Book Description

Self-sufficiency for military aircraft operating from remote advanced bases can be attained with small on-board air breathing gas turbine auxiliary power units (APUs) supplying main engine start and aircraft secondary power. The small, fixed shaft, gas turbine configuration comprising the single-stage radial compressor and radial inflow turbine, mounted back-to-back, and overhung from a 'cold end' bearing capsule has found favor in providing this duty due to inherent attributes low cost, simplicity and high power-to-weight ratio. This configuration of APUs first entered service in the early 1950s, and derivatives have been designed, developed and produced to meet aircraft industry demands. Extensive experience with these APUs has led to the formulation of several major design constraints, within the objective of minimum life cycle costs, that enhance development of both modified and derivative versions. This paper highlights some of these design constraints and identifies advantageous areas of research and development for future APUs. (Author).