Low Speed Static Wind Tunnel Investigation Of A Half Span Fuselage And Variable Sweep Pressure Wing Model

The experimental balance and pressure data obtained from tests of an untwisted variable-sweep wing with an outboard pivot exhibited nonlinearities in both total normalforce-coefficient and pitching-moment-coefficient curves for all sweep angles and fuselage conditions. These total effects have been traced back through the section data and pressure distributions to find the causes. The causes of these nonlinearities were found to be (1) separation of flow on the outer panel and (2) a leading-edge vortex flow on the inner panel. A fuselage added to the wing had little effect on the aerodynamic characteristics. Predictions of wing loadings and performance characteristics were made by using the modified Multhopp method and a comparison with experimental results indicated reasonable agreement. The changes in span loading as a result of leading-edge shed-vortex formation and flow separation at the higher angles of attack caused an increase in the induced-drag parameter.