Aircraft engines, particularly turbine and high-performance piston types, often operate at very high rotational speeds to maximize thermal efficiency and power-to-weight ratios. However, when such engines drive propellers, a challenge arises. Propellers are only aerodynamically efficient within a limited RPM range, and if they approach or exceed transonic speeds - typically around 1,100 to 1,150 feet per second at sea level - shock waves can form. This phenomenon, known as compressibility or transonic drag, leads to reduced thrust, increased aerodynamic drag, excessive noise, and elevated mechanical stress on the propeller system. Read more >>

Piston engine technology has a long history for automobiles and aircraft engine assemblies, ensuring the generation of thrust and propulsion through the combustion of fuel-and-air mixtures. Since their inception, various piston engine types have come about for aircraft and automobiles, examples being in-line, rotary, V-type, radial, and horizontally opposed engines. The opposed piston engine in particular is a more specialized type, featuring cylinders that have a piston on both ends and a lack of a cylinder head. Read more >>