Sci-fi Weapons, Vehicles and Equipment

Scaling things down to infantry weapons - would it be possible to build a rapid-fire coilgun or railgun?

I've decided I want the alien race I'm developing to primarily - if not exclusively - use ballistic weapons, for a number of reasons. For starters, their soldier caste are genetically engineered to be extra-resistant against explosive shock and shrapnel, and most of their cities are underground, so they're especially good at building heavily-fortified bunkers, which are typically equipped with point-defence systems, to boot. All of which greatly limit the usage of conventional explosives (and even the explosives they do use are typically designed to latch onto targets) and traditional chemical-propelled ammunition, while energy weapons capable of eating through all this armour are still in the experimental phase - infantry-scale magnetic weapons feel like the ideal solution, since they need their guns to hit hard and fast.

Only thing is, whenever I see magnetic weapons in sci-fi they usually tend to be single-shot deals, possibly because of some limits of the technology that I'm ignorant of - the only exception I can think of is probably Mass Effect, but the tech level there is beyond what these aliens have.

If it helps, I did imagine that their 'Automatic Gauss Guns' (obviously they'd have a different name for them) would be considered a specialty weapon like a SAW, as opposed to a standard-issue assault rifle, and it would function in the same way as a Gatling Gun, with two coilgun/railgun barrels operating in tandem with each other.

Edited by PresidentStalkeyes on Mar 5th 2020 at 10:45:05 AM

Yes, both are posible to be rapid fire, the problem is electrical use and cooling....

If you can solve those, railguns would actualy be capable of much higher firerates then the guns we use now, since the only moving part is the projectile and the feed, you dont have all the systems needed in a modern gun.

But agian, those electrical use and cooling problems are pretty... there.

Multiple barrels helps with cooling, but it adds a significant amount of weight to the weapon, the barrel is about half the guns weight after all... and it also adds complexity, which is exactly opposite of what a rapid fire rail-gun would want to capitalize on.

Edited by Imca on Mar 5th 2020 at 10:12:55 AM

With my plane question, I guess the follow-up is what kinds of atmospheric/gravitational differences might cause what changes to aircraft performance? Higher/lower pressure, atmospheric composition, etc.?

Also, I think I overstated my ignorance on aircraft stealth. I do lurk on some defense, military history, and Ace Combat subreddits, so I know a little more than the average Joe. When it comes to using memory metal for adaptable planes, there's three areas that I would really like to know more about.

Tail: I remember reading that having a vertical stabilizer on the tail enlarges radar returns, hence why things like the B-2 Spirit and a few planned drones don't have tails. From a layman's perspective, making twin vertical stabilizers that can fold down to become flush with the wings seems like one of the simpler applications of memory metal for a warplane. It would need extreme precision in order to prevent any gaps between the wings and the folded tails, but that's nothing new for modern warplane design.

Wings: I am a lot fuzzier on the details, so correct me if I'm wrong: forward-swept wings have been tried a few times and have advantages in maneuverability at the cost of worse stability (which modern avionics can overcome), putting a lot of stress where the wing sweeps forward, and being bad for stealth. I can see some value in memory material wings that can switch between normal and forward-swept shapes, but wings contain things like fuel tanks and control surfaces (and maybe internal weapons bays?) which would be difficult to engineer so that they could shift with the wing transformation.

Canards: Canards, if I remember correctly, are good for maneuverability but bad for stealth and not great for speed. I don't think canards typically have any components in them that would have trouble adjusting to a canard that folded down into the fuselage, so it seems doable.

Did I get anything wrong, miss any other areas of interest, or spark any ideas?

Your basic parameters for defining flight are gravity and air pressure. The higher the gravity, the more lift you need to generate to get or stay aloft. The lower the air pressure, the more surface area you need to generate lift (and/or the faster you need to go). Lower air pressure also reduces overall maneuverability, but by the same token you can go much faster without worrying about supersonic turbulence.

Atmospheric composition (and density) determines your choice of engines. For combustion-based engines, you need oxidizer. If there's enough oxygen around, you can get that from the air. If not, you have to bring it with you. Having to supply your own oxidizer reduces the specific impulse of your engines and thus the range you can get from any given amount of fuel. If air pressure is too low, then jet or propeller style engines become a lot less efficient regardless of composition.

If pressure and gravity are low enough, you can go into orbit without expending a ton of energy like you would have to on Earth. On the Moon, there's no atmosphere at all, so "aircraft" is an oxymoron. Anything traveling above the surface would use rockets. On Mars, planes would travel very fast and have extremely long wings to make up for the fact that the air pressure is 1/100th of Earth, but the low gravity would make them very fuel-efficient, given that there's no oxygen to support combustion.

On a planet with a really dense atmosphere, like Venus or Jupiter, drag becomes a big issue and you're better using flotation for lift.

Edited by Fighteer on Mar 5th 2020 at 3:13:20 PM

Efficiency isn't all that's reduced. Capability is what is also reduced. Lower air pressure is why bush planes and helicopters can't simply fly over the Colorado Rockies (that and severe winds at altitude), they have to find a pass or saddle low enough for them to traverse. Given most of the Colorado Rockies are in excess of 3500 meters elevation (~11,000 feet) this heavily restricts where a propeller plane or helicopter can go.

It is quite plausible to have a rapid-fire rail gun or coil gun. The mechanisms can, in theory, operate fast enough for rapid-fire. Like Immy already noted power and heating control are going to be important factors but also you have to consider recoil management. Most depictions of rail guns firing single shots at a time are fairly reasonable as a slow rate of fire is a common method to helping control high recoil weapons. The idea behind EM weapons is to put a lot of velocity behind a projectile. The faster you accelerate a projectile the more recoil you have to contend with.

You can play with the idea a bit and some use something like a flechette like projectile others have hand-wavy tech like Mass Effect.

So the main issues are power handling, cooling systems, weight and recoil?

Thinking on it further; this race's soldier caste are also much stronger than the rest of their kind, so the extra weight and recoil shouldn't be an issue for them. As for the power issues, I had considered having the gun wired up to an external battery which the gunner wears like a backpack. Would add even more weight, of course, but that's considered a fair sacrifice for the extra stopping power.

They probably have flechette-based weapons, too, except they're usually reserved for small arms against the more fragile castes since they're basically useless against the soldiers. Hell, they might even be glorified nailguns.

Forgive me if this has been discussed here before, but I haven't been lurking for a while and I've read some interesting stuff about US Army modernization programs. In all of the myriad things that the Army wants to new versions of and entirely new things, one of them really stands out to me as being out of left field: The Strategic Long Range Cannon.

This article details some leaked concept images and speculation as to how the SLRC might achieve its hoped-for 1000 mile range. Now, it isn't even in the prototype stage and I would be kinda surprised if it actually succeeded, but the mere fact that they think it's worth looking at surprised me. I can't recall ever hearing of a similar science fiction weapon. What do you make of this whole idea?

In a realistic examination, it is an idiotic boondoggle. Super guns have been examined and rejected repeatedly in the past simply because there are other systems that do the same job better overall.

Super guns are limited in terms of everything from mobility, very limited situational use, and frankly trying to reinvent the wheel.

Sounds like a launch platform for a hypersonic weapon. Which is kinda silly because we've already launched a hypersonic weapon from a plane.

The Strategic Long Range Cannon, from what I've read, will not fire hypersonic projectiles. It is intended as a complement to the Army's hypersonic missile (Still in development), both of which are options for strategic fires in areas where air defenses may be too formidable for planes. The hypersonic missile is more precise, longer ranged, probably harder to intercept, and can be launched from a more mobile platform— but it is super expensive. The SLRC is envisioned as a cheaper counterpart that can achieve a relatively high volume of fire, since the rounds will probably only cost several hundred thousand dollars each. Of course, that all assumes that it's possible to achieve such ranges with a gun (albeit probably using ramjet-assisted projectiles).

You can do the exact same thing with a plane mounted munition. At a 1000km it is going to need some pretty solid guidance packages to be worth anything.

If the SLRC works as intended (which is a big if) why wouldn't it have any advantages over planes? Besides the obvious (for the Army) perspective that planes aren't under Army control and the SLRC would be.

A fast plane can haul nearly 10,000kg of munitions to the target, your not going to load that into a gun.

It would have crappy mobility one of the known issues with any very large long-range artillery piece, you get more range out of well designed aerial munitions thanks to the fact they are carried by aircraft, and you can get way more range out of rockets and missiles. You can only squeeze in so many adaptions before the line between shell and missile is effectively meaningless. What they are describing is top to bottom a gun fired the missile. Cut the middle man and just turn it into a multi-platform weapon like the Israeli LAHAT. There is literally no need for a big dick waving cannon. It offers nothing unique or any real advantages at all. The only benefit is in the munitions which can also be applied to air carried missiles.

I really can’t imagine a relevant strategic or tactical situation where this would outperform air or ground-launched missiles.

I’ll also add that with the INF gone we suddenly have a bunch more options for missiles in this area, which the USMC is already pursuing as per recent budget documents.

Edited by archonspeaks on Mar 8th 2020 at 12:14:34 PM

So using a gun-launched missile doesn't even make it significantly cheaper for a given range?

SLRC is another pipe dream from Big Army. Really the chief advantage is that a gun can hit enemy forces with a speed that can only be matched by the hypersonic missiles.

But even if they used a ramjet projectile, there is no way they can get a 1,000 mile range.

Edited by TairaMai on Mar 8th 2020 at 4:23:39 PM

Taira: Actually projectile velocities for big artillery are still lower than most rockets in the same roles. The only "big" guns to fire hypersonic projectiles where either Project HARP guns or the Rail Gun. Both of those had hypervelocity muzzle velocities at least around Mach 6. The HARP was very slow loading and the rail gun is a colossal power hog for even smaller projectiles.

Cactus: It doesn't do anything unique. Its basically just firing a boosted ramjet. The difference between strapping a cheap solid rocket booster for the initial acceleration that drops off the ramjet vs a shell with a boost from a gun propellant charge is almost nil. All you are doing is changing what the initial launch stage will be. The actual functioning projectile cost would be about the same.

Strategic gun artillery has existed before but big guns all have the same weakness. They lack mobility and also have a good-sized logistical footprint. Large guns also have very slow rates of fire because of projectile size and weight and propellant charge size. They also tend to have more ammo limitations because weight and bulk of ammo limit how many can be practically lugged around with the weapon. They also make big whopping targets. They lack shoot and scoot capability which is still important in strategic weapons systems. MLRS and mobile artillery both can do that.

To date the most reasonable balance between mobility and large bore artillery was something around 8" to 9" bore and those are pushing the limits of vehicle weight with one of the biggest mobile US examples being the T92 Howitzer Motor Carriage at 58 tons.

We might make something newer like that but given the host of logistical issues, we have had with 60 ton MBT's making anything as big as the beefy 11" towed artillery or bigger, roughly 90 tons of weight for gun and prime movers alone not counting shells, makes such an endeavor impractical.

Now for such things in fiction they are rule of cool writ large. They look impressive, cause massive destruction, and are a great set-piece.

Edited by TuefelHundenIV on Mar 8th 2020 at 12:04:56 PM

^ The only role big gun artillery may have in the future is with railguns being a fixed defensive emplacement or bunker style weapon. Kinda like old school coastal artillery. In sci-fi terms I could see this being like an anti-orbital gun.

Nothing mobile or even thinking of mobile. The old railway guns for all the reasons you listed became obsolete by the end of World War Two, anything trying to emulate them these days is going to meet a swift end by way of JDAM or SCUD strike. You're not going to fit a railgun on a train or trailer or tank chassis and expect much different. At least not if you built the gun for 1000+ km range. I could see smaller railgun artillery in the 100+ km range being a thing.

Could ram accelerators, railguns, or coilguns make it more worthwhile to use a gun-launch system for strategic missiles?

It's all the same problems only with all the problems of an energy-intensive platform. Honestly if you really want a strategic missile just build a missile. The primary reason you use gun fired missiles is mostly for versatility with a gun system without having to add missile launcher to a platform.

The gun fired satellite launchers HARP had a part in testing may have had a shot at being practical but it wasn't looking to try and launch a barrage and was a fixed location piece of equipment.

Actualy, that does leave me with a question, if you can use a gun to launch a satalite....

Why cant you put the projectile into a near orbital trajectory and get almost infinite range out of your gun.

Well planetside range.

You could, in theory, do orbital trajectories but like with any missile that even has brief visit into space it requires a lot of preparation and has some extra weight for fuel for steering and shielding for re-entry like anything else that has to descend back into the atmosphere.

Okay I'm looking at a large ship design, it's relatively hard scifi (give or take a torch drive and FTL travel) so it's pretty much thrust gravity and spin gravity. It's meant to ferry heavy vehicles around colonized space and carry a contingent meant to pilot those vehicles, and as I'm looking at my plans I'm now wondering.

What would be the things you outfit a ship like this with? I don't mean "What should I put in" this is more a general "what would you outfit a ship of this nature with?"