Current preliminary aircraft design cycles use empirical relations to great the wing and power loading diagrams to size the aircraft and its engine. These empirical relations are based on historical aircraft data to relate the aircraft weight to engine power. To enhance the design capability for novel propeller aircraft types and increase the accuracy in general, a takeoff performance analysis and propeller sizing method is developed to create analytical and physics based takeoff and cruise constraints. The sizing method focusses on takeoff conditions, taking into account the low speed aerodynamic effects on the propeller and the resulting effect on the takeoff performance. The point mass takeoff performance model and BEM propeller analysis iterate the propeller sizing parameters; number of blades and chord ratio factor to determine the propeller that precisely achieves the required takeoff distance. Two case studies with reference aircraft are presented to demonstrate the impact of the developed sizing method on the preliminary aircraft and engine design solution with respect to reality and the empirical method. The results show the created constraints follow the same trends, however the power loading takeoff constraint is lower than the empirical constraint.