What is the purpose of the free wheeling unit in a helicopter drive system?
The freewheeling unit automatically disengages the engine from the main rotor when engine revolutions per minute (rpm) is less than main rotor rpm. [Figure 4-12] This allows the main rotor and tail rotor to continue turning at normal in- flight speeds.
What type of clutch is used in the freewheeling unit on the Bell 206?
The freewheeling unit or autorotative clutch allows the main rotor transmission to drive the tail rotor drive shaft during autorotation. In some helicopter designs, such as the Bell BH-206, the freewheeling unit is located in the accessory gearbox.
Does a helicopter can fly without an electrical power?
Does the helicopter need any electricity to stay flyable? Yes, fly-by-wire helicopters are very rare. While they will no longer be augmented, stabilized, or power assisted, the mechanical linkages will still work. And they’ll be able to autorotate, as @GdD described, and as demonstrated in this Smarter Every Day video.
How does a helicopter sprag clutch work?
A sprag clutch is used in many helicopter designs to transfer power from the engine to the main rotor. In the event of an engine failure, the sprag clutch allows the main rotor to continue rotating faster than the engines so that the helicopter can enter autorotation.
How is directional control maintained in a helicopter?
B- tail to pivot in the direction of torque rotation around the main rotor axis. A- relative position of the blades during rotation. 8- In a hovering helicopter equipped with a tail rotor, directional control is maintained by. C- varying the pitch of the tail rotor blades.
What is mass bumping?
Mast bumping is contact between an inner part of a main rotor blade or a rotor hub and the main rotor drive shaft (or ‘mast’). Serious mast bumping in flight usually results in the helicopter breaking up in flight, which is fatal for those on board.
What is the rpm of helicopter rotor?
Depending on the model and size of the helicopter, a helicopter’s blades, which are between 40-60ft long, spin from about 225 RPM to 500 RPM. Speed is determined by the power of the rotor and the length of the blade.
What is the inside of a helicopter called?
Fuselage — The main body of the helicopter is known as the fuselage. In many models, a frameless plastic canopy surrounds the pilot and connects in the rear to a flush-riveted aluminum frame.
Can a helicopter land without an engine?
Unlike a plane, which can glide a large distance with no power, a helo has no way to slow down—or so the thinking goes. Actually, helicopters have a built-in mechanical control called the collective pitch lever that allows them to descend slowly and land even if the engine dies. This maneuver is called autorotation.