Effects of yaw angle on aerodynamic response in locusts

Aerodynamic forces and moments produced by locusts (Schistocerca americana) were investigated in a low-speed wind tunnel. The experimental setup included locusts mounted on a sensitive six-component microbalance using a sting. Tests were conducted at tunnel speeds of 0, 2, 3, 3.5 and 4 m/s at two body angles of attack and five positive yaw angles at each body angle of attack. The experimental results are presented for stroke-averaged forces and moments normalized using the insect body weight and length. Locusts generated more lift at higher velocities and at higher angles of attack, but none of locust generated lift greater than its weight. They generally produced net thrust at lower velocities and lower angles of attack and net drag at higher velocities, as expected. Interestingly, locusts responded to yaw by generating more positive side force, yawing moment and negative rolling moment. The lift force and pitching moment were largely insensitive to yaw.