The Hiller OH-23 Raven is a three-place, military light observation
helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...
based on the Hiller Model 360. The Model 360 was designated by the company as the UH-12 ("UH" for
United Helicopters United Helicopters was formed in 1945 as a joint venture between American helicopter poineer Stanley Hiller and American industrialist Henry J. Kaiser, Henry Kaiser. The company made a very wide range of helicopters, including the world's first succ ...
),
[Donald, David. ''The Complete Encyclopedia of World Aircraft''. New York: Barnes & Noble Books, 1998.] which was first flown in 1948.
Development
In 1947,
United Helicopters United Helicopters was formed in 1945 as a joint venture between American helicopter poineer Stanley Hiller and American industrialist Henry J. Kaiser, Henry Kaiser. The company made a very wide range of helicopters, including the world's first succ ...
(later renamed
Hiller Aircraft
Hiller Aircraft Company was founded in 1942 as Hiller Industries by Stanley Hiller to develop helicopters.
History
Stanley Hiller, then seventeen, established the first helicopter factory on the West Coast of the United States, located in Berkel ...
) developed the prototype Model 360X helicopter. A year later, on 14 October 1948 the
Civil Aeronautics Authority
The Civil Aeronautics Board (CAB) was an agency of the federal government of the United States, formed in 1938 and abolished in 1985, that regulated aviation services including scheduled passenger airline serviceStringer, David H."Non-Skeds: T ...
(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. 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
, date = {{Ubl, 25 June 1950 – 27 July 1953 (''de facto'')({{Age in years, months, weeks and days, month1=6, day1=25, year1=1950, month2=7, day2=27, year2=1953), 25 June 1950 – present (''de jure'')({{Age in years, months, weeks a ...
. 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 Bell 47 is a single-rotor single-engine light helicopter manufactured by Bell Helicopter. It was based on the third Bell 30 prototype, which was the company's first helicopter designed by Arthur M. Young. The 47 became the first he ...
.
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.
[Bridgman 1953, pp. 240–241.] The OH-23 had a top speed of . 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
The Franklin O-335 (company designations variations on 6A and 6V) was an American air-cooled aircraft engine of the 1940s. The engine was of six-cylinder, horizontally-opposed layout and displaced . The power output of later variants was .
...
-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
The Lycoming O-540 is a family of air-cooled six-cylinder, horizontally opposed fixed-wing aircraft and helicopter engines of displacement, manufactured by Lycoming Engines. The engine is a six-cylinder version of the four-cylinder Lycoming ...
-9A six-cylinder, horizontally opposed, air-cooled engine. The OH-23G could seat three. The
MEDEVAC
Medical evacuation, often shortened to medevac or medivac, is the timely and efficient movement and en route care provided by medical personnel to wounded being evacuated from a battlefield, to injured patients being evacuated from the scene of a ...
version carried two external skid-mounted litters or pods. The Raven saw service as a scout during the early part of the
Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
before being replaced by the
Hughes OH-6A Cayuse
The Hughes OH-6 Cayuse is a single-engine light helicopter that was designed and produced by the American aerospace company Hughes Helicopters. Its formal name is derived from the Cayuse people while its "Loach" nickname comes from the acronym fo ...
in early 1968. A Raven piloted by
Hugh Thompson, Jr.
Hugh Clowers Thompson Jr. (April 15, 1943 – January 6, 2006) was a United States Army Major, and a former warrant officer in the 123rd Aviation Battalion of the 23rd Infantry Division. He is credited with ending the Mỹ Lai Massacre of the S ...
played a crucial role in curtailing the
My Lai Massacre
My or MY may refer to:
Arts and entertainment
* My (radio station), a Malaysian radio station
* Little My, a fictional character in the Moomins universe
* ''My'' (album), by Edyta Górniak
* ''My'' (EP), by Cho Mi-yeon
Business
* Market ...
. When a Raven of the 59th Aviation Company strayed north of the
Korean DMZ
The Korean Demilitarized Zone (Korean: ; Hanbando Bimujang Jidae) is a strip of land running across the Korean Peninsula near the 38th parallel north. The demilitarized zone (DMZ) is a border barrier that divides the peninsula roughly in hal ...
in August 1969 it was shot down and the crew were kept prisoner until released on December 2.
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
Royal Naval Air Station Culdrose (RNAS Culdrose, also known as HMS ''Seahawk''; ICAO: EGDR) is a Royal Navy airbase near Helston on the Lizard Peninsula of Cornwall UK, and is one of the largest helicopter bases in Europe. Its main role is ser ...
located in
Cornwall
Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...
, England.
Variants
Military
;YH-23
:One Model UH-12A, modified with two-seat cabin and 178 hp Franklin engine for U.S. Army evaluation.
[Harding 1990, p.141.]
;H-23A
:Initial production version with 178 hp (133 kW)
Franklin O-335
The Franklin O-335 (company designations variations on 6A and 6V) was an American air-cooled aircraft engine of the 1940s. The engine was of six-cylinder, horizontally-opposed layout and displaced . The power output of later variants was .
...
-4 piston engine and two-seat cockpit, 100 built for the U.S. Army
[Harding 1990, p.142.] and 5 for evaluation by the U.S. Air Force.
[Swanborough and Bowers 1963, p.274.]
;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 U.S. 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 U.S. 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 U.S. 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 U.S. Army.
;H-23G
:Three-seat dual control version of H-23F, redesignated OH-23G in 1962, 793 built.
;HTE-1
:U.S. Navy version of the Model UH-12A with Franklin O-335 engine, two-seater with dual controls, and wheeled tricycle undercarriage, 17 built.
[Swanborough and Bowers 1976, p.440.]
;HTE-2
:U.S. Navy version of H-23B with Franklin O-335-6 engine, 35 built.
;Hiller HT Mk 1
:Royal Navy designation for 20 former U.S. Navy HTE-2s.
;Hiller HT Mk 2
:UH-12Es for Royal Navy. 21 supplied.
[Thetford 1978, p.400.]
;CH-112 Nomad
:Canadian military designation for the UH-12Es.
Civilian
;UH-12A
:Original production model for the U.S. Army, powered by a six cylinder fan-cooled Franklin 6V4-178-B33 engine with a maximal power of 178hp at 3000 rpm. The main rotor blades (produced by the Parsons Industries Inc.) are of solid wood laminations. The body of the blade is in fact essentially made up of numerous strip and block wooden laminations designed to provide a strong but highly flexible blade. The entire blade surface is covered with fiberglass cloth with the leading edge covered with an additional stainless steel sheet. The tail rotor is of all metal construction.
;UH-12B (HTE-2)
:Training version for the U.S. Navy. U.S. Navy designation HTE-2 prior to 1962.
;UH-12C
:Three-seat version, equipped with wood rotor blades and one-piece 'goldfish bowl' canopy.
U.S. Army designation H-23C.
;UH-12D
:Improved version of the H-23C for the U.S. Army. U.S. 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-12E-3
:New three-seat production version.
;UH-12E-3T
:New turbine-powered production version.
![Hiller SE-HHU](https://upload.wikimedia.org/wikipedia/commons/2/27/Hiller_SE-HHU.jpg)
;UH-12-E4
:Four-seat civilian version. United States Army designation H-23F. VO-540 powered. Conversion kit available for E-12 models.
;UH-12E-4T
:Four-seat turbine-powered production version.
;UH-12L-4
:Lengthened version with wider cabin windows.
Operators
;
*
Argentine Army Aviation
The Argentine Army Aviation ( es, Comando de Aviación de Ejército, AvEj) is the army aviation branch of the Argentine Army. Their members have the same rank insignia and titles as the rest of the Army.
Along with its primary role of supporting ...
*
Buenos Aires Provincial Police
The Buenos Aires Provincial Police (Spanish: ''Policía de la Provincia de Buenos Aires'', informally ''Policía Bonaerense'') is the police service responsible for policing the Province of Buenos Aires, in Argentina.
It is one of the biggest pol ...
;
*
Bolivian Air Force
The Bolivian Air Force ( es, Fuerza Aérea Boliviana or 'FAB') is the air force of Bolivia and branch of the Bolivian Armed Forces.
History
By 1938 the Bolivian air force consisted of about 60 aircraft (Curtiss Hawk fighters, Curtiss T-32 Co ...
;
*
Canadian Army
The Canadian Army (french: Armée canadienne) is the command responsible for the operational readiness of the conventional ground forces of the Canadian Armed Forces. It maintains regular forces units at bases across Canada, and is also respo ...
;
*
Chilean Air Force
"With full speed to the stars"
, colours = Indigo White
, colours_label =
, march = Alte Kameraden
, mascot =
, anniversaries = 21 March ...
;
*
Colombian Air Force
, "We are the Force"
, colours =
, colours_label =
, march = Colombian Air Force Hymn
, mascot = Capitan Paz
, anniversaries = 8 November
, ...
;
*
Dominican Air Force
The Air Force of the Dominican Republic ( es, Fuerza Aérea de República Dominicana), is one of the three branches of the Armed Forces of the Dominican Republic, together with the Army and the Navy.
History
At the end of the United States ...
;
*
French Air Force
The French Air and Space Force (AAE) (french: Armée de l'air et de l'espace, ) is the air and space force of the French Armed Forces. It was the first military aviation force in history, formed in 1909 as the , a service arm of the French Army; ...
;
*
Bundesgrenzschutz
Bundesgrenzschutz (BGS; en, Federal Border Guard) is the former name of the German ''Bundespolizei'' (Federal Police). Established on 16 March 1951 as a subordinate agency of the Federal Ministry of the Interior, the BGS originally was primari ...
;
*
Guatemalan Air Force
The Guatemalan Air Force ( es, Fuerza Aérea Guatemalteca or ''FAG'') is a small air force composed mostly of U.S.-made aircraft throughout its history. The FAG is a subordinate to the Guatemalan Military and its commanding officer reports to th ...
;
*
Indonesian Air Force
The Indonesian Air Force ( id, Tentara Nasional Indonesia Angkatan Udara (TNI-AU), literally "''Indonesian National Military-Air Force''") sometimes shortened as IDAF / IdAF, is the aerial branch of the Indonesian National Armed Forces. The ...
;
![Hiller OH23 IDF Air Force1952](https://upload.wikimedia.org/wikipedia/commons/6/62/Hiller_OH23_IDF_Air_Force1952.jpg)
*
Israeli Air Force
The Israeli Air Force (IAF; he, זְרוֹעַ הָאֲוִיר וְהֶחָלָל, Zroa HaAvir VeHahalal, tl, "Air and Space Arm", commonly known as , ''Kheil HaAvir'', "Air Corps") operates as the aerial warfare branch of the Israel Defense ...
;
*
Mexican Air Force
The Mexican Air Force (FAM; es, Fuerza Aérea Mexicana) is the primary aerial warfare service branch of the Mexican Armed Forces. It is a component of the Mexican Army and depends on the National Defense Secretariat (SEDENA). The objective of t ...
;
*
Royal Netherlands Air Force
, colours =
, colours_label =
, march = ''Parade March of the Royal Netherlands Air Force''
, mascot =
, anniversaries =
, equipment ...
;
*
Paraguayan Air Force
The Armed forces of Paraguay ( es, Fuerzas Armadas de Paraguay) consist of the Paraguayan army, navy (including naval aviation and marine corps) and air force.
The constitution of Paraguay establishes the president of Paraguay as the commander- ...
;
*
Peruvian Air Force
The Peruvian Air Force ( es, link=no, Fuerza Aérea del Perú, FAP) is the branch of the Peruvian Armed Forces tasked with defending the nation and its interests through the use of air power. Additional missions include assistance in safeguardin ...
;
*
Republic of Korea Army
The Republic of Korea Army (ROKA; ko, 대한민국 육군; Hanja: 大韓民國 陸軍; RR: ''Daehanminguk Yuk-gun''), also known as the ROK Army or South Korean Army, is the army of South Korea, responsible for ground-based warfare. It is the l ...
;
*
Royal Thai Police
The Royal Thai Police (RTP) ( th, สำนักงานตำรวจแห่งชาติ; ) is the national police force of Thailand. The RTP employs between 210,700 and 230,000 officers, roughly 17 percent of all civil servants (excludi ...
;
*
Bristow Helicopters
Bristow Helicopters Limited is a British civil helicopter operator originally based at Aberdeen Airport, Scotland, which is currently a part of the U.S.-based Bristow Group (, S&P 600 component) which in turn has its corporate headquarters in ...
*
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
;
*
Columbia Helicopters
Columbia Helicopters, Incorporated (CHI) is an aircraft manufacturing and operator company based in Aurora, Oregon, United States. It is known for operating tandem rotor helicopters; in present times, exclusively the Boeing Vertol 107 and Boeing ...
*
United States Army
The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...
*
United States Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
;
*
Uruguayan Air Force
The Uruguayan Air Force ( es, Fuerza Aérea Uruguaya, abbreviated FAU) is the air service branch of the Armed Forces of Uruguay. Originally created as part of the National Army of Uruguay, the Air Force was established as a separate branch on Dec ...
Specifications (H-23D)
See also
References
Bibliography
* Bridgman, Leonard. ''Jane's All the World's Aircraft 1953–54''. London: Sampson Low, Marston & Co. Ltd, 1953.
*
* Harding, Stephen. ''U.S. Army Aircraft since 1947''. Shrewsbury, UK: Airlife, 1990.
*
* Spenser, Jay. ''Vertical Challenge: The Hiller Aircraft Story''. AuthorHouse. 2003.
* Swanborough, F.G. and Bowers, Peter M. ''United States Military Aircraft since 1909''. London: Putnam, 1963.
* Swanborough, Gordon and Bowers, Peter M. ''United States Navy Aircraft since 1911'' (second edition). London: Putnam, 1976. ]
* Thetford, Owen. ''British Naval Aircraft since 1912'' (fourth edition). London: Putnam, 1978.
*
OH-23 Factsheet
External links
Hiller Helicopters on Helicopter History SiteHiller Helicopter Owners and Pilots ForumUH-12 & Stanley Hiller at United Helicopter's site
{{Thai helicopter designations
Hiller aircraft, OH-23
1940s United States helicopters
Hiller OH-23 Raven
The Hiller OH-23 Raven is a three-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),Donald, David. ''The Complete Encyclopedia of W ...
H-23, Hiller
Single-engined piston helicopters
Aircraft first flown in 1948