Curtiss O-40 Raven

History of Curtiss O-40 Raven

The O-40 Raven, supplied by American aircraft manufacturer Curtiss-Wright, was originally a prototype biplane. The aircraft was developed to perform light battlefield observation missions for the U.S. Army Air Corps (USAAC) during the interwar period ("interwar"). The aircraft appeared as a single prototype under the designation YO-40 (Curtiss' Type 62) and housed a pilot and an observer in an in-line open-air (back-to-back) cockpit, and the aircraft's construction was mostly metal.

Power came from a single Wright R-1820E "Cyclone" engine, mounted on the nose, driving a two-bladed propeller. A traditional upper and lower biplane wing arrangement was used (called a "halfplane", the lower wing members were much shorter than the upper wing members), while the landing gear was retractable.

Of note is the slight swept back of the upper wing elements.

The first flight of the YO-40 was recorded in 1932, but the specimen crashed in May. The airframe was mostly salvaged, and the delay gave engineers an opportunity to make changes to improve the design. This work resulted in a stronger and more capable aircraft, now with an enclosed crew cockpit, changes sufficient to warrant the subsequent designation "YO-40A". Additional work developed the design further, resulting in the complete elimination of the lower wing panels, making the YO-40 a true monoplane (though it still retained the high-mounted upper wing panels). The aircraft has now been reborn with the "Y10-40B" series, a version powered by the Wright R-1820-27 "Cyclone" 9-cylinder, 670 hp, air-cooled radial engine.

USAAC saw enough promise in the revised design to order four examples under the new standard.

When completed, the aircraft will have an overall length of 28.9 feet, a wingspan of 41.7 feet, and a height of 10.7 feet. Empty weight is 3,755 lbs and maximum takeoff weight (MTOW) is 5,180 lbs.

Power from the Wright engine gives the aircraft a top speed of 188 mph, a range of up to 325 miles, and a service ceiling of 23,100 feet. The climb rate was reported to be 1,660 feet per minute.

The O-40 was designed to travel light, carrying only two medium machine guns: 1 x .30 caliber Browning air-cooled machine gun mounted on a fixed forward firing bracket (for pilot use) and 1 x .30 caliber Browning gas Cooling machine guns Cooling machine guns are mounted on trainable mounts in the rear cockpit (for observers, mainly for self-defense).

The aircraft entered Army service in June 1933 and was officially designated the O-40B "Crow" for flying in the air. This line was mainly in service with the 1st Observation Squadron (established in March 1913 and, surprisingly, still exists today as the "1st Reconnaissance Squadron"). Due to limited range, the service only procured these four models, and the line only operated until 1939.

The salvaged YO-40A prototype mentioned above was destroyed after rework as early as 1938. Therefore, no Raven aircraft survived World War II (1939-1945).

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