Development began in 1956 as the Vertol model 114. In Jun 1959 a US Army contract for 5 prototype effective battlefield medium/heavy lift helicopters was awarded. The second prototype was the first to fly on 21 Sep 1961 and the CH-47A entered US Army service in Aug 1962. In the meantime (1960) Boeing had acquired Vertol.

The CH-47 Chinook is tandem rotor medium/heavy lift helicopter with a pair of 3 bladed, contra-rotating rotors atop a square section, semi-monocoque, all-metal fuselage, supported on a non-retracting quadricycle undercarriage. Twin engines mounted externally on either side of the rear rotor head above a downward opening rear loading cargo ramp. Variable number of cargo hook hard points on the fuselage underside.

Hugely successful design has been developed and improved for over forty years in a number of versions and for a variety of customers, with every prospect of life extensions for another thirty.

Also built by Kawasaki in Japan and Meridionali in Italy. Chinooks have served in all branches of the US military and para-military and the armed forces of Argentina, Australia, Egypt, Greece, Iran, Italy, Japan, Libya, Morocco, Netherlands, Singapore, South Korea, Spain, Taiwan, Thailand and the UK. A commercial version (the Model 234) is also available. Canadian military examples are designated CH-147.

The much improved variant CH-47D is listed separately