Hiller OH-23 Raven

The Hiller OH-23 Raven was a three-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.

Development
Stanley Hiller designed his first helicopter at the age of 15, and built and flew his first helicopter, the Hiller XH-44, when he was aged 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, as well as being used by civil commercial operators in several countries.

Operational history
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. The OH-23 had a top 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 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 OH-6A Cayuse in early 1968. A Raven piloted by Hugh Thompson, Jr. played a crucial role in curtailing the My Lai Massacre. 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.

The Royal Navy used Hiller 12E's for many years as its basic helicopter trainer - at 705 Sqn based at RNAS Culdrose in Cornwall, England.

Military

 * YH-23
 * One Model UH-12A, modified with two-seat cabin and 178 hp Franklin engine for US Army evaluation.


 * H-23A
 * Initial production version with 178 hp (133 kW) Franklin O-335-4 piston engine and two-seat cockpit, 100 built for the US Army and 5 for evaluation by the US Air Force.


 * H-23B
 * H-23A with skid/wheel undercarriage and 200 hp (149 kW) O-335-6 engine (some later re-engined with a 250 hp VO-435-23B), re-designated OH-23B in 1962, 273 built for the US Army and 81 for military export.


 * H-23C
 * Model UH-12C with three-seat cabin, one-piece canopy and metal rotor blades, 145 built for the US Army. Re-designated OH-23C in 1962.


 * H-23D
 * H-23C with new rotor, transmission and 250 hp (187 kW) Lycoming VO-435-23B engine, 348 built for US Army. Re-designated OH-23D in 1962.


 * H-23E
 * Model UH-12E, not bought


 * H-23F
 * Model UH-12E-4, four-seat model with 25-inch cabin extension and a 305 hp VO-540-A1B engine, redesignated OH-23F in 1962, 22 built for US Army.


 * H-23G
 * Three-seat dual control version of H-23F, redesignated OH-23G in 1962, 793 built.


 * HTE-1
 * US Navy version of the Model UH-12A with Franklin O-335 engine, two-seater with dual controls, and wheeled tricycle undercarriage, 17 built.


 * HTE-2
 * US Navy version of H-23B with Franklin O-335-6 engine, 35 built.


 * Hiller HT Mk 1
 * Royal Navy designation for 20 former US Navy HTE-2s.


 * Hiller HT Mk 2
 * UH-12Es for Royal Navy. 21 supplied.


 * CH-112 Nomad
 * Canadian military designation.

Civilian

 * UH-12A
 * Original production model for the US Army, powered by a 178 hp Franklin O-335-4 piston engine. US Army designation H-23A.


 * UH-12B
 * Training version for the US Navy. US Navy designation HTE-1.


 * UH-12C
 * Three-seat version, equipped with all-metal rotor blades and one-piece 'goldfish bowl' canopy.

US Army designation H-23C.
 * UH-12D
 * Improved version of the H-23C for the US Army. US Army designation H-23D.


 * UH-12E
 * Three-seat dual-control version of the H-23D.


 * UH-12ET
 * Turbine-powered version of the UH-12E, fitted with an Allison 250 turboshaft engine.


 * UH-12E3
 * New three-seat production version.


 * UH-12E3T
 * New turbine-powered production version.


 * UH-12E4
 * Four-seat civilian version. US Army designation H-23F.


 * UH-12E4T
 * Four-seat turbine-powered production version.


 * UH-12L-4
 * Lengthened version with wider cabin windows.

Operators

 * Argentine Army
 * Buenos Aires Provincial Police
 * Canadian Army
 * Chilean Air Force
 * Colombian Air Force
 * Dominican Air Force
 * Guatemalan Air Force
 * Indonesian Air Force
 * Colombian Air Force
 * Dominican Air Force
 * Guatemalan Air Force
 * Indonesian Air Force
 * Guatemalan Air Force
 * Indonesian Air Force
 * Indonesian Air Force
 * Israeli Air Force
 * Mexican Air Force
 * Netherlands Air Force
 * Paraguayan Air Force
 * Peruvian Air Force
 * 🇰🇷 South Korea
 * South Korea Army
 * Royal Thai Police
 * Bristow Helicopters
 * Royal Navy
 * Columbia Helicopters
 * United States Army
 * United States Navy
 * Uruguayan Air Force
 * Bristow Helicopters
 * Royal Navy
 * Columbia Helicopters
 * United States Army
 * United States Navy
 * Uruguayan Air Force
 * Uruguayan Air Force
 * Uruguayan Air Force

Popular culture
A UK registered civil UH-12 was seen attacking James Bond in the 1963 film From Russia with Love. A UH-12E4 (A UK registered civil aircraft with faux U.S. Army markings) was used in the 1964 Bond film  Goldfinger. One was also seen in the 1967 Bond film You Only Live Twice.

The 1978 film Attack of the Killer Tomatoes contains footage of a real helicopter crash. A Hiller Aircraft UH-12E, U.S. civil registry N81959, suffered a tail-rotor strike during a scene where the helicopter was supposed to have landed in a tomato patch behind police officers. The aircraft spun out of control, rolled over, and burst into flames. The helicopter pilot escaped without serious injury.

The type has also been seen in numerous other films.