|Hiller 360 / UH-12 / OH-23|
The Hiller UH-12, derived from the Model 360 two-seater of 1948 with a 180hp Franklin engine, occupies an important place in the history of the American helicopter industry in the fifties. Stanley Hiller Jr., who built the aircraft, was something of a whiz kid, in that he designed and built his first helicopter, the XH-44, in 1944 at the age of only 18. It was the first efficient American helicopter with coaxial, contra-rotating rotors. The later Hiller 360 leapt to fame in the summer of 1949 when it made the first transcontinental commercial flight. With an uprated engine and new UH-12A rotor blades, it was purchased by the US Army and Navy for battlefield evacuation and observation tasks, with the designation H-23 Raven, whilst the Navy ordered the same basic model as the HTE-1 for training.
Its successor, the H-23B, powered by a 200-210hp Franklin engine, was the first version used by the US Army as a trainer. A considerable number were built: 216 were assigned to the Primary Flying School at Fort Walters and another 237 were used for various tasks.
The UH-12B normally had skid or flotation gear, but a wheeled undercarriage was fitted to a batch ordered by the US Navy (the HTE-2). In 1955 a new variant, the UH-12C, appeared. It retained the 200hp Franklin engine, but had all-metal rotor blades and a "goldfish bowl" cockpit canopy. From 1956, 145 were delivered to the US Army as the H-23C. A purely military version, the OH-12D, flew on 3 April 1956 and 483 went to the US Army. The Franklin engine had been replaced by the more powerful 320hp Lycoming VO-540, and the transmission had also been changed to increase the service life of the helicopter.
The commonest version of this sturdy little helicopter was the UH-12E which had a more powerful engine. The US Army replaced nearly all the OH-23Ds by Hiller 12Es, designated OH-23G. In 1960 the Model E4 was developed from the Hiller 12E, with a longer cabin to seat four and an anhedral stabilizer on the tail boom. Twenty-two of these were acquired by the US Army as the OH-23F, for geodetic research.
The last civil variant, which appeared in 1963, was the Hiller 12L-4 which was also used as a test-bed for a PT6 turbine, but the project was taken no further.
Total sales of the Hiller 12E family exceeded 2000; more than 300 were exported. Operators of the Hiller included Argentina, Canada, Chile, Colombia, Great Britain, Guatemala, Japan, Morocco, Mexico, the Netherlands, Peru and Uruguay.
G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984
Hiller Helicopters Inc. was formed in 1942 for the development and production of rotary-wing aircraft. Early work on the Hiller Model XH-44, UH-4 Commuter and the UH-5, which introduced a newly-developed 'Rotor-Matic' rotor control system, led to the Hiller Model 360 prototype. The company's first production helicopter followed and this, known as the Hiller UH-12 as Hiller had become part of United Helicopters, was of simple construction, incorporating a two-bladed main rotor and a two-bladed tail rotor on an upswept boom. The design was highly successful, being built extensively in two- and three-seat configurations for both civil and military use, and an early Model 12 was the first commercial helicopter to record a transcontinental flight across the United States. More than 2,000 were built before production ended in 1965, some 300 of this total being exported, and throughout this period the power and capability of the helicopter was steadily improved.
The commercial UH-12A to UH-12D became the OH-23A to OH-23D Raven respectively for service with the US Army, and the US Navy acquired UH-12As as HTE-1 and HTE-2. The UH-12E was basically a three-seat dual control version of the OH-23D and was built also as the military OH-23G. A lengthened-fuselage four-seat civil UH-12E4 was produced as the military OH-23F, and late civil versions with uprated powerplant included the UH-12E variants suffixed L3, L4, SL3 and SL4. OH-23s were exported to Argentina, Bolivia, Colombia, Chile, Cuba, Dominica, Guatemala, Guyana, Mexico, Morocco, the Netherlands, Paraguay, Switzerland, Thailand and Uruguay. The Canadian army acquired OH-23Gs which it operated with the designation CH-112 Nomad, and the Royal Navy used a number of ex-US Navy HTE-2s under the designation Hiller HT.Mk 2.
At the height of UH-12/OH-23 production Hiller was taken over by the Fairchild Corporation, but in 1973 a new company, Hiller Aviation, acquired design rights and production tooling for the UH-12E, and for some years provided support for the world-wide fleet of UH-12 variants. In April 1984 Hiller became a subsidiary of Rogerson Aircraft of Port Angeles, Washington. Renamed Hiller Helicopters and later Rogerson Helicopters, the company, now known as Rogerson Hiller, relaunched the piston-engined UH-12E in 1991 as the Hauler, and a number have been exported. The company is also proposing the Allison turbine-powered UH-12ET development for the US Army's NHT (New Training Helicopter) requirement.
D.Donald "The Complete Encyclopedia of World Aircraft", 1997
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It received its FAA (Federal Aviation Administration) approval in October 1948 and a year later a production model designated Model 12 made the first transcontinental helicopter flight across the USA. At that time it still had an open cockpit, and the 178hp Franklin 6V4-178-B33 was in an open engine bay.
Models 12A, B and C were powered by a 200hp 6V4-200-C33 or a 210hp 6V-335-B Franklin piston engine. The 12C was the first version with a goldfish bowl canopy.
The Korean War gave an added impetus to improvements and when the Hiller 12E appeared in 1959 it came either as the L3 with a 305hp Lycoming VO-540-C2A or as the SL3 with a supercharged 315hp TIVO-540-A2A engine.
The 12E has been used for the usual range of civil work, like fire-fighting, crop and forestry control, and as a private and business transport.
A Model E4 was built with a longer fuselage to take a bench for three passengers and it introduced stabilized tail surfaces. All new helicopters now have these features and they can be retrofitted on Model 12Es. A turbine-powered retrofit kit is available as the UH-12E4. This engine pack was jointly developed with Soloy Conversions of Chehalis, Washington who began work on it in 1976.
The Model 12 has the usual equipment for helicopter safety and civil work, but can also be fitted with a night-lighting kit, a 454kg capacity cargo hook, twin heavy duty cargo racks, and auxiliary fuel tanks. Equipped with extra tanks the 12E has a maximum range of 676km. Production of both the 12E and 12E-4 is running at about five a month and with over 2200 helicopters built since the introduction of the Model E there is a world-wide maintenance service.
Bill Gunston "The Illustrated Encyclopedia of Commercial Aircraft", 1980
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- An early UH-12 was the first commercial helicopter to log a transcontinental flight across the United States.
- Over 1,600 UH-12s went to the US Army and were used in Korea and Vietnam.
- As a flying ambulance, the UH-12 can carry two stretcher cases.
- UH-12s were exported to at least 18 countries, many via the Mutual Defense Aid Program.
- The Hiller UH-12 was the US Army's primary trainer until 1965.
- UH-12s were manufactured by Hiller in Palo Alto, near San Francisco, California.
Lynn S Beedle Jr, e-mail, 23.04.2021 James Palmer
I just got back from a visit to Fort Wolters. I wont begin to explain what a astounding trip that was. Everything is the same...only 52 years gone by...I spent the day there and drove over to the Main Heliport on the road between the briefing rooms and the hangars, Grant Road, and told my wife "There has GOT to be a 23 here someplace besides the main gate" (restored I might add) I saw the old hangars where the engine shops used to be. I drove around back and there was a "B" model. The hangar doors were open. I saw an A&E type and his junkyard dog. and inside his boss and.....rows of 23s in every state and condition. and racks of spares. So there is a guy who works on these things!. Pat Pockrus 888-925-5971. 940.325.5971 fax: email@example.com "Fort Wolters Helicopters" 517 Grant Road, Mineral Wells, TX....if anybody has a bubble its Mister Pockrus. He's a for-profit old-timer. Good Luck. LBeedle 10th WOC 69-49 B-1