Helicopter rotor of gravity fore-aft. However, it requires the expense of two large rotors rather than the more common one large main rotor and a much smaller tail rotor. The Boeing CH-47 Chinook is the most common tandem rotor helicopter. Coaxial rotors are a pair of rotors mounted one above the other on the same shaft and turning in opposite directions. The advantage of the coaxial rotor is that, in forward flight, the lift provided by the advancing halves of each rotor compensates for the retreating half of the other, eliminating one of the key effects of dissymmetry of lift: retreating blade
Boeing CH-47 Chinook 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. The Chinook possesses several means of loading various cargoes, including multiple doors across the fuselage, a wide loading ramp located at the rear of the fuselage, and a total of three external ventral cargo hooks to carry underslung loads, as well. Capable of a top speed of 170 knots (196 mph, 315 km/h), upon its introduction to service in 1962, the helicopter was considerably faster than contemporary 1960s utility helicopters and attack helicopters, and is still one