To compete with the expanding range of lightplanes offered by other aircraft manufacturers, Piper produced in 1938 the Piper J-4 Cub Coupe. Retaining basically the same airframe as the J-3 Cub, this had a small increase in wing span and introduced improved landing gear with a fully-castoring tailwheel, hydraulic brakes and-speed fairings for the wheels. As powered initially by a 37kW Continental A50-1 it had the designation J-4, but introduction of the 48kW Continental A65-1 or -8 engine in 1940 brought redesignation as the J-4A, and later of the 56kW Continental A75-9 as the J-4E. In 1939 Piper introduced the J-4B, differing only in powerplant which initially, was a 45kW Franklin 4AC-171, but that was soon replaced by the 48kW Franklin 4AC-176-B2 without any change in designation. Last of the J-4s was the version powered by Avco Lycoming engines, the 41kW O-145-A1 or -A2, or 48kW O-145-B1, both of these Cub Coupes having the designation J-4F. Production of J-4s reached 1,250, and during World War II 17 J-4Es were impressed for service with the USAAF under the designation L-4E.