Unsteady Separated Flows. Generation and Use by Insects,
COLORADO UNIV AT BOULDER DEPT OF AEROSPACE ENGINEERING SCIENCES
Pagination or Media Count:
The novel lift generation mechanism postulated by Weis-Fogh and evaluated by Lighthill in regard to hovering insects provided graphic evidence for the possible utility of unsteady flows. The present report summarizes flight mechanisms in dragonflies that appear to exploit unsteady flows to achieve rather remarkable aerodynamics. Overall, these experiments indicate that unsteady flows may be used to support quite sophisticated insect flight maneuvers. No significant change in wing geometry is needed to achieve such flight and only modest alterations in dynamic wing stroke variables are required. The observations made here indicate that dragonflies use mechanisms quite different from those used by the Chalcid wasp, as described by Weis-Fogh. Other means of exploiting unsteady separated flows may exist also within the insect world.