What is the stalling speed with flaps down and power off?

What is the stalling speed with flaps down and power off?

• A. 149 knots
• B. 43 knots
• C. 70-80 knots
• D. 55 knots

Answer: (B)

Stall speed in a given configuration is the minimum airspeed at which the wing can still produce enough lift to balance the aircraft’s weight. Extending flaps increases the wing’s lift capability (Cl_max goes up), so the airplane can reach that lift at a lower speed. When power is off, engine thrust isn’t contributing to lift, so the stall speed is determined only by the wing’s lift at the flaps-down configuration and the aircraft’s weight. For a typical light aircraft in this setup, that results in a stall speed in the low 40s of knots. So the stalling speed with flaps down and power off is about 43 knots. The other speeds correspond to different configurations or conditions and do not represent this particular stall scenario.

Stall speed in a given configuration is the minimum airspeed at which the wing can still produce enough lift to balance the aircraft’s weight. Extending flaps increases the wing’s lift capability (Cl_max goes up), so the airplane can reach that lift at a lower speed. When power is off, engine thrust isn’t contributing to lift, so the stall speed is determined only by the wing’s lift at the flaps-down configuration and the aircraft’s weight. For a typical light aircraft in this setup, that results in a stall speed in the low 40s of knots. So the stalling speed with flaps down and power off is about 43 knots. The other speeds correspond to different configurations or conditions and do not represent this particular stall scenario.