SPC Basic Aerodynamics Principles 2 — Questions and Answers
Question 1: What is the primary cause of induced drag on a wing?
- Skin friction from airflow over the surface
- Wingtip vortices created by pressure differential between upper and lower surfaces (Correct answer)
- Turbulent boundary layer separation at the trailing edge
- Interference between the wing and fuselage
Correct answer: Wingtip vortices created by pressure differential between upper and lower surfaces
Induced drag results from wingtip vortices that form because high-pressure air beneath the wing spills around the tip toward the low-pressure upper surface.
Question 2: As angle of attack increases beyond the critical angle, what happens to lift?
- Lift increases sharply
- Lift remains constant
- Lift decreases rapidly as the wing stalls (Correct answer)
- Lift decreases gradually over several degrees
Correct answer: Lift decreases rapidly as the wing stalls
Beyond the critical angle of attack, airflow separates from the upper wing surface, causing a sudden loss of lift known as a stall.
Question 3: Which aerodynamic force acts perpendicular to the relative wind?
- Drag
- Thrust
- Weight
- Lift (Correct answer)
Correct answer: Lift
Lift always acts perpendicular to the relative wind, regardless of the aircraft's attitude.
Question 4: What effect does increasing airspeed have on parasite drag?
- Parasite drag decreases proportionally
- Parasite drag increases with the square of airspeed (Correct answer)
- Parasite drag remains constant
- Parasite drag increases linearly with airspeed
Correct answer: Parasite drag increases with the square of airspeed
Parasite drag varies with the square of airspeed, so doubling speed quadruples parasite drag.
Question 5: In steady, level, unaccelerated flight, which statement about the four forces is correct?
- Thrust exceeds drag and lift exceeds weight
- Lift equals weight and thrust equals drag (Correct answer)
- Thrust equals weight and lift equals drag
- All four forces are equal to zero
Correct answer: Lift equals weight and thrust equals drag
In straight-and-level unaccelerated flight, the four forces are in equilibrium: lift equals weight and thrust equals drag.
Question 6: What is the relationship between air density and lift production at a constant angle of attack and airspeed?
- Lower air density produces more lift
- Air density has no effect on lift
- Higher air density produces more lift (Correct answer)
- Lift is inversely proportional to the square of density
Correct answer: Higher air density produces more lift
Lift is directly proportional to air density; denser air contains more molecules per unit volume, generating greater aerodynamic force on the wing.
Question 7: Which statement correctly describes the camber of an airfoil?
- The straight-line distance from leading edge to trailing edge
- The curvature of the mean camber line from chord line (Correct answer)
- The thickness of the airfoil at its widest point
- The angle between the chord line and relative wind
Correct answer: The curvature of the mean camber line from chord line
Camber is the curvature of the mean camber line (midpoint between upper and lower surfaces) measured from the chord line.
SPC Basic Aerodynamics Principles 2
What is the primary cause of induced drag on a wing?