Flight Controls Flashcards
(17 cards)
Why is it important to keep the leading edge of a wing and the upper surface of the forward half of the wing free of dents and contamination?
The air flowing over this portion of the wing must be smooth to produce the maximum amount of lift. If the surface is rough or dirty, the air flow will be distorted and lift will be lost.
What is meant by the angle of attack of an airplane wing?
The acute angle that is formed between the chord line of an airfoil and the direction of the air that strikes it.
What are the four basic forces that act on an aircraft in flight?
Lift, drag, thrust, and gravity.
What is meant by the angle of incidence of an airplane wing?
The acute angle that is formed between the chord line of an airfoil and the longitudinal axis of the aircraft on which it is mounted.
What causes parasite drag on an airplane?
The friction of the air flowing over the surface.
Name the three axes of an airplane and the control that rotates the airplane about each of its three axes.
Longitudinal axis — ailerons, Lateral axis - elevators, Vertical axis — rudder.
Does the lift produced by the horizontal tail surfaces of an airplane act upward or downward in normal flight?
Downward.
What is the function of lateral dihedral in the wings of an airplane?
Lateral dihedral gives the aircraft roll stability, or stability about the longitudinal axis.
What is the purpose of a stall strip on an airplane wing?
Stall strips distort the air flowing over the top of the wing in the root area at high angles of attack. They cause the root of the wing to stall out at a lower angle of attack than the portion of the wing ahead of the ailerons.
What is the function of a servo tab on an aircraft control surface?
A servo tab produces an aerodynamic force on a control surface that aids the pilot in moving the surface.
Why do most high-performance aircraft use slotted flaps?
Slotted flaps can be deflected to a greater angle than other types of flaps before the airflow over their surface breaks away.
What is the purpose of a movable slat in the leading edge of some airplane wings?
The movable slat remains flush with the leading edge of the wing during all low-angle-of-attack flight conditions. When the angle of attack becomes high, the slat automatically moves out of the wing and forms a duct which forces the air back over the upper surface of the wing. This delays the stall.
Why is it important that the leading edge of a supersonic airplane wing be kept free from dents and damage?
A sharp leading edge allows an oblique shock wave to attach to the airfoil in supersonic flight. If the leading edge is dented or blunt, a normal shock wave will form and slow the air immediately behind it to a subsonic velocity.
What is the purpose of vortex generators on the wing of a high-speed airplane?
Vortex generators pull high-energy air down to the surface of the wing and keep shock-induced separation from occurring.
Why are the control cables of large airplanes normally equipped with automatic tension regulators?
The large amount of aluminum in the aircraft structure contracts so much as its temperature drops in flight that the control cables could become dangerously loose. The automatic tension regulators keep the cable tension constant as the dimensions of the aircraft change.
Why is it important that any repairs to the control surfaces of an airplane not change their original condition of balance about their hinge line?
A control surface that is out of static balance can flutter in certain flight conditions. Flutter normally tears the surface off the aircraft.
In what FAA publication could you find correct control surface movement for a particular airplane?
In the Type Certificate Data Sheet for the airplane.
