Side force control on slender body by self-excited oscillation flag

Abstract

Strong asymmetrical vortices appear on the leeward of slender body at high angles of attack, which has very unfavorable effect on the stability and control of the aircraft. A method is developed to control the side force of slender body at high angles of attack, and is verified in wind tunnel. A thin-film triangular self-excited oscillation flag is fixed at the tip of the slender body model whose semi-apex angle is 10°. Side force is approximately linearly proportional to roll-setting angle of self-excited oscillation flag at high angles of attack, and the slop of fitting straight line obtained by the least square method is −0.158. The linear relationship between side force and roll-setting angle provides convenience for developing side force control law of slender body at high angles of attack. Experimental data shows that the side force coefficients vary linearly with roll-setting angles when a specific plastic self-excited oscillation flag is used as the control flag. The range of side force coefficient and roll-setting angle are, respectively, −3.2 to 3.0 and −20° to 20°. The device is simple, effective, and is of great potential in engineering application.

Keywords

• Self-excited oscillation flag
• Slender body
• High angle of attack
• Proportional control
• Side force