Marquardt's Mach 4.5 Supercharged Ejector Ramjet High-Performance Aircraft Engine Project

The supercharged ejector ramjet (SERJ) engine developments of the 1960's, as pursued by The Marquardt Corporation and its associated industry team members, are described. In just three years, engineering work on this combined-cycle powerplant type evolved, from its initial NASA-sponsored reusable space transportation system study status, into a U.S. Air Force (USAF)/U.S. Navy (USN)-supported exploratory development program as a candidate Mach 4.5 high-performance military aircraft engine. Bridging a productive transition from the spaceflight to the aviation arena, this case history supports the expectation that fully integrated airbreathing/ rocket propulsion systems hold high promise toward meeting the demanding propulsion requirements of tomorrow's aircraft-like Spaceliner class transportation systems. Lessons to be learned from this "SERJ story" are offered for consideration by today's advanced space transportation and combined-cycle propulsion (CCP) researchers and forward-planning communities. Authors' Perspectives As active participants in NASA's advanced space transportation development field (see Acknowledgments), the authors express some concern that the relevance of the engine development history related here, to such ongoing spaceflight activities, will not always be clear to the reader. After all, the propulsion application focus covered is high-performance military aircraft, not reusCopyright © 2000 by William J.D. Escher. Published by the American Institute for Aeronautics and Astronautics, Inc., with permission. able space transports. A further concern we have is that, since the SERJ engine never evolved beyond its exploratory-development entry status—no full-scale engines were ever built or flown—this project may be viewed as an "also-ran" non-success, therefore, presumably one not contributing significantly to the advanced propulsion knowledge base. But we believe otherwise. The fact that this engine, as a type (a combined-cycle airbreathing/rocket propulsion system), was tentatively accepted in its day as a real candidate aircraft powerplant by government and industry personnel "in the aviation business." is viewed as a major plus for the cause of spaceflight. NASA's announced Spaceliner 100 technology-roadmap initiative firmly asks for a future "aircraft-like" space transportation system. Clearly, its highly challenging flight-safety, operationaldependability and ticket-price affordability goals strongly urge a full understanding and informed emulation of the larger aviation experience. Addressing our second concern, the fact that this particular engine project was foreshortened at its exploratory development stage—it was terminated in 1970 for reasons expressed in the paper—does not reflect desparagingly on its basic propulsion system technical approach, per se. Rather, those negative programmatic factors leading to this termination, related to top-priority, warfighting materiel needs which taxed available budgets, a lack of established requirements for a Mach 4.5 combat aircraft capability, and the less-forward-looking status and direction of military aviation developments, in general, at that time. This perception of the positive nature of the engine's technical attributes, is supported by the ongoing CCP technology effort being pursued today by NASA and industry, as well as those further comments to follow.