Questions and CORRECT Answers
What is the definition of induced drag? - CORRECT ANSWER - The aft-acting
component of lift.
How does velocity impact induced drag? - CORRECT ANSWER - Faster aircraft have less
induced drag
How does AOA impact induced drag? - CORRECT ANSWER - Increase in AOA=Increase
in induced drag
What determines induced drag? - CORRECT ANSWER - Lift
Do wingtip vortices provide induced drag? - CORRECT ANSWER - Yes
What is the sphere of influence? - CORRECT ANSWER - Airflow that is affected by the
airfoil
What happens to induced drag as AR goes up? - CORRECT ANSWER - As aspect ratio
goes up induced drag goes down.
What is aspect ratio? - CORRECT ANSWER - 1) The ratio of a wing's length to it's chord.
2) A long and skinny wing has a high AR, whereas short and stubby wing has a low AR.
What happens to induced drag as weight goes up? - CORRECT ANSWER - 1) As weight
goes up induced drag goes up.
2) Heavier aircraft must fly at a higher AOA therefore increasing induced drag.
, What happens to induced drag as speed increases? - CORRECT ANSWER - Induced drag
goes down, faster speed=less downwash on the wing and rearward inclination of lift is less.
What happens to induced drag as altitude goes up? - CORRECT ANSWER - Induced drag
increases, higher altitudes air is less dense meaning we must fly at higher AOA increasing
induced drag.
Why are wingtip vortices included in induced drag? - CORRECT ANSWER - Because
vortices are caused by lift and take out energy.
What is viscosity? - CORRECT ANSWER - Resistance to shear
*High viscosity fluids are thick and resist flow, low viscosity is thin and flows easily.
What happens to the boundary layer during the adverse pressure gradient? - CORRECT
ANSWER - The boundary layer weakens
*Flow can also slow to a point of reversing, once reversed the boundary layer separates from the
surface.
What two types of drag increase as the boundary layer separates? - CORRECT
ANSWER - 1) Pressure Drag
2) Induced Drag
What causes parasite drag? - CORRECT ANSWER - All forces that work to slow an
aircraft's movement
Is parasite drag associated with the production of lift? - CORRECT ANSWER - No
What are 3 examples of parasite drag? - CORRECT ANSWER - 1) Interference drag
2) Skin Friction Drag
3) Form Drag