The lowest steady horizontal flight speed occurs when the wing is at maximum lift coefficient.

• A. Only at high altitude
• B. Only with flaps
• C. True
• D. False

Answer: (C)

The main idea is how lift, speed, and lift coefficient relate in steady flight. For level flight, lift must balance weight. Lift increases with the lift coefficient (and with speed), following L = 1/2 ρ V^2 S Cl. If you want to fly at the lowest possible speed while staying level, you should maximize lift per unit speed, which means using the highest lift coefficient you can without stalling. That maximum usable lift coefficient is Cl_max—the point just before the wing stalls. At Cl_max, you achieve the smallest speed that still supports the weight in calm, steady level flight. If you tried to go any slower, the wing would stall and you’d lose steady flight.

So the statement is true. It’s not about altitude or requiring flaps; those factors can change how large Cl_max is, but the principle stays: the lowest steady horizontal speed occurs when the wing operates at its maximum lift coefficient for the current configuration.