Performance of solid fuel ramjet guided projectile for USN 5"/54 gun system

Abstract

This report covers work done on performance analysis of a 5 inch, 54 caliber gun-launched guided projectile with solid fuel ramjet (SFRJ). A computer program (TRAJET) was developed. The program contains ramjet and trajectory analysis. The ramjet part considers conical shock wave losses, - inlet boundary layer losses, normal shock losses, subsonic diffuser recovery, expansion into combustor losses, heat losses at the combustor and nozzle losses A flat earth trajectory with drag and thrust was donsidered. The various drag coefficients which were considered are: cowl drag coefficient, skin drag coefficient, wing (or fin) wave drag coefficient and wing (or fin) friction drag coefficient. Base drag is assumed to be zero due to the jet from ramjet nozzle. It was found that the cowl drag coefficient has a major influence on the results. Therefore, a separate program (AERO) was developed to calculate this parameter. The 5"/54 solid fuel ramjet has a capability to produce fuel specific impulse in the order of 400 - 900 sec. depending mostly on the flight altitude, The thrust coefficient varies in the range of 0.3 ± 0.1 depending on the internal areas. A range in the order of 50 miles can be achieved with the ramjet operation compared to only 13 miles achieved by the conventional projectile. At low-altitude launch, a range of over 18 ronles can be reached in Air-Defense Scenario. The ramjet propelled projectile reaches the ranges mentioned above at high Mach numbers (Mg >. 1.8). It is, therefore, clear that the ramjet concept provides significant improvement and has an Anti-Ship Missile Defense (ASMD) capability.