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 A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

version, the O-40B, which remained in use until 1939.

Development and design

In 1931, in response to a

United States Army Air Corps The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical r ...

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 Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

fuselage and had a retractable

tailwheel undercarriage Conventional landing gear, or tailwheel-type landing gear, is an aircraft undercarriage consisting of two main wheels forward of the center of gravity and a small wheel or skid to support the tail.Crane, Dale: ''Dictionary of Aeronautical Term ...

with inwards retracting mainwheels, and was powered by a

Wright Cyclone Wright Cyclone was the name given to a family of air-cooled radial piston engines designed by the Wright Aeronautical Corporation and used in numerous American aircraft in the 1930s and 1940s. Background The Wright Aeronautical Corporation wa ...

radial engine The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ...

. The crew of two sat in tandem in open cockpits.Bowers 1979, pp. 331–332.Curtiss:K through Z
. ''aerofiles''. 24 January 2009. Retrieved 10 March 2010.''Flight'' 4 January 1934, p.20. A prototype, designated YO-40, flew in February 1932. Although it crashed in May that year, it was rebuilt 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.Bowers 1979, pp. 332–333.

Operational history

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.Factsheets : 1 Reconnaissance Squadron (ACC)
". Air Force Historical Research Agency, ''United States Air Force''. Retrieved 10 March 2010. 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.

Variants

;YO-40 :Prototype powered by 653 hp (487 kW) Wright R-1820E Cyclone engine.Bowers 1979, p.332. ;YO-40A :YO-40 rebuilt with stronger wings and enclosed cockpit. Scrapped 1938. ;Y1O-40B :Monoplane derivative with lower wing removed. Powered by 670 hp (500 kW) R-1820-27. Four built. ;O-40B :Redesignation of Y1O-40B.

Operators

; *

** 1st Observation Squadron

Specifications (O-40B)

References

;Notes ;Bibliography * Bowers, Peter M. ''Curtiss Aircraft 1907-1947''. London:Putnam, 1979. .
A Modern American Observation Aircraft:The Curtiss "Raven" (Wright "Cyclone F") developed for the U.S. Army Air Corps
. ''

Flight Flight or flying is the process by which an object moves through a space without contacting any planetary surface, either within an atmosphere (i.e. air flight or aviation) or through the vacuum of outer space (i.e. spaceflight). This can be a ...

'', 4 January 1934, p. 20.

External links

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{{USAAF observation aircraft 1930s United States military reconnaissance aircraft O-040 Single-engined tractor aircraft Sesquiplanes Aircraft first flown in 1932