RDS-Professional is a conceptual aircraft design and analysis system developed for operation on a personal computer. Based on the methods in the AIAA textbook ‘Aircraft Design: A Conceptual Approach’, RDS features a 3-D CAD module for design layout, and has analysis modules for aerodynamics, weights, propulsion, and cost. RDS includes capabilities for aircraft sizing, mission analysis, and performance analysis including takeoff, landing, rate of climb, Ps, fs, turn rate, and acceleration. RDS also provides graphical output for drag polars, L/D ratio, thrust curves, flight envelope, and range parameter, and features both traditional carpet plot optimization and a multivariable design optimizer. Comparative studies indicate that RDS-Professional produces results within the usual accuracy for conceptual design efforts.