BAvn Bachelor of Aviation Bachelor of Aviation Theory of Flight 2 — Questions and Answers
Question 1: What is the primary cause of induced drag on a wing?
- Skin friction along the fuselage
- Wingtip vortices creating a downwash that tilts the lift vector rearward (Correct answer)
- Interference between the wing and engine nacelles
- Boundary layer separation at the leading edge
Correct answer: Wingtip vortices creating a downwash that tilts the lift vector rearward
Induced drag results from wingtip vortices that cause downwash, effectively tilting the lift vector aft and producing a drag component.
Question 2: An aircraft is in a 60-degree banked level turn. What is the load factor (G)?
- 1.5 G
- 1.7 G
- 2.0 G (Correct answer)
- 2.4 G
Correct answer: 2.0 G
In a level banked turn, load factor = 1/cos(bank angle); cos(60°) = 0.5, so load factor = 2.0 G.
Question 3: Which phenomenon occurs when a swept-wing aircraft approaches the stall and the wingtips stall before the wing root?
- Dutch roll
- Pitch-up tendency (Correct answer)
- Spiral instability
- Mach tuck
Correct answer: Pitch-up tendency
Tip stall before root stall causes a pitch-up tendency because the center of pressure moves forward as the tips lose lift.
Question 4: What is the effect of increasing aspect ratio on a wing's aerodynamic efficiency?
- Increases parasite drag and decreases induced drag
- Decreases induced drag and improves lift-to-drag ratio (Correct answer)
- Increases both induced and parasite drag equally
- Has no significant effect on drag characteristics
Correct answer: Decreases induced drag and improves lift-to-drag ratio
Higher aspect ratio wings have smaller wingtip vortices relative to span, reducing induced drag and improving the lift-to-drag ratio.
Question 5: In subsonic flight, where does the center of pressure typically move as angle of attack increases toward stall?
- Moves progressively forward
- Moves progressively aft
- Moves forward then rapidly aft at stall (Correct answer)
- Remains fixed at the quarter-chord position
Correct answer: Moves forward then rapidly aft at stall
In subsonic flow, as AoA increases the center of pressure moves forward, but at stall the abrupt loss of lift causes it to shift rapidly aft.
Question 6: Which condition defines the best glide speed (L/D max) in terms of drag?
- Parasite drag equals zero
- Induced drag equals parasite drag (Correct answer)
- Total drag is equal to weight
- Induced drag is twice parasite drag
Correct answer: Induced drag equals parasite drag
L/D max (best glide) occurs at the speed where induced drag equals parasite drag, minimizing total drag for a given lift.
Question 7: What is 'washout' in wing design, and why is it used?
- Increased chord at the wing root to improve structural strength
- A decrease in angle of incidence from root to tip to ensure root stalls first (Correct answer)
- Swept leading edge to delay transonic effects
- Downward camber on the lower wing surface to reduce drag
Correct answer: A decrease in angle of incidence from root to tip to ensure root stalls first
Washout is a gradual reduction in angle of incidence toward the wingtip, ensuring the root stalls before the tip to maintain aileron effectiveness.
BAvn Bachelor of Aviation Bachelor of Aviation Theory of Flight 2
What is the primary cause of induced drag on a wing?