New experiments in a 120-mm ram accelerator at high pressures

Initial experimental results are presented for the U.S. Army Research Laboratory's 120-mm bore ram accelerator test apparatus, which is currently the world's largest. Muzzle velocities of more than 2.6 km/sec have been experimentally demonstrated, and theoretical prospects exist for velocities above 7 km/sec. Experimental results are presented for fuel pressures as high as 102 atmospheres, and an evaluation is made of the impact of such high pressure operations on facility design and applications. Attention is given to the effects of high pressure unstarts on ram-accelerator hardware.