ABSTRACT
This chapter examines the engine designs, propellers, and the systems that bring these components together resulting in the overall propulsion system design. The following sections provide an overview of the engine types used on UAVs. The following sections describe two- and four-cycle engines, as well as Wankel regardless of fuel type. To produce enough heat and achieve the autoignition temperature of the fuel, diesel cycle engines have higher compression ratios than four-cycle engines. The assembled to create what is known as the core engine or the gas generator. Large UASs, such as the turboprop Reaper, will use constant speed propellers in an attempt to maintain an efficient angle of attack where the lift to drag ratio is maximized. Gas turbine engines require gas temperature, fuel flowmeter, fuel pressure, tachometer, an air induction system ice protection indicator, fuel filter capacity indicator, an oil strainer warning, and a means to indicate that any fuel filter heater is functioning.
