What is the designation for power-off stalling speed with flaps up?

The designation for power-off stalling speed with flaps up is indeed Vs. This term specifically refers to the minimum speed at which an aircraft can be flown in stable flight before entering a stall as the angle of attack increases.

In more detail, Vs is important for pilots to understand because it helps them recognize the critical airspeed associated with the stall during clean configurations, which is when the aircraft is not experiencing any additional drag from extended flaps or landing gear in a deployed position. Knowledge of Vs aids pilots in maintaining safe flight practices, particularly during approaches and landings where they may inadvertently reduce their airspeed close to stall conditions.

Other terms such as Vg, Vx, and Va denote different flight parameters. Vg represents the best glide speed, Vx is the speed for the best angle of climb, and Va is the maneuvering speed. Each of these speeds serves a distinct function in flight operations, but they do not directly relate to power-off stalling speed with flaps retracted. Understanding these distinctions helps pilots operate their aircraft more effectively and enhances safety in various flight conditions.