Abstract: A variable-geometry ramjet engine, capable of operation over the Mach 3 to 12 speed range, is provided by disposing a movable cowl around a centerbody. The engine is axisymmetric and features a translatable cowl which slides relative to the centerbody on circumferentially spaced radially extending support struts. Forward translation of the cowl provides a variable inlet area resulting in higher compression at the high Mach numbers than is possible with a fixed-geometry configuration. Rearward cowl translation increases the combustor length and combustor area ratio at the low flight Mach numbers to improve low-speed combustion characteristics. Cowl translation changes the nozzle area ratio to provide a large expansion ratio at high flight speeds and a low expansion ratio at the low flight speeds.