Sturtevant 5A The Sturtevant 5A engine, rated at 140 hp, powered the Sturtevant S-4 and some L.W.F. V-1 training airplanes used by the Signal Corps at North Island, Calif., and Mineola, N.Y., during 1916 and 1917. Neither of these airplanes proved suitable, partly because of the 5A engine's high power to weight ratio of 3.5 pounds per horsepower. The Army soon replaced those aircraft with the Standard J-1 and Curtiss JN-4 trainers. Click here to return to the Early Years Gallery.