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On a helicopter, the main rotor or rotor system is the combination of several rotary wings (rotor blades) with a control system, that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerodynamic drag in forward flight.
The tail rotor is powered by the helicopter's main power plant, and rotates at a speed proportional to that of the main rotor. In both piston and turbine powered helicopters, the main rotor and the tail rotor are mechanically connected through a freewheeling clutch system , which allows the rotors to keep turning in the event of an engine ...
However, the rear rotor works in the aerodynamic shadow of the front rotor, which reduces its efficiency. This loss can be minimized by increasing the distance between the two rotor hubs, and by elevating one hub over the other. [4] [5] Tandem-rotor helicopters tend to have a lower disk loading than single-rotor helicopters. [6]
The Boeing Vertol CH-46 Sea Knight is a medium-lift tandem-rotor transport helicopter, furnished with a set of counter-rotating main rotors in a tandem-rotor configuration. It was typically powered by a pair of General Electric T58 turboshaft engines, which were mounted on each side of the rear rotor pedestal; power to the forward rotor was ...
In response, Robinson Helicopter Company instituted stringent quality procedures and requirements, and replaced all main rotor blades on the fleet of 33 helicopters in service at the time. [ 26 ] In the early 1980s, the R22 experienced a number of student-pilot related accidents due to the R22's use as a primary flight trainer.
Ducted fan tail rotors have also been used in the Russian Kamov Ka-60 medium-lift helicopter, [17] and also on the Japanese military's Kawasaki OH-1 Ninja reconnaissance rotorcraft. French light helicopter manufacturer Hélicoptères Guimbal has also used a Fenestron for their Guimbal Cabri G2, a compact reciprocating engine-powered rotorcraft ...
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Vibration in the framework then coupled with a helicopter phenomenon known as ground resonance. [3] The vibration was sufficient to cause a structural failure as the starboard rear helicopter broke off its mounting, its rotors cutting into the gasbag. [3] The unbalanced lift then made the vibrations worse and the remaining three helicopters ...