Subsonic aerodynamic performance of nozzle installations in supersonic airplanes.

The external aerodynamic performance of supersonic airplane nozzle systems at subsonic speeds is studied and some significant results of analytical and experimental investigations of exhaust system subsonic drag are shown. Experimental techniques are described which can minimize model scaling uncertainties in wind-tunnel tests. An analysis method for successfully predicting drag on axisymmetric bodies at subsonic speeds combines axisymmetric potential flowfield predictions with laminar and turbulent boundary-layer computation procedures. The results for certain applications are compared with experiment, and application of the analysis to the design of asymmetric models for detailed experimental investigations is demonstrated. For accurate extension of model test results to full-scale airplane performance predictions, an analytical method is proposed. This discussion concludes with a mention of some limitations of the analysis and of areas where further work is needed.