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An ______ in velocity or density will produce more lift.
An _____ in wing surface area produces greater lift.
Within the lift equation, pilots have no control over the CL factors of ____, ____, or _____.
viscosity; compressibility; aspect ratio
Three lift equation factors a pilot can control are ____, ____, and ______.
velocity; angle of attack; shape of the airfoil or camber
What is the critical angle of attack?
- The AOA that corresponds to the max coefficient of lift
- Increasing the AOA beyond the critical angle of attack causes a decrease in lift due to boundary layer separation
As the AOA is increased, the pilot will have to ____ velocity to maintain level flight
If AOA is _____ then velocity must increase
What is aerodynamic twist?
- decrease in camber from the wing root to the wing tip
- Positive camber at wing root, symmetric shape at wing tip
What does an aerodynamic twist do to stall characteristics?
- The wing root will stall before the wing tip
- Positively cambered airfoil stalls at a lower AOA than a symmetric airfoil
What is a geometric twist?
- Decrease of angle of incidence from wing root to wing tip
- Wing root is always at a greater AOA than the wing tip
What does a geometric twist do to stall characteristics?
Wing root will always stall first, providing a stall indication before the ailerons become ineffective
What is parasite drag?
- drag that is not associated with the production of lift
- Increases as velocity increases
- Form drag
- Friction drag
- Interference drag
What is form drag?
- The result of separation of airflow from a surface and the wake that is created by that separation
- Occurs as object moves through a fluid
- Difference between leading edge static pressure and trailing edge static pressure
What is friction drag?
- turbulent airflow in the boundary layer
- Reduced by smoothing the exposed surface
What is interference drag?
generated by mixing airstreams between aircraft components
What is induced drag?
- drag that is associated with production of lift
- Weight and AOA are directly related to induced drag
- Wingtip vortices
In level flight where lift is constant, induced drag varies _____ with velocity and directly with AOA.
What is significant about L/DMAX?
- Minimum total drag
- Parasite drag = induced drag
- Greatest ratio of lift to drag (not max lift)
- Most efficient AOA for the wing
What is ground effect?
Within one wingspan of the ground, induced drag is significantly reduced because the ground blocks the downwash from the wing
Define thrust available
The amount of thrust that is produced by an engine at a give PCL setting, velocity and density
What is maximum velocity?
- At max power, equilibrium flight will be maintained when thrust available equals thrust required.
- 255 KIAS
What is thrust excess?
- Occurs if thrust available is greater than thrust required at a particular velocity
- Positive thrust excess will cause a climb, acceleration or both depending on AOA
- Lack of excess thrust causes a descent, deceleration or both depending on AOA
- Max excess thrust occurs at a velocity less than L/DMAX
Define power available
The amount of power that an engine is producing at a given PCL setting, velocity, and density
What is power required?
Is the amount of power required to produce thrust required
What is power excess?
- Positive power excess results in a climb, acceleration or both
- Lack of excess power causes a descent, deceleration, or both
- Maximum excess power occurs at L/DMAX
What happens to the thrust and power required curves as weight is added?
The net result is that increased weight shifts the power and thrust curves up and right
What happens to the thrust required factor as altitude is increased, assuming weight is constant?
- Velocity must increase due to the decrease in air density.
- The curve must shift to the right as altitude increases.
What happens to the power required curve as altitude increases?
Curve shifts to the right and up due to the increase in velocity, because power is a constant function of thrust required and velocity
What happens to thrust available and power available at altitude increases?
- Max engine output decreases with decreased air density
- Both will decrease
Simple hinged portion of trailing edge of the wing that is forced down into the airstream
- Plate deflected from the lower surface of the wing.
- Creates more drag
- T6 has split flap
Similar to plain flap, but moves away from the wing to open a narrow slot between the flap and wing for boundary layer control
- Used on large aircraft
- Moves down to increase camber and aft to increase wing surface area, increasing lift
What flap setting gains more lift than increased drag?
50% of flap setting
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