|The original prototype YO-40|
|National origin||United States of America|
|Primary user||United States Army Air Corps|
The Curtiss O-40 Raven was an American observation aircraft of the 1930s which was built and used in small numbers. A single example of the YO-40, a single-engined Sesquiplane with a retractable undercarriage was built, followed by four examples of a modified monoplane version, the O-40B, which remained in use until 1939.
Development and design
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. 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.
A prototype, designated YO-40, flew in February 1932. Although it crashed in May that year, it was re-built with stronger wings and an enclosed cockpit as the YO-40A. 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.
The four Y1O-40Bs were delivered in June 1933, and after service tests, were redesignated O-40B, being operated by the 1st Observation Squadron of the USAAC. While the aircraft's performance and manoeuvrability were good, the Air Corps were 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 The last O-40B was withdrawn from use in 1939.
- Prototype powered by 653 hp (487 kW) Wright R-1820E Cyclone engine.
- YO-40 rebuilt with stronger wings and enclosed cockpit. Scrapped 1938.
- Monoplane derivative with lower wing removed. Powered by 670 hp (500 kW) R-1820-27. Four built.
- Redesignation of Y1O-40B.
Data from Curtiss Aircraft 1907–1947
- Crew: 2
- Length: 28 ft 10 in (8.79 m)
- Wingspan: 41 ft 8 in (12.70 m)
- Height: 10 ft 8 in (3.25 m)
- Wing area: 266 sq ft (24.7 m2)
- Empty weight: 3,754 lb (1,703 kg)
- Gross weight: 5,180 lb (2,350 kg)
- Powerplant: 1 × Wright R-1820-27 Cyclone 9-cylinder air-cooled radial engine, 670 hp (500 kW)
- Maximum speed: 187.7 mph (302 km/h; 163 kn)
- Cruise speed: 160.5 mph (139 kn; 258 km/h)
- Stall speed: 62 mph (54 kn; 100 km/h)
- Range: 324 mi (282 nmi; 521 km)
- Service ceiling: 23,100 ft (7,041 m)
- Rate of climb: 1,660 ft/min (8.4 m/s)
- Guns: 1× fixed forward firing .30 in machine gun and 1× .30 in machine gun in observers cockpit
- Bowers 1979, pp. 331–332.
- "Curtiss:K through Z". aerofiles. 24 January 2009. Retrieved 10 March 2010.
- Flight 4 January 1934, p.20.
- Bowers 1979, pp. 332–333.
- Bowers 1979, p.333.
- "Factsheets : 1 Reconnaissance Squadron (ACC)". Air Force Historical Research Agency, United States Air Force. Retrieved 10 March 2010.
- Bowers 1979, p.332.
- Bowers, Peter M. Curtiss Aircraft 1907-1947. London:Putnam, 1979. ISBN 0-370-10029-8.
- "A Modern American Observation Aircraft:The Curtiss "Raven" (Wright "Cyclone F") developed for the U.S. Army Air Corps". Flight, 4 January 1934, p. 20.
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