OH-6 Cayuse

The Hughes OH-6 Cayuse is a single-engine light helicopter designed to meet United States Army Technical Specification 153, issued in 1960 to replace the Bell H-13 Sioux. Hughes submitted the Model 369, which competed against Bell and Fairchild-Hiller. The first prototype flew on February 27, 1963, and the U.S. Army awarded Hughes a production contract in May 1965. Hughes produced 1,422 OH-6As for the U.S. Army, and Kawasaki Heavy Industries license-produced 387 OH-6/Hughes 369s in Japan.

Design

The aircraft has a teardrop-shaped fuselage designed with internal bulkheads and self-sealing fuel tanks for crashworthiness. It features a four-bladed fully-articulated main rotor, a large plexiglass windscreen, and a light aluminum skin that crumples to absorb impact energy. Powered by an Allison T63-A-5A turboshaft engine, the OH-6A has a maximum takeoff weight of 2,700 lb and a maximum cruise speed of 130 knots. It is operated by a pilot and observer, carrying up to five passengers or 1,000 lb of internal cargo. Weapon systems are provisioned on the port side, accommodating either an XM-27 7.62 mm machine-gun with 2,000 to 4,000 rounds of ammunition, or an XM-75 grenade launcher.

Operational History

Entering U.S. Army service in 1966, the OH-6 set 23 world helicopter records, including a 2,213.04-mile non-stop flight. In the Vietnam War, where first units arrived in December 1967, the helicopter operated in "hunter-killer" teams with Bell AH-1 Cobra attack helicopters, drawing ground fire and marking targets with smoke grenades. Ground fire claimed 964 of the 1,422 Army OH-6As in the conflict. In December 1972, the CIA used two acoustically modified OH-6As (designated 500P) for a covert wiretapping mission near Vinh, North Vietnam. Following the failure of Operation Eagle Claw, the U.S. Army selected the OH-6A for its specialized tactical units, which became the MH-6 light assault and AH-6 light attack platforms of the 160th Special Operations Aviation Regiment. Former international operators include Spain, Denmark, Japan, Malta, Nicaragua, and Taiwan.

Variants

• YOH-6A: Prototype aircraft powered by a single Allison T63-A-5A turboshaft engine.
• OH-6A: Initial production model powered by a 263 kW (317 shp) Allison T63-A5A turboshaft engine.
• OH-6B: Upgraded variant fitted with a 313.32 kW (420 shp) Allison T63-A-720 turboshaft engine.
• OH-6D: JGSDF variant based on the Hughes Model 500D and built under license by Kawasaki.
• AH-6C: Modified OH-6A armed transport configured for light attack operations with the 160th SOAR(A).