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Hiller OH-23 Raven

{{Short description|Family of light helicopters}}

{{Redirect-synonym|OH 23|{{Ushr|Ohio|23}}}}

{{More footnotes|date=February 2020}}

{{Infobox aircraft

| name = OH-23 Raven

| image = File:OH-23 inflight colour photo.jpg

| caption = Hiller OH-23G Raven

| type = Multipurpose light helicopter

| manufacturer = United Helicopters
Hiller Aircraft

| designer =

| first_flight = 1948

| introduction = 1948

| retired =

| status = Retired

| primary_user = United States Army

| more_users = Colombian Air Force
Royal Navy

| produced = 1948–1965

| number_built = 2000+

| variants =

}}

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),{{cite book|last=Donald|first=David|title=The Complete Encyclopedia of World Aircraft|location=New York|publisher=Barnes & Noble Books|year=1998|isbn=0760705925}}{{page needed|date=February 2020}} 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.

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.{{Cite web |title=Hiller 360 / UH-12 / OH-23 helicopter - development history, photos, technical data |url=http://www.aviastar.org/helicopters_eng/hiller_oh-23.php |access-date=2024-05-14 |website=www.aviastar.org}}

Development

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.{{Cite web |last=Bazzani |first=Mario |title=Hiller UH-12B |url=https://www.heli-archive.ch/en/helicopters/in-depth-articles/hiller-uh-12b |access-date=2024-05-14 |website=www.heli-archive.ch |language=en}}

It was produced until 1965, with over 2,000 produced.{{Cite web |title=Hiller 360 / UH-12 / OH-23 helicopter - development history, photos, technical data |url=http://www.aviastar.org/helicopters_eng/hiller_oh-23.php |access-date=2024-03-14 |website=www.aviastar.org}}

Operational history

File:330-PS-683 (USN 707952) (19529141719).jpg

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.Bridgman 1953, pp. 240–241. The OH-23 had a top speed of {{cvt|97|mph|km/h 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 {{cvt|305|hp|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.{{cite book|last1=Angers|first1=Trent|title=The Forgotten Hero of My Lai: The Hugh Thompson Story|publisher=Acadian House|date=2014|isbn=978-0925417909|edition=Rev|pages=69–66}} 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.{{cite book|last=Bolger|first=Daniel|title=Scenes from an Unfinished War: Low intensity conflict in Korea 1966–1969|publisher=Diane Publishing Co|isbn=978-0788112089|year=1991|url=https://apps.dtic.mil/sti/pdfs/ADA245460.pdf|archive-url=https://web.archive.org/web/20210907061520/https://apps.dtic.mil/sti/pdfs/ADA245460.pdf|url-status=live|archive-date=7 September 2021|pages=107–9}}{{PD-notice}}

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.

Variants

File:Hiller HT.1 XB474 FAA Stretton 25.07.53 edited-2.jpg

File:Hiller UH-12 (H-23) bw.jpg

= 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-335-4 piston engine and two-seat cockpit, 100 built for the U.S. ArmyHarding 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."[https://web.archive.org/web/20081202171704/http://www.aero-web.org/specs/hiller/hte-2.htm Hiller HTE-2 'Raven']". Aero-web.org. Retrieved 15 November 2009.

;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.

;H.2

:({{langx|th|ฮ.๒}}) Royal Thai Armed Forces designation for the UH-12.{{Cite web |title=Thai Military Aircraft Designations |url=https://designation-systems.net/non-us/thailand.html |access-date=2025-03-20 |website=designation-systems.net}}

;H.2A

:({{langx|th|ฮ.๒ก}}) Royal Thai Armed Forces designation for the UH-12B.

= Civilian =

File:Hiller UH-12A G-ANOC Fison-Awk RWY 09.07.55 edited-2.jpg

File:G-ASAZ (14389405782).jpg, 2014]]

;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.

File:Hiller SE-HHU.jpg

;UH-12E-4

:Four-seat civilian version (pilot in front, with back seat for three passengers). United States Army designation H-23F. VO-540 powered. Conversion kit available for E-12 models.{{Cite journal | journal=Flying Magazine | date=November 1960 | title=E-4 "Station Wagon" | author=A.C. Bass}}

;UH-12E-4T

:Four-seat turbine-powered production version.

;UH-12L-4

:Lengthened version with wider cabin windows.

Operators

;{{ARG}}

  • Argentine Army Aviation{{Cite web | url=http://www.flightglobal.com/pdfarchive/view/1987/1987%20-%202490.html | title=World Air Forces 1987 pg. 40 | publisher=flightglobal.com | access-date=23 March 2013}}
  • Buenos Aires Provincial Police{{Cite web | url=http://www.helis.com/database/modelorg/586/ | title=Policia de la Provincia de Buenos Aires UH-12E | access-date=23 March 2013}}

;{{BOL}}

;{{CAN}}

  • Canadian Army{{Cite web | url=http://www.canadianwings.com/Aircraft/aircraftDetail.php?NOMAD-174 | title=CH-112 Nomad | publisher=canadianwings.com | access-date=23 March 2013}}

;{{CHL}}

  • Chilean Air Force{{Cite web | title=World Helicopter Market 1968 pg. 50 | publisher=bell47.net | url=http://www.flightglobal.com/pdfarchive/view/1968/1968%20-%201206.html | access-date=2013-03-23}}

;{{COL}}

;{{DOM}}

  • Dominican Air Force{{Cite web | url=http://www.flightglobal.com/pdfarchive/view/1968/1968%20-%201207.html | title=World Helicopter Market 1968 pg. 51 | publisher=flightglobal.com | access-date=23 March 2013}}

;{{FRA}}

;{{FRG}}

;{{GTM}}

  • Guatemalan Air Force{{Cite web | title=World Helicopter Market 1968 pg. 52 | publisher=bell47.net | url=http://www.flightglobal.com/pdfarchive/view/1968/1968%20-%201208.html | access-date=2013-03-23}}

;{{IDN}}

;{{ISR}}

File:Hiller OH23 IDF Air Force1952.jpg H-23A (model UH-12A), Jerusalem 1952]]

;{{MEX}}

  • Mexican Air Force{{Cite web | url=http://www.flightglobal.com/pdfarchive/view/1968/1968%20-%201209.html | title=World Helicopter Market 1968 pg. 53 | publisher=flightglobal.com | access-date=23 March 2013}}

;{{NLD}}

  • Royal Netherlands Air Force{{Cite web | url=http://www.helis.com/database/modelorg/202/ | title=Koninklijke Luchtmacht UH-12E | access-date=23 March 2013}}

;{{PRY}}

  • Paraguayan Air Force{{Cite web | url=http://www.flightglobal.com/pdfarchive/view/1987/1987%20-%202527.html | title=World Air Forces 1987 pg. 77 | publisher=flightglobal.com | access-date=23 March 2013}}

;{{PER}}

  • Peruvian Air Force{{Cite web | url=http://www.flightglobal.com/pdfarchive/view/1968/1968%20-%201210.html | title=World Helicopter Market 1968 pg. 54 | publisher=flightglobal.com | access-date=23 March 2013}}

;{{Flag | South Korea}}

  • Republic of Korea Army{{Cite web | url=http://armstrade.sipri.org/armstrade/page/trade_register.php | title=US→South Korea (1966-1967) | publisher=armstrade.sipri.org | access-date=23 March 2013 | archive-date=14 April 2010 | archive-url=https://web.archive.org/web/20100414022558/http://armstrade.sipri.org/armstrade/page/trade_register.php | url-status=dead }}{{Cite web | url=http://www.airliners.net/photo/South-Korea--/Hiller-OH-23G-Raven/1482292/L/&sid=01dc45da79525a8bb08b52cb5e6b2cae | title=South Korean Army OH-23 | publisher=Demand media | access-date=23 March 2013}}

File:KAB-202 Hiller UH-12B at Swiss Air Force Museum Dübendorf (Ank Kumar) 02.jpg

{{flag |Switzerland}}

  • UH-12B{{Cite web |last=Bazzani |first=Mario |title=Hiller UH-12B |url=https://www.heli-archive.ch/en/helicopters/in-depth-articles/hiller-uh-12b |access-date=2024-05-14 |website=www.heli-archive.ch |language=en}}

;{{THA}}

  • Royal Thai Police{{Cite web | title=World Helicopter Market 1968 pg. 55 | publisher=bell47.net | url=http://www.flightglobal.com/pdfarchive/view/1968/1968%20-%201211.html | access-date=2013-03-23}}

;{{GBR}}

  • Bristow Helicopters
  • Royal Navy{{Cite web | url=http://www.helis.com/database/modelorg/53/ | title=Royal Navy Fleet Air Arm UH-12B HTE-2 | access-date=23 March 2013}}

;{{USA}}

  • Columbia Helicopters{{Cite web | url=http://www.flightglobal.com/pdfarchive/view/1968/1968%20-%201215.html | title=World Helicopter Market 1968 pg. 59 | publisher=flightglobal.com | access-date=23 March 2013}}
  • United States Army{{Cite web | title=The H-23 Raven Helicopter | publisher=bell47.net | url=http://olive-drab.com/idphoto/id_photos_h23raven.php | access-date=2013-03-26}}
  • United States Navy

;{{URY}}

  • Uruguayan Air Force{{Cite web | url=http://www.flightglobal.com/pdfarchive/view/1975/1975%20-%201692.html | title=World Air Forces 1975 pg. 314 | publisher=flightglobal.com | access-date=23 March 2013}}

Specifications (H-23D)

File:Hiller H-23 Raven 3-view line drawing.png

{{Aircraft specs

| ref = United States Military Aircraft since 1909Swanborough and Bowers 1963, p.276.

|prime units?=imp

|crew=2

|capacity=

|length ft=

|length in=

|length note=

|height ft=9

|height in=9.5

|height note=

|empty weight lb=1816

|empty weight note=

|gross weight lb=

|gross weight note=

|max takeoff weight lb=2700

|max takeoff weight note=

|fuel capacity=

|more general=

|eng1 number=1

|eng1 name=Lycoming VO-435-23B

|eng1 type=6-cylinder air-cooled horizontally-opposed piston engine

|eng1 hp=250

|eng1 note=

|rot number=1

|rot dia ft=35

|rot dia in=5

|rot area sqft=985

|rot area note=Harding 1990, p.143.

  • Blade section: NACA 0012{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |access-date=16 April 2019}}

|max speed mph=95

|max speed note=

|cruise speed mph=82

|cruise speed note=

|never exceed speed mph=

|never exceed speed note=

|range miles=197

|range note=

|ferry range miles=

|ferry range note=

|endurance=

|ceiling ft=13200

|ceiling note=

|climb rate ftmin=1050

|climb rate note=

|time to altitude=

|disk loading lb/sqft=

|disk loading note=

|fuel consumption lb/mi=

|power/mass=

|more performance=

}}

See also

{{Portal|Aviation}}

{{Aircontent

| related=

| similar aircraft=

| lists=

}}

References

{{Reflist}}

Bibliography

  • Bridgman, Leonard. Jane's All the World's Aircraft 1953–54. London: Sampson Low, Marston & Co. Ltd, 1953.
  • {{cite magazine|last=Elliot|first=Bryn|title=Bears in the Air: The US Air Police Perspective |magazine=Air Enthusiast|date=March–April 1997|issue=68|pages=46–51 |issn=0143-5450}}
  • Harding, Stephen. U.S. Army Aircraft since 1947. Shrewsbury, UK: Airlife, 1990. {{ISBN|978-1-85310-102-1}}
  • {{cite journal|title=Pentagon Over the Islands: The Thirty-Year History of Indonesian Military Aviation|journal=Air Enthusiast Quarterly |date=n.d. |issue=2 |pages=154–162 |issn=0143-5450}}
  • Spenser, Jay. Vertical Challenge: The Hiller Aircraft Story. AuthorHouse. 2003. {{ISBN|978-0-7596-3398-8}}
  • 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. {{ISBN|978-0-370-10054-8}}]
  • Thetford, Owen. British Naval Aircraft since 1912 (fourth edition). London: Putnam, 1978. {{ISBN|978-0-370-30021-4}}
  • {{cite magazine |last=Vetter |first=Frank |title=Debrief: German Border Police 50th anniversary |magazine=International Air Power Review |volume=17 |year=2005 |pages=20–21 |issn=1473-9917}}
  • [https://web.archive.org/web/20101105085856/http://www.redstone.army.mil/history/aviation/factsheets/oh23.html OH-23 Factsheet]

External links

{{Commons|H-23 Raven}}

  • [http://www.jewishvirtuallibrary.org/jsource/Society_&_Culture/Hiller360.html Hiller 360]
  • [http://www.helis.com/timeline/hiller.php Hiller Helicopters on Helicopter History Site]
  • [https://web.archive.org/web/20170603234753/http://helihiller.com/ Hiller Helicopter Owners and Pilots Forum]
  • [http://www.unitedhelicopter.com/about-hiller UH-12 & Stanley Hiller at United Helicopter's site]

{{Hiller aircraft}}

{{US helicopters}}

{{USN helicopters}}

{{Canadian Forces aircraft}}

{{Thai helicopter designations}}

{{Spanish helicopters}}

OH-23

Category:1940s United States helicopters

Hiller OH-23 Raven

H-23, Hiller

Category:Single-engined piston helicopters

Category:Aircraft first flown in 1948