Bell YOH-4
From Wikipedia, the free encyclopedia
| YHO-4 / YOH-4 | |
|---|---|
 YOH-4A LOH in flight |
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| Type | Observation/scout helicopter |
| National origin | United States |
| Manufacturer | Bell Helicopter |
| Maiden flight | 8 December 1962[1] |
| Primary user | United States Army |
| Number built | 5 |
| Variants | Bell 206 |
The Bell YOH-4 (originally YHO-4) was a single-engine, single rotor, light helicopter developed for the United States Army's Light Observation Helicopter program. While the YOH-4A was unsuccessful in the original LOH competition, Bell redesigned it as the sleek Bell 206A JetRanger for the commercial market, and enjoyed instant and lasting success. In 1967, the Army reopended the LOH competition, and the 206A-based OH-58 Kiowa was selected.
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[edit] Development
In October 1960, the Army submitted a request for proposals (RFP) for the Light Observation Helicopter (LOH). Bell, along with 12 other manufacturers (including Fairchild-Hiller and Hughes Tool Co. Aircraft Division), entered the competition.[2] In January 1961, Bell proposed their Model 206 design,[3] which was selected out of the design phase of the Navy-run competition by the Army[4] and designated as the YHO-4A.[5][6]
Bell produced 5 prototypes in 1962 to submit to the Army for the Test and Evaluation phase, the first prototype making its maiden flight on 8 December 1962.[1] That same year, all aircraft began to be designated according to the new Joint Services designation system, so the prototype aircraft were redesignated as YOH-4A. During the flight testing phase, the power problems of the YOH-4A eliminated it from consideration for selection.[1][verification needed]
After the failed military contract bid, Bell attempted to market the Model 206, but it didn't fare well at all commercially. Bell's market research showed that customers found the body design mostly unpalatable. Bell redesigned the body of the airframe to a more sleek and aesthetic design and reintroduced it as the Bell 206A JetRanger, and Bell found they had a commercial success on their hands.[7]
In 1967, the Army reopened the LOH competition for bids because Hughes Helicopters couldn't meet the contractual production demands.[citation needed] Bell resubmitted for the program using the Model 206A.[5] Fairchild-Hiller did not resubmit their bid with the YOH-5A, which they had somewhat-successfully marketed as the FH-1100.[3] In the end, Bell underbid Hughes to win the contract and the Bell 206A was designated as the OH-58A.
[edit] Variants
- YHO-4
- Bell 206 powered by a 250shp T63-A-5 for Army evaluation, five built later re-designated YOH-4A
- YOH-4A
- YHO-4s re-designated.
[edit] Operators
[edit] Specifications (OH-4A)
Data from U.S. Army Aircraft Since 1947 [8]
General characteristics
- Crew: 1 pilot, up to 3 passengers or 2 stretchers
- Length: 38 ft 8 in (m)
- Rotor diameter: 33 ft 3 in (m)
- Height: 8 ft 10 in (m)
- Empty weight: 1,536 lb (kg)
- Max takeoff weight: 2,537 lb (kg)
- Powerplant: 1× Allison T63-A-5 turboshaft, 250 shp (6 kW)
Performance
- Maximum speed: knots (135 mph, km/h)
- Cruise speed: knots (111 mph, km/h)
- Range: 283 mi ()
- Service ceiling 20,000 ft ()
[edit] See also
Related development
Comparable aircraft
Related lists
[edit] References
- ^ a b c Johan Visschedijk (16 October 2003). Bell 206 JetRanger.
- ^ Steve Remington. The Cessna CH-1 Helicopter. CollectAir (commercemarketplace.com).
- ^ a b Michael J. Hirschberg and David K. Daley (7 July 2000). US and Russian Helicopter Development In the 20th Century. American Helicopter Society. Retrieved on 2007-04-20.
- ^ George A. Spangenberg, edited by Judith Spangenberg-Currier. "George A. Spangenberg Oral History" (pdf pp.187-190). . www.spangenberg.org
- ^ a b Robert Beechy (18 November 2005). U.S Army Aircraft Acquisition Programs. Uncommon Aircraft 2006.
- ^ Rotary Aircraft Designation Crosswalk. GlobalSecurity.org.
- ^ American Helicopter Museum: Bell 206 JetRanger.
- ^ Harding, Stephen (1997). U.S. Army Aircraft Since 1947. Atglen, PA, USA: Schiffer Publishing Ltd., 42. ISBN 96-69996.
[edit] External links
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