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The purpose of this program was to design a hot gas motor that would subsequently be used as the prime mover in an advanced aircraft auxiliary power unit starter system. The report describes the APU starter system approach and the design details of the hot gas motor. The hot gas motor is a rotary vane device that would be powered with the decomposition products of a hydrazine-based fuel blend. Two computer models are presented for predicting the thermal-structural and thermal-performance characteristics of the hot gas motor over the required ambient temperature range of -65 to +130 F. (Author)

Design, analysis, and testing has been conducted on a hot gas rotary vane motor for aircraft APU starting over the environmental temperature range of - 65 deg F to + 130 deg F. Experimental testing of the motor was conducted with gaseous nitrogen and with hydrazine based monopropellant hot gas decomposition products. Initial testing indicated problems with excessive gas consumption and binding of parts due to differential expansion. Subsequent revision to the motor configuration reduced gas consumption by 52% compared to the original baseline and eliminated end clearance sensitivity. Analytical studies, verified by test results, indicated the effect of friction coefficient, vane weight, venting, and blade linking on overall internal friction. Design approaches were evolved to minimize overall friction and loads on the vanes. With design revisions implemented to solve initial problems, a motor successfully demonstrated operation at environmental temperatures down to - 65 deg F as well as repeated restart capability. Design criteria have evolved to allow application of the rotary vane motor to specific aircraft starting requirements., This article is from 'Auxiliary Power Systems: Conference Proceedings of the Propulsion and Energetics Panel B Specialists' Meeting (61st) Held at Copenhagen, Denmark on 30-31 May 1983,' AD-A136 220, p10-1-10-14.