FAA Commercial Pilot Airplane (CAX)Aerodynamics and PerformanceMedium
Two airplanes of equal weight fly at the identical true airspeed and identical 45° bank angle in a coordinated turn. Airplane A has a larger wing area (lower wing loading) than Airplane B. Which statement correctly compares their turn radii under these conditions?
- AAirplane B turns tighter because higher wing loading generates more lift for the turn
- BAirplane A turns tighter because it stalls at a higher speed, allowing more control authority
- CBoth airplanes have the same turn radius, since radius depends only on true airspeed and bank angle, not wing loading
- DAirplane A turns tighter because lower wing loading produces greater centripetal force
Show answer & explanationAnswer & explanation
Correct answer: C. Both airplanes have the same turn radius, since radius depends only on true airspeed and bank angle, not wing loading
Turn radius is calculated as r = V²/(g × tan(bank angle)) and depends only on true airspeed and bank angle — not on wing loading or weight. Wing loading affects stall speed and thus the minimum speed/maximum bank achievable, but at the same TAS and bank angle, radius is identical regardless of wing loading.
Why the other options are wrong
- A. Higher wing loading does not tighten turn radius at the same TAS and bank.
- B. Lower wing loading typically produces a lower stall speed, not higher, and stall speed does not directly determine radius at a given TAS.
- D. Wing loading does not appear in the turn radius formula; this reasoning is incorrect.
Turn Radius Independence from Wing Loading
Turn radius depends only on true airspeed and bank angle (r = V²/(g·tanφ)); wing loading does not directly appear in this formula.
- Wing loading affects achievable stall speed and bank angle limits, not radius directly at a given speed.
- Radius formula: r = V² / (g × tanφ).
- Lower wing loading allows flying slower, which indirectly can produce tighter turns.
Memory trick: Radius cares about speed and bank, not how much wing you've got.