02/28/2011. The A-3 (Curtiss Model 44) was an attack aircraft converted from O-1B observation machines, incorporating bomb racks under the wings and a 0.30 in (7.62 mm) machinegun in each lower wing panel to supplement the two 0.30 in (7.62 mm) forward-firing nose machinegun and the twin 0.30 in (7.62 mm) Lewis guns on the rear cockpit Scarff ring.
In all, 76 A-3s were produced, s/n 27-243, 27-245 to 27-262, 27-298 to
27-317, 28-083 to 28-118, of which five, including 27-306, 27-310, and 27-315 were converted to A-3A dual control trainers. The pictured first A-3 was tested at McCook Field under the Project Number P-493, it was scrapped in 1932.
Later 78 A-3Bs (Curtiss Model 37H) were produced, s/n 30-1 to 30-28 and
30-231 to 30-280, these incorporated O-1E structural and aerodynamic improvements, including balanced ailerons and elevators, a 36 gal (136 l) belly fuel tank, oleo struts and a tail wheel.
The sole XA-4, s/n 27-244, was identical to the A-3 except for installation of a 410 hp Pratt & Whitney Wasp R-1340. Under Project Number P-500 it was also tested at McCook Field.