Deploying flaps decreases stall speed.

• A. Stall speed decreases
• B. Stall speed increases
• C. Stall speed unchanged
• D. Flaps do not affect stall speed

Answer: (A)

The essential idea is that stall speed is tied to how much lift the wing can produce before it stalls. Lift must balance weight, and lift rises with speed, wing area, air density, and the lift coefficient. For a given weight, the speed at which you can just maintain level flight is governed by the maximum lift coefficient the wing can reach before stalling (CLmax). When flaps are deployed, the wing’s camber and lifting capability increase, raising CLmax. Because CLmax is higher, you can generate the required lift at a lower airspeed, so the stall speed drops. That’s why extending flaps lets you fly slower without stalling. The other options would only be correct if CLmax didn’t change with flap deployment, which isn’t the case.