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Family of light helicopters From Wikipedia, the free encyclopedia
The Hiller OH-23 Raven is a two, three, or four-place, military 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),[1] which was first flown in 1948. Initially it was a two-place helicopter powered by a piston engine that entered service in the late 1940s, it went on to be a popular military and civilian light helicopter in the late 20th century.
 | This article includes a list of general references, but it lacks sufficient corresponding inline citations. (February 2020) |
| OH-23 Raven | |
|---|---|
| Hiller OH-23G Raven | |
| General information | |
| Type | Multipurpose light helicopter |
| Manufacturer | United Helicopters Hiller Aircraft |
| Status | Retired |
| Primary users | United States Army |
| Number built | 2000+ |
| History | |
| Manufactured | 1948–1965 |
| Introduction date | 1948 |
| First flight | 1948 |
A Hiller UH-12 was the first helicopter to make a transcontinental flight across the USA, in 1949. It served in the Korean War with U.N. forces and also in Vietnam. It was an important early helicopter and was widely used internationally, in U.K. service it was called the Hiller HT Mk 1 and Mk 2, and the U.S. Navy also used it as the HTE-1 for training. It was sold commercially as the UH-12 (This was a company designation not military), though some military operators used the company designation. Some later models were designed for turbine power, and a version with 4-seats was also sold. In Canada, UH-13E served the military as the CH-112 Nomad.
Hiller was taken over by Fairchild in 1964. A new company, Hiller Aviation, took over support of some UH-12 variants in the 1970s, and later became Rogerson Hiller.[2]
In 1947, United Helicopters (later renamed Hiller Aircraft) developed the prototype Model 360X helicopter. A year later, on 14 October 1948 the Civil Aeronautics Authority (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 as the UH-12A. The UH-12A would be adopted by both the French and United States militaries, as well as being used by civil commercial operators in several countries.
The helicopter began production in the late 40s and had a trial by fire in the Korean war; a lot of hard won lessons resulted in the B model, the UH-13B and production capacity greatly increased in this period.[3]
It was produced until 1965, with over 2,000 produced.[4]
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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.
The Raven used Hiller's "Rotor-Matic" cyclic control system, with two small servo rotor paddles offset 90 degrees to the main rotor blades. The paddles were attached to the control column, so that movement of the column would cause the pitch of the servo paddles to change, loading the main rotor blade so that the desired cyclic changes to the rotor occurred.[5] The OH-23 had a top speed of 97 mph (156 km/h; 84 kn). 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 Lycoming O-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 (227 kW) engine. The OH-23G could seat three. 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 Hughes OH-6A Cayuse in early 1968. A Raven piloted by Hugh Thompson, Jr. played a crucial role in curtailing the My Lai Massacre.[6] When a Raven of the 59th Aviation Company strayed north of the Korean DMZ in August 1969 it was shot down and the crew were kept prisoner until released on December 2.[7]
The Raven could be armed with twin M37C .30-caliber 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 aiming the guns.
The Royal Navy's No. 705 Training Squadron used Hiller HTE-2s for several years from 1953 and later operated Hiller 12E's for many further years as its basic helicopter trainer based at RNAS Culdrose located in Cornwall, England.
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Data from United States Military Aircraft since 1909[34]
General characteristics
Performance
Related development
Aircraft of comparable role, configuration, and era
Related lists
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