Liberty L-4

The Liberty L-4B was an experimental water-cooled inline four-cylinder aircraft engine developed in the United States during World [War I]. The engine was designed and manufactured by the Hudson [Motor Car Company] and was mainly intended for use in training airplanes. Only two examples of the L-4B were produced, since other types of engines were available and in production. While the engine was ground-tested, it is unknown if the L-4 was ever test-flown. The L-4 was created as part of a US aircraft engine development effort which also created the six-cylinder Liberty L-6, eight-cylinder Liberty L-8 and twelve-cylinder Liberty L-12.