Development of a Small Multi-Fuel Capable APU for Abrams, Bradley, and Stryker Vehicles

In the Phase I effort, Mainstream has addressed the need for a separate auxiliary power unit (APU) for military ground vehicles by designing a naturally-aspirated, 2-cylinder, 0.726-L diesel engine coupled with an alternator that meets the strict requirements for Abrams, Bradley, and Stryker vehicles. The gen-set is capable of providing 12 kW of electrical power at sea level (8.4 kW at 10,000 ft.), and was designed specifically to fit the unique space claim requirements for all three vehicles. Performance plots (power, torque, BSFC, etc.) at a wide range of operating conditions (engine speed, ambient temperature, muffler geometries, etc.) were created. The alternator and associated power electronics for the generator include a brushless permanent magnet integrated starter/alternator with active rectification. In the Phase II effort, the prototype 12-kW APU will be built and initial performance testing will be performed. The assembly of the APU will include integrating Mainstream-designed and fabricated components (such as the engine block, flywheel, and alternator rotor and stator) with supplier components (such as the unit injectors, oil pump, piston). Mainstream will be able to successfully complete this ambitious program by leveraging other complementary programs in the development of diesel engines, electronic unit injector systems, and power electronics.