Bell YOH-4

YHO-4 / YOH-4

YOH-4A LOH in flight
Role	Observation/scout helicopter
National origin	United States
Manufacturer	Bell Helicopter
First flight	8 December 1962^[1]
Primary user	United States Army
Number built	5^[2]
Variants	Bell 206A JetRanger

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 reopened the LOH competition, and the 206A-based OH-58 Kiowa was selected.

Development

On 14 October 1960, the United States Navy solicited responses from 25 aircraft manufacturers to a request for proposals (RFP) on behalf of the Army for the Light Observation Helicopter (LOH). Bell entered the competition along with 12 other manufacturers, including Hiller Aircraft and Hughes Tool Co., Aircraft Division.^[3] In January 1961, Bell submitted Design 250 (D-250), which would eventually be designated as the YHO-4.^[4] On 19 May 1961, Bell and Hiller were announced as winners of the design competition.^{[note 1]}^[5]

YOH-4A LOH

Bell produced five prototypes of the D-250, as Model 206, in 1962, 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 YOH-4A.^[1] The YOH-4A also became known as the Ugly Duckling in comparison to the other contending aircraft.^[6] Following a flyoff of the Bell, Hughes and Fairchild-Hiller prototypes, the Hughes OH-6 was selected in May 1965.^[7]

After the failed military contract bid, Bell attempted to market the Model 206, but it did not fare well at all commercially. Bell's market research showed that customers found the body design mostly unpalatable. Bell would eventually redesign the body of the airframe to a more sleek and aesthetic design and reintroduced it as the Bell 206A JetRanger.^[8]

Variants

OH-58 Kiowa

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.

Operators

United States

United States Army

Survivors

The remaining OH-4A 62-4202 is in storage at the Army Aviation Museum, Fort Rucker, Alabama.^[9]

Specifications (OH-4A)

Data from U.S. Army Aircraft Since 1947^[2]

General characteristics

Crew: 1 pilot
Capacity: up to 3 passengers or 2 stretchers
Length: 38 ft 8 in (11.79 m)
Rotor diameter: 33 ft 3 in (10.13 m)
Height: 8 ft 10 in (2.69 m)
Empty weight: 1,536 lb (697 kg)
Max. takeoff weight: 2,537 lb (1,150 kg)
Powerplant: 1 × Allison T63-A-5 turboshaft, 250 shp (186 kW)

Performance

Maximum speed: 117 knots (135 mph, 217 km/h)
Cruise speed: 96 knots (111 mph, 179 km/h)
Range: 246 nmi (283 mi, 455 km)
Service ceiling: 20,000 ft (6,100 m)

References

Notes

↑ The Navy, which was assisting the Army in the selection phase, recommended the Hiller Model 1100, while the Army team preferred the Bell D-250, and then the 1100. The Selection Board accepted both aircraft for an evaluation test. Afterwards, the acting Army Chief of Staff directed the Selection Board to include the Hughes 369 in the fly-off competition.

Citations

1 2 3 Johan Visschedijk (16 October 2003). "Bell 206 JetRanger".
1 2 Harding, Stephen (1997). U.S. Army Aircraft Since 1947. Atglen, PA, USA: Schiffer Publishing Ltd. p. 42. ISBN 978-0-933424-53-1.
↑ Remington, Steve. "The Cessna CH-1 Helicopter". CollectAir.com
↑ Beechy, Robert. "U.S Army Aircraft Acquisition Programs". Uncommon Aircraft 2006. 18 November 2005. Accessed on 19 September 2006.
↑ Spangenberg, George A. George A. Spangenberg Oral History. www.spangenberg.org. Judith Spangenberg-Currier, ed. pp.187-190. Accessed on 29 April 2008.
↑ Aastad, Andy. "The Introduction to the JetRanger". Rotor Magazine. Helicopter Association International. Winter 2006-2007. Accessed on 5 April 2009.
↑ Spenser 1998, p. 263.
↑ "American Helicopter Museum: Bell 206 JetRanger".
↑ 8 December 1962

Bibliography

Spenser, Jay P. "Bell Helicopter". Whirlybirds, A History of the U.S. Helicopter Pioneers. University of Washington Press, 1998. ISBN 0-295-98058-3.

External links

Wikimedia Commons has media related to OH-58 Kiowa.

HO-4/OH-4 page on GlobalSecurity.org

United States Army helicopter designations (1956–62)

Helicopter, Cargo	HC-1A/HC-1B

Helicopter, Observation	HO-1 HO-2 HO-3 HO-4 HO-5 HO-6

Helicopter, Utility	HU-1

Helicopter, Experimental	HZ-1

United States helicopter designations, Army/Air Force and Tri-Service systems

Numerical sequence used by USAAC/USAAF/USAF 1941–present; US Army 1948–1956 and 1962–present; US Navy 1962–present

Main sequence
(1941–1962)

Prefix R-, 1941–1948	R-1 R-2 R-3 R-4 R-5 R-6 R-7 R-8 R-9 R-10 R-11 R-12 R-13 R-14 R-15 R-16

Prefix H-, 1948–1962	H-5 H-6 H-9 H-10 H-11 H-12 H-13/J H-15 H-16 H-17 H-18 H-19 H-20 H-21 H-22 H-23 H-24 H-25 H-26 H-27 H-28 H-29 H-30 H-31 H-32 H-33 H-34 H-35 H-36¹ H-37 H-38¹ H-39 H-40 H-41 H-42 H-43 H-44¹ H-45¹

Main joint sequence
(1962–present)

1962 redesignations	OH-13/UH-13J UH-19 CH-21 OH-23 UH-25 CH-34 CH-37 HH-43

New designations	CH-46/HH-46/UH-46 CH-47 UH-48 XH-49 QH-50 XH-51 HH-52 CH-53/HH-53/MH-53/CH-53E/CH-53K CH-54 TH-55 AH-56 TH-57 OH-58 XH-59 UH-60/SH-60/HH-60/HH-60J YUH-61 XCH-62 YAH-63 AH-64 HH-65 RAH-66 TH-67 MH-68 H-69¹ ARH-70 VH-71 UH-72 H-73 to H-91¹ VH-92

1962 redesignations
reusing old numbers

¹ Not assigned

Aircraft produced by Bell Aircraft and Bell Helicopter

Manufacturer designations	1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 32 33 34 35 36 38 39 40 41 42 43 44 45 47 48 49 50 52 54 58 59 60 61 65 66 67 68 200 201 204 205 206 207 208 210 211 209 212 214/214ST 222 230 249 301 309 400 407 409 412 417 427 429 430 440 445 449 505 525 533 D-188 D-255 D-292

Fighter aircraft	YFM-1 P-39 XFL P-59 P-63 XP-77 XP-83

Target drones	PQM-56

Attack helicopters	207 AH-1 (singles) AH-1 (twins) 309 YAH-63

Observation and utility helicopters	H-13 UH-1 UH-1N UH-1Y TH-57 OH-58 TH-67 ARH-70

Commercial helicopters	47 204 205 206 210 212 214 214ST 222 230 407 412 427 429 430 505 525

Tiltrotors	V-22 BA609 TR918 QTR

UAVs	MQ-8C

Non-production helicopters	400 417 440

Experimental aircraft	ATV 201 533 D-188 D-255 D-292 L-39 LLRV/LLTV X-1 X-2 X-5 X-14 X-22 XF-109 XP-52 XV-3 XV-15

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