Sci-fi Weapons, Vehicles and Equipment

That depends on their chemistry. The kinds of batteries that you find in an electric vehicle are indeed flammable, but while they can burn very hot and for a long time, they don't "explode" in the same sense as a bomb or a fuel tank. I don't know what kinds of batteries we'd need to power a railgun.

Edited by Fighteer on Apr 19th 2024 at 11:50:19 AM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"

I'd say we'd need more capacitors than batteries for coil and rail guns.

It is all about storing and discharging quickly.

Inter arma enim silent leges

I'm pondering how a misfire from damage can cause the capacitors in a Battletech Gauss Rifle to explode. Because the ammo doesn't explode, instead the rifle itself does.

The same way circuit breaker panels do. Damage causes a short circuit which causes an overheat which causes it to catastrophically fail.

"Allah may guide their bullets, but Jesus helps those who aim down the sights."

You can substitute supercapacitors for batteries. They're better in this case anyway. Capacitors can explode but it's a lot less energetic. No burning lithium, just the accumulated charge releasing all at once. Supercaps, however, tend to leak charge so they're not useful for long term storage. The gun will be cold between battles and will need a few seconds to charge if you're ambushed.

You can get a fire or explosion anywhere that potential energy exists in sufficient amounts. Batteries, capacitors, and fuel all rely on chemical potential energy. When that energy is released rapidly and in an uncontrolled manner, spectacular things can happen. It's not magic.

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"

Yes it is. It’s absolutely magic. The magic of science!

Edited by MajorTom on Apr 19th 2024 at 11:07:51 AM

"Allah may guide their bullets, but Jesus helps those who aim down the sights."

Aperture Science
We do what we must because we can
For the good of all of us
Except the ones who are dead

Now there's no sense crying over every mistake
You just keep on trying 'til you run out of cake
And the Science gets done
And you make a neat gun
For the people who are still alive

Edited by Fighteer on Apr 19th 2024 at 2:20:51 PM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"

Delicious, magical science.

Making capacitors explode was a common prank in the electronics lab at college.

Though large enough charges can start fires and spot weld components. Weapon grade energy can vaporize or severely heat up any surface.

Inter arma enim silent leges

Add in every mech runs off of a fusion reactor. In old Battletech they'd explode in a nuclear fireball, until somebody told the designers how physics really works, and now it's a violent plasma vent if a reactor gets hit. Less mushroom cloud more a good chunk of the mech gets vaporized.

Yea, very much. E.g. an Abrams M1 already has a 1.1WM turbine. With 9MJ shots, you'd basically need an entire second power assembly just to keep the railgun going.

Not to mention that you need a lot of power in a very short amount of time, demanding you have capacitor banks, which are big and heavy.

As a stationary emplacement, maybe, but not in the field.

Honestly thinking on the topic kind of has mmo thinking on a related one.

I wonder how much power you could get out of an engine that is designed to draw the energy out of chemical fuels as rapidly as posible.

Almost all the engine designs we have are designed to pull the energy out over a relitivly speaking long duration.... since we are using them as a method of locomotion primarily.

But if you just wanted to turn chemical power into electrical power as fast as posible, what can you do.

There really isn't that much of a difference. These systems are already optimized to extract as much energy as possible because that's how you get horsepower.

The main things that are different for a generator setup is that it tends to run very steadily at optimal RPM, rather than doing a bunch of gearboxing+RPM throttling.

Unless you're talking about a fuel cell, but that doesn't really run on regular fuels.

The most power you can get out of chemical potential energy without destroying the equipment is a rocket engine. A single SpaceX Raptor 2 engine, for example, produces over 8 GW with nearly 99% chemical efficiency. Unfortunately, rocket engines don't generally produce much in the way of electricity. I suppose you could wire a dynamo into the turbines, but that's added complexity to no real benefit.

By contrast, jet engines are incredibly fuel-efficient, mainly because they can get a big portion of their energy (the oxidizer) from the air itself. Again, most of their power output is in mechanical, not electrical energy.

This brings us back to, hey-presto, power plants. As difficult as it is to imagine, power plants are incredibly efficient at converting the maximum possible amount of chemical potential energy from combustion into electricity. They aren't exactly field-portable, though.

Of course, combustion isn't the only way to harness chemical potential energy. Taking into account the full spectrum of inputs to outputs, batteries give you by far the best delivery efficiency for chemical reactions, but tend to fall flat on energy density.

There is no "best" fuel or "best" power source. It all depends on what you are using it for.

Edited by Fighteer on Apr 20th 2024 at 2:28:49 PM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"

There isn't anything stopping from making a separate generator for the weapons as well.

The M 1 A 2 and M 1 A 1 Abrams have an auxiliary APU to power its systems so they don't draw power from the turbine.

The laser pod projects for the Apache, F-35 and C-130 Hercules also take vantage that turbines are really good at generating electrical power and tapping that power is relatively easy.

The closes thing we have for a land systems using railguns is the General Atomics Blitzer which is advertised as a counter battery and missile/artillery interception system that is cheaper per shot than conventional systems using missiles and has a better range, lower interception time, kill probability and magazine than conventional shells.

It still a sizable battery, but it isn't unfeasible in theory.

Inter arma enim silent leges

Technically? yes. practically, lots of things are stopping you.

Another advantage of an EM gun is that you can possibly dial your velocity to suit your needs. From hypersonic projectiles to possibly subsonic velocity allowing for a wider range of projectiles and payloads.

Edited by TuefelHundenIV on Apr 21st 2024 at 6:10:26 AM

Who watches the watchmen?

Slower velocities will let you fire more complex rounds like gun fired missiles. It'll also let you dial in the penetration of the round so the shot penetrates the front armor but bounces against the inside of the back armor.

What about indirect fire? Any advantages?

"We learn from history that we do not learn from history."

The fact that you can shoot over things.

Also vehicles tend not to have much roof armor.

Edited by Imca on Apr 23rd 2024 at 1:17:21 AM

No, I meant in terms of using rail guns. The power plant wouldn't be as much a disadvantage, it seems to me. But what other considerations are there?

"We learn from history that we do not learn from history."

Diable performance maters a lot more in indirect fire.

There is a reason the really big guns use seprate powder bags that you can adjust the number of.

It adds another way to adjust the ranging.... you can also use it for multiple shots simultaneous impact.

Edited by Imca on Apr 23rd 2024 at 1:19:04 AM

You could use it to fine-tune your shot velocity and provided your power supply can keep your capacitor banks charged appropriately; you could fire quite a few shots. As long as you have shells, you can likely keep firing for a while. It's one of the reasons the US military was looking into Coil gun-based mortars a while back.

Who watches the watchmen?

You can also use the same system for multiple purposes.

Need to hit something far and need to reduce the chances of a successful intercept? get them at max speed.

Need to spam as many projectiles as you can at a target that isn't that far? Lower velocity with a faster charge rage.

Needs something gone? Just aim low and almost directly at what you want dead and turn the settings up to eleven.

All using the same system. Basically it can turn into a one-size-fits-all.

Inter arma enim silent leges