Space transportation main engines for single-stage vehicles

Studies are currently being conducted that could lead to the development of new hydrocarbon booster and hydrogen upper-stage engines. More advanced engines are also being considered which could be developed instead of the baseline designs if the vehicle programs allow time. This paper describes results of the analyses of the advanced engines on single-stage-to-orbit vehicles. The results show that the vehicle dry mass can be reduced about 20 percent with advanced engines when compared to the baseline engines. Some of the advanced engines may not require much extra development time.