Liquid oxidizer injection in the compressor section of turbojet may allow it to operate at high Mach numbers and altitudes. The evaporation of the oxidizer decreases the compressor discharge temperature and inter-stage cooling increases the airflow. These effects allow fuel flow to the combustion chamber and afterburner to be increased with resultant higher thrust. The oxidizer increases the concentration of oxygen available for reaction with fuel. This reduces flameouts during high altitude operation. The oxidizer mass flow contributes to the mass expulsion rate of the engine further increasing thrust. Such an engine may be used in the future on the first stage of space boosters. Spath Engineering proposes conducting analysis of oxidizer injection into a J-85 turbojet engine with afterburner. A NASA provided computer program would be used for engine cycle analysis. Modification and test of a government furnished engine is also proposed. The modifications to the engine will allow liquid oxidizer to be injected at the inlet and two compressor stages. The test data will validate the predictions of the analytical work. This analysis and test program is designed to stay within the funding limits of a phase I SBIR. A turbojet engine that has the ability to operate at high Mach numbers and high altitude has the potential to revolutionize space operations. A launch vehicle with an air-breathing first stage could cause space launch logistics to approach those of present day aircraft operations. The potential impact of such an engine is difficult to overstate. Spath Engineering has identified a dual use commercial application that is feasible within the funding and scope confines of an SBIR phase II program. Some models of Learjets are FAA certified to operate at FL 510 (51,000'). Early models of Learjets, including some certified to FL 510, use the General Electric CJ-610 (the civilian version of the J-85). Flight International of Newport News, Virginia is the world's largest operator of special mission Learjets. They have expressed an interest in a modified CJ-610 to allow special mission operations at very high altitudes. Flight International has several Learjets that have been modified to carry external stores. Some carry the stores under-wing and some at a fuselage belly station. Use of these aircraft may simplify the modifications to the airframe that would be required to carry liquid oxidizer.
