On Tue, 10 May 2005 01:10:46 -0500, Richard J Kinch
wrote:
Joseph Gwinn writes:
There
really was a fellow who got his PhD by "proving" that bumblebees cannot
fly, using the best aeronautical theory of the day (the 1930s or 1940s).
Who was that? Thesis title?
Insect aerodynamics: Flipping and flapping for flight forces,
presented by Michael Dickinson, of the Dickinson Lab, in the
Department of Integrative Biology at UC Berkeley.
Abstract: An engineer once proved that a bumblebee cannot fly. The
difficulty for this anonymous individual (and many other researchers
throughout the past century) was that the application of conventional
aerodynamic theory to the wing motion of insects predicted forces that
are much too low to keep an animal aloft. The failure of conventional
steady-state theory has fueled the search for unsteady mechanisms that
might account for the elevated performance of insect wings. In order
to facilitate this search, we constructed a large dynamically scaled
model of a flapping fruit fly. Direct measurement of the forces and
flows produced by a flapping wing suggests that the aerodynamics of
insect flight may be explained by the interaction of three distinct,
yet interactive mechanisms: delayed stall, rotational circulation, and
wake capture. While delayed stall is a translational mechanism,
rotational circulation and wake capture depend explicitly on the rapid
rotation of the wings during stroke reversal. The regulation of
rotational phase provides insects with a potent means of controlling
flight forces during steering maneuvers. A general theory of insect
aerodynamics that incorporates both translational and rotational
mechanisms shows promise in explaining the force generating mechanisms
of many species as well providing insight for the design of biomimetic
robots"
"War is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and patriotic feeling
which thinks that nothing is worth war is much worse. The person who has nothing for which he is willing to fight,
nothing which is more important than his own personal safety, is a miserable creature and has no chance of being
free unless made and kept so by the exertions of better men than himself."
- John Stewart Mill
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