re guns for space okay lets get the record straight on the livermore gas gun the project manager is dr john hunter and he works for the laser group at livermore what you may ask does gas guns have to do with lasers nothing really but the gun is physically located across the road from the free electron laser building and the fel building has a heavily shielded control room thick walls from which the gun firings are controlled so i suspect that the office he works for is an administrative convenience i visited hunter at the beginning of feb and we toured the gun at the time i was working on gas gun r d at boeing where i work but i am now doing other things helping to save the space station the gun uses a methane air mixture which is burned in a chamber about ft long by inch id i e it looks like a pipe the chamber holds a ton piston which is propelled at several hundred m s down the chamber on the other side of the piston is hudrogen gas initially at room temperature andsome tens of atmospheres the piston compresses and heats the hydrogen ahead of it until a stainless steel burst diaphragm ruptures at around psi the barrel of the gun is about feet long and has a inch bore it is mounted at right angles to the chamber i e they intersect this was done so that in the future the barrel could be raised and the gun fired into the air without having to move the larger and heavier chamber the projectile being used in testing is a kg cylinder of lexan plastic in in diameter and about cm long all of the acceleration comes from the expansion of the hydrogen gas from psi downwards until the projectile leaves the barrel the barrel is evacuated and the end is sealed with a sheet of plastic film a little thicker than saran wrap the plastic is blown off by the small amount of residual air trapped in the barrel ahead of the projectile the gun is fired into a bunker filled with sandbags and plastic water jugs in the early testing fragments of the plastic projectile were found at the higher speeds in later testing the projectile vaporizes the testing is into a bunker because the livermore test range is about miles across and the projectile would go km if fired for maximum range the intent is to move the whole gun to vandenberg afb after the testing is complete where they can fire into the pacific ocean and use the tracking radar at vafb to follow the projectiles the design goal of the gun is to throw a kg projectile at km s half of orbital speed so far they have reached km s and the gun is currently down for repairs as on the last test they blew a seal and damaged some of the hardware i think it had to do with the methane air more detonating than burning but i haven t had a chance to talk to hunter directly on this there are people waiting to test scramjet components in this gun by firing then out of the gun into the air at mach km s since the most you can get in wind tunnels is mach this gun cost about million to develop and is basically a proof of concept for a bigger gun capable of firing useful sized payloads into space this would require on the order of kg projectiles which deliver on the order of kg useful payload to orbit dani eder dani eder meridian investment company w h rt box athens al location deg n deg w m alt
