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

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.

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.