail in six modules and assembled at its destination. The commander would have to give orders to the crew by means of electric light signals, including two drivers who would have to steer blindly based on the signals they got from the commander. Even assuming that it would have been able to crawl along at 7.5 kph without getting stuck or breaking down (in which case they probably wouldn't have been able to tow it away in one piece), it would have been a huge target for artillery and cost so much that they wouldn't be able to afford the loss of one. Two prototypes begun under Hindenberg's orders were almost compete at the war's end, and were destroyed under the terms of the Armistice.
  • Adolf Hitler loved this trope. Here are just a few of the awesome and extremely impractical weapons that never quite made it:
    • If the Tiger and Panther could have been considered Awesome but Impractical, what can one say about the superheavy Panzerkampfwagen VIII Maus? It's 10.2 meters (33 ft 6 in.) long, and at 188 tonnes it's the most massive fully enclosed AFV ever actually built. It was designed by Ferdinand Porsche, so the transmission was—guess what?—electric! The internal combustion engine ran an electrical generator, which sent power to electric final drive motors. It's a cautionary tale about the Square-Cube Law, since the extremely wide tracks and voluminous powerplant required barely fit inside the armored shell: the engine and generator combined took up the central and rear two-thirds of the hull, so that the driving compartment in the front of the hull was cut off from the inside of the turret, while the running gear hogged most of the space underneath. The power-to-weight ratio was a lousy 6.4 hp/tonne: they couldn't get it to go any faster than 14 miles per hour, and the operational range was less than 100 miles despite carrying over 1000 gallons of fuel. A special 14-axle rail transport car of tremendous size was designed for it. Since bridges were out of the question, the planned method for crossing deep rivers was for one Maus to drive underwater with a snorkel for breathing, while a second Maus remained on shore running its generator and supplying the submerged tank with electricity through underwater cables. It was nigh invulnerable to antitank guns because of slab-like armor up to 250 mm thick—including side armor 180 mm thick and side skirts 150 mm thick—but this couldn't change the fact that it would have been a big, slow-moving target for Allied fighter-bombers. The non-removable side skirts made most kinds of track maintenance impossible in the field, and while it could be jacked up to replace a road wheel, one almost wonders if it might have been easier to just dig a hole under part of the track instead. It would have been a disaster if it ever got stuck. As for the armament, while its 128mm main gun was the most powerful of any WWII tank, Hitler personally insisted on another bit of impracticality: whereas rational tank designs usually have a co-axial machine gun alongside the main gun, the Maus also had a co-axial 75mm cannon, the same caliber as the main gun of the Panzer IV. All this really accomplished was to take up space and reduce the main gun's ammo storage to just 32 rounds. And there were persistent worries the design team that Hitler would change the armament again, because of his having expressed disappointment that the 128mm gun, despite its huge size, looked small compared to the even bigger tank. There were two examples manufactured by Krupp and assembled by Alkett, in December 1943 and March 1944, respectively: V1 was a turretless petrol-electric prototype, and V2 was diesel-electric prototype complete with a turret. By July 1944, Krupp was working on four more hulls, but was ordered to halt production and scrap them. A turret was supposed to have been made for V1, but it never happened. The Soviets captured the prototypes after the Germans succeeded in destroying the hull of V2, so they put together the hull of V1 and the turret of V2 to make a complete Maus for testing. It's now displayed in the Kublinka tank museum.
    • The Landkreuzer P.1000 Ratte would have been even more awesome and impractical. A literal landship dwarfing even the enormous Maus in size and powered by U-boat diesel engines, not only would bridge crossings have been completely impossible for the 1000 tonne vehicle (the plan was that it would simply drive though rivers), it would have destroyed any road it attempted to travel on! This tank (if you could even call it that) would have carried two naval guns as its main armament, the same 280mm guns used by the Scharnhorst-class battleships. Its secondary armament was a 128mm gun of the same type used by Maus, the intended location of which is uncertain (variously depicted as mounted in the font hull, in between the main guns in the turret, or on an independent rear turret), and numerous anti-aircraft turrets would've rounded out the armament. Nevertheless, it would have been an juicy target for Allied bombers and artillery which could have killed it outright, or at least disabled it by destroying the constant train of supply vehicles that would have been required to keep it going. According to some reports, the turret for the Ratte was actually built before Armament Minister Albert Speer cancelled the project, and was eventually used as coastal artillery in Norway. Wehrmacht General Heinz Guderian summed up the absurdity of the Ratte nicely, saying "Hitler's fantasies sometimes shift into the gigantic."
    • The proposed Landkreuzer P.1500 Monster took the concept from impractical to nearly-certifiable insanity. A tracked, super-heavy self-propelled artillery piece specified at 1500 tonnes, the aptly-named Monster would have a crew of over 100 and use the Schwerer Gustav-type 800 mm gun as its main armament! In reality the idea that it would weigh only 1500 tonnes was highly optimistic, since the railway gun it was based on weighed 1350 tonnes. What's more, even if it were true that nothing on land could have stopped it, the giant and slow-moving Monster with its large train of supply vehicles would be an almost unmissable target for Allied aircraft. Albert Speer cancelled the project in 1943 before it had a chance to leave the drawing board and waste even more of Germany's resources.
    • Both Ratte and Monster were the brainchildren of Edvard Grotte, the engineer well known for his bouts of gigantism and reliance on the awesomeness to the detriment of practicality. During the times of the Weimar Republic, when Germany and the Soviet Union entertained a brief alliance, both being something of the pariahs to the West, he did some work in Russia, producing several designs for his Russian employers. While the first of them, the unimaginatively named Grotte Tank, AKA TG-1, was a fairly conventional medium that advanced to the prototype stage, generally pleased everyone, and wasn't adopted largely due to the sorry state of the early-Thirties Soviet industry, his subsequent designs were a clear indication of what will then follow. The TG-5 dwarfed even the aforementioned T-35 in its sheer insanity, and was essentially an early version of Ratte, weighing the same 1000 tonnes and boasting 12-inch naval guns. It was to be driven by four marine diesels and to have the 1000 mm frontal armor.
    • The Japanese, whose dynamics with their allies could be sometimes described as "everything that the Jerries can screw up we can screw up better", and their armor department being the proverbial redheaded stepchild of their military industry, produced the O-I, the superheavy tank that might be best described as a lovechild of T-35 and the Maus. Equipped with five turrets with 100-to-150 mm guns, and driven with the two naval diesels, it was to weigh from 100 to 120 tons in its various incarnations, and used for coastal defence and invasion protection. There's very little information on this tank, but at least one prototype was reportedly built in 1944, and sent to Manchuria for trials, where it was reportedly blown up by the retreating Japanese forces during the Russian offensive the next year. The only material remains of this tank are several huge track links in some Japanese armor museums.
    • The Bachem Ba 349 Natter, whose name means "Grass Snake", was a vertically launched rocket-engined interceptor that carried its offensive armament of rockets directly in front of the pilot. Endurance was even shorter than the Komet, but missions ended with the aircraft breaking apart and the pilot being thrown free. So impractical it was never used operationally - and the only manned test killed the test pilot.
      • Because it wasn't already insane enough, the original project (later scrapped) had the pilot expend his rockets on the enemy aircraft, then steer the Natter on a collision course with one of the surviving bombers and only then eject. With any luck.
    • Blohm & Voss BV 40 Glider fighter was proposed to spare fuel and strategic materials for resource-strapped Germany late in the war. By getting rid of the engine and having the pilot lying prone on his belly instead of sitting, they could make the fuselage really narrow to improve aerodynamics and make it a smaller target. The fuselage was made almost entirely of wood. A Bf 109 fighter would tow two BV 40 gliders at once to operational altitude, and the gliders would dive to attack the enemy bombers at high speed with two 30 mm cannons. The wheeled dolley was discarded upon takeoff, so after its brief attack it would have to land on a single skid. Pretty impressive for an unpowered aircraft, but the prone position was uncomfortable and it was dangerous to fly. Seven were produced before the project was cancelled.
      • Related, the Blohm & Voss BV 246 guided glide bomb, which was also designed to be built from non-strategic materials. It never went into series production, but tests showed that it could indeed fly. The awesome part? The use of non-strategic materials...specifically, the wings made of concrete.
    • The Silbervogel bomber, a semi-orbital intercontinental bomber. Too impractical to build at the time, and in any case it would have had two problems: that it would have had a disappointing payload, and that it would have burned up upon atmospheric reentry. The inventor figured out that the thing would never be able to work half way through designing it, but continued to work on it anyway for the insane amount of money the Nazis were giving him.
    • The ne plus ultra of impractical Nazi inventions was the Sun Gun, an idea for an orbiting space station with a giant parabolic mirror made from metallic sodium and at least three square kilometers in area. By concentrating the sun's rays into a focused beam of it could function as a Kill Sat, with the ability to deliver scorching death from space to all enemies of the Third Reich. Fortunately, Nazi Germany didn't have the technology or industry to launch hundreds of tons of equipment and millions of tons of sodium into orbit (even today nothing has been attempted on that scale), and a single mirror might not have been able to concentrate that much energy on such a distant focal point, though perhaps numerous smaller ones could have. Oddly enough, also counts as Mundane Utility: in addition to establishing Nazi supremacy, the designers recognized its usefulness as a weather satellite and communications platform.
  • In 1918, Italy completed two prototypes of the Fiat 2000, a heavy tank weighing 40 t. It had full length tracks, a 240 hp engine, 20 mm of front armor, several machine guns, and a hemispherical rotating turret on top equipped with a 65 mm howitzer. In some ways it was more promising than the comparable A7V, with much better obstacle-crossing ability and an innovative layout, but at an average of 4 kph it was just too slow, particularly when they tried to use it in Libya. It never entered serial production.
  • When Japan began work on copying the Me 163 (based on blueprints and samples provided by the Nazis), they apparently felt that the tendency of the rocket fuel to explode wasn't a bug, it was a feature. The intended use was for each pilot to take a pass or two shooting at B-29s, then ram the next one they saw. The pilot wasn't expected to bail out. Fortunately the war ended before any of these got into service.
  • The Northrop XP-79 was intended to be a rocket-powered flying wing fighter that would destroy incoming bombers by ramming them. (No, they thought of that, it was designed to take the impact without significant damage.) Three prototypes were built, two were abandoned after the rocket engine failed to perform adequately, and the project was entirely cancelled when the remaining prototype, fitted with conventional jet engines (and with the ramming concept abandoned), was lost (and the pilot killed) after an unexplained loss of control during test maneuvering.
  • The Soviet Union/Russia, like the Nazis mentioned above, came up with some impractical gems for battle. In fact, it sometimes seems that the only reason they would design and build these weapons was just to prove that they could:
    • Cast in 1586, the Tsar Pushka/Tsar Cannon is recognized as the largest cannon by calibre, with a barrel nearly 18ft in length and a bore of nearly three feet. However, it wasn't actually designed as a bombard (the mount and shot displayed nearby are decoration made in 1835): its intended purpose was to be the largest shotgun ever made. Mounted on a fortress wall, it was to be loaded with 1,600 pounds of grapeshot and used against attackers. But by the time it was finally completed, the Tatar threat to Moscow greatly diminished and it never had a chance to be used in a battle.note  Still made a neat showpiece, though. In fact, showing off the prowess Russian bronzeworkers was a major purpose from the start.
    • The Antonov A-40 "Krylya Tanka" is... a Flying. Tank. It's a tank with wings. If anyone remembers making paper airplanes as a child, you can understand where the problem comes in. Tanks weren't/aren't designed to fly for good reason: they're heavy and aerodynamically unsound. To actually make it possible for it to fly this stinkin' thing, it was stripped of most of its ammunition, armament, armor, and headlights. This made it less a tank and more of a very heavy and cumbersome armored car that would have had very limited survival once on the ground, let alone still in the air. Only one was made, and in its solitary test, it did in fact fly... but was still far too heavy and overtaxed the tow-plane's engines to the point it risked a fire. The project, not surprisingly, was scrapped afterwards.
    • After limited success with an experiment to create a flying jeep - basically a modified jeep with helicopter rotors allowing it to be towed into the air and for it then to fly under its own power for limited distances - there was serious work done on extending the "flying jeep" idea to a Cromwell tank. This was scrapped on saner reflection when it was realised the rotor blades necessary to support a tank would need to have a two hundred foot span, and at least two heavy bombers would be required, plus a one-shot wheeled undercarriage, to get nearly thirty tons of tank into the air.
  • The Western Allies got in on this, too. Due to the German blockades, the British had a huge shortage of steel during the early part of the war, which was needed to create new carriers and the like. One genius came up with an idea: "Pykrete", a mixture of ice and wood pulp, such as sawdust or even old newspaper, that creates a material stronger not only than regular ice, but still light enough to float and also resistant to melting. Then, make a huge unsinkable aircraft carrier out of the stuff. It never got past a theoretical stage, because the giant refrigeration units that would be needed to produce ice on a scale to build a capital ship would consume just as much steel as one built the conventional way.
  • Project Pluto and the Supersonic Low-Altitude Missile (SLAM). Imagine a cruise missile. Now, imagine that cruise missiles with a ramjet engine powered by a nuclear reactor the size of a locomotive, flying at low altitude to avoid radar at three times the speed of sound, lobbing nuclear bombs at things. In addition to the nuclear bombs, the shockwaves and radioactive exhaust from the engine would destroy, kill and irradiate whatever it flew over. Project Pluto involved the development of a nuclear reactor and engine that could withstand such air pressure and temperatures, a feat achieved through huge experimental efforts and at great expense. Unfortunately, the problem with building a weapon that spews nuclear waste everywhere is that nobody will give you permission to test-fly the damn thing, and your allies might disapprove of it flying over their countries to get to the USSR. Nuclear-tipped ICBMs turned out to be a lot cheaper, a lot safer, and a lot faster. On the other hand, the guidance system developed for it was used in later cruise missiles.
  • The Convair X-6, a nuclear powered bomber. The X-6 had potential if it was practical, such as being able to stay aloft in the air for weeks at a time without refueling. But to shield the crew at a minimal safety level required 12 tons of lead and rubber. There were also concerns about the fact that peacetime crashes carried the possiblity of contaminating large swaths of civilian land, both yours and your allies, not to mention the fact that even the best shielding scheme wouldn't guarantee against the constant emission of hot radioactive byproducts directly into the open atmosphere above everyone's heads. While test flights with an operational nuclear reactor on board were conducted on a similar aircraft as a testbed, the all-nuclear X-6 never got off the drawing board.
  • The Soviets had their own nuclear powered bomber, the Tu-95LAL, which did partly solve the weight problem of the Corvair X-6 by mainly shielding the crew instead of the reactor itselfnote , but while it was more practical (it even flew a couple of times with the reactor on), it still was too large, unwieldy and expensive, not to mention an absolute nightmare to maintain (fix a tire? Step 1: don full radiation gear...) and hugely dangerous in a crash. When the first practical ICBMs arrived, the project was canceled.
  • The nuclear pulse propulsion rocket concept made even the SLAM and Corvair X-6 look sedate and practical by comparison. This design used the periodic detonation of nuclear bombs for launch and forward propulsion. Surprisingly, it might have been quite practical for space travel from an engineering perspective, but it was hideously impractical politically (the nuclear detonations would violate the Partial Test Ban treaty, and that's before even considering public opinion).
  • The Mauler was ahead of its time. Aircraft speed increased and helicopters became a viable threat to armor so the US Army decided to make a mobile SAM system for Forward Area Air Defense (FAAD). The M113 based Mauler would have a radar to track any aircaft so that the fire control would shine a radar beam on the target. The missile would follow the beam and then use IR to finish the job. The operator just had to press a button so the system would do the rest, which piqued the interest of the US Navy and the British Army. The problem? This was 1960 - computers filled entire rooms back then. The radar barely worked, and the missile would fly off course. There were issues with the missiles falling apart or bad rocket casings. The missiles (mounted in a 3 x 3 box launcher) would shake their launcher apart. In the end, the both the Navy and the British Army bailed and the US Army canceled the project.
    • The concept eventually became successful twenty years later with the Bradley Linebacker, which was the same idea, only scaled down. It had the 25mm gun in addition to four Stinger missiles. With it, the Army finally had a FAAD system that could keep up with the M2 Bradley and the M1 Abrams. It even cost the same as a regular Bradley. Problem was, with the Soviet Air Force no longer a threat necessitating its use, it was easier just to use it as a regular Bradley. All were converted by 2004.
  • So far, railguns are much more Awesome than they are Practical. Despite current tests showing that a railgun can fire a 3.2 kilogram/7 pound projectile at Mach 7 speeds, there are still crippling issues with powering the gun as well as the heat from firing wearing it out quickly,note  limiting how useful it would be as an actual weapon. However, the project cost for developing the railgun is a lot lower compared to some of the other examples on this page (along with the finished version expected to a little more damage than a Tomahawk missile at a fraction of the cost), which has seen it survive several rounds of budget cuts.
    • More feasible than railguns are coilguns. Some already exist, as seen here. Coilguns circumvent the projectile-on-barrel friction that is the cause of a railgun's severe firing wear, by hurling a maglev bullet.
  • Not really a weapon per-se, but in World War II, the British experimented with a "Parachute-less Air Drop". Basically, the idea was to use small rocket thrusters to negate the speed at which a supply crate fell from the air, allowing it to safely lower to the ground. Unfortunately, the rockets were very finicky. In tests, they would either activate too soon and thus spend their fuel before they hit the ground, or slam into the ground at near-terminal velocity then fly up into the air, flinging whatever was inside and large splintered timbers about the landing zone. This idea was so impractical, it never got past the 'drop twenty feet from a crane' stage.
    • There was a reason for this: very poor supply of silk in Britain to make traditional parachutes. Other fibers are either too heavy, or too weak, and the three major producers of silk were China, Japan and Northern Italy - all in Axis hands during the war. The large (millions-strong) number of parachutes made for the D-Day airborne ops were made with nylon.
    • Other nations continued the development, though, and similar technology (in addition to conventional chutes, mind you) was introduced by the Soviet Union to cushion the final landing impact of heavy airdropped loads, such as APCs and supply containers. Both the USSR/Russia and the US used it as a last-second landing engine for their space capsules/interplanetary probes, and as recently as August 2012 the US used a pure rocket-engined sky crane to land its latest Mars rover. The newest Russian capsule is also planned to eschew parachutes and land on aerobraking and rockets only, and Elon Musk has declared that if SpaceX's Dragon capsules cannot make a soft landing on Earth using only rockets and aerobraking, the project will have been a failure in his eyes.
  • Project Babylon was Iraq's attempt to build a supergun that would have rivaled the Nazis' V-3 project. The project would have called for the construction of two 1000mm cannons and a 350mm prototype, each 156 meters long. The full size cannons would have been capable of firing conventional shells over 1000 kilometers, or firing rocket assisted shells straight into orbit. The guns' intended uses were to either deliver nuclear, biological, or chemical tipped warheads or to disable enemy satellites. However, like the V-3, the Babylon guns suffered from the drawback of being locked into facing a single direction, as well as being gigantic and impossible to hide. The gun was so impractical the Israelis never considered it a serious threat; after a few shots, the Israeli Air Force would quickly put a laser-guided bomb right down the muzzle. The project ground to a halt after its lead designer was assassinated (whether by Israel or Iran remains uncertain; both were more concerned with his simultaneous work on improving the accuracy of Iraq's ballistic missiles), and the guns were dismantled and destroyed by the UN after the First Iraq War.
  • The Boeing YAL-1 Airborne Laser. Essentially a Boeing 747 with a Wave Motion Gun, designed to shoot down ICBMs with a laser beam during the missile's launch stage. Unfortunately the laser itself proved too expensive and required too much power, plus the massive aircraft would be a sitting duck against enemy fighters (problematic since the laser would need a line of sight to the ICBM immediately after launch, requiring flight very close to the launch site), and the project was cancelled.
  • The so-called Tumbleweed Tank, proposed by Texan inventor A. J. Richardson in 1936, would work like a giant hamster ball with the crew contained in a stationary internal sphere, while hemispherical outer shells on either side would rotate to roll it along. It would turn left or right by rolling the hemispheres on either side at different speeds, and fire on the enemy using machine guns sticking out of the center and from turrets on the left and right hubs. The inventor claimed that it would be gas-proof, and that anything but a direct hit would glance off of its curved surfaces. However, it appears from the picture that the only way to see out would be tiny slits above the machine guns, and since there's no periscope, cupola, or hatches on the roof or front the crew would have been driving and shooting almost blind. It's not even clear how they were supposed to get in and out of the ball! If you think about it, the problems are numerous: The big ball wouldn't have nearly as much flotation or obstacle-climbing ability as continuous tracks; it has nothing more powerful than machine guns; there's no fully traversing turret where a proper tank gun could be mounted; it looks as if the driver is also expected to manually fire a machine gun; and the most vulnerable part of the armor is the dead center of the vehicle. Richardson's version was not built, but in 1945 the Soviets captured a strange German-made "Kugelpanzer" (spherical tank) in Manchuria that uses the same principle. The mysterious object has a single-stroke engine, a crew of one man, a little vision slit, no weapons, and armor just 5 mm thick. No German record has been found of what it supposed to be used for. It might have been made for scouting, but in any case it now resides in the Kublinka Tank Museum.
  • The Panjandrum was one of the few Allied experimental weapons in WWII that was too crazy to work. It consisted of two wooden wheels ten feet in diameter with rockets strapped to them, connected by a central drum that would be filled with 4,000 pounds of explosives. It was designed to be released off a landing craft so that it could run over everything in its path and then blow up the fortifications on the beach. Unfortunately, the thing was literally impossible to control, and had the nasty habit of veering off course and going into unpredictable directions. Not to mention the fact that the rockets would sometimes separate from the wheel, firing off in random directions as well. Suffice to say, the project was scrapped after one demonstration went horribly awry when the panjandrum veered off course and nearly collided with the gathered panel of high-ranking spectators.
  • The Mark 90 Nuclear Bomb (aka 'Betty') used as a depth charge. It entered service in 1955, and left it in 1960. The Betty had a 5 kiloton warhead. Just for reference, the Hiroshima bomb had a 15 kiloton warhead. Tests showed that the nuclear depth charge was in of itself a feasible weapon, as the immense shockwave generated by the explosion would almost guarantee the destruction of a submarine. Problem was that the detonation of a nuclear depth charge at a shallow depth produced radioactive rain and steam that is much more concentrated than the dust produced by an aerial explosion over ground, which could badly affect the crew that launched the thing. Pairing it with the ASROC (Anti-Submarine Rocket) system solved this problem, but by then there was a comprehensive ban on underwater nuclear explosions, and the development of guided anti-submarine torpedoes provided a weapon that was nearly as effective at destroying submarines, without the potential complications posed by a nuclear weapon.
  • The TOG II, a British interwar tank prototype whose name was an abbreviation for "The Old Gang", referring to its designers who had been responsible for tank design in World War I. It was based around the idea that WWII would be just like WWI; thus, the TOG was to be a "breakthrough tank". Slow, lumbering, but heavily armed and armored, designed to dismantle enemy trenchlines and allow smaller tanks to pour into the gap and exploit the hole the TOGs had made. It was 33 feet long, propelled by petrol-electric drive, and weighed eighty tonnes; despite this, it reportedly trialled successfully, reporting no reliability or mechanical issues. Sadly, WWII was not like WWI, and this feat of engineering - though not common sense - was not put into mass-production and never saw action.
  • Towards the end of WWII, Allied planners had to find ways of breaching the German Siegfried line of defenses on the River Rhine. One school of thought held that very heavy armored vehicles - purpose built for the task - would be sufficient to knock a large enough hole in the German defenses that the Allies could then exploit with faster armor. Both the United States and Britain designed and built vast super-heavy tanks designed for the sole purpose of breaching the lines:
    • The US offering was the T28 Super-Heavy Tank. To confuse matters, they later changed the name to 105mm Gun Motor Carriage T95, and finally changed it back to T28. Weighing in at 95 tons, 36 feet long, with a high-velocity 105mm main gun and 300 mm of frontal armor, this lumbering monster had a top speed of only 8 miles per hour on roadsnote . It was low and very wide, with a double set of tracks on each side to distribute the ground pressure; in order to make it narrow enough to get on a flatcar or LST, the outer track modules were designed to unbolt from the main body and attach to each other, so the main vehicle could tow them behind it. Getting a T28 to the front would have been a huge logistical problem, and the whole assumption that super-heavy armor was required turned out to be erroneous when unarmored heavy artillery in theatre managed to creep up to the German bunkers under cover of smokescreens or blind spots and then blast them apart. One of the two T28 prototypes was destroyed by a fire. The other was supposed to be destroyed, but the Army somehow managed to misplace the heaviest armored vehicle it has ever built, so it sat forgotten in a field in Fort Belvoir, Virginia for 27 years, until a hunter found it "hidden" behind a much smaller bush and decided to tell the army about it. When he told them what it looked like, at first they didn't believe him! It is now on display in Fort Benning, Georgia, and supposedly in running condition.
    • The British came up with the Tortoise, which was (slightly) more practical than its American cousin. Weighing 87 tons, and 33 feet long, it was slightly less well armed and armored than its American counterpart with a 94mm gun and 228mm of frontal armor, it was however designed as though it might actually, y'know, drive somewhere, with a more powerful engine. In trials it was found to be a decent gun platform and also fairly reliable... unfortunately, the military need for it had completely dried up. Six prototypes were built; one - in running condition - is displayed in Bovington Tank Museum, whilst another is used as a target at Kirkcudbright Military Training Area.
  • Winston Churchill was so convinced trench warfare was coming back in 1939, he came up with the Cultivator No. 6, a trench-cutting device. It would operate at night, digging a trench to intersect with enemy trenches, so the following infantry would be protected from most enemy fire. A larger version would accommodate tanks. Because Churchill was First Lord of the Admiralty at the time, he got the Department of Naval Land Equipment to create and build it. The French were prevailed upon to provide soil samples from the front. A scale model performed as advertised, and a full prototype was completed in 1941. By this time, even Churchill had to concede that it was not needed. As its use could not possibly be stealthy, one must assume the enemy would not simply sit and wait for it to break through. Churchill was very proud of his concept: "I am responsible but impenitent." Even weirder: there was a competing design, independent of Churchill's.
  • Vehicles with a cockpit for a human pilot that walk (or at least stand) on two legs—Humongous Mecha, in a manner of speaking—have been produced by private individuals and companies. For example, Masaaki Nagumo and farm machinery manufacturer Sakakibara Kikai have produced a gundam-style robot called LW-Mononofu, which is equipped with an Arm Cannon that shoots sponge balls. Perhaps in theory they could do things that tracked vehicles couldn't, such as climb steep cliffs or manipulate objects with their arms. Unfortunately, we aren't remotely close to making them work like they do in fiction. For example, bipedal walking is actually quite dangerous for a sluggish, heavy machine that can't replicate the complex, fluid movements of human gait, since it would be likely to lose its balance and damage itself by falling. Nagumo's robots don't actually walk by lifting their feet off the ground, but have to shift their legs around to simulate walking while actually scooting on wheels concealed under the feet. The easier way is to make them outright tracked or wheeled on the bottom, such as Suidobashi Heavy Industry's Kuratas which has wheels on the end of each of its tripod "legs", or MegaBots, Inc.'s Eagle Prime which stands on catapillar treads. Merely having legs is a weakness: if it only has two legs, just take out one and the machine will collapse in a wreck. The Square-Cube Law makes it unlikely that they would be fast or structurally sound under stress, their large surface area to volume ratio would make them more difficult to armor adequately, and their tall posture would make them easier targets than wheeled or tracked vehicles. Even a mecha with a humanoid upper body sitting on a tracked base would have the same problem of an unnecessarily high silhouette. As of The New '10s, the money to be made is in using them for amusement, either selling mecha rides or making entertainment out of robot fights and contests. Meanwhile, militaries are focusing their development on more practical UAVs, bomb disposal robots, etc. Even the legged robots in military testing such as BigDog are small, unpiloted, and have four or more legs.
  • Speaking of robots:
    • BigDog is four-legged pack mule robot created by Boston Dynamics in 2005 to carry up to 400 lbs. of equipment for U.S. soldiers. It was cancelled at the end of December 2015; The reported reason is that its engine was extremely noisy, and it would be difficult to maintain if it broke down.
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