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
450 Tactical Helicopter Squadron (Uplands) in May 1970 and the squadron received Royal Assent for the designation 450 Transport Helicopter Squadron on May 20, 1970. On August 1, 1991, the squadron was re-designated 450 Composite Helicopter Squadron. This was followed by another name change on April 1, 1993, when the squadron became 450 Tactical Helicopter Squadron. In August the following year, 450 Tactical Helicopter Squadron was transferred back to 1 Wing at St. Hubert. 450 Squadron was deactivated in 1996 before being officially disbanded on January 1, 1998. On May 2, 2012, the squadron was re-established to operate the CH-147F Chinook helicopters of the