The Hiller OH-23 Raven was a four-place, light observation helicopter based on the Hiller Model 360. The Model 360 was designated by the company as the UH-12 ("UH" for United Helicopters), which was first flown in 1948.
Stanley Hiller built and flew his first helicopter, the Hiller XH-44, when he was 19. With the help of shipping mogul Henry Kaiser, Hiller established the United Helicopters company in 1946. In 1947, United Helicopters developed the Model 360X, the prototype that would become the basis for the H-23. A year later, on 14 October 1948 the CAA issued a production certificate for the Model 360. United Helicopters began producing the Model 360 as the UH-12. In 1949, the UH-12 became the first helicopter to make a transcontinental flight from California to New York. When Hiller upgraded the engine and the rotor blades, the company designated the new model the UH-12A. It was the UH-12A that would be adopted by both the French and United States militaries.
The H-23 Raven performed as a utility, observation, and MedEvac helicopter during the Korean war. Model numbers ranged A through D, F and G. The H-23A had a sloping front windshield. The H-23B was used as a primary helicopter trainer. Beginning with the UH-23C, all later models featured the "Goldfish bowl" canopy similar to the Bell 47, it also featured a unique cyclic control system, through two paddles offset 90 degrees to the main rotor blades. The OH-23 had a speed of 97 mph (84 knots). The Raven had a two-bladed main rotor, a metal two-bladed tail rotor. Both the OH-23B and the OH-23C were powered by one Franklin O-335-5D engine.
The OH-23D was a purely military version with a 0-435-23C engine and a more reliable transmission. Most OH-23Ds were replaced by the OH-23G, the most common version of the Raven, with a more powerful Lycoming O-540-9A six-cylinder, horizontally opposed, air cooled 305 hp engine. The OH-23G could seat four. The MEDEVAC version carried two external skid-mounted litters or pods. The Raven saw service as a scout during the early part of the Vietnam war before being replaced by the OH-6A Cayuse in early 1968. The Raven could be armed with twin M37C .30 Cal. machine guns on the XM1 armament subsystem or twin M60C 7.62 mm machine guns on the M2 armament subsystem. The XM76 sighting system was used for sighting the guns.
US Army designation H-23C.
Published - July 2009
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