FAA Flight Instructor Airplane (FIA)Aerodynamics and Principles of FlightHard
Two airplanes execute a coordinated, level turn at the identical 30° bank angle, but Airplane A maintains twice the true airspeed of Airplane B. Compared to Airplane B, Airplane A's turn radius will be approximately:
- AHalf as large
- BTwice as large
- CFour times as large
- DThe same
Show answer & explanationAnswer & explanation
Correct answer: C. Four times as large
Turn radius is given by r = V²/(g × tanθ). Since bank angle θ is the same for both airplanes, radius is proportional to V². Doubling the velocity (V) increases V² by a factor of 4, so Airplane A's turn radius is four times larger than Airplane B's.
Why the other options are wrong
- A. Reverses the relationship; higher speed increases, not decreases, radius.
- B. Incorrectly assumes radius scales linearly with velocity.
- D. Ignores that radius depends on velocity, not just bank angle.
Turn Radius Formula
Turn radius r = V²/(g tanθ); for a constant bank angle, radius increases with the square of true airspeed.
- Radius proportional to V² at constant bank
- Doubling speed quadruples radius
- Steeper bank at same speed decreases radius
Memory trick: Radius grows with speed-squared — double the speed, quadruple the circle.