US inter-war Attack aircraft

The Curtiss A-3 was a ground attack aircraft produced for the US Army Air Corps by modifying the existing O-1 Falcon observation aircraft.
The Curtiss XA-4 was a single A-3 attack aircraft modified to test the 440hp Pratt & Whitney Wasp radial engine.
The Curtiss A-8 Shrike was a ground attack aircraft developed for the US Army Air Corps and which would eventually enter service as the A-12
The Curtiss YA-10 was the designation given to the first YA-8 Shrike when it was given a Pratt & Whitney Hornet air-cooled radial engine.
The Curtiss A-12 Shrike was a ground attack aircraft produced for the US Army Air Corps in 1934.
The Curtiss XA-14 Shrike was a two-man twin-engined ground attack aircraft designed in 1934 for the US Army Air Corps.
The Curtiss A-18 Shrike was the service-test version of the XA-14 twin-engined ground attack aircraft.
The Curtiss XA-43 was a design for a twin-engined attack aircraft proposed in 1945 as the Model 29, but which eventually flew as the XF-87 Blackhawk
The Northrop XA-13 was the first of a series of attack aircraft based on the Northrop Gamma, one of the first aircraft produced by the newly founded Northrop Corporation in 1932
The Northrop XA-16 was the designation given to the XA-13 after it was given a different engine in an attempt to imrpove visibility.
The Northrop A-17 was the standard US Army Air Corps attack aircraft during the second half of the 1930s.
The Douglas A-33 was the designation given to thirty-one Douglas 8A-5s that had been ordered by the Norwegian government in 1940, but were taken over by the US Army Air Force after the German invasion of Norway