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These are the recollections of John E. Lamar as he grew to adulthood in the city of Columbus Georgia as it was being colonized following the seizure of those lands from the Creek and Cherokee Indian nations following 1828.
Geometrical, flight, computational fluid dynamics (CFD), and wind-tunnel studies for the F-16XL-1 airplane are summarized over a wide range of test conditions. Details are as follows: (1) For geometry, the upper surface of the airplane and the numerical surface description compare reasonably well. (2) For flight, CFD, and wind-tunnel surface pressures, the comparisons are generally good at low angles of attack at both subsonic and transonic speeds; however, local differences are present. In addition, the shock location at transonic speeds from wind-tunnel presure contours is near the aileron hinge line and generally is in correlative agreement with flight results.
The suction analogy concept of Polhamus for predicting vortex lift in conjunction with an appropriate potential-flow solution is called the present method. This method is applied herein to an aspect ratio of 0.25 sharp-edge delta wing from a Mach number of 0.143 to 10.4 in free air and at 0.074 in ground effect, and also to an aspect ratio of 0.35 triangular cross-sectional body at Mach number of 6.9. The models had subsonic leading edges at the test Mach numbers. Vortex-flow effects could be neither confirmed nor denied to exist at high speeds because of the lack of flow visualization above a Mach number of 0.143. The data, however, could be better predicted by including a vortex-flow effect, although not always to the extent predicted from the present method because of the presence of actual and hypothesized unmodeled flow situations.
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.
This paper summarizes a variety of optically based flow-visualization techniques used for high-speed research by the Configuration Aerodynamics Wind-Tunnel-Test Team of the High-Speed Research Program during its tenure. The work of other national experts is included for completeness. Details of each technique with applications and status in various national wind tunnels are given.