An Experimental Investigation of the Effects of Planform and Thickness Discontinuities on the Aerodynamic Characteristics of a Family of Low Aspect Ratio Wings.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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An experimental investigation to determine the aerodynamic coefficients of a family of symmetric wing planforms with abrupt planform and thickness discontinuities was conducted. The wing consists of a rectangular center panel with two small, tapered outboard panels. Six different pairs of outboard panels attached to the center panel at different locations were tested. Wind tunnel tests were conducted at Reynolds numbers between 1,740,000 and 1,990,000 and Mach numbers of approximately 0.13. Aspect ratios were between 0.875 and 2.29 The lift curve slopes increase at high angles of attack for small and intermediate outboard panel configurations, suggesting vortex lift due to the low aspect ratio center panel. Drag polars are parabolic except over ranges of angle of attack where outboard panel stall overrides center panel vortex lift. The pitching moment about the center panel quarter chord is near zero for outboard panels mounted at the position, becoming nose down as the outboard panels move aft. Fore and aft shifting of the outboard panels had little effect on Cl, Cd, and lift-to-drag ratio. A vortex lattice analysis consistently predicted Cl and Cm well, but predicted induced drag poorly. Author