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Curtiss-Wright 62 / O-40 Raven
The original prototype YO-40
In 1931, in response to a United States Army Air Corps requirement for a new observation aircraft, Curtiss designed the Model 62, a single-engined biplane with the lower wing much smaller than the upper, known as a sesquiplane (i.e. "one-and-a-half wings"), while the outer panels of the upper wings were swept back to avoid centre-of-gravity problems. The lower wing was connected to the upper wing by one set of struts. It was of all-metal construction, with a monocoque fuselage and had a retractable tailwheel undercarriage with inwards retracting mainwheels, and was powered by a Wright Cyclone radial engine. The crew of two sat in tandem in open cockpits. It was armed with one fixed forward firing .30in machine gun in the right upper wing and one flexibly mounted .30in gun in the rear cockpit.
A prototype (sn 32-343), designated YO-40, flew in February 1932. It crashed on 20 May that year, and had to be returned to Curtiss where it was rebuilt with stronger wings and an enclosed cockpit as the YO-40A. The YO-40A was scrapped in 1938.
A further four YO-40As were ordered, but they were redesigned as monoplanes by removing the lower wing, the resultant aircraft being designated Y1O-40B. A stub of the lower wing had to be retained as it contained the retractable landing gear. The engine was upgraded to a more powerful R-1820-27 and the wingspan reduced by 2ft 4in. The new aircraft were heavier than the original prototype, and their performance was generally worse.
The four Y1O-40Bs (sn from 32-415 to 32-418) were delivered in June 1933, and after service tests, were re-designated O-40B Raven, being operated by the 1st Observation Squadron of the USAAC. While the aircraft's performance and manoeuvrability were good, the Air Corps was disappointed with the cockpit arrangements and the low fuel capacity, and no more orders followed. The last O-40B was withdrawn from use in 1939.
Engine: Wright R-1820E Cyclone, 653 hp / 487 kW
Y1O-40B / O-40B
Engine: Wright R-1820-27 Cyclone, 670 hp / 500 kW
Wingspan: 41 ft 8 in (12.70 m)
Wing area: 266 sq.ft (24.7 sq.m)
Length: 28 ft 10 in (8.79 m)
Height: 10 ft 8 in (3.25 m)
Empty weight: 3,754 lb (1,703 kg)
Gross weight: 5,180 lb (2,350 kg)
Maximum speed: 187.7 mph (302 km/h; 163 kn)
Cruise speed: 160.5 mph (258 km/h; 139 kn)
Stall speed: 62 mph (100 km/h; 54 kn)
Range: 324 mi (282 nmi; 521 km)
Service ceiling: 23,100 ft (7,000 m)
Rate of climb: 1,660 ft/min (8.4 m/s)
Armament: 1× fixed forward firing .30 in Browning machine gun and 1× .30 in Browning machine gun in observers cockpit
Crew: two

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