Sci-fi Weapons, Vehicles and Equipment

When we talk about radiator fins, I keep thinking of gothing rayguns with all the fins on the barrels. I'm also picturing something with a water jacket like an old WWI machine gun as a possibility. Maybe in that case you just periodically flush and replace the coolant, like a barrel change.

And I recall the discussion on one of the Firefly TV Tropes pages about Vera needing air to work, one potential possibility brought up was that Vera didn't need air to fire the bullets, but she might have needed air for her lubricant to work properly. Evidently many oils do interesting but unproductive things in hard vacuum, not unlike water and air. So not only would the weapon need to have heat managmeent in mind, but also friction management (just to get it out of the way, the oxygen is not needed to actually fire the bullet, since they have their own oxidizes in the powder, or can have them easily added).

Water is the single most efficient thermal transfer agent in the known universe. It's why it is used for cooling. (And heating.)

Why? It's high specific heat means it's resistant to heating up (and resistant to cooling down in the case of using it for heating). Meaning on a strictly liter for liter basis, you get the same cooling as other much faster agents for a lot less mass. Plus unlike some cooling agents, water is endlessly reusable so long as you don't shoot it out into space. And unlike other cooling agents, it only need be cooler than the weapon itself to do its job properly, which means in a circulating system, you have endless supply of coolant and a means to dispose of it.

If you had an active internal cooling system such as laser cooling, you could also cycle water throughout the ship and cool it off too without excessive need for spindly wiry radiators everywhere.

Be careful of overdesigning the gun though, this is meant for actual human hands to use in space

Actually in terms of liquid coolant water is not the best option in every scenario. It depends on what you are trying to transfer heat from, chances of corrosion, heat transfer and capacity, and other considerations. Sure it works well in most situations but even straight up water is often modified to be more suitable. Like deionized and distilled waters for example.

Yeah, there’s lots of stuff better than water. Metals are also almost universally better thermal conductors than liquids.

There’s a reason why most spacecraft use ammonia coolant and not water. It performs much better in the heat transfer role.

While Ammonia is more thermally conductive, water has more heat capacity which is important as hard vacuum means your radiators are less effective.

The entire point of a rotary system is to keep fresh coolant on the barrel. The whole thing becomes a centrifuge with cold, dense coolant on the outside and hot, light coolant on the inside. Normally, you'd need extensive plumbing to do the same and still be running into issues with bubbles and pumps. This does mean the system will inevitably be too heavy for anything less than a crew served weapon but it's not without merits.

If you really want sustained automatic fire for a hard vacuum weapon then you need compressed air and heat sinks. Slap the radiator/heat sink right on the barrel and flush with compressed air when it gets too hot.

I personally find Mechs not good forms of combat in any instance, beyond my own settings where I make sure they fit a niche role. But good points here none the less.

edited 23rd Jun '18 11:41:34 AM by EchoingSilence

That was kind of meh. Especially the pro-mech side. The elevation of sensors is achievable without putting it on a giant target and there are far more viable methods for that. Active protection systems are not unique to mechs, and a mechs effectiveness in terrain tank couldn't go is dubious at best largely in part because the most effective mechs approach and rapidly exceed MBT weights. Her end rebuttal was utterly stupid and demonstrated a clear lack of understanding of how both armored warfare works but also a distinct lack of knowledge of how aircraft carriers work.

It still boils down to a simple fact. If you can spend the resources and tech to make a giant walking war machine what exactly is stopping you from applying it to everything else?

You know what. For giggles I will do a little bit of a devils advocate approach.

Mechs offer a wide variety of capability often on the same general frame and mech weights often allow for a greater range of versatility outside of standardized units. The highly nimble scout mechs are comparable to a tank in overall stature but often at appreciably reduced weight with good sensor capability. They have superior mobility over even their mech counter parts offering up a scouting and light weight weapons platform with flexibility from mobility. The heavier units carry the heaviest weapons and greatest armor at least on par with tanks and their added balanced mass lends them stability making it hard to knock them down. The various also have a unique ability granted by legs that is step over obstacles a tank would have to go around arrange for engineering support to go through.

The taller mech units offer launch platforms for missile systems which do well with elevated positions and artillery type weaponry benefits from similar advantages. The common weapon sets while largely aimed at mechs are able to tackle a wide range of targets from enemy armor, infantry, and even enemy emplacements and hardened positions. Most weapon sets are standardized with a number of possible variations being able to be fitted to suit a given mission profile.

edited 23rd Jun '18 12:55:00 PM by TuefelHundenIV

The first guy got it in the video with the line "anything a mech can do a tank can do better". If you have the technology required to make working mechs you may as well just build a better tank with it.

I just found it a interesting video.

Last I checked for Battletech/Mechwarrior, the Mechs are the result of politics, being tools of war devised to alter the course of warfare and try to make people do it less or end it with a more definitive side, hence why Clans became a thing.

The points from the pros side are pretty shallow. All of them are either outright false (a mech can be as armored as a tank), or ultimately in favor of tanks anyways (APS).

I think that wheeled vehicles should be the default with legged vehicles having application only in certain environments where wheeled or tracked vehicles cannot operate.

When the height of commonly occurring obstacles approaches or exceeds the height of your vehicle your wheeled/tracked vehicles will no longer be able to move around and something with legs and arms is needed to maneuver. Using just legs is practical if all limbs are grasping or manipulating limbs so climbing can occur. Just using non manipulating legs limits mobility.

As the size of a vehicle shrinks the commonality of a walking/crawling vehicle should go up as you are more likely to run into obstacles similarly scaled or larger than it. A tank sized walker will be rarer than an infantry sized walker and insect sized crawling machines should be commonplace.

In my setting you'll see a balance of walking and non walking vehicles where the size cut off is determined by the obstacles of the environment.

Say quick question, high tech melee weapons, what would they be useful for? High Frequency Blades and such, how would this affect combat and warefare, would they even have a niche role?

I'll give you the definitive argument in favor of mechs: They're friggen' cool. Come back to me when you figure out how to paint a skull on a 100-ton tank without it looking goofy.

It takes quite a bit to actually fully stop a tank. Terrain utterly impassible to armored vehicles is few and far between, and areas that are impassible to armored vehicles would be all but impassible to mechs as well. Don't forget that mechs, particularly climbing ones, put a much greater amount of pressure on the surfaces they're on. A mech also isn't really any faster in a strategic sense than an armored vehicle, due to the slower overall pace of travel and the larger logistics and maintenance train required.

In terrain denied to armored vehicles you'd be best served with aircraft, particularly helicopters or other vertical lift designs. In open terrain conventional vehicles are still dominant, it's hard for a mech to take a hull down position for example.

These days a combat knife is mostly a tool, not a weapon. And it's frankly an amazing tool, there's a lot you can get done with one. They're versatile enough that carrying one day-to-day is something I think is a good idea, provided it's legal of course. I carry a folding knife and it comes in handy surprisingly often.

Advanced technology could theoretically make a useful tool even more useful, but you have to be careful not to overdesign a tool that's useful in part because of its simplicity. If your fancy force field dagger is useless when its micro-fuses burn out you might be better off with a conventional knife.

Why paint a skull when you can mount a skull? [1]◊

edited 23rd Jun '18 6:28:29 PM by archonspeaks

See above, re: not looking goofy.

A high frequency blade is just a blade that thanks to tech vibrates, allowing it to better cut through matter, presumably a HF knife would still be a effective knife, just slower than itself powered.

But how do they compare to VHF or UHF blades?

I admit to being unfamiliar with the subject but I have to assume regulations are pretty strict when it comes to liveries for tanks. The slab sides of the Abrams seem like a pretty good place to do some painting.

I believe you can buy carving knives that more or less work like that. I think the technology would need to be refined a lot to be durable enough for militar use though.

A fixed-blade knife is damn near indestructible if you treat it right. It’s badically just a sharp bit of metal. Electric knives have additional points of failure.

I've seen some science videos that discuss the viability of a "vibroknife" or equivalent, and they mainly conclude that there's no real benefit gained by vibrating a blade at high frequencies when it comes to high-pressure cutting power. Now, ultrasonics are extremely useful in surgery and other precision applications, but those all involve cutting slowly and carefully, not quickly and destructively.

The purpose of a blade is to concentrate force in a very small surface area, increasing the pressure applied to a material. If the pressure exceeds the strength of its molecular bonds, it is cut. Simple.

Now, you can use sound to cause a material to vibrate at its resonant frequency, shaking itself to pieces, but that has nothing to do with cutting, and the two principles applied together wouldn't really synergize. Do you want to cut it or shatter it?

edited 23rd Jun '18 8:59:57 PM by Fighteer

You've never been to mountainous terrain have you? Or dense jungle and forest? Utter quagmires of swamps, bogs and marshes?

There are plenty of places vehicles, armored or otherwise cannot go but infantry can albeit sometimes with difficulty.

Also, mecha particularly humanoid mecha would be perfectly fine in low gravity environments such as asteroids, space stations and floating in space. The legs and arms give something to grab hold of objects or use them as landing and traversal gear which saves fuel unlike pod-designs like Universal Century Gundam's Ball.

Surprisngly, many of those areas are not absolute barriers to the passage of armored vehicles. Additionally, like I mentioned, mechs would actually do worse in a place like a swamp or ultra-dense forest.

Using grasping limbs to traverse a space station works, but it’s not fuel free movement since you’re still burning power to actuate the limbs. There’s also no reason to use a humanoid form there, something like an octopus or squid would probably be a better form factor to emulate.

edited 24th Jun '18 4:00:41 AM by archonspeaks

Say we had the technology to develop a man portable energy shield about the size of a Riot Shield, and the capacity to manufacture it, would anything with warefare change about this?

Think like Reinhardt's Shield from Overwatch in terms of design (sans Lion head).

Not really. We already have armor grade shields that can eat fire power but they are largely relegated to special use.

What role would the shields be relegated to?