Advanced military fixed and rotary wing aircraft will require more compact, lighter weight small gas turbine auxiliary power units (APU's) and jet fuel starters (JFS), capable of faster starting and delivering high specific power outputs over wider operating envelopes.
APU start system weights can be a significant fraction of the total installed APU weight, especially if fast starts are demanded under sub-Arctic environments. It is shown that both start system weight, and rotor containment armor weight are proportional to the product of rotational speed squared and rotating assembly inertia. Significant weight savings are therefore feasible with rotating assemblies using lower density materials such as ceramics and composites.
This paper discusses the results of analytical studies supported by current development efforts and research paths to implement fast start technology for small gas turbine APU's.