Reusable Launch of Small Satellites Using Scramjets

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Reusable Launch of Small Satellites Using Scramjets

Preller, Dawid / Smart, Michael K.

Reduced scale and improved responsiveness will be the technical and economic drivers of future satellite systems. Based on decades of practical experience with rocket-only expendable launch vehicles, current technology is operated close to theoretical limits. Scramjets have an advantage over rocket propulsion in terms of a significantly higher specific impulse. Other benefits of airbreathing propulsion for access to space are increased launch flexibility and the possibility of reusable aircraftlike operations. This paper describes the use of a three-stage rocket–scramjet–rocket system for transporting payloads of the order of 100 kg to a sun-synchronous orbit. The reusable second stage is based on a winged-cone vehicle and is powered by hydrogen-fueled scramjets. An assessment of the complete three-stage system is conducted here by performing a fully trimmed trajectory simulation of the airbreathing second stage, along with simplified trajectory simulations of the rocket stages. The scramjet-powered second stage accelerates from Mach 5.1 to Mach 9.5 with an average net specific impulse of 933 s, which is more than double that of a rocket. As a result, this partially reusable system shows a payload mass fraction of 1.17% to sun-synchronous orbit, which compares favorably with expendable rocket-based systems of this scale. These results indicate that scramjets should be investigated further for use on the second stage of satellite launch systems.