This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Pneumatic Link Secondary Power Systems for Military Aircraft
Annotation ability available
Sector:
Language:
English
Abstract
A frequently used method of starting aircraft prime propulsion gas turbine engines is by means of a small auxiliary power unit (APU) providing compressed (bleed) air to an accessory drive gearbox-mounted air turbine starter. This APU may be carried on-board or mounted externally on ground support equipment. The majority of these APU's deliver a bleed pressure of approximately 4.0 at standard day conditions, as constrained by oil auto-ignition temperature limits no higher than 450-500°F for mostly commercial aircraft applications.
The requirements for in-flight cross bleed starting of military engines at higher Mach numbers have necessitated increasing bleed internal air duct temperatures up to 1200°F and have afforded the feasibility of either higher APU bleed pressure ratios or power augmentation with the “bleed and burn” option.
This study examines the influences of these two options on the power density of pneumatic link start systems for military aircraft, and leads to the conclusion that higher bleed pressure ratios of up to 6.0 can provide more than a 10 percent savings in power/volume ratio dependent upon APU location. The utilization of bleed power augmentation can provide more than 25 percent reduction in weight and volume, but may conflict with increasing demands for higher avionics systems ground cooling capacity.
Recommended Content
Authors
Topic
Citation
Rodgers, C., "Pneumatic Link Secondary Power Systems for Military Aircraft," SAE Technical Paper 881499, 1988, https://doi.org/10.4271/881499.Also In
References
- Nicholls B.H. et al. “Auxiliary Power System Study for a 1975 Fighter Aircraft” AFAPL-TR-67-135
- Borosdy B.J. Secondary Power and Engine Starting for the F/A-18A Hornet SAE A-6 Committee October 1982
- Kaufman P. Mooney J. “Starting the System – Air Turbine Starters” Secondary Power Systems Inst. of Mechanical Engineers London November 1984
- Lucci A.D. Williams J.A. Bedeer E.C. McFadden B.L. “Super Integrated Power Unit for Fighter Aircraft” AGARD-CP-352, Auxiliary Power Systems
- Rominek J.P. “Pressurized Air Start System (PASS) for Small Gas Turbine Engines” SAE SP-598 Starting Systems Technology October 1984
- Rodgers C “Impingement Starting and Power Boosting of Small Gas Turbines” ASME 84-GT-188
- Rodgers C. ‘The Performance of Single-Shaft Gas Turbine Load Compressor Auxiliary Power Units” AIAA-83-1159
- Rodgers C. Johnson D.C. “APU Fuel Efficiency and Affordability for Commercial Aircraft” AIAA 1987-1907 San Diego
- Scicchitano E. Tepes F. “A System Approach to Engine Starting System Design” SAE 861734