WIND TUNNEL TESTS OF AN ULTRALIGHT SAILPLANE WING SEGTION

Abstract

The UAG 88-143/20 wing section was designed for use on an ultralight sailplane wing that would require good performance at low Reynolds number. A model was tested in the University of Alberta low turbulence wind tunnel at Reynolds numbers of 0.5 x 10^6, 1.0 x 10^6 and 2.1 x 10^6 with camber flap at 0, +10, and -10 degrees. Tests were repeated with simulated insect roughness to check on sensitivity to roughness. The measurcd results were interpolated to present drag polars for flight Reynolds number which would occur for any given sailplane geometry. Curves were drawn to represent wing tip, wing root and mean chord Reynolds number with and without water ballast. The new wing section has excellent lift-drag characteristics, particularly at lift coefficients in the range from 0.5 to 1.5, and at low Reynolds number. It displays very docile stall characteristics that will enhance flight safety. Sensitivity to roughness was low, particularly at the lower Reynolds numbers. The new section should be suitable for the proposed ultralight sailplane.