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
Birdman Chinook 2008, described the Chinook Plus 2 with the HKS 700E engine: The factory claims that a first time builder can complete the Chinook Plus 2 in 220 hours of labour. The rights to the Chinook Plus 2 were sold to US company, the Aeroplane Manufactory in 2013, which put the design back into production in 2016. The Chinook WT-11 design won Reserve Grand Champion at AirVenture in 1983 and again in 1984. In August 1983 test pilot Dennis Maland flew a WT-11 with the standard Rotax 277 engine to a height of . In November 1984 Jack Hughes flew a