OH-23 Raven

Infobox Aircraft
name=OH-23 Raven


caption=Hiller OH-23
type=Multipurpose light helicopter
manufacturer=Hiller Aircraft Corporation
designer=
first flight=
introduced=1948
retired=
status=
primary user=United States Army
more users=
produced=
number built=
unit cost=
variants with their own articles=

The Hiller OH-23 Raven was a four-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),Donald, David. "The Complete Encyclopedia of World Aircraft". New York: Barnes & Noble Books, 1998.] which was first flown in 1948.

Development

Stanley Hiller built and flew his first helicopter, the Hiller XH-44, when he was 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.

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, it also featured a unique cyclic control system, through two paddles offset 90 degrees to the main rotor blades.Verify source|date=August 2007 The OH-23 had a 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 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 four. 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. 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.

Variants

Military

;YH-23:One Model UH-12 for US Army evaluation;H-23A:Initial production version with 178 hp Franklin O-335-4 piston engine, 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 0-335-6 engine (some later re-engined with a 250 hp VO-435-23B), re-designated OH-23A 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, redesignated OH-23C in 1962, 145 built for the US Army.;H-23D:H-23C with 250hp VO-435-23B engine, 348 built for US Army.;H-23E:Model UH-12E, not bought;H-23F:Model UH-12E-4, four-seat model with 25-inch cabin extension and a 305hp VO-540-A1B engine, redesignated OH-23F in 1962, 33 built for US Army.;H-23G:Three-seat dual control version, 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, 17 built.;HTE-2:US Navy version with Franklin 6V4-200C033 engine, 35 built;HT Mk 1:Royal Navy designation for former US Navy HTE-2s;HT Mk 2:UH-12Es for Royal Navy.;CH-112 Nomad:Canadian military designation.

Civilian

;UH-12A:Original production model for the US Army, powered by a 178hp 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:Lengthed version with wider cabin windows.

Operators

Military operators

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*: Biafran Air Force
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*: Canadian Army - CH-112 Nomad
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*: Royal Navy
*: USAF, US Army, US Navy
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Civilian operators

;UK
*Bristow Helicopters
*Columbia Helicopters

pecifications (H-23)

aircraft specifications

plane or copter?=copter
jet or prop?=prop

ref=

crew=2
capacity=
payload main= lb
payload alt= kg
length main=(overall) 28 ft 11 in
length alt=8.8 m
span main=25 ft 3 in
span alt=7.7 m
height main=8 ft 3 in
height alt=2.5 m
area main=
area alt=
airfoil=
empty weight main= 1008 lb
empty weight alt= 457 kg
loaded weight main= 1850 lb
loaded weight alt= 839 kg
useful load main=
useful load alt=
max takeoff weight main=
max takeoff weight alt=
more general=

engine (jet)=
type of jet=
number of jets=
thrust main=
thrust alt=
thrust original=
afterburning thrust main=
afterburning thrust alt=
engine (prop)=Lycoming HIO-360-B1A
type of prop=6 cylinder, horizontally opposed
number of props=1
power main= 180 hp
power alt=134 kW
power original=

max speed main=95 mph
max speed alt=153 km/h
cruise speed main=75 mph
cruise speed alt=121 km/h
stall speed main=
stall speed alt=
never exceed speed main= kts
never exceed speed alt= mph
range main= nm
range alt=204 miles
ceiling main=13,205ft
ceiling alt=4,025m
climb rate main=
climb rate alt=
loading main=
loading alt=
thrust/weight=
power/mass main=
power/mass alt=
more performance=

armament=* 2 .30 caliber M37C machine guns on the XM1 Armament Subsystem or 2 7.62mm M60C machine guns on the M2 Armament Subsystem.

avionics=

ee also

aircontent
related=
similar aircraft=
* Bell 47
* Schweizer (Hughes) 300

lists=
* List of military aircraft of the United States

References

* [http://www.redstone.army.mil/history/aviation/factsheets/oh23.html OH-23 Factsheet]

External links

* [http://www.jewishvirtuallibrary.org/jsource/Society_&_Culture/Hiller360.html Hiller 360]
* [http://www.helis.com/timeline/hiller.php Hiller Helicopters on Helicopter History Site]