Hughes H-6: Wikis


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OH-6 Cayuse
Right side view of the OH-6A Cayuse helicopter in flight.
Role Light observation helicopter
Manufacturer Hughes Tool Co. - Aircraft Division
First flight 27 February 1963
Introduced 1966
Status Active service
Primary user United States Army
Produced 1965-
Number built 1420 (OH-6A)[1]
Unit cost US$19,860 (1966)[2][note 1]
Variants MH-6 Little Bird
MD 500
MD 500 Defender

The Hughes Helicopters OH-6 Cayuse (nicknamed "Loach", after the requirement acronym LOH - light Observation Helicopter) is a single-engine light helicopter with a four-bladed main rotor used for personnel transport, escort and attack missions, and observation. Hughes also developed the Model 369 as a civilian helicopter, the Hughes Model 500, currently produced by MD Helicopters.

Contents

Development

In 1960, the United States Army issued Technical Specification 153 for a Light Observation Helicopter (LOH) capable of fulfilling various roles: personnel transport, escort and attack missions, casualty evacuation and observation. Twelve companies took part in the competition and Hughes Tool Company's Aircraft Division submitted the Model 369. Two designs, those submitted by Fairchild-Hiller and Bell, were selected as finalists by the Army-Navy design competition board, but the U.S. Army later included the helicopter from Hughes as well.

The first Model 369 prototype flew on February 27, 1963. Originally designated as the YHO-6A according to the Army's designation system, the aircraft was redesignated as the YOH-6A in 1962 when the Department of Defense created a Joint designation system for all aircraft. Five prototypes were built, fitted with a 252 shp (188 kW) Allison T63-A-5A[3], and delivered to the U.S. Army at Fort Rucker, Alabama to compete against the other 10 prototype aircraft submitted by Bell and Fairchild-Hiller. During the course of the competition, the Bell submission, the YOH-4, was eliminated[4] as being underpowered (it used the 250 shp (190 kW) T63-A-5). The bidding for the LOH contract came down to Fairchild-Hiller and Hughes. Hughes won the bid[5], and the Army awarded a contract for production in May 1965, with an initial order for 714 which was later increased to 1300 with an option on another 114. Production reached 70 helicopters in the first month.

Japanese OH-6

In Japan, 387 OH-6s were produced under licence by Kawasaki Heavy Industries and used by the Japanese Ground Self-Defense Force (JGSDF), Japanese Maritime Self-Defense Force (JMSDF), the Japanese Coast Guard, and civilian operators. Beginning in 2001, the OH-6s of the JGSDF are in the process of being replaced by Kawasaki's new observation helicopter, the Kawasaki OH-1.

Operational history

Hernando County Sheriff's Office OH-6A Cayuse[6] Note original slanted stabilizer design on tail and four-bladed main rotor, characteristics shared with the civilian Hughes 500C.

Shortly after production began, the OH-6 began to demonstrate what kind of an impact it would have on the world of helicopters. The OH-6 set 23 world records for helicopters in 1966 for speed, endurance and time to climb. On March 23, 1966, Jack Schwiebold set the closed circuit distance record in a YOH-6A at Edwards Air Force Base, California. He flew without landing for 1,739.96 mi (2,800.20 km). And on April 7, 1966, Robert Ferry set the long distance world record for helicopters. He flew from Culver City, California to Ormond Beach, Florida, covering a total of 1,923.08 nm (2,213.04 mi, 3,561.55 km).

In 1964 the US Department of Defense issued a memorandum directing that all US Army fixed-wing aircraft be transferred to the US Air Force, while the US Army transitioned to rotor-wing aircraft. The US Army's fixed wing airplane, the O-1 Bird Dog, which was utilized for artillery observation and reconnaissance, would be replaced by the OH-6A helicopter.[7] The aircraft entered service in 1966, arriving in the Vietnam War thereafter. The pilots dubbed the new helicopter Loach, a word created by pronunciation of the acronym of the program that spawned the aircraft, LOH (light observation helicopter).

"The Quiet One"

A heavily-modified pair of OH-6As were utilized by the CIA via Air America for a covert wire-tapping mission in 1972. The aircraft, dubbed 500P (penetrator) by Hughes, began as an ARPA project, Operation "Mainstreet", in 1968. Development included test and training flights in Culver City, California and at Area 51 in 1971. In order to reduce their acoustic signature, the helicopters (N351X and N352X) received a four-blade 'scissors' style tail rotor (later incorporated into the Hughes-designed AH-64 Apache), a fifth rotor blade and reshaped rotor tips, a modified exhaust system and various performance-boosts, like INS and LORAN C navigational systems were added, plus AN/AAQ-5 FLIR. 2 other regular OH-6A also obtained by Air America acted as cover for medivac air taxi helicopters operating in Thailand ahead of the operation in order to keep up the cover story for the 2 500P's. Also a Sikorsky S-58T was assigned as recovery helicopter, in case the sensitive 500P went down on the mission. 2 teams were trained in Hsin Chu AB and Tainan AB, Taiwan, by Air Asia, which the company at the time owned by Air America/CAT, one team was made of US CIA personnel, the other drawing from Taiwan's 34th Squadron, with 12 crew, 6 trained to fly S-58T, the other 6 trained on 500P, all came from the ROC/Taiwan Air Force's 34th Squadron, The Black Bat Squadron, which in 1971 was providing Special Ops transport in Vietnam. The Taiwan crew selection started in March 1971, and started training on UH-1H in Hsin Chu AB, later with S-58T and 500P arrived and trained on those helicopters on mountain and jungle flight training and later with only instrument flight training, with cockpit blacked out and only relied on the 8 inch monitor and forward looking camera, plus receiving the necessary jungle survival courses. In June 1971, the group was sent to Fort Rocker to train on DH-6, later sent to Area 51 to fly 500P and later sent back to Taiwan to finish up training. In November 1971, the group was sent back to Area 51 again to fly 500P again with newly added FLIR system. In June 1972, C-130 ferried all 3 helicopters to Thailand and the helicopters flew to a secret base in southern Laos (PS-44), one of the helicopters was heavily damaged during a training mission late in the summer, most likely the one flew by the Taiwanese pilots. The Taiwanese team was sent back to Taiwan in September. S-58T had already dropped off a much bigger signal relay station on a mountaintop near the target area few days ago while the remaining 500P helicopter deployed a wiretap near Vinh, Vietnam on the night of December 5-6, 1972 with 2 Laos agents climbed on top the telephone pole to install the wiretap, while 500P after dropped off the 2 agents went to a nearby hilltop to drop off a smaller solar powered signal relay station. This secret operation provided the United States with useful information during the Linebacker II campaign and Paris Peace Talks. Shortly thereafter, the aircraft were returned to the U.S., dismantled and quietly found new homes as the now-standard 500s.[8][9][10]

160th Special Operations Aviation Regiment

Following the April 1980 failure of Operation Eagle Claw (the attempted rescue of American hostages in Tehran), it was determined that the military lacked aircraft and crews who were trained and prepared to perform special operations missions. To remedy this shortcoming, the Army began developing a special aviation task force to prepare for the next attempt to rescue the hostages: Operation Honey Badger.

Task Force 160

The architects of the task force identified the need for a small helicopter to land in the most restrictive locations and that was also easily transported on Air Force transport aircraft. They chose the OH-6A scout helicopter to fill that role, and it became known as the Little Bird compared to the other aircraft in the task force, the UH-60A and the CH-47C. As a separate part of the project, armed OH-6As were being developed at Fort Rucker, Alabama. [11]

The pilots selected to fly the OH-6A helicopters came from the 229th Attack Helicopter Battalion and were sent to the Mississippi Army National Guard's Army Aviation Support Facility (AASF) at Gulfport, Mississippi, for two weeks of qualification training in the aircraft. When the training was completed, C-141 aircraft transported the aircraft and crews to Fort Huachuca, Arizona, for two weeks of mission training. The mission training consisted of loading onto C-130 transport aircraft which would then transport them to forward staging areas over routes as long as 1,000 nautical miles (1,900 km). The armed OH-6 aircraft from Fort Rucker joined the training program in the fall of 1980.[12]

Operation Honey Badger was canceled after the hostages were released on 20 January 1981, and for a short while, it looked as if the task force would be disbanded and the personnel returned to their former units. But the Army decided that it would be more prudent to keep the unit in order to be prepared for future contingencies. The task force, which had been designated as Task Force 158, was soon formed into the 160th Aviation Battalion. The OH-6A helicopters used for transporting personnel became the MH-6 aircraft of the Light Assault Company and the armed OH-6As became the AH-6 aircraft of the Light Attack Company.[13]

Variants

A TH-6B Cayuse helicopter takes off for a training flight from NAS Patuxent River, Md.
YOH-6A
Prototype version.
OH-6A
Light observation helicopter, powered by a 263-kW (317-shp) Allison T63-A5A turboshaft engine.
OH-6A NOTAR
Experimental version.
OH-6B
Re-engined version, powered by a 298-kW (420-shp) Allison T63-A-720 turboshaft engine.
OH-6C
Proposed version, powered by a 313.32-kW (400-shp) Allison 25-C20 turboshaft engine, fitted five rotor blades.
OH-6J
Light observation helicopter for the JGSDF. Built by Kawasaki Heavy Industries under licence in Japan. Based on the OH-6A Cayuse helicopter.
OH-6D
Light observation, scout helicopter for the JGSDF. Built by Kawasaki Heavy Industries under licence in Japan. Based on the Hughes Model 500D helicopter.
EH-6B
Special Forces electronic warfare, command post version.
MH-6B
Special Forces version.
TH-6B
A Navy derivative of the MD-369H, six McDonnell Douglas TH-6B Conversion-in-Lieu-of-Procurement aircraft are used as an integral part of the United States Naval Test Pilot School's test pilot training syllabus. The aircraft and associated instrumentation and avionics are used for the in-flight instruction and demonstration of flying qualities, performance and missions systems flight test techniques.[14]
AH-6C
Modified OH-6A to carry weapons and operate as a light attack aircraft for the 160th SOAR(A).
MH-6C
Special Forces version.

For other AH-6 and MH-6 variants, see MH-6 Little Bird and Boeing AH-6.

Operators

A Danish OH-6 Cayuse helicopter lifts off from a landing zone
Japanese OH-6D of the JGSDF
 Argentina
 Brazil
 Bahrain
 Bolivia
 Chile
 Colombia
 Costa Rica
 Denmark
 Dominican Republic
 Ecuador
 El Salvador
 Finland
 Haiti
 Honduras
 Indonesia
 Iraq
 Israel
 Italy
 Japan
 Jordan
 Kenya
 Mauritania
 Mexico
 Morocco
 Nicaragua
 North Korea
 Philippines
 Republic of China (Taiwan)
 South Korea
 Spain
 United States

Specifications

General characteristics

  • Crew: 2
  • Length: 30 ft 10 in - 32 ft 2 in (9.4 m - 9.8 m)
  • Rotor diameter: 27 ft. 4 in (8.33 m)
  • Height: 8 ft 6 in - 11 ft 2 in (2.6 m - 3.4 m)
  • Empty weight: 1,975 lbs (896 kg)
  • Max takeoff weight: 3,549 lbs (1,610 kg)
  • Powerplant: 1× One Allison T63-A-5A or T63-A-700 turboshaft, 317 hp (236 kW)

Performance

Armament

See also

Related development

Comparable aircraft

Related lists

Notes

  1. ^ Holley and Sloniker state that Hughes underbid the competition to buy-in to the contract.

References

Footnotes

  1. ^ Francillon 1990, p. 248
  2. ^ Holley & Sloniker 1997, p. 8
  3. ^ FAA Document in PDF format
  4. ^ Hughes OH-6 "Cayuse" / MD 500 / MD 530 helicopter - development history, photos, technical data
  5. ^ Hughes Aircraft
  6. ^ N53HC
  7. ^ Adcock, p. 32
  8. ^ Chiles, James R. (February-March 2008). "Air America's Black Helicopter". Air & Space Smithsonian (Washington: Smithsonian Business Ventures): pp. 62–70. ISSN 0886-2257. http://www.airspacemag.com/issues/2008/february-march/the_quiet_one.php. Retrieved 2008-02-06.  
  9. ^ (Chinese)Taiwan BBS Org, 台海風雲軼史. April 8, 2006, retrieved September 19, 2009
  10. ^ (Chinese)Taiwan BBS Org, 台海風雲軼史. October 10, 2006, retrieved October 4, 2009
  11. ^ Michael J. Durant, Steven Hartov. The Night Stalkers. G. P. Putnam's Sons, New York. p. 48–49. ISBN 0-399-15392-6.  
  12. ^ Durant. p. 56.  
  13. ^ Durant. p. 57.  
  14. ^ Navy fact sheet

Sources

  • Adcock, Al. O-1 Bird Dog In Action. Squadron Signal Publications number 87; 1988. ISBN 0-89747-206-3.
  • Francillon, René J. McDonnell Douglas Aircraft Since 1920. Annapolis, Md: Naval Institute Press, 1988. ISBN 9781557505507
  • Holley, Charles and Mike Sloniker. Primer of the Helicopter War. Grapevine, Tex: Nissi Pub, 1997. ISBN 9780944372111

External links








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