One of the crucial items in the design of operational VTOL aircraft is the specification of realistic control power requirements for low-speed flight conditions. Various attempts to develop empirical design requirements have yielded inconsistent results that have often been subject to individual interpretation. This paper examines the problem from a fundamental, analytical viewpoint, viz., the computation of control power as the output of a randomly disturbed mechanical system. Use of the proposed method also permits the rational consideration of closely related handling quality aspects. Contrary to data available in the VTOL literature, this paper shows that control system sensitivity and power are not strongly related, although both can affect the vehicle handling qualities. The method probably exhibits its greatest utility as a preliminary design tool, where it can serve to evaluate competing system designs quantitatively, even with estimated system characteristics. Numerical examples are presented to illustrate the application of the method. The main disadvantages of the method are the requirements for detailed knowledge of the maneuver requirements, the atmospheric turbulence, and the airframe stability derivatives. An intimate knowledge of analytical handling qualities is also a prerequisite.