An experimental investigation of the low Reynolds number performance of the Lissaman 7769 airfoil

TLDR: In this article, a Lissaman 7769 airfoil was tested in a low turbulence subsonic wind tunnel and lift and drag data were collected at chord Reynolds numbers at angles of attack from -10 to +20 deg by using an external strain gage force balance.

Abstract: A Lissaman 7769 airfoil, used on the Gossamer Condor and Gossamer Albatross human-powered aircraft, was tested in a low turbulence subsonic wind tunnel. Lift and drag data were collected at chord Reynolds numbers of 100,000, 150,000, 200,000, 250,000, and 300,000; at angles of attack from -10 to +20 deg by using an external strain gage force balance. Lift curves, drag curves, and drag polars were generated from both uncorrected data and data corrected for wind tunnel blockage effects. A flow visualization study was performed to correlate with the force data. The results of the investigation have shown that the airfoil exhibits a significant degradation in performance for chord Reynolds numbers below 150,000.