Curtiss O-40 Raven

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.

O-40 Raven
The original prototype YO-40
Role Observation aircraft
National origin United States of America
Manufacturer Curtiss-Wright
First flight 1932
Introduction 1933
Retired 1939
Primary user United States Army Air Corps
Number built 5

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.[1][2][3]

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.[2][4]

Operational history

The four Y1O-40Bs were delivered in June 1933, and after service tests, were redesignated O-40B,[5] being operated by the 1st Observation Squadron of the USAAC.[6] While the aircraft's performance and manoeuvrability were good, the Air Corps was disappointed with the cockpit arrangements and the low fuel capacity,[2] and no more orders followed. The last O-40B was withdrawn from use in 1939.[5]

Variants
YO-40
Prototype powered by 653 hp (487 kW) Wright R-1820E Cyclone engine.[7]
YO-40A
YO-40 rebuilt with stronger wings and enclosed cockpit. Scrapped 1938.[2][5]
Y1O-40B
Monoplane derivative with lower wing removed. Powered by 670 hp (500 kW) R-1820-27. Four built.[5]
O-40B
Redesignation of Y1O-40B.[5]

Operators
 United States

Specifications (O-40B)

Data from Curtiss Aircraft 1907–1947[5]

General characteristics

  • Crew: two
  • 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)

Performance

  • Maximum speed: 187.7 mph (302.1 km/h, 163.1 kn)
  • Cruise speed: 160.5 mph (258.3 km/h, 139.5 kn)
  • Stall speed: 62 mph (100 km/h, 54 kn)
  • Range: 324 mi (521 km, 282 nmi)
  • Service ceiling: 23,100 ft (7,000 m)
  • Rate of climb: 1,660 ft/min (8.4 m/s)

Armament

  • Guns: 1× fixed forward firing .30 in machine gun and 1× .30 in machine gun in observers cockpit

References
Notes
  1. Bowers 1979, pp. 331–332.
  2. "Curtiss:K through Z". aerofiles. 24 January 2009. Retrieved 10 March 2010.
  3. Flight 4 January 1934, p.20.
  4. Bowers 1979, pp. 332–333.
  5. Bowers 1979, p.333.
  6. "Factsheets : 1 Reconnaissance Squadron (ACC) Archived 2011-09-13 at the Wayback Machine". Air Force Historical Research Agency, United States Air Force. Retrieved 10 March 2010.
  7. Bowers 1979, p.332.
Bibliography
  • 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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