Railguns?

[Arugela]

Slight off the point of the below thread. It mentions it's inefficient and some of that is lost in heat. How much is lost to heat. And what if you made the shell out of a very heat absorbing(heat storage and intake. But not outake?! Or outtake in a direction adding or adjusting direction or speed.) and make the shell absorb the energy. Would this help retain the energy and make it more efficient. Let alone aid in it's job as a shell down the road. And would it get rid of some of the guns problem itself and make it last longer? Or is this too simple of a solution. Assuming it's simple of course.

https://www.quora.com/Does-an-Iowa-class-battleship-have-the-capability-with-or-without-upgrades-to-power-and-operate-rail-guns

Edited May 26, 2022 by Arugela

[Spacescifi]

38 minutes ago, Arugela said:

Slight off the point of the below thread. It mentions it's inefficient and some of that is lost in heat. How much is lost to heat. And what if you made the shell out of a very heat absorbing(heat storage and intake. But not outake?! Or outtake in a direction adding or adjusting direction or speed.) and make the shell absorb the energy. Would this help retain the energy and make it more efficient. Let alone aid in it's job as a shell down the road. And would it get rid of some of the guns problem itself and make it last longer? Or is this too simple of a solution. Assuming it's simple of course.

https://www.quora.com/Does-an-Iowa-class-battleship-have-the-capability-with-or-without-upgrades-to-power-and-operate-rail-guns

 

 

Have you seen a diagram of how railguns work?

It involves literally two rails that the projectile is launched from from off what is called an armature (a metal piece that pushes the projectile as it is accelerated from the rails below).

 

Basically we are talking friction. Lots of it. Do that again and again and you melt your rails. So if you have spare rails and the means to reprocess melted ones back to tip top shape, you can fire away and view rails as expended ammo lol... reprocess them at your leisure. Hopefully when not in a combat situation lol.

[sevenperforce]

3 hours ago, Arugela said:

How much is lost to heat. And what if you made the shell out of a very heat absorbing(heat storage and intake. But not outake?! Or outtake in a direction adding or adjusting direction or speed.) and make the shell absorb the energy. Would this help retain the energy and make it more efficient.

Some energy in the system is lost to heat because of the inherent resistance of the conductor (whether the conductor is a sacrificial armature which pushes the projectile, as @Spacescifi notes, or if the projectile itself is the conductor). That's just Ohm's Power Law. But by far the bulk of the heat in the system is the result of frictional losses, which act in largely similar ways on both the conductor and the rail itself, since the materials must both be conductive. The laws of thermodynamics tend to frown on any attempts to force heat to flow from something cooler into something warmer, which is what you'd need to do in order to use the projectile as a heat sink for the system.

 However, that doesn't mean it's a lost cause. There are many ways to cool things, after all. For rocket engines, you can use radiative cooling (requires the vacuum of space and a large surface area), regenerative cooling (requires a fuel you can use as a coolant), or ablative cooling. Ablative cooling sucks for rocket engines, generally, but it's used to great effect on spacecraft heat shields. An ablator carries away heat by being vaporized and carrying that vaporization heat with it.

So, one way to make a railgun work would be to use a conductive projectile, but place a layer of an ablative, conductive material on either side. Then, use rails that are slightly narrower at the exit than they are at the entrance. Thus as the projectile travels down the barrel, the ablative coating is gradually vaporized by the combination of Ohmic heating and friction. As long as the ablative coating vaporizes at a much lower temperature than the rails, the rails themselves will remain undamaged. The process causes the overall size of the projectile+coating to shrink, which is why the bore of the railgun narrows toward the exit. This way the heat is carried away not by the projectile, but by what the projectile leaves behind.

With a little extra design work, you could even shape the rear of the projectile such that the escaping vaporization gases expand against it like an aerospike engine, adding to its velocity.

Bonus if the reduced stresses on the rails mean that you can use the rails themselves as a supercapacitor, rather than needing a separate capacitor bank to fire. Air is not an ideal dielectric for a capacitor by any means, but perhaps it would still be doable.

[kerbiloid]

Then the ablator vapor will condense on the rails, covering them with a thin and non-uniform layer.
And the gun will overheat and vibrate, then crash.