Wing Movements and Lift Regulation in the Flight of Desert Locusts

Abstract

ABSTRACT We simultaneously recorded lift/body weight, flight speed, body angle and 12 variables of wing movement for locusts performing tethered long-term flight with low movement scatter. The movements of the forewings and hindwings were recorded in three dimensions by means of miniature induction coils. By adjusting the body angle, we could reproducibly manipulate lift generation as a consequence of induced changes in the wings’ movement patterns. We were therefore able to analyse various relationships between the movement patterns and lift. The most prominent variations of kinematic variables were observed for the forewing movements. The relative lift and the steady angle of pitch were positively correlated but there was a negative correlation between relative lift and pitching amplitude. We found no correlation between relative lift and flapping amplitude. Our results seem to correspond to a new theory about unsteady aerodynamics of oscillating aerofoils. We sometimes observed variations in lagging. The forewing downstroke was delayed by 0–8ms following the hindwing downstroke. Relative lift was positively correlated to this delay.