The Hughes OH-6 Cayuse "Loach" four-bladed light observation single-engine helicopter prototype first flew on 27 February 1963. So successful was the design that it went on the break 23 world records and that it is still produced today as the MD 500.
In early 1960 the United States Army issued a specification for a Light Observation Helicopter (LOH) capable of acting in the transport, reconnaissance, observation, escort, attack and casualty evacuation roles. The Army-Navy Design Competition board chose two designs, one each from Fairchild-Hiller and Bell from the twelve designs submitted. The Army at a later stage included the Hughes design as well and it was declared the eventual winner.
Hughes's bid of $19,700 per airframe, less engine was lower than his production cost and almost $8,000 less than that of Hiller resulting in a massive loss on the army deal. Hughes, however, anticipated recouping his losses in an extended production run. That was however not to be. In 1968 he submitted a bid to build a further 2,700 airframes and the Army reopened the contract for rebidding. Hiller did not participate but Bell did and their redesigned Model 206 won the bid.
Even before it went into full scale production the OH-6 Cayuse showed its mettle by setting speed, endurance and time to climb records. Before long it would hold twenty three including a close circuit without landing distance of 1,739.96 miles (2,800.20km) set on 26 March 1966 with Jack Schwiebold at the controls. Less than a month later on 6 April 1966 Robert Ferry set a world long distance record when he flew from Culver City to Ormond Beach with over a ton of fuel on-board covering the distance of 2,213.04 miles (3,564.55 km) in 15 hours. To top it Ferry, near the end of the attempt, flew to 24,000 feet to also set an altitude record.
During 1964 all U.S. Army fixed-wing aircraft was transferred to the U.S. Air Force, while the U.S. Army transitioned to rotor-wing aircraft and in May 1965 the Army awarded Hughes a contract for an initial 714 Cayuse. The order was later increased to 1,300 with an option for a further 114.
War was raging in Vietnam when the Cayuse or Loach as it was dubbed by the pilots, entered service in 1966. In 1968 it found itself in the thick of the action when it was deployed to replace the Cessna O-1 Bird Dog in the artillery observation and reconnaissance role. Armed with various weapons, including 7.62-mm Miniguns, Mk19 automatic grenade launchers, pods with 12.7-mm machine guns, pods with Hydra 70-mm unguided rockets, TOW and Hellfire anti-tank guided missiles huge numbers served with distinction during the war.
The OH-6 Cayuse's relatively low noise signature and its ability to fly low and fast whilst performing difficult manoeuvres made it the ideal companion for the AH-1 Cobra in hunter killer teams. Flying at tree top height the OH-6 would serve the roll of hunter, drawing fire to revealing enemy positions that would then be destroyed by the superior fire power of the Cobra.
Cayuse losses in Vietnam were high, almost 300 were lost in accidents whilst another 658 where downed by enemy fire.
The end of the war in Vietnam did not end the OH-6 Cayuse's service in the military. Hughes's little egg shaped Cayuse went on to see service in Grenada, Nicaragua, Panama, Iran, Iraq as well as Somalia during the "Black Hawk Down" incident. Besides the US Army it served with distinction with the US Navy and US Customs and Border Protection Service, the Nicaraguan National Guard, Danish Army, Japanese Self Defence Forces as well as Army of the Republic of China.
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)
Maximum take-off weight: 3,549 lbs (1,610 kg)
Powerplant: 1 ◊ One Allison T63-A-5A or T63-A-700 turbo shaft, 317 hp (236 kW)
Maximum speed: 152 knots (175 mph, 282 km/h)
Cruise speed: 135 knots (155 mph, 250 km/h)
Range: 232 nm (430 km)
Service ceiling: 15,994 ft (4,875 m)
Rate of climb: 2,067 ft/min (10.5 m/s)
Guns: Two M60 or M134 Minigun 7.62 mm machine guns; Two .50 (12.7 mm) MG pods
Rockets: Fourteen 2.75 in (70 mm) Hydra 70 rockets in two pods
Missiles: Four TOW missiles in two pods; Four Hellfire missiles in two pods