The OX-5 is a type of aircraft engine that was developed in the early 1920s. It is a water-cooled, V-type engine with five cylinders, primarily used in training aircraft during the interwar period. The OX-5 was known for its reliability and ease of maintenance, making it a popular choice for flight schools. This engine powered several notable aircraft, including the Waco YMF and the Travel Air 2000. Its design contributed to the advancement of aviation technology, helping to train many pilots who would later serve in military conflicts. The OX-5 remains an important part of aviation history.