20 Questions
What is the primary function of ailerons in a fixed-wing aircraft?
To rotate the aircraft around the longitudinal axis (roll)
Which flight control surface is responsible for rotating the aircraft around the lateral axis (pitch)?
Elevator
What is the effect of moving the control stick or yoke to the left on the ailerons?
The left aileron goes up and the right aileron goes down
What is the phenomenon that occurs when the deflection of an aileron on a wing tip causes the aircraft to perform a roll movement contrary to what was initially intended?
Aileron reversal
What is the purpose of dividing flight control surfaces into primary and secondary groups?
To distinguish between main and auxiliary control surfaces
Which axis is controlled by the movement of the rudder?
Vertical axis (yaw)
What is the result of moving the control stick or yoke to the right?
The right aileron goes down and the left aileron goes up
What is the term for the rigidity of a wing to resist twisting?
Torsional rigidity
What occurs when an aileron is deflected on a wing with low torsional rigidity?
The wing twists and causes aileron reversal
Under what conditions is it necessary to fix the aileron?
During high dynamic pressures and with wings with low torsional rigidity
What is the primary purpose of a stabilator in an aircraft?
To combine the action of the horizontal stabilizer and elevator
What is the effect of deflecting the elevator downward?
The nose of the aircraft pitches down
What is the function of a canard wing in an aircraft?
To create lift and hold the nose up
What is the purpose of a variable incidence stabilizer in an aircraft?
To minimize drag when trimming the aircraft in flight
What happens when the control wheel is pulled back in an aircraft with a stabilator?
The leading edge of the stabilator moves down
What is the result of aileron-rudder coupling in an aircraft?
The rudder deflects in the correct direction for a coordinated turn
What is the primary function of a variable incidence stabilizer in an aircraft?
To adjust the angle of incidence of the horizontal stabilizer
Why is a canard wing aircraft configuration used in some aircraft?
To provide a more stable and controlled flight
What is the effect of moving the control stick forward in an aircraft with a stabilator?
The nose of the aircraft pitches down
What is the purpose of a moverable horizontal tail section in an aircraft?
To combine the action of the horizontal stabilizer and elevator
Study Notes
Flight Control Surfaces
- Primary flight control surfaces include ailerons, elevator, and rudder
- Ailerons are attached to the outboard trailing edge of both wings and rotate the aircraft around the longitudinal axis (roll)
- Elevator is attached to the trailing edge of the horizontal stabilizer and rotates the aircraft around the lateral axis (pitch)
- Rudder is attached to the trailing edge of the vertical stabilizer and rotates the aircraft around the vertical axis (yaw)
Influence of CG on Pitch Control
- CG ahead of CP: bigger deflection of elevator needed, high longitudinal stability, bigger control force needed
- CG behind of CP: smaller deflection of elevator needed, smaller control force needed, low longitudinal stability
Directional Control
- Pressing the right rudder pedal deflects the rudder to the right (tail goes left) which yaws the aircraft to the right
- Rudder is used to overcome adverse yaw during turns and crosswind and one-engine operation
- Rudder limiter prevents involuntary motion of the rudder unless commanded from the flight deck and depending on aircraft speed
Hybrid Control Surfaces
- Ruddervator (rudder and elevator) for V-tail gives both pitching and yawing
- Elevon (elevator and aileron) used on tail-less aircraft gives both pitching and rolling
Secondary or Auxiliary Devices
- High lift devices provide good compromise between high cruising speed and low landing speed
- Flaps are usually located on inboard wing trailing edge, leading edge flaps are also common
- Aileron-rudder coupling: when pilots turn the control wheel, rudder will deflect in correct direction for a coordinated turn
Longitudinal Control
- Movement of control stick forward deflects elevator downward, causing nose to go down (tail goes up)
- Stabilator is a movable horizontal tail section that combines action of both horizontal stabilizer and elevator
- Variable incidence stabilizer refers to any horizontal stabilizer with adjustable angle of incidence, used to minimize drag when trimming the aircraft in flight
- Canard wing aircraft has a small wing or horizontal airfoil ahead of the main lifting surfaces, creating lift and holding the nose up
Learn about the impact of center of gravity on pitch control, including the effects of CG position on elevator deflection and control force. Also, discover how directional control works, including the use of rudder and aileron to turn the aircraft.
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