The Huff-Daland Type XV Training Water-Cooled TW-5 was a biplane trainer designed by the Huff-Daland Aero Corporation in the early 1920s for the United States Army Air Service. Design and development It was a development of the TA-6 (which itself was a one-off redesigned TA-2 with a 220 hp Lawrance J-1 air-cooled engine) but powered by a 190 hp Wright-Hispano E2. In 1924, the letter-and-number system was revised, and the TW-5 became an Advanced Trainer AT-1. In 1927, Huff-Daland Aero Corporation became a division of Keystone Aircraft Corporation. Operational history Versions of the AT-1 were built for the United States Navy as training and observation aircraft. Variants The TA-6 (Trainer, Air-cooled type 6) Powered by the 200 hp Lawrance J-1 air-cooled engine, 1 built TW-5 (Trainer, Water-cooled type 5) Powered by the 150-hp (112-kW) Wright-Hispano I engine, 5 built. AT-1 U.S. Army Advanced Trainer, 10 built. AT-2 One aircraft tested in a number of single-seat and two-seat versions HN-1 United States Navy version of the AT-1 powered by a 180hp Wright-Hispano E2 engine, 3 built. HN-2 United States Navy version of the AT-1 powered by a 200hp Lawrance J-1, 3 built. HO-1 United States Navy observation version of the HN-1 powered by a 180hp Wright-Hispano E2 engine with interchangeable wheel or float undercarriage, 3 built Operators United States Army Air Service United States Navy Specifications (AT-1) See also References "United States Military Aircraft Since 1908" by Gordon Swanborough & Peter M. Bowers, 1977, 675 pp. Huff-Daland TW-05 TW-05 Single-engined tractor aircraft Biplanes