The Curtiss A-3 was the winner of a design/fly-off competition with the Douglas A-2. The A-3 was based on the Curtiss O-1B observation plane. Similarly, Douglas A-2 was a modification of the Douglas O-2 design. During the mid to late 1920s, the Army Air Corps leadership wanted the observation airplane to expand its role from simply scouting enemy activity to a more active role including attacking ground forces. Modification of existing observation planes was seen as a quick was to gain ground attack capability until new designs could be completed and built.
The A-3 was very similar to the Curtiss O-1B with just a few changes incorporated for the ground attack mission. Two additional .30-cal. machine guns were added, one in each lower mid-wing. Bomb racks were installed on the lower wing also.
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 ordered. Later, six aircraft were modified as pilot trainers with dual controls and redesignated A-3A. A second batch of improved A-3Bs, based on the Curtiss O-1E were purchased beginning in 1929.
Attack version of Curtiss O-1B
Dual-control A-3 conversion
Attack version of Curtiss O-1E
TECHNICAL NOTES: Armament: Four forward-firing .30-cal. Browning machine guns and two flexible .30-cal. Lewis machine guns on a Scarff ring, plus provisions for 200 lbs. of bombs mounted on lower wing racks
Engine: Curtiss D-12D (V-1150-3) of 435 hp Maximum speed: 153 mph Cruising speed: 110 mph Range: Approx. 600 miles Service ceiling: 18,700 ft. Span: 38 ft. 0 in. Length: 27 ft. 10 in. Height: 10 ft. 3 in. Weight: 4,506 lbs. maximum takeoff weight Crew: Two (pilot, observer-rear gunner) Serial numbers: (A-3): 27-243 to 27-262; 27-298 to 27-317; 28-83 to 28-118; Curtiss Model 44: Depending on the source, serial numbers for the O-1B are sometimes listed as 27-243 to 27-287, which makes the first lot of A-3s conversions (S/N 27-243 to 27-262). Other sources list the O-1Bs as 27-263 to 27-287. Some sources list the last lot of A-3s as 28-83 to 28-108, which is almost certainly wrong since three of the six A-3A conversions were 28-116 to 28-118. The second A-3 (S/N 27-244) became the XA-4.