The design of the Model 15 was based on studies of the Fokker D.VII,[REF] of which 142 were brought back to the U.S. for evaluation as part of the Armistice Agreement ending World War I.
The original engine was a Wright-Hispano, but when the liquid-cooled Curtiss D-12 became available the aircraft was redesigned, moving the radiator from the nose to a "tunnel" under the engine [REF].