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The number of rotors is also important, many helicopters have two rotors in a single line, and another configuration is 4 rotors. [22] An example of two-blade rotor is the Bell 212 , and four blade version of this helicopter is the Bell 412 . [ 23 ]
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 ...
The main rear landing gear retracts into the sponsons. [2] The Bell 222's rotor systems include: Two-blade, semi-rigid high-kinetic energy main rotor with preconing and underslinging. The rotor head incorporates elastomeric bearings for hub springs, and flapping and pitch change bearings. The system is similar in design to that used by the AH-1 ...
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 ...
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 ...
The UH-1H's dynamic components include the engine, transmission, rotor mast, main rotor blades, tail rotor driveshaft, and the 42-degree and 90-degree gearboxes of the tail rotor. The main rotor transmission consists of a 90 degree bevel gear assembly with a reduction ratio of 2.14:1, followed by a 2-stage planetary gearset with a ratio of 9.53 ...
NOTAR ("no tail rotor") is a helicopter system which avoids the use of a tail rotor. It was developed by McDonnell Douglas Helicopter Systems (through their acquisition of Hughes Helicopters ). The system uses a fan inside the tail boom to build a high volume of low-pressure air, which exits through two slots and creates a boundary layer flow ...