Describe lift coefficient behavior up to CLmax?

• A. It remains linear after CLmax.
• B. It decreases linearly with angle of attack until CLmax.
• C. It increases with angle of attack linearly until CLmax, then stall occurs and lift declines.
• D. It increases indefinitely.

Answer: (C)

As you increase the angle of attack, the lift coefficient rises roughly linearly in the pre-stall region because the pressure difference between the upper and lower surfaces grows, producing more lift. This linear increase continues up to a specific point called the critical angle of attack, where the flow can no longer remain attached to the wing. At that moment, boundary-layer separation occurs, the lift stops increasing and then declines as the angle grows further. The highest lift before separation is CLmax, which depends on the airfoil shape, Reynolds number, and Mach number. So the behavior described is a linear rise with angle of attack until CLmax, then stall and a drop in lift.