J. Phys. IV France 10 (2000) Pr11-11-Pr11-21
Ram accelerator operating characteristics at elevated fill pressuresC. Bundy, C. Knowlen and A.P. Bruckner
University of Washington, AERP, Box 352250, Seattle, WA 98195, U.S.A.
An experimental investigation of the starting and operational characteristics of a 38-mm bore ram accelerator with propellant fill pressures greater than 5 MPa is in progress. Successful starts with 60 - 124 gm projectiles have been achieved using methane/oxygen/nitrogen propellants at fil1 pressures ranging from 6 to 15 MPa. At fill pressures of 8.5 MPa and above, it was found that projectiles having the nominal throat diameter (29 mm) required a minimum entrance velocity of 1250m/s, which is about 100m/s faster than the minimum needed to successfully start the ram accelerator at fill pressures below 7.5 MPa. Projectiles with a reduced throat diameter (25 mm) and a solid magnesium nose cone were successfully started at fill pressures up to 15 MPa with entrance velocities around 1300 m/s. The average accelerations achieved using high pressure stages were in general less than predicted for thermally choked operation by the Boltzmann equation of state.
© EDP Sciences 2000