You really should take the time to read what people are actually saying.BattleRaptor wrote:You said increasing speed doesnt increase energy, then made a comment about acceleration.
He said halving the mass doesn't double the speed and energy. It doubles the acceleration. The assumption is clearly that force and gun length are equal, he's comparing how projectile mass and exit velocity scale relative to each other, which is what you appeared to be talking about.
In a sense...he's arguing using physics.BattleRaptor wrote:You arguing with physics then?
45 km/s, actually, but it took the Z machine at Sandia firing a rather tiny (0.9 mm thick, 25x13 mm) projectile.BattleRaptor wrote:Or are you arguing its impossible to make railguns able to project something that fast?
Then I would like to point out small projectiles have been accelerated to over 30kms in real life.
http://www.sandia.gov/pulsedpower/prog_ ... -lemke.pdf
It's not a railgun, though it seems somewhat similar. The rails of a railgun are pushed apart during launch, the Z accelerator just replaces the projectile with a short at the end and the rails with lightweight "flyer plates", minus the mechanical support that holds a railgun together. The flyer plates explode outward in opposite directions when it fires. The configuration puts the projectile and fields deep inside the machine, and only a tiny amount of energy expended goes into accelerating the flyer plates...the one-sided experiment that got the 45 km/s number gave the projectile about 700 kJ (assuming a rectangular plate, it's probably lighter and lower-energy than my estimate), out of 12000 kJ input. And there's the little issue with the projectile vaporizing...even with their pulse shaping efforts, the flyer plates apparently must be placed quite close to the target (5 mm) in order to still be partly solid when they hit it.
In any case, firing a projectile of half the mass at even the same energy is a more difficult task, requiring higher peak powers, faster switching of higher currents, etc. They need to impart a very large amount of kinetic energy into the projectile in a very short period of time, and increasing the velocity and decreasing the mass makes that harder...if the projectiles are fast enough to do the job, the speeds they're using may well be optimal for their intended use.