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30 Cards in this Set

  • Front
  • Back
What is the major difference between a fixed wing aircraft's airfoil from a rotary wing airfoil?
The fixed wing airfoil is unsymmetrical, the rotary wing airfoil is symmetrical.
What theories explain rotor lift?
Newton's law of momentum:
Lift results from accelerating amass of air downward (lift only).
Blade Element Theory:
Airflow over an airfoil section of the rotor blade acts the same as it does on a fixed wing aircraft (lift & drag).
What causes lift to change?
Incrasing the angle of attack (pitch) of the rotor blades.
What is blade flapping?
The ability for rotor blades to move vertically to compensate for dissymmetry of lift.
What component offsets the vibrations caused by blade flapping?
A drag hinge, allowing the blade to move back and forth in a horizontal plane.
What is gyroscopic precession?
The 90 degree offset in cyclic pitch change.
What is ground effect?
The cushion of air produced downward from the main rotor when close to the surface.
What is transitional lift?
The transition from hover to forward flight, where the helicopter moves from the cushion of air & lift briefly less abundant.
What is autorotation?
It occurs when the main rotor rotates by air passing up through the rotor instead of by the engine.
What is power settling?
An occurance at low-speed flight in which the helicopter experiences uncontrollable loss in altitude. Caused by downwash from the rotor recirculating at high velocity.
Three basic flight control systems of rotary wing aircraft.
Cyclic & collective pitch and the rotary rudder control.
What controls forward, aft and lateral movements of the helicopter?
Cyclic pitch.
Movement of the pilots cyclic stick transmit through control rods nd bell cranks to what components?
Auxiliary servo cylinders, the mixing unit, and three primary servo cylinders.
What do the primary servo cylinders control?
Movement of the rotary-wing blades.
What vertically controls movement of the helicopter?
Collective pitch.
Movement of the collective pitch stick is sent through control rods and bell cranks to what components?
Auxiliary servo cylinders, mixing unit, primary servo cylinders, and the rotary wing swashplate.
T or F: Collective pitch control increases/decreases the pitch of the rotar blades simultaneously?
What component balances the weight of the collective stick?
Balancing spring attached to the control rods.
What system controls the pitch of the rotary rudder blades?
The rotary rudder control system.
What component prevents sudden movements of the rudder control pedals?
Hydraulic pedal damper located in the auxiliary servo cylinder bank.
What does the negative force gradient spring do?
It cancels feedback loads exerted by the rotary rudder during flight, and when the hydraulic system is off.
The negative force gradient spring is preloaded to ______ pounds.
What are the four basic components of the helicopter flight control system?
Auxiliary servo cylinder, mixing unit, primary servo cylinder, and the swashplate.
How many psi does the auxiliary servo cylinder operate at?
1500 psi.
What is the purpose of the mixing unit?
The unit coordinates and transfers independent movements of the lateral, forward, aft and directional controls. Causes the controls to move the 3 primary servo cylinders simultaneously in the same direction. Cahnges pitch on the rotary rudder blades to compensate for the change in pitch of the rotary-wing blades.
What is the purpose of the Primary Servo Cylinders?
To send flight control movements to the stationary swashplate of the rotary-wing head.
What is the purpose of the Swashplate Assembly?
To send movement of the flight controls to the rotary-wing blades.
What allows the swashplate assembly to tilt off its horizontal plane and move on its vertical axis?
A ball ring socket.
The assembly consists of a __________ swashplate, connected to the rotary-wing ______ by the rotating _________ and adjustable pitch control ________.
The stationary swashplate connects to the main gearbod by what 2 components?
Stationary scissors & Primary Servo Cylinders.