The Boeing CH-47 Chinook is an American twin-engined, tandem rotor, heavy-lift helicopter developed by American rotorcraft company Vertol and manufactured by Boeing Vertol (later renamed Boeing Helicopter, then Boeing Rotorcraft Systems, and now known as the Vertical Lift division of Boeing Defense, Space & Security). The CH-47 is among the heaviest lifting of Western helicopters. Its name, Chinook, is from the Native American Chinook people of Washington state.
The Chinook was originally designed by Vertol, which had begun work in 1957 on a new tandem-rotor helicopter, designated as the Vertol Model 107 or V-107. Around the same time, the United States Department of the Army announced its intention to replace the piston engine–powered Sikorsky CH-37 Mojave with a new, gas turbine–powered helicopter. During June 1958, the U.S. Army ordered a small number of V-107s from Vertol under the YHC-1A designation; following testing, it came to be considered by some Army officials to be too heavy for the assault missions and too light for transport purposes. While the YHC-1A would be improved and adopted by the U.S. Marine Corps as the CH-46 Sea Knight, the Army sought a heavier transport helicopter, and ordered an enlarged derivative of the V-107 with the Vertol designation Model 114. Initially designated as the YCH-1B, on 21 September 1961, the preproduction rotorcraft performed its maiden flight. In 1962, the HC-1B was redesignated CH-47A under the 1962 United States Tri-Service aircraft designation system.