A methodology and software to automatically define airplane configurations is presented. The general airplane configuration has wing, fuselage, vertical tail, horizontal tail, canard, pylon, and engine nacelle components. The wing, tail, canard, and pylon components are manifested by solving a fourth order partial differential equation subject to Dirichlet and Neumann boundary conditions. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage and nacelles are described with analytic equations. The methodology is called Rapid Airplane Parametric Input Design (RAPID), and both batch and interactive software based on the technique are described. Examples of high-speed civil transport configurations and subsonic transport configurations are presented.