Rail gun damage?

[Beast]

which means the craft carrying that type of weapon will need to be much larger than the A10 in comparision to the GAU-8 gun(more like x10's the force pounds in wt

Tex
the reason you do not put a gun on the SR-71 is because
Once a round is fired it will start to decelerate after leaving the barrel
in space you do not have that problem

Right, but here we have an example of a weapon of a weapon with a kinetic energy output way below what's being discussed for rail guns and it has a substantial effect on the vehicle - even though the A-10's a pretty bulky aircraft. And you are right - the reason stalling is not a problem is because the plane already has a great deal of momentum: nonetheless, even at this level, firing the weapon has a noticeable slowing effect.

A 64 megajoule rail gun - the navy's goal - is going to generate 566,447,730 pound-force (if I've done the numbers correctly) or the equivalent of firing 56,000 gatling guns simultaneously. That's going to have an effect ....

cheers, Mark

[Nyrath]

If it's a spaceship weapon (which I think is how the thread started), it's worth pointing out that the relative velocities of hostile spaceships are likely to be several km/s. That contribution to impact velocity is rather greater than the ~1 km/s that is contributed by the weapon itself.

Indeed it will.

And for those who didn't look closely, the important word is relative.

If the enemy cruiser Sky Trash is sitting "stationary", and you fire a railgun shell through it at 3 kilometers per second, it will do X amount of damage.

If the railgun shell is sitting "stationary", and the Sky Trash is flying at 3 kilometers per second and hit the shell, it will do an identical X amount of damage.

The key is that in both cases the relative velocity between the shell and the Sky Trash is 3 kilometers per second.

[Tex Jones]

Yes but I assume torch ships with acceleration to mid point flip and slow down. Which makes bullets in the samr bracket again they don't get the extra G's but on the other end they do speed up towards planets and other massive bodies. Star Trek's speeds are hard to think the few sat's I worked with the delta-Vee ability wasn't much. The life of a sat is limited mainly by how much fuel it can carry to correct it's "orbit" which it the geometry we use there is no such thing as a orbit. It's a straight following the folds of space. Most Gameing systems require artificial Gravity and gravity compensator. So you can ignore that problem or it's possible with the right charges the gun could be a part of the deflector system and firing it might even cause the ship to go faster behind a bigger bubble. But lets leave the two headed Lama's out of it. Push Me Pull You's but that's a longer story. the game system would all in all call it some form of a STR Min or Size Min.

[Nyrath]

Yes but I assume torch ships with acceleration to mid point flip and slow down. Which makes bullets in the samr bracket again they don't get the extra G's but on the other end they do speed up towards planets and other massive bodies.

Yes, this is true if you and the enemy are engaging around a stationary point. Say if force Alfa is trying to enter Mars orbit to drop bombs, while force Bravo is in orbit around Mars trying to defend it.

But if force Alfa is at the midpoint flip in between Earth and Mars, and is intercepted at that point by force Bravo also doing a midpoint flip, the relative velocities between the two will be very high indeed.

[tkdguy]

Another possibility is to make your railguns "recoilless" in the same way existing RCL weapons are recoilless. Include a reaction-mass projectile (doesn't have to be the same mass, probably better if it's more massive) simultaneously launched in the opposite direction. I.e., your railguns are "double barreled" with the second one pointing the opposite way of the first. It means you're cutting your launcher efficiency (KE of weapon projectile per unit of supplied power) by of order 50%, but it solves some other problems elegantly. (It's "of order" 50% because what you want is the reaction projectile to have equal but opposite momentum, not KE, as the warhead projectile.)

Just make sure no friendlies are standing behind when you fire....

If you are using real physics, another serious problem happens if your railgun is mounted in any way except fixed directly on the momentum axis. If you have the gun in a steerable turret, there's going to be a bunch of angular momentum deposited into the ship when you fire, that is, you're going to make your ship spin. Even a pair of coaxially-mounted guns will do this unless their firing is carefully synchronized; if they have the same rate of fire but are out of sync you'll wag the nose back and forth with a series of alternating jolts in yaw. How bad this effect is depends on the comparison of the mass of the ship and the momentum of the projectiles. I think the whole point of a simple kinetic-kill shot-type weapon is that the projectile's impact is substantial compared to the target, so assuming combatants of comparable mass, the firer's momentum is going to be altered if the railgun is at all effective.

Now, you could turn that into a feature rather than a bug, assuming an adequately high rate of fire; your fire control system could take into account the recoil-driven back-rotation of the firing platform and use that to deliver a preplanned pattern of projectiles, sweeping out an arc in the sphere centered on the ship's center of mass. I'd have to do some numerical experiments to see how that might work.

One of the reasons I thought of the thrusters was because of the recoil when the ship fired in a direction other than straight ahead or behind. I like your solution to this problem. Thanks.