tested at MAHLE Powertrain in the United Kingdom and in the United States; test results show that it has multi-fuel capabilities. The Duke engine's benefits of lightness and compactness should render this design ideal for motorcycles engines; and these benefits might make the powerplant suitable for light aircraft as well. (There is little data on whether the Duke engine is smooth; the mainshaft has a large counterweight attached). INNengine A classical, Spanish built design, parallel pistons working in opposition, sine-wave swashplate, in 2023 with two versions, a car sized, with liquid cooling, as prototype, and an air cooled four cylinder, 125 cc, 22 HP, 4.5 kg unit, aimed at drones and big aeromodels, in pre-production stage. Cylindrical Energy Module The Cylindrical Energy Module (CEM) is a sine-wave swashplate engine that can also be used as a standalone pump, powered by an external source. The rotating swashplate rotor assembly is moved back and forth with the help of piston drive pins, which follow a stationary sinusoidal cam track that encircles the rotor assembly. Applications The most well-known application is in torpedoes, where the cylindrical shape is desirable. The modern Mark 48 torpedo is powered by a 500 hp swashplate engine geared to a pump-jet propulsor. It is fueled by Otto fuel II, a monopropellant that requires no oxygen supply and can propel the torpedo at up to (74.56 mph). Other applications include pneumatic and hydraulic motors, hydrostatic transmissions such as Honda's Hondamatic CVT, and air conditioner pumps. Also, some Stirling engines use a swashplate arrangement, e.g., Stirling Thermal Motors' STM 4-120 engine. See also Axial piston pump Notes References External links Barrel Engine - Part 2 Flight December 1941 Engine technology Piston engines