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The rotorhead is where the lift force from the rotor blades act. The rotorhead is connected to the main drive shaft via the Jesus nut, and houses several other components such as the swash plate, flight control linkages and fly-bars. [1] The rotor hub is also where the centre of gravity acts on the helicopter. The rotor head of a Sikorsky S-92
The FAA states "The height–velocity diagram or H/V curve is a graph charting the safe/unsafe flight profiles relevant to a specific helicopter. As operation outside the safe area of the chart can be fatal in the event of a power or transmission failure it is sometimes referred to as the dead man's curve."
Abrasion strips on helicopter rotor blades are made of metal, often titanium or nickel, which are very hard, but less hard than sand. When a helicopter flies low to the ground in desert environments, sand striking the rotor blade can cause erosion. At night, sand hitting the metal abrasion strip causes a visible corona or halo around the rotor ...
The pitch of the tail rotor blades is adjustable by the pilot via the anti-torque pedals, which also provide directional control by allowing the pilot to rotate the helicopter around its vertical axis. Its drive system consists of a shaft powered from the main transmission and a gearbox mounted at the end of the tail boom.
Tandem-rotor helicopters, however, use counter-rotating rotors, with each cancelling out the other's torque. Therefore, all of the power from the engines can be used for lift, whereas a single-rotor helicopter uses some of the engine power to counter the torque. [1] An alternative is to mount two rotors in a coaxial configuration.
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The collective changes the pitch angle of all the main rotor blades collectively (i.e., all at the same time) and is independent of their position in the rotational cycle. Therefore, if a collective input is made, all the blades change equally, and as a result, the helicopter increases or decreases its total lift derived from the rotor.
A helicopter is susceptible to a rolling tendency, called dynamic rollover, when close to the ground, especially when taking off or landing. For dynamic rollover to occur, some factor has to first cause the helicopter to roll or pivot around a skid, or landing gear wheel, until its critical rollover angle is reached.