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
Joint Helicopter Support Unit in Sept 2009. www.jhsu.co.uk Joint Helicopter Support Unit The Joint Helicopter Support Unit (JHSU) was a joint organisation of the British Army and the Royal Air Force, located in RAF Odiham. It was formed in July 1982, following the introduction of the Chinook HC MK1 Helicopter. Personnel were drawn from the Royal Corps of Transport (RCT) and Royal Army Ordnance Corps (RAOC) (both now amalgamated into the Royal Logistic Corps (RLC)) plus the Royal Corps of Signals and the Royal Air Force (RAF). The JHSU became the Joint Helicopter Support Squadron (JHSS) following its merger with the RAF Mobile Air