Rig Rotary Wing Aircraft Flashcards
What causes dissymmetery of lift produced by the rotor of a helicopter?
The forward speed of the helicopter produces dissymentry of lift. The rotor blade that is traveling forward as the helicopter is flying produces more lift than the blade that is traveling rearward
Why do single-rotor helicopters use an auxiliary rotor on their tail?
The thrust from the tail counteracts the torque produced by the main rotor
Why is it important that the blades of a helicopter rotor system be in track?
If the blades are not in track, vertical vibration can develop
What is the function of the cyclic pitch control?
It changes the pitch of the rotor blades at a particular point in their rotation to tilt the plane of the rotor. The cyclic pitch controls the lateral movement of the helicopter
What is the function of the tail rotor on a single main rotor helicopter?
The thrust from the tail rotor counteracts the torque of the main rotor to control the yaw of the helicopter. The control pedals change the pitch of the tail rotor blades to vary the thrust
What is the purpose of the stabilizer system in a helicopter?
A helicopter is statically stable but dynamically unstable. The stabilizer system restores the helicopter to level flight when outside forces cause it to pitch or roll
What is meant by a fully articulated rotor system?
It is a rotor system in which the individual blades are free to flap, drag, and feather
What is meant by a semi rigid rotor system?
A two-blade rotor system in which the blades can feather, but cannot flap or drag. The rotor hub is mounted on the mast with teetering hinge that allows the entire rotor to rock as a unit
What is meant by a rigid rotor system?
A rotor system that has freedom of motion about its feather axis only. The flexibility of the blades is sufficient to provide the needed flapping and dragging
What is the basic cause of low-frequency lateral vibration?
The main rotor blades being out of static balance
What is the basic cause of low-frequency vertical vibration?
One of the main rotor blades producing more lift than the other
What is usually the cause of high frequency vibration?
The engine, cooling fan, or tail rotor
What is the most effective way to check a helicopter rotor for dynamic balance?
Use a special computerized analyzer/balancer
