The Curtiss OX-5 is an early aircraft engine developed by the Curtiss Aeroplane and Motor Company in the 1910s. It is a V-type, water-cooled engine with five cylinders, known for its reliability and performance in various early aircraft. The OX-5 produced around 90 horsepower, making it suitable for training and light aircraft during its time. This engine played a significant role in the development of aviation, powering many popular aircraft, including the Curtiss JN-4 Jenny. The OX-5 was widely used during World War I and the post-war era, contributing to the growth of civilian aviation and the aviation industry in the United States.