A Comparative Analysis of Single-Stage-To-Orbit Rocket and Air-Breathing Vehicles

This study compares and contrasts the performance of a variety of rocket and air breathing, single-stage-to-orbit, reusable launch vehicles. Fuels considered include bi-propellant and tri-propellant combinations of hydrogen and hydrocarbon fuels. Astrox Corporations HySIDE code was used to model the vehicles and predict their characteristics and performance. Vehicle empty mass, wetted area and growth rates were used as figures of merit to predict the procurement, operational and maintenance cost trends of a vehicle system as well as the systems practicality. Results were compared to those of two-stage-to-orbit reusable launch systems using similar modeling methods. The study found that single-stage-to-orbit vehicles using scramjet air breathing propulsion outperform rocket systems. Findings also demonstrate the benefits of using hydrocarbon fuel in the early phases of ascent to reduce the size and mass of launch vehicles. An all-hydrocarbon, air breathing, single-stage-to-orbit vehicle was found to be a viable launch vehicle configuration and performed comparably to two-stage-to-orbit rocket systems.