Stalls Flashcards
(51 cards)
What is a stall in aviation?
A stall is a loss of lift and an increase in drag as an aircraft is flown at an angle of attack (AOA) greater than the angle for maximum lift.
The AOA for maximum lift is also called the critical AOA.
What is the stall speed?
The stall speed is the speed at which the critical AOA is exceeded.
It is most affected by variations in airplane loading, i.e., weight and CG.
At what angle of attack does the critical AOA typically occur?
Approximately 18° to 20° on most airfoils.
This is when the airstream can no longer follow the upper curvature of the wing.
What happens as the critical AOA is approached?
The airstream begins separating from the rear of the upper wing surface, leading to a loss of lift.
Increasing the angle further causes turbulent airflow to spread over the entire upper wing surface.
What must be done to recover from a stall?
The AOA must be decreased to allow the airstream to flow smoothly over the wing surface.
True or False: An airplane can be stalled at any airspeed and any power setting.
True.
The stall can occur if the critical AOA is exceeded.
What factors remain constant regardless of the aircraft’s weight or angle?
The critical AOA remains constant regardless of weight, dynamic pressure, bank angle, and pitch attitude.
What factors affect stall speed?
Stall speed is affected by:
* Weight
* Load factor
* Power setting
What is washout in wing design?
Washout is when the wingtips have less angle of incidence than the wing roots.
How does flap extension affect stall speed?
Flap extension generally increases the lifting ability of the wings, thus reducing the stall speed.
Fill in the blank: The load factor is the ratio of the lifting force produced by the wings to the actual weight of the airplane and its contents, usually expressed in _______.
[Gs]
What happens to stall speed in a constant-altitude turn?
Increased load factors will cause the airplane’s stall speed to increase as the angle of bank increases.
How does the center of gravity (CG) affect stall recovery?
Stall recovery becomes progressively more difficult when the CG moves aft.
What can cause an increase in stall speed?
Snow, ice, or frost on the wings can cause an increase in the stall speed.
What is the effect of turbulence on stall speed?
Turbulence can cause an airplane to stall at a significantly higher airspeed than in stable conditions.
What is a key factor in recognizing an impending stall?
Vision, hearing, kinesthesia, and the feeling of control pressures are key indicators.
What is the first step in stall recovery?
Regaining positive control of the airplane by reducing the AOA.
What is the angle of attack (AOA)?
The angle between the chord line of the wing and the direction of relative wind.
What does the angle of incidence refer to?
The angle formed by the chord line of the wing and the longitudinal axis of the airplane.
True or False: The angle of incidence can be changed by the pilot.
False.
It is determined by airplane design and is a fixed angle.
What is the center of pressure?
The point along the chord line of a wing at which all aerodynamic forces are considered to be concentrated.
What is the relationship between lift, angle of attack, and airspeed?
Lift is directly related to AOA and airspeed; as AOA or airspeed increases, lift increases.
What is the effect of increased weight on AOA and stall speed?
Increased weight requires a higher AOA at a given airspeed, causing the critical AOA to be exceeded at a higher airspeed.
What is the relationship between drag and airspeed?
As airspeed decreases, AOA increases, causing an increase in induced drag.
