Feasibility of SCRAMJET technology for an intermediate propulsive stage of an expendable launch vehicle

Abstract

The single largest contributor to the cost of putting objects into space is that of the launch portion. The currently available chemical rockets are only capable of specific impulse (Isp) values on the average of 300-350 seconds, with a maximum of 450 seconds. In order to improve the performance of the current families of launch vehicles, it is necessary to increase the performance of the rocket motors, and conversely the amount of propellant/oxidizer carried. The purpose of this thesis was to determine the feasibility of employing SCRAMJET technology for an intermediate propulsive stage of an expendable launch vehicle. This was motivated by the fact that SCRAMJETS offer a very high propulsive efficiency when compared to conventional chemical rockets. The incorporation of a SCRAMJET engine into the configuration "stack" of an expendable launch vehicle, offers the promise of increased payload mass fraction or an increase in the number of attainable orbital profiles. Analytical tools were developed using open-source software to identify launch trajectories for the SCRAMJET-enabled rocket configurations, and to determine how these would differ from conventional launch profiles. The effects of incremental increases in configuration lift and drag coefficients due to the SCRAMJET stage was analyzed. It was determined that incorporation of SCRAMJET Technology into an expendable rocket configuration offered marked improvement in performance, reduction in total launch weight, and increase operational flexibility when compared to a similarly sized conventional chemical rocket.