A Trans-Atmospheric Turbojet Engine

Period of Performance: 11/21/2001 - 07/30/2002


Phase 1 SBIR

Recipient Firm

Hmx, Inc.
350 South Center Street
Reno, NV 89501
Principal Investigator


A novel turbojet based propulsion system is described that is capable of continuous operation from takeoff to orbital insertion. This engine concept utilizes a conventional turbojet as its core with a dual function inlet that can accommodate both atmospheric air and cryogenic liquid oxidizer. By varying the percentage of liquid oxidizer injected, the engine can operate either in turbojet mode, rocket mode or in a combination mode. At all times the delivered performance is equal to or better than an equivalent rocket. The system has the potential for high performance while maintaining the low lifecycle costs associated with conventional turbojet engines. The investigation includes determination of appropriate operating scenarios for the system through engine cycle analysis. Hardware interactions are evaluated to determine what modifications may be necessary to allow utilization of existing turbojets for component testing. Lab-scale testing is conducted to demonstrate concept operation as well as investigate injector performance. A plan is prepared to investigate full scale concept testing using a representative turbojet engine during Phase 2. Commercial applications for this propulsion technology exist not only in orbital space transportation systems, but high-speed point to point air transport systems as well. The long life and low lifecycle costs of the core turbojet engine make it well suited for high flight rate transportation systems requiring high thrust to weight, high speed engines with reasonable propellant economy. Potential applications include orbital transportation, high speed, long range trans-atmospheric package delivery aircraft, as well as trans-atmospheric military strike or reconnaissance aircraft.