The Curtiss Falcon was a family of military biplane aircraft built by the American aircraft manufacturer Curtiss Aeroplane and Motor Company during the 1920s. Most saw service as part of the United States Army Air Corps as observation aircraft with the designations O-1 and O-11, or as the attack aircraft designated the A-3 Falcon. U.S. Navy variants were used initially as fighter-bombers with the designation F8C Falcon, then as the first U.S. Marine Corps dive bombers with the name Helldiver. Two later generations of Curtiss dive-bombers were also named Helldiver. The type was introduced in 1925 and saw first-line service in the United States until 1934. Curtiss Falcons fought in the Constitutionalist Revolution of 1932 in Brazil, used by the forces of São Paulo. Design and development The Falcon XO-1 prototype was evaluated by the USAAC along with eleven other prototypes in 1924 and the Douglas XO-2 was declared the winner of that competition. So Curtiss re-engined the prototype with the Packard 1A-1500 for the 1925 trials, which it won. The engine failed to live up to expectations and the O-1 ordered by the Army was fitted with the 435 hp (324 kW) Curtiss V-1150 (D-12) engine. The aircraft was a conventional unequal-span biplane design with wooden wings, while the fuselage was built using aluminum tubing with steel tie rod bracing. The landing gear was fixed and the tail included a balanced rudder with a rear skid originally, later changed to a tailwheel. The initial A-3 Falcon order was placed in the winter of 1927 and delivery of the first plane was in October 1927. A total of 76 A-3s were received. Later, six aircraft were modified as pilot trainers with dual controls and redesignated A-3A. A second batch of 78 improved A-3Bs, based on the Curtiss O-1E, was purchased beginning in 1929. Operational history Reasonably successful as an observation aircraft, Falcons flew primarily in the 1st, 5th and 99th Observation Squadrons of the 9th Observation Group, Mitchel Field, New York. The A-3 Attack Falcon saw considerable use, in frontline service with the 8th, 13th and 19th Attack Squadrons of the 3rd Attack Group, Barksdale Field, Louisiana, and the 26th Attack Squadron in Hawaii from 1928 to 1934 and with reserve units until 1937. The U.S. Navy introduced the F8C-1 and F8C-3 Falcon as a shipboard fighter in 1927–1928. They were later redesignated OC-1 and OC-2 for Marine Corps use