What speed is associated with maximum excess power in level flight?

The speed associated with maximum excess power in level flight is the best climb speed, commonly referred to as Vy. This speed provides the maximum rate of climb for an aircraft, allowing it to gain altitude at the most efficient rate.

Excess power refers to the power available to climb after overcoming the power required to maintain level flight. At Vy, the aircraft operates in a way that optimally balances the thrust and drag forces to maximize the excess power. This means that the plane is maintaining the best climb performance possible, as it achieves a favorable lift-to-drag ratio while also providing the necessary thrust to overcome drag.

The other speeds mentioned are not specifically tied to maintaining the optimum excess power for climbing. For instance, Vx is associated with the best angle of climb, which maximizes altitude gain over distance but not necessarily the rate of climb. The best glide speed is particularly relevant during glide scenarios and serves to keep the aircraft in a lower drag configuration, while minimum drag speed is focused on achieving the lowest possible drag rather than optimizing power for climb.