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Showing results for tags 'rarefaction wave'.
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I've been following this for a while: http://www.dtic.mil/ndia/2002gun/kathe.pdf http://www.dtic.mil/ndia/2007gun_missile/GMTueAM2/MinerPresentation.pdf http://www.dtic.mil/ndia/2009gunmissile/katheEmertechtuesday.pdf It's a remarkably good idea. RAVEN a drastically improved design for a recoilless rifle. In a traditional recoilless rifle, at the moment of ignition gas is free to exit the rear of the gun out of a De Laval nozzle: If the thrust of gas going through the nozzle is close enough to the momentum of the gas and projectile exiting the muzzle, the weapon is recoilless or close enough to. The problem is that this is hideously inefficient; most of the propellant mass is used to counteract projectile momentum instead of pushing the projectile. In the RAVEN, the breech is closed to gas flow at the moment of firing: But it is opened shortly afterward, while the projectile is still in-bore. The wave cause by the sudden drop in pressure due to the breech vents opening cannot catch up with the projectile in time to affect it, so there is no velocity loss and the recoil reduction is essentially free. Timing of the opening of the breech is most easily achieved by a blowback breech, IMO. The acceleration of a delay mass should be extremely repeatable, and could easily give consistent timing. The vent holes and nozzle will likely be consumable items, just as they are in traditional recoilless rifles. Unlike traditional recoilless rifles, which are limited to low-to-medium velocities due to their inefficiency, RAVEN works better with high velocities, since the projectile will be moving a higher percentage of the speed of sound of the propellant gas, and so venting can occur earlier. Furthermore, in high velocity weapons the momentum of the gas at the muzzle is a higher percentage of total recoil, so the percentage reduction of recoil will be higher.