Curtiss 59A / A-8
To find a successor to its attack biplanes, the US Army Air Corps issued a 1929 requirement for a high-speed monoplane, and Curtiss responded with its Model 59 design that first flew in prototype form during June 1931 with the 600-hp (447-kW) Curtiss V-1570-C inline engine with a radiator beneath the nose, slightly forward of the wing leading edge.
The first Curtiss all-metal low-wing monoplane, with such advanced features as automatic leading-edge slots and trailing-edge flaps. The wing was strut-and wire-braced, and the main landing gear comprised two fully-enclosed trousered units, these fairings housing also two 7.62mm machine-guns. Pilot and observer-gunner were accommodated in widely separated cockpits, the former under a fully enclosed canopy and the latter protected by an extended windscreen. Power was provided by a 447kW Curtiss V-1570C inline engine.
These entered service with the 3rd Attack Group in April 1932 as the US Army’s first monoplanes. Another 46 Shrikes were ordered with the designa-tion A-8B, but because of maintenance difficulties with the A-8s’ inline engines, the aircraft were recast as radial-engined A-12s.
Curtiss won a contract for five service test YA-8 (Model 59A) aircraft on 29 September 1931, and these were followed by eight Y1A-8 machines in 1932. Both YA-8s and Y1A-8s had open pilot's cockpits. All were later redesignated A-8 except for one YA-8 which was reworked as the experimental YA-10 (Model 59B) with a 466kW radial engine and one Y1A-8 which became the Y1A-8A with a 503kW V-1570-57 geared engine and a redesigned wing.
The A-8s, powered by Prestone-cooled V-1570-31 engines each of 447kW, went into service with the 3rd Attack Group at Fort Crockett, Texas in April 1932. That eight months before the Boeing P-26A Peashooter.
The US Army had ordered a further 46 Shrikes under the designation A-8B, but maintenance problems with the liquid-cooled engines of the A-8s led to the new aircraft being powered by Wright R-1820-21 radial air-cooled engines of 500kW, resulting in the new designation A-12 (Model 60).
After long service with the US Army's attack groups the Shrikes were relegated to second-line units in 1939, but nine A-12s still remained in service in Hawaii when Pearl Harbor was attacked in December 1941.