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.


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