All aircraft must meet controllability requirements to be certified for commercial use or adopted by the mi1itary. Aircraft maneuverability is often 1imited by control authority. Thus, it is essential for designers to evaluate a candidate concept's control authority early in the conceptual design phase. In this thesis, a methodology for rapid control power evaluation of preliminary design configurations against requirements at the key flight conditions is established. First, a collection of critical flight conditions to be considered using this methodology is identified. To examine a variety of aircraft configurations and accelerate the process of estimating stability and control derivatives, a FORTRAN program using the Vortex-Lattice Method was written to estimate subsonic, low angle-of-attack aerodynamics. Then, a spreadsheet processes the aerodynamic data to check whether the design configuration possesses adequate control power to satisfy the requirements of the critical flight conditions. / Master of Science