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 aircraft-like operations. This article 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. Analysis of the complete three-stage system was performed based around a fully trimmed trajectory simulation of the second stage. The scramjet powered second stage accelerated from Mach 6.0 to Mach 9.3 with an average net specific impulse of 923 seconds. As a result, the overall system showed a payload mass fraction of 1.26% to Sun Synchronous orbit, which is significantly higher than expendable rocket based systems of this scale.
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