In RealLife, an engineer's job is to design machines or structures that perform a certain task, and perform it efficiently, reliably and safely. It's a challenging job, involving analytical thinking and mathemathics as well as creativity and last but not least, ''common sense''.

Not so in fiction. When you let a writer of fiction dream up a machine, odds are good that you'll end up with something that is horribly inefficient, [[NoOSHACompliance unsafe]], or just plain [[YouFailPhysicsForever impossible]].

The reasons for this vary:
* Many writers [[CoolButInefficient will not even think about functionality]] when designing a machine; they're more concerned with the "look" and "feel" their machines convey rather than whether they actually make sense given the function they're supposed to perform. This is often the case with spaceships in [[MohsScaleOfScienceFictionHardness softer]] ScienceFiction.
* Even those writers that pay some attention to functionality often can't be bothered to think things through. Fuel consumption? Maintenance needs? Heat dissipation? They're the last things most writers worry about.
* And then there's failure to think outside the box that is, failure to consider that there might be [[BoringButPractical other, perhaps less spectacular ways]] to get the job done. Even machines that have been properly "designed" and thought through will make no sense whatsoever if there is clearly another, much more efficient way to do what they do.

If the work is set in modern times, you're supposed to [[MST3KMantra ignore it]], but if it is in a sci-fi or fantasy setting, it's a toss-up whether it will be ignored completely, explained as being made of {{Unobtainium}} or AppliedPhlebotinum of some nature, or only working because AWizardDidIt or a HigherTechSpecies show us how.

A ''very'' frequent cause of AwesomeButImpractical. CoolButInefficient is a subtrope. Related to NoOshaCompliance, as process safety is a pretty big issue for most engineers in RealLife.

See also: ArtistsAreNotArchitects, SciFiWritersHaveNoSenseOfScale, SquareCubeLaw.

[[AC:{{Anime}} & {{Manga}}]]
* Most {{Humongous Mecha}}s except for these:
** Creator/ShirowMasamune, is in fact, an engineer. (Even he applies [[AcceptableBreakFromReality Artistic Licence]] though.)
** ''TwentiethCenturyBoys'' features an engineer who gets kidnapped to build one and rants at his kidnappers about just how undoable it really is. Eventually, it does get built, [[spoiler: but it's a barely-functional one just for show so that the BigBad can steal credit from the hero for saving the world from it.]]
** ''LightNovel/FullMetalPanic'' actually used this in an interesting way: One HumongousMecha fell apart once the AppliedPhlebotinum allowing it to ignore its own weight failed.
* Mecha in general often touch this trope. A bipedal machine is, with anything resembling modern technology (or in the near-future sans [[HandWave Handwavium]]), a horribly complex, inefficient, and dangerous way to design a war machine. Just the stabilizing and moving systems alone would be a nightmare.
** Add a double dose of this when considering combining or transforming mecha. The sheer number of moving parts alone would give any engineer worth his salt a drinking problem let alone connecting the control systems and electrical circuits from two or more separate craft into a cohesive whole. Also consider how hard it is for pilots to refuel in mid-flight through a fuel line and then imagine ''ramming'' another mecha in order to combine...
* While ''Anime/NeonGenesisEvangelion'' narrowly averts this, it still gets caught in [[ArtisticLicensePhysics bad physics]] and [[ArtisticLicenseBiology impossible anatomy]]. The Evangelion mechas are actually [[spoiler: giant humanoid gods/aliens cloned from a giant alien that is linked to the creation of man. They were also placed in armor so tight and confining that they couldn't move without being piloted.]] However, the SquareCubeLaw would still keep the evangelions from moving fast at all. Also, the midsections of the evangelions are very thin, being even more narrow than their heads. So, they shouldn't even be able to stand, let alone move around.

* ''Franchise/StarWars'': There is a lot of debate of how possible/impossible the city-planet of Coruscant is, and not least the concept of miles-high buildings and the infrastructure required to maintain them and the population they contain.
** One notable offender is the Senate Building. Its central chamber is so large that unless the air inside was kept extremely dry, clouds would condense in the upper tiers.
** There's also the issue of how a city-spanning planet could possibly void all the heat that it generates, and the gaseous exhaust of trillions of vehicles, building systems, and industrial facilities. It's even mentioned in one novel that Coruscant somehow still has ice caps, and the characters go skiing.
** The supposed ice caps are actually an area which was built as a ski resort for anyone rich (or famous) enough to use. Although in the same book it explains that there are apparently a network of stations in orbit which are giant mirrors which HEAT the planet. Given the above mentioned exhaust though this really doesn't make much sense as making the planet warmer would seem to be a really bad idea.
** Another: The SquareCubeLaw notwithstanding, the buildings are so slender in comparison to height, that the slightest breeze would probably cause them to [[ buckle]].
** On the subject of Webcomic/DarthsAndDroids and this trope, the players decry Naboo as being unrealistic for structural reasons...except for [[TheDitz Jim]], who it turns out is a postgraduate student getting his Ph.D. in geophysics, and actually goes to the trouble to work out how such a planet ''would'' be feasible.
** The chicken walkers (AT-ST's) are just walking targets. The Hoth walkers (AT-AT's) make a bit more sense, if we take into account that repulsor coils big enough to make something as big as an AT-AT float would be such an energy drain that the power plant wouldn't be feasible for mass production. The only reason two AT-AT's got taken out at all was more Luke's RuleOfCool then anything else. [[note]]Then again, ExpandedUniverse information implies that the only reason the AT-AT's were a threat in the first place was because weather conditions on Hoth prevented the Rebels from using anything other than modified civilian airspeeders, which lacked the firepower necessary to dispatch the walkers[[/note]]
** Wookiepedia suggests that the reason for the legs was two-fold. First, a giant walking death machine is really scary, and second, Repulsor-lift vehicles are vulnerable to mines, while the extremely long legs of the AT-AT means the blast never reaches the vital components.
** Various books have suggested that walkers were designed for regions where ground-level repulsorcraft were unsuited such as very uneven ground or unstable gravity. Interesting, but Tanks seem more effective.
** They did in fact have tanks, but like most Imperial weapons systems, they were AwesomeButImpractical, having huge wheels and being very unmaneuverable.
** The prequels and Clone Wars series make this worse, since the earlier designs were much more effective. The Clone equivalent to an AT-AT could walk straight up cliffs, had a lower center of gravity distributed further apart on more limbs, and had weapons that didn't [[FixedForwardFacingWeapon all face forward]] just for one example... and [[{{Handwave}} vulnerable to the above-mentioned mines that the AT-AT have long legs against]]. For the record, the disadvantages of low height actually came up in the first ''[[WesternAnimation/StarWarsTheCloneWars Clone Wars]]'' cartoon, where Durge and his lancer droids were able to trash the AT-TE walkers with their lances.
*** [[FridgeBrilliance This is likely due to]] the Emperor rejecting less intimidating designs in favour of something more likely to cause fear. He prefers to rule through terror and epitomise WeHaveReserves than to actually keep the system stable, and would thus put intimidation much higher on the priority list than practicality.

* Architecture and machinery that fits, or appears to fit, this trope is common in Dr. Seuss books, [[ItRunsOnNonsensoleum which are nonsensical anyways.]]
* Trantor, the capitol of the Galactic Empire in Creator/IsaacAsimov's {{Foundation}} series, is a planet-spanning city like Coruscant in the example below (in fact, it's been suggested that Trantor was the inspiration for Coruscant). The engineering problems might be somewhat averted by the fact that unlike Coruscant, most of Trantor is underground. However, in later books in the series, people seem to have no trouble at all stripping away entire sections of the city, with apparently no concern for what it might do to the structural stability of surrounding parts of the city. Well, they do call that period "The sacking of Trantor". There had been said at some point in the books Trantor was inhabited by 40 billion people whose entire way of life depended of fleets of spaceships [[CasualInterstellarTravel bringing in foodstuffs each day and taking trash out]].
* Averted in the ''Literature/VorkosiganSaga''; all the engineering is realistic, and the 5-space theory expounded in ''Komarr'' sounds plausible.
* Averted in ''Literature/HonorHarrington'', where the characters are fully aware that their architecture of multi-hundred-story skyscrapers is ''only'' possible because of countergrav. Grayson, which didn't have it, has low buildings (Also, high is bad on a DeathWorld).

* ''Series/{{Revolution}}'': [[spoiler: Electricity isn't the only thing Monroe needs to get his helicopters flying from [[Recap/RevolutionS1E10NobodysFaultButMine episode 10]] onward. These machines have sat idle for 15 years, and fuel and lubricants do not last indefinitely. There's also a good chance that the avionics have physically degraded with time and exposure to the elements]].
* ''Franchise/StarTrek'': Routinely violates sound engineering principles. If you took a drink for every time the TNG ''Enterprise'' was nearly destroyed because something like the reactor [[FailsafeFailure failsafes failing]], you'd be comatose within a few episodes. Limited (or lack of) systems redundancy, no compartmentalization of critical systems, lack of surge protectors that cause control consoles to explode just about every time the ''Enterprise'' gets shot, using active measures like force fields for biohazard containment (instead of, say, a freaking ''box'' marked "biohazard") ... the list is endless.
** ''Star Trek'' also misuses terms such as "alloy" and "compound".
** But averted in [[Series/StarTrekTheNextGeneration TNG]] when Scotty tells Geordi that he wrote the original regulations conservatively. It's not (just) that it makes him look good when Kirk asked for more and Scotty could deliver, it's also that it's simply a good idea to not run the device at redline the whole time (reduces wear and tear, for one thing).
** On a more philosophical level, the franchise generally doesn't seem at all clear on the ''vast'' differences between engineers, spacegoing engineers, scientists, and so on. Presumably an artifact of having TheMainCharactersDoEverything... on the other hand, this might explain a lot about Starfleet.
* ''Series/StarTrekVoyager'':
** They decided that it would be a great idea if instead of metal wiring, most of the ships utterly vital systems are connected with gel packs, which are basically biological goo. Not only does it open up engineering weaknesses that no good old copper wire would face (such as one instance where it was poisoned by Neelix's [[LethalChef cooking]]) but also cannot be replicated or grown. Yes, they chose the one system that couldn't be made on the fly with their replicators. They also have have other engineering slip ups like have no emergency lights and ''manual'' door overrides that don't work if it doesn't have ''power.''
** And perhaps the most incomprehensible engineering choice in all of Star Trek, making the power supply for the Voyager holodeck ''incompatible'' with the rest of the ship. A power generator ''built into Voyager'' is somehow incompatible with the rest of Voyager. Why any engineer would design such a baffling system has never been explained.

* Just about every single thing to come out of Warhammer 40k is either made out of shot traps, should collapse in on itself, or both, even the more reasonably designed Imperial Guard tanks, like the Baneblade, are literally built out of shot traps, with short ranged guns that have bores nearly as large as their length as standard armament. It's only that tabletop rules forbid doing so that stops anyone from simply shooting the Baneblade in it's Demolisher cannon and destroying it.
** Digging into the lore of Battlefleet Gothic produces quite a few more of these. Among other things a "torpedo" is an eighty-metre long self-steering engine that overloads its reactor core when it gets close enough to something, which sounds reasonable enough...until you realize it gets transported from the magazine to the tubes by [[WeWillUseManualLaborInTheFuture armies of serfs with pulleys and a trolley]].
** When they actually go and present the specifications behind the equipment in the setting, the results are often underwhelming, as [[ one image]] comparing the aforementioned Baneblade to the [[CoolTank M1 Abrams]].

* This trope came back to bite the creators of the latest ''RedFaction'' game. Apparently [[GoneHorriblyRight the combination of their famed Geomod engine with a realistic physics engine caused the outrageous "futuristic" buildings they planned on using in the game to collapse under their own weight]], forcing them to go back to the drawing board with more sensible architecture. Explained by Volition themselves [[ here]].
* ''VideoGame/TheSims'', falling under acceptable breaks of reality, since house building can take a long time without you thinking how many pillars to put to support the entire structure. Of course, there is also the bugs that allow things like a ''floating house''.
* ''VideoGame/{{Minecraft}}'' doesn't so much have an artistic license as it has ''[[ToonPhysics entirely separate laws of physics from reality]]''. On one hand, sand, gravel, and most living things will respect the laws of gravity while most other blocks ignore it entirely, enabling [[FloatingContinent floating continents]] and [[OminousFloatingCastle fortresses]] to be built and naturally generate with a little effort. Yet on the other, most anything electronic baring mods follow the laws of electronics mostly swimmingly (well, minus the fact that [[PerpetualMotionMachine redstone torches]] produce seemingly infinite power.)
* ''VideoGame/DwarfFortress''. An entire fortress held up off the ground by one single brick of soap? They've been done, and that's considered ''relatively insignificant''. Then again, without Dwarfy physics, we wouldn't get the mind-bendingly complex {{Death Trap}}s and megaprojects that Dorfs have been known to build. Case in point, DOMAIN, a suborbital KillSat defense network that works by ''[[CrowningMomentOfAwesome pumping magma up to dozens of Z-levels above ground level and dropping it on opponents]]'', is still making the rounds on the Bay 12 forums.
* Rado's Annex, a free-standing two story subtower connected to Darm Tower by a walkway on the ''sixteenth floor'' in the ''VideoGame/{{Ys}}'' series is pretty much structurally impossible. Yunica actually points this out when she first sees it in ''Origins''.
* In ''StarcraftII'' the Viking transforming assault fighter can flip from starfighter to ground-walking mecha. The background description in the game strongly implies that ''transforming can kill an insufficiently agile pilot'' somehow, which is just plain idiotic. There's no call for the interior of the cockpit to be somehow involved in the transformation, nor would you ever want to field something that could kill the pilot as part of its normal performance going right.
** An InUniverse version with Terran buildings, which continue to burn down when their HP is in the red without enemy assistance, due to electrical shorts, ruptured vespene tanks and "hasty and often improvised construction". You'd think after decades in the Terran sector they'd have learned to fix these, especially when the UED (remember, the guys from Earth) show up using the exact same buildings. One of the available upgrades in the campaign are firefighter drones that deploy when a building is in the red and fix it up to half its HP.
** A subversion with the Odin, which is noted to be laughably AwesomeButImpractical. So Swann comes up with the Thor, a smaller-scale, mass-producible version... but by no Means a MiniMecha, the thing needs to be airlifted by a DropShip that can hold two tanks.
* The ''Series/MetalGear'' series makes heavy use of HumongousMecha in general. Notable in that [[VideoGame/MetalGearSolid3 one of the games]] actually lampshades [[SelfDeprecation how impractical the design is.]]
* The Scorpion tank of {{Halo}} has what is probably the single ''stupidest'' tank design in all of fictional history. The Scorpion is apparently a "Light tank" with a 90mm cannon the same size as the '''''[[MilitaryMashupMachine Panzerkampfwagen VII Maus]]'''''. Here's a scale comparison between the [[ Scorpion, aforementioned Maus, and the sanely designed M1 Abrams]]. Note that both the Maus and Abrams are armed with ''much'' larger guns than the Scorpion, (128 and 120mm respectively). The Scorpion also features the most idiotic decision of all, ''to put the cockpit on top the tank with giant windows''. Just top top it all of, said glaringly vulnerable cockpit is inside a shot trap when the cannon is facing forwards, so any shot that doesn't damage the equally vulnerable gun mechanisms, will promptly fly into the cockpit, killing the pilot.