Sensing a long-standing need in the helicopter market, Hughes Helicopter turned its attention to a very-lightweight two-seat, single-engine type to interest domestic and foreign military and civilian market buyers. The result of this work became the Hughes Model 269, a Light Utility Helicopter (LUH) that, despite its seemingly toy-like appearance, was a rugged, highly versatile rotary-wing platform for many services and industries of the world. This same form established the basis for the U.S. Army's TH-55 "Osage" series - the focus of this article.
The United States Army originally became interested in the helicopter as a combat-level Light Observation Helicopter (LOH) and evaluated no fewer than five examples under the "YHO-2" designation. This was intended to succeed an aging stock of Bell OH-13 and Hiller OH-23 types then in service. Evaluations were held during 1957-1958 and used the slightly modified version of the Model 269, the "Model 269A", which did away with the exposed, skeletal truss-style tail stem and introduced a shrouded boom structure instead. However, the Army passed on the design, citing a lack of funding and the type's inability to convince Army authorities of its over-battlefield value.
The Model 269A was revisited for the role of dedicated two-seat training platform and, in this guise, was adopted for Army service under the designation of TH-55 "Osage". Deliveries ultimately totaled 792 units and its contributions were such that no replacement for this compact helicopter was found until the arrival of Bell UH-1 "Huey" training forms in 1988 - resulting in decades of American helicopter airmen being trained on the Hughes product.
The Army took delivery of the TH-55A from 1964 until 1967 and these were the standard helicopter trainers of the service for their time aloft. Several were outfitted with various engines for testing. Kawasaki of Japan also produced the TH-55/Model 269A under local license as the TH-55J, these to serve directly with the Japanese Ground Self-Defense Force (JGSDF). Kawasaki produced 38 such helicopters for the service.
The basic design of the TH-55/Model 269 carried the crew of two ( in side-by-side seating) at the bulbous cockpit/fuselage section at front. The crew shared a single console which sat ahead of them and against the bubble-style front glass panel. Views out-of-the-cockpit were excellent and controls were duplicated at each crewman's position and Army models were outfitted with standardized U.S. Army instrumentation and radio equipment. Overhead was the main rotor mast mounting a three-bladed articulated main rotor unit. The engine system was installed under and aft of the fuselage and also drove a simple two-bladed tail rotor unit facing port side. An upward-cranked tailplane was fitted to starboard. For ground support, the helicopter sat on a simple, braced four-point landing skid assembly.