WINGED BOOSTER PERFORMANCE WITH COMBINED ROCKET AND AIRBREATHING PROPULSION

A conceptual level analysis was performed on a horizontal-takeoff, two -stage-to-orbit system consisting of a rocket and turboramjet powered hypersonic booster and a rocket-powered orbiter. The analysis includes estimates of vehicle aerodynamics, performance, and weights. Rocket a nd airbreathing systems on the booster are operated in parallel and at full thrust for ascent to a Mach 6 staging point, whereas cruise back is accomplished using airbreathing propulsion alone. Rocket engines o n the orbiter are ignited at staging to propel the orbiter. Booster we ights were determined for various combinations of rocket and airbreath ing propulsion. The combinations that resulted in the lowest vehicle g ross and empty weights were determined. Results show that the lowest g ross weight occurs when only airbreathing engines are used. The empty weight of the all airbreathing booster, however, is quite high. Signif icant reductions in booster empty weight is accomplished with the addi tion of rocket engines. Also, the use of rockets on the booster greatl y decreases the time to staging and the cruise-back distance.