Preliminary Study on Lift Coefficient of Biplane Airfoil in Smoke Wind Tunnel

In the present study, flow visualizations around a biplane airfoil equipped with the leading and trailing edge flaps are performed in a low-speed smoke wind tunnel. And we estimate the lift coefficient on the biplane airfoil utilizing the method based on the smoke line pattern measurements. The results of present study are as follows. It was confirmed that all lift curve slopes were nearly identical with and without uses of the leading edge and trailing edge flaps. When the trailing edge flaps are deflected downward, the lift coefficient increases. The zero lift angle of the present result is not directly proportional to the angle of trailing edge flaps δf. The leading edge deflection increasing angle of flaps increase the stall angle of attack of the biplane airfoil.