Space Shuttle performance with a heads-up ascent

Abstract

A method of increasing the space transportation system (STS) lift capability by flying the Space Shuttle vehicle in a heads-up, conventional airplane-piloting attitude during the first-stage atmospheric flight as opposed to the current heads-down attitude is presented. It is revealed that the STS lift capability and solid rocket motor burnrate definition are sensitive to the magnitude and direction of normal aerodynamic force acting on the Space Shuttle vehicle during atmospheric ascent. The STS operational trajectory design angle of attack will permit increases in the solid rocket motor (SRM) burnrate definition and STS lift capability for the proposed heads-up ascent when compared to the current heads-down ascent. For a heads-up ascent, the SRM burnrate can be increased 7% with a corresponding 4000 Ib increase in STS lift capability. A comparison of the heads-up and heads-down ascent reveals similar performance trades for changes in trajectory-shaping parameters, SRM and Space Shuttle main engine (SSME) performance characteristics.