CPL Aerodynamics 3 — Questions and Answers
Question 1: What is the primary aerodynamic effect of fowler flaps compared to plain flaps?
- They only increase drag without changing lift
- They increase wing area and camber simultaneously (Correct answer)
- They reduce stall speed more than any other device
- They decrease the critical angle of attack
Correct answer: They increase wing area and camber simultaneously
Fowler flaps slide rearward and then deflect, increasing both wing chord area and camber, providing a greater lift increase than plain flaps.
Question 2: During a coordinated level turn at 60 degrees of bank, the load factor is approximately:
- 1.4 G
- 2.0 G (Correct answer)
- 2.4 G
- 3.0 G
Correct answer: 2.0 G
Load factor in a level turn equals 1/cos(bank angle); at 60° bank, 1/cos(60°) = 1/0.5 = 2.0 G.
Question 3: What aerodynamic phenomenon causes 'Mach tuck' in transonic flight?
- Loss of elevator effectiveness due to shock wave formation
- Aft movement of the center of pressure as shockwaves develop (Correct answer)
- Increase in induced drag at high altitude
- Compressor stall in jet engines
Correct answer: Aft movement of the center of pressure as shockwaves develop
As speed increases through the transonic range, shockwaves cause the center of pressure to shift rearward, creating a nose-down pitching moment.
Question 4: Which type of drag is NOT a component of parasite drag?
- Form drag
- Skin friction drag
- Interference drag
- Induced drag (Correct answer)
Correct answer: Induced drag
Induced drag is produced by lift generation and vortices; it is separate from parasite drag, which includes form, skin friction, and interference drag.
Question 5: How does a symmetrical airfoil behave at zero angle of attack?
- It produces maximum lift
- It produces zero lift (Correct answer)
- It produces negative lift
- It produces lift equal to a cambered airfoil
Correct answer: It produces zero lift
A symmetrical airfoil generates equal pressure on both surfaces at zero angle of attack, resulting in no net lift force.
Question 6: What is 'washout' in wing design, and why is it used?
- Twist reducing angle of attack toward the wingtip to delay tip stall (Correct answer)
- Wing sweep angle that reduces transonic drag
- Increased camber at the root for extra lift
- Downward deflection of ailerons during cruise
Correct answer: Twist reducing angle of attack toward the wingtip to delay tip stall
Washout is a geometric twist that reduces the angle of attack at the wingtip so the wing root stalls first, preserving aileron effectiveness.
Question 7: An aircraft in a 45-degree banked level turn must increase lift by approximately what factor to maintain altitude?
- 1.2
- 1.4 (Correct answer)
- 1.7
- 2.0
Correct answer: 1.4
At 45° bank, load factor n = 1/cos(45°) ≈ 1/0.707 ≈ 1.41, requiring about 41% more lift than in level unbanked flight.
CPL Aerodynamics 3
What is the primary aerodynamic effect of fowler flaps compared to plain flaps?