Wing detail of the Curtiss YA-8, showing the leading edge slats "B" (slots) and trailing edge flaps "C.". "A" is the wing and "D" is the aileron. Also note the barrel of the .30-cal. machine gun in the landing gear fairing. (U.S. Air Force photo)
In the late 1920s the U.S. Army conducted a competition for a new attack aircraft to replace the biplane Curtiss A-3 Falcons. Two companies submitted similar low-wing, all-metal monoplane aircraft. Both aircraft were powered by the Curtiss V-1570 Conqueror V-12 liquid-cooled engine. The Atlantic-Fokker Co. (also known as General Aviation) aircraft was designated XA-7 and the Curtiss aircraft was XA-8. The XA-8 was declared the winner after a flight test program was completed. The initial five service test aircraft were ordered in September 1931 and designated YA-8. An additional eight aircraft were ordered with a different funding source and designated Y1A-8, but were otherwise identical to the YA-8.
The YA-8 was very similar to the prototype XA-8 with only a few changes. The engine was upgraded from a water-cooled Curtiss V-1570-23 to the Prestone-cooled Curtiss V-1570-31. The armament was actually installed in the YA-8 also -- the XA-8 was designed for armament but never actually had armament installed. The YA-8 forward defensive armament consisted of four .30-cal. machine guns mounted in the landing gear fairings. This unusual location was selected primarily for convenience. There was easy access for maintenance and ammunition loading. The guns were outside the propeller arc so, synchronization gear wasn't necessary.
After completion of service testing, the last four YA-8s were assigned to an operational Attack Group (3rd) and re-designated A-8. The first YA-8 (S/N 32-344) was retained for use as an engine test bed. This YA-8 was fitted with a radial engine and designated YA-10. The radial engine was coming into favor in the early 1930s and many combat aircraft were converted to test the feasibility of a radial engine version. The radial, being air cooled, was thought to be more combat-capable because it lacked the vulnerable liquid cooling system.
Type
Number built/
converted
Remarks
XA-8
1
Low-wing monoplane design
YA-8
5
Service test aircraft
Y1A-8
8
Service test aircraft
A-8
11 (cv)
Operational YA-8 and Y1A-8
Y1A-8A
1 (cv)
A-8 with geared engine
A-8A
1 (cv)
Operational Y1A-8A
A-8B
0
Design study; ordered as A-12
TECHNICAL NOTES: Armament: Four forward-firing .30-cal. machine guns and one flexible .30-cal. machine gun for the rear gunner plus provisions for up to 488 lbs. (4x122 lbs.) of bombs mounted on wing racks Engine:Curtiss V-1570-31 Conqueror of 600 hp Maximum speed: 183 mph Cruising speed: 153 mph Range: 480 miles Service ceiling: 18,100 ft. Span: 44 ft.
Length: 32 ft.
Height: 9 ft. Weight: 5,890 lbs. gross takeoff weight Crew: Two (pilot and observer/rear gunner) Serial numbers: 32-344 to 32-348; Curtiss Model 59A Other notes: The first YA-8 (S/N 32-344) became the YA-10 after an engine change (radial)
