Physics Photo of the Week
April
8, 2011
Flight of the Bumblebee
A
bumblebee's flight was recently photographed with a new high speed
video camera (Casio Exilim Model EXFH25) made possible with funding
from the Pugh Foundation. Photographing the bumblebee's flight at
420 frames/sec with an exposure of 1/2000 sec for each frame provided
ample stop-action images of the bumblebees wings.
As can be seen in the image at left, the wings appear to be flat, not
very aerodynamic, and rather small considering the size of the
bumblebee. 
However,
the high speed video - recorded at 420 frames/sec and played back
at 5 frames per second in the animated image at right - clearly shows
how the insect can hover and fly using flat wings. If you watch
carefully, the wings pivot where they are joined to the insect's
thorax. The bee clearly changes the pitch angle of the wings
between the forward and reverse strokes. The process resembles
canoeing without taking the paddle out of the water - pivoting the
paddle differently on the forward and reverse strokes.
The bumble bee is seen here hovering pretty much in the same place, but
the insect makes nearly a 90 degree turn through subtle (undetectable)
manipulation of the pitch angles of the four wings. In watching
these insects in flight, they can be seen hovering for awhile, then
they they suddenly dart at a fast crusing speed of roughly 10
meters/sec. Presumably they achieve the fast speeds by
drastically different attack angles (close to 90 degrees on the forward
stroke and much smaller on the return strokes). Analysis of the
video clip shows that the bee's wings make about 120 complete cycles
per second. It's amazing that insects have the ability to control
the wing movements so rapidly - varying the pitch of the wings between
the forward and reverse strokes in a precise enough manner to maneuver
complicated flight paths.
Look for more high speed animations at this site in the future.
Physics
Photo of the
Week is
published weekly during the academic year on Fridays by the Warren
Wilson College Physics
Department. These photos feature interesting phenomena in
the world around us. Students, faculty, and others are invited to
submit digital (or film) photographs for publication and
explanation. Atmospheric phenomena are especially welcome.
Please send any photos to dcollins@warren-wilson.edu.
All photos and discussions are copyright by Donald
Collins or by the person credited for the photo and/or
discussion. These photos and discussions may be used for private
individual use or educational use. Any commercial use without
written permission of the photoprovider is forbidden.
Click
here
to see the Physics Photo
of
the Week Archive.
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