Design of an Airbreathing Second Stage for a Rocket-Scramjet-Rocket Launch Vehicle

摘要

The most promising alternative to rockets for improved access to space involves staged systems using airbreathing propulsion. With scramjet technology improving, a number of airbreathing assisted access-to-space vehicle concepts have recently been proposed, including a three-stage rocket-scramjet-rocket launch architecture for payload masses on the order of 100 kg. This article presents a design methodology developed for the airbreathing second stage of such a system. This methodology uses multidisciplinary design optimization with simplified methods for the calculation of vehicle aerodynamics, propulsion, and mass. It has been applied to the design of a reusable scramjet-powered winged cone vehicle with a near-term Mach 6-12 hydrogen-fueled scramjet for propulsion. Through the manipulation of five vehicle design parameters, including the size and position of the engines, and flying the vehicle along constant dynamic pressure trajectories, a configuration was developed to maximize payload mass fraction to low Earth orbit The mass of the whole system was 11.3t, and that of the airbreathing vehicle was 4625 kg, delivering a 211 kg payload to low Earth orbit This corresponds to an overall payload mass fraction of 1.87%. This methodology supplies a useful framework for developing a better understanding of the key drivers for airbreathing hypersonic accelerators.