A radial engine is a type of internal combustion engine where the cylinders are arranged in a circular pattern around a central crankshaft. This design allows for a compact engine that can produce a significant amount of power relative to its size. Radial engines are commonly used in aircraft, particularly in vintage models, due to their reliability and ability to provide a high power-to-weight ratio. The radial engine operates by having each cylinder fire in a sequence, which helps to balance the engine and reduce vibrations. This configuration was popular in the early 20th century, especially in military aircraft like the Boeing B-17 and P-51 Mustang. Today, radial engines are less common but are still appreciated by aviation enthusiasts and collectors.