Boeing CH-47 Chinook

It is hard to say which variant of the chinook this is with all the development work done at PAX NAS.

Late in 1956 the Department of the Army announced plans to replace the CH-37 Mojave, which was powered by piston engines, with a new, turbine-powered aircraft. A design competition was held and, in September 1958, a joint Army-Air Force source selection board recommended that the Army procure the Vertol medium transport helicopter. However, the necessary funds to proceed with full-scale development were not available and the Army vacillated in its design requirements. Some in the Army felt that the new helicopter should be a light tactical transport aimed at the mission of the old H-21s and H-34s and, consequently, sized for approximately fifteen troops. Another faction believed that the new transport should be much larger to serve as an artillery prime mover and have minimum interior dimensions compatible with the Pershing Missile System. This "sizing" problem was a critical decision.

Vertol began work on a new tandem rotor helicopter designated Vertol Model 107 or V-107 in 1957.[3] In June 1958, the US Army awarded a contract to Vertol for the aircraft under the YHC-1A designation.[4] The YHC-1A was tested by the Army to derive engineering and operational data. Three aircraft were built with a maximum troop capacity of twenty. However, the YHC-1A was considered by most of the Army users to be too heavy for the assault role and too light for the transport role. The decision was made to procure a heavier transport helicopter and at the same time upgrade the Huey as a tactical troop transport. This decision was to determine the pattern of airmobile operations for the next decade. As a consequence, the Army concept of air assault operations differed from the Marines because, among many reasons, the very nature of the equipment demanded different methods of employment.[5] The YHC-1A would be improved and redesignated CH-46 Sea Knight in 1962.


HC-1B in flight being tested and evaluated.The Army then ordered the larger Model 114/HC-1B. The pre-production Boeing Vertol YCH-1B made its initial hovering flight on September 21, 1961. In 1962 the HC-1B was redesignated the CH-47A under the 1962 United States Tri-Service aircraft designation system. The name "Chinook" alludes to the Chinook people of the Pacific Northwest.

The Chinook is powered by two turboshaft engines, mounted on either side of the helicopter's rear end and connected to the rotors by driveshafts. The counter-rotating rotors eliminate the need for an anti-torque vertical rotor, allowing all power to be used for lift and thrust. If one engine fails, the other can drive both rotors.[6]

The "sizing" of the Chinook was directly related to the growth of the Huey and the Army's tacticians' insistence that initial air assaults be built around the squad. There was a critical stage in the Huey program when the technicians insisted not to go beyond the UH-1B model with Bell; that there should be a new tactical transport "between" the Huey and medium transport helicopter. By resolutely pushing for the Huey and the Chinook, the Army accelerated its airmobility program by years.[7]

A commercial model of the Chinook, the Boeing-Vertol Model 234, is used worldwide for logging, construction, fighting forest fires and supporting petroleum exploration operations. As of December 15, 2006 Columbia Helicopters, Inc. of Aurora, Oregon has purchased the Type Certificate of the Model 234 from Boeing.[8] Currently the company is seeking FAA issuance of a Production Certificate to produce parts with eventual issuance of a Production Certificate to produce aircraft.

The Chinook was also built under license by Elicotteri Meridionali (Agusta) in Italy and Kawasaki in Japan.