ANALYSIS OF WALL INTERFERENCE EFFECTS ON ONERA CALIBRATION MODELS IN THE NAE 5-FT. multiplied by 5-FT. WIND TUNNEL.

Measurements on three geometrically similar aircraft models by ONERA are used to analyze lift interference effects in the solid and perforated wall test sections of the NAE 5-ft. multiplied by 5-ft. test facility. The prediction of the angle of attack correction for both test sections is based on the representation of the model by lifting lines and the solution of the subsonic wall interference problem by the finite difference method. The value of the porosity factor ascribed to the test section with perforated walls is checked by comparing the measured wall pressure distributions with the theoretical ones, predicted by the present method. The lift interference effects on two models having wing span to wind tunnel width ratios of 0. 188 and 0. 311, respectively, were found to be within the limits of experimental errors. For a model having a wing span to wind tunnel width ratio of 0. 644, the solid and perforated test section measurements, corrected using a uniform angle of attack correction, show good agreement up to lift coefficients of about 0. 5.