High power density, low weight, compact dimensions, high efficiency and reliability are key factors in the design and dimensioning of piston engines for general aviation power plants and UAVs, . Despite the new technologies available, conventional solutions continue to struggle to simultaneously meet all these requirements.
The document explores the application of a new design of 2 stroke engines ejected externally to aircraft. The new concept basically consists of the use of a patented rotary valve to control the flow through a set of input ports, which allows supercharging and achieving extremely high power densities compared to conventional solutions. The sweeping is performed by the use of an external pump, formed by an additional cylinder, whose piston is connected to the same crank. The piston pump allows the crankcase to be used as a conventional oil sump and greatly improves the balance of the crankshaft. It is not necessary to install stem valves or camshafts, since the flow is driven by piston controlled ports and by two sets of plate valves.
The engine can adopt two types of combustion system: Gasoline Direct Injection (GDI) for SI operations and Common Rail direct injection for the diesel cycle. The article focuses on the latest version as it can run on standard airplane fuel.
The diesel engine has three cylinders and three piston pumps, for a total displacement of 1.5 liters. The engine is turbocharged and cooled down to achieve a sea level power objective of 150 kW at 4000 rpm. Another fundamental objective is the minimum power of 100 kW, at an altitude of 20,000 feet. The article reviews engine design and presents the numerical prediction of key performance parameters.