This volume describes engineering methods for the prediction of the aerodynamic and stability and control characteristics of STOL aircraft employing internally ducted jet flaps, externally blown jet flaps, and mechanical flap systems with vectored thrust. These methods are intended to be used in conjunction with the theoretical methods and the associated computer program (STOL Aerodynamic Methods Computer Program) discussed in Volumes I and II, respectively. These engineering methods are intended to provide a rational approach for the aerodynamic analysis of complete STOL aircraft configurations and to provide semi-empirical methods to account for those effects not treated by the theoretical methods. These methods have been applied to configurations representative of each of the powered high-lift concepts, and the results of these analyses have been presented along with available experimental data to indicate the validity and range of applicability of the methods.