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Advanced technology air separation modules for use in on-board Inert gas generation systems (OBIGGS) were investigated in a recently completed Air Force development program. These modules use hollow fiber permeable membranes that are compatible with a fighter aircraft environment and have no moving parts. Extensive ground testing revealed that the advanced modules offer an order of magnitude savings of weight and volume compared to other air separation modules. Hence, the advanced modules were used in an in-dapth study of OBIGGS for fighter aircraft applications. A best choice OBIGGS for a generic ATF configuration and a comparison of the best choice OBIGGS with other aircraft fuel tank fire protection systems are discussed.

An optical telemetry technique has been developed for obtaining piston temperatures in reciprocating engines. The technique employs a transmitter mounted on the underside of the piston which transmits the temperature information as frequency modulated infrared pulses. This signal is picked up by a photodetector mounted in the crankcase which is wired to an external receiving unit. The transmitter consists of a thermocouple or thermistor, voltage-to-frequency converter, calibrating circuitry, and an infrared light-emitting-diode. The receiver consists of a phototransistor, frequency-to-voltage converter, calibrating circuitry and voltage readout. The transmitter is powered by lithium batteries. The signal has been successfully transmitted at speeds up to 4500 RPM in a 2-stroke engine and up to 5000 RPM in a 4-stroke engine. The accuracy of the infrared telemetry device using thermocouples is ±2.8°C (95% confidence level).