Editing Curtiss Falcon (section)

===U.S. Army Air Corps===
;A-3: Model 44, [[attack aircraft]] version of O-1B, armed with two 0.30&nbsp;in (7.62&nbsp;mm) machine guns and 200&nbsp;lb (91&nbsp;kg) of bombs; 66 built for the USAAC.
;A-3A: Six A-3s converted into trainers.
;A-3B: Model 37H, attack version of O-1E, with six machine guns, including two mounted in wings; 78 built.
[[File:Curtiss XA-4 parked.jpg|thumb|right|Curtiss XA-4 Falcon]]
;XA-4: One A-3 with a [[Pratt & Whitney R-1340-1]] Wasp radial piston engine. Scrapped in March 1932, but the design was the basis for the naval variants.
;A-5: Proposed A-3 variant with [[Curtiss V-1570 Conqueror]] engine
;A-6: Proposed A-3 variant with [[Curtiss H-1640 Chieftain]] engine
[[File:Curtiss XBT-4.jpg|thumb|right|XBT-4]]
;XBT-4: Model 46, one O-1E converted into a basic trainer for the USAAC.
;XO-1:Liberty 12A powered Prototype, later modified to use a Packard 1A-1500, one built.
;O-1: Model 37A, two-seat observation aircraft, the first production model, ten built. One converted into the '''O-1 Special''' VIP transport.
;O-1A: Two-seat observation aircraft, powered by the Liberty piston engine, one built.
;O-1B: Model 37B, first major production version, powered by [[Curtiss D-12D]] (V-1150-3) engine; 45 ordered, 25 built and 20 diverted on the production line to the A-3.
;O-1C: Four O-1Bs converted into VIP transports.
;O-1E: Model 37I, variant powered by {{cvt|435|hp}} [[Curtiss D-12E]] (V-1150-5) piston engine; 41 built.
;O-1F: Model 37J, one O-1E converted into VIP transport.
;O-1G: Model 38, final O-1 variant, powered by a {{convert|712|hp|kW|abbr=on}} [[Wright R-1820 Cyclone|Wright R-1820F-2 Cyclone]] engine; 30 built for USAAC.
;XO-11: Two O-1 modified as O-11 prototypes.
;O-11: O-1 airframe powered by the Liberty V-1650 piston engine; 67 built concurrently with the O-1s.
;XO-12: One XO-11 prototype redesignated XO-12.
;XO-13: O-1 fitted with {{cvt|720|hp}} Conqueror engine for the 1927 [[National Air Races]].
;XO-13A: Second XO-13, fitted with wing skin radiators.
;O-13B: One O-1C fitted with a Conqueror engine, tested as an observation aircraft, and provided to Secretary of War.
;YO-13C: Three O-1Es re-engined with {{cvt|600|hp}} direct-drive Conqueror engines.
;YO-13D: One O-11 fitted with supercharged Conqueror engine.
;XO-16: One O-11 with Prestone cooling system.
;XO-18: One O-1B testbed for [[Curtiss H-1640 Chieftain]] engine.
;Y1O-26: One O-1E fitted with a geared Conqueror engine.
;O-39: O-1G refitted with a Conqueror engine and cockpit canopy; ten built.