CH-47A, CH-47B & CH-47C Chinook
The first Chinooks — the tandem-rotor workhorses of the Vietnam era, each model a step up in power · First flight 1961 · In service 1962
The Chinook began as the Boeing Vertol Model 114, a twin-turbine, tandem-rotor medium-lift helicopter for the US Army. The pre-production YHC-1B flew on 21 September 1961, deliveries began in August 1962 and the type — redesignated CH-47A — served with the 11th Air Assault Division before deploying to Vietnam with the 1st Cavalry Division in 1965. The A model, 354 of which were built, had a maximum gross weight of 33,000 lb and could lift about 10,000 lb, but its transmission could not absorb the full power of both engines and it struggled in Vietnam's heat and mountains.
The CH-47B was an interim fix: 108 were built with 2,850 shp T55-L-7C engines, an improved transmission, a strengthened fuselage, redesigned rotor blades, a blunted rear pylon and strakes for better handling. Deliveries began in May 1967. The CH-47C followed later that year; 233 were built for the US Army, and the 'Super C' with T55-L-11 engines raised maximum gross weight to 46,000 lb.
The C model was the main export Chinook of the 1970s: Elicotteri Meridionali built it under licence in Italy, Iran received 90 Agusta-built examples, and Canada and Libya also bought it. Four CH-47As were converted into heavily armed ACH-47A gunships in Vietnam. Most surviving US A, B and C airframes were later remanufactured into the CH-47D.
