The mechanisms of lift enhancement in insect flight

Abstract

Recent studies have revealed a diverse array of fluid dynamic phenomena that enhance lift production during flapping insect flight. Physical and analytical models of oscillating wings have demonstrated that a prominent vortex attached to the wing's leading edge augments lift production throughout the translational parts of the stroke cycle, whereas aerodynamic circulation due to wing rotation, and possibly momentum transfer due to a recovery of wake energy, may increase lift at the end of each half stroke. Compared to the predictions derived from conventional steady-state aerodynamic theory, these unsteady aerodynamic mechanisms may account for the majority of total lift produced by a flying insect. In addition to contributing to the lift required to keep the insect aloft, manipulation of the translational and rotational aerodynamic mechanisms may provide a potent means by which a flying animal can modulate direction and magnitude of flight forces for manoeuvring flight control and steering behaviour. The attainment of flight, including the ability to control aerodynamic forces by the neuromuscular system, is a classic paradigm of the remarkable adaptability that flying insects have for utilising the principles of unsteady fluid dynamics. Applying these principles to biology broadens our understanding of how the diverse patterns of wing motion displayed by the different insect species have been developed throughout their long evolutionary history.

Ontogeny of aerodynamics in Mallard ducks: comparative performance and developmental implications

“…It is known from robotic models that unsteady aerodynamics contribute significantly to the forces produced during hovering and slow flight (Ellington et al, 1996;Dickinson et al, 1999;Lehmann, 2004). Recent work using flapping insect wings (Mountcastle and Daniel, 2009) and ).…”

Aerodynamics of the flying snake Chrysopelea paradisi: how a bluff body cross-sectional shape contributes to gliding performance

“…Although many open questions remain in the study of animal flight, the aerodynamic basis of flight in birds, bats and insects has received focused attention, leading to extensive understanding of kinematics, steady and unsteady effects, 2D and 3D dynamics, wake patterns and fluid-structure interactions (Lehmann, 2004;Wang, 2005;Tobalske, 2007;Hedenström and Spedding, 2008;Song et al, 2008;Usherwood and Lehmann, 2008;Lehmann, 2009;Spedding, 2009;Johansson et al, 2010). In comparison, there have been far fewer studies on the aerodynamics of animals that can only glide (Emerson and Koehl, 1990;McCay, 2001;Bishop, 2007;Alexander et al, 2010;Miklasz et al, 2010;Park and Choi, 2010;Bahlman et al, 2013), despite their large morphological and taxonomic diversity and the far greater number of independent evolutionary origins of gliding flight (Dudley et al, 2007;Dudley and Yanoviak, 2011).…”

Aerodynamic Experiments on DelFly II: Unsteady Lift Enhancement

“…Although a peak in lift force is expected due to the Magnus effect [9], the lift decreases considerably and reaches negative values before rotation at the maximal stroke angle. The drop in lift is supposedly attributed to the diminishing downwash, the reaction force on the abrupt upward motion of the leading edges (figure 4) and the starting vortex travelling slowly into the wake and counteracting the buildup of bound circulation ( figure 6C).…”