The Curtiss N-9H was a seaplane version of the famous Curtiss JN-4D trainer used by the U.S. Air Service during the First World War. During the war, 2,500 Navy pilots were trained on the N-9H. In addition to training a generation of Navy pilots, the N-9H was used to develop tactics for ship-borne aircraft operations in 1916 and 1917, using catapults mounted on armored cruisers. After the war, an N-9 was again employed to successfully demonstrate a compressed air turntable catapult.