OH-6 Cayuse | |
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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.
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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.
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.
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).
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 Rucker 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]
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.
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]
For other AH-6 and MH-6 variants, see MH-6 Little Bird and Boeing AH-6.
General characteristics
Performance
Armament
Related development
Comparable aircraft
Related lists
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