AERODYNAMICS AND THE ORIGIN OF INSECT FLIGHT

Protopterygotes or winglets or protowings are the immediate ancestors of winged insects. This chapter deals with the problem of estimating glide performance for the protopterygotes. It evaluates the plausibility of different hypotheses about the origin of flight using suitable theories. The chapter suggests that the winglets might have a strong aerodynamic advantage from the outset by reducing the terminal velocity of vertical descents and therefore lowering the risk of injury. The terminal velocity of insects, even a few centimetres long, is dangerously high. The winglets could also provide pitch stability and control if articulated and mobile. Caudal filaments and/or paired cerci were also likely to be used for stability and control of pitch and yaw. If injurious landings were a major problem, the pitch control should have been used for vertical descents with a horizontal body; the speed is least in that attitude. © 1991 Academic Press Limited.