How does the maximum lift coefficient relate to stall speed in clean configuration?

• A. Stall speed is inversely proportional to CLmax; increasing CLmax (e.g., with flaps) lowers stall speed; clean config has lower CLmax, so stall speed is higher.
• B. Stall speed increases as CLmax increases.
• C. Stall speed is independent of CLmax.
• D. Stall speed decreases as CLmax decreases.

Answer: (A)

Stall speed is determined by the amount of lift the wing can produce at a given speed. At the stall point, the lift coefficient is at its maximum (CLmax). For level flight, lift must equal weight, so using L = 0.5 ρ V^2 S CL, the stall speed V_s is:

V_s = sqrt( (2W) / (ρ S CLmax) )

This shows an inverse relationship with CLmax: as CLmax increases, the required speed to produce that lift decreases. Flaps or other devices that increase CLmax lower the stall speed, while clean configuration has a lower CLmax, so the stall speed is higher in clean configuration. The other statements misstate the relationship: stall speed does not increase with CLmax, is not independent of CLmax, and does not decrease when CLmax decreases.