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Flight of the Bumblebee

This is an old "world wide cobweb" page, one of the first pages I wrote. Way back when I was young(ish). It was moved to this location September, 2008. To learn more about it read this article: End of an Era.

by Doug Craigen, PhD (physics)

Revision 1.0 - Feb. 9, 1996

How often have you heard it said either as part of a point being made in a sermon, or in conversation, that science cannot explain how a bumblebee can fly. I've lost count of all the times I've heard this. Usually it goes something like this:

And then there's the case of the bumblebee. According to the greatest minds of science, it cannot fly. Its wings aren't big enough. Aerodynamics says it is impossible. The biggest computers in the world all come to the same conclusion, it can't fly. But what does the bumblebee do? It ignores the great minds, the skeptics, the computers... and it just goes ahead and flies.

A statement of this generic sort is then used as a springboard for one of many moral lessons.

Aside from the obvious overstatement, the question then is: among those scientists who actually care, those who study the aerodynamics of winged insects, are they able to explain how it is that a bumblebee can fly?

The first error is the belief that the biggest problem in explaining the flight of the bumblebee is its body weight. Certainly there is a lot of weight for such little wings, but the biggest problem is its static aerodynamic design.

If you were to take a bird carcass, spread out the wings, and throw it, it would glide for a while and come to rest on the ground some distance away. If you were to do the same with a bumblebee carcass, it would tumble end over end and plummet. The difference is that whereas a bird has a nice static aerodynamic design which allows air to flow easily around it, a bumblebee creates turbulance that flips it around. This is the mystery, how is it that a bumblebee can fly without tumbling?

The answer lies in the fact that static (still) objects are governed by different stability laws than dynamic (moving) objects. For example, take a bicycle. As a static object it is not stable (like a tricycle would be). Leave a bicycle standing without support and it will fall over. However, a moving (dynamic) bicycle is perfectly stable, and it is easy to explain why with basic physics. The bumblebee is the same, as a static object it is not aerodynamically stable, it cannot glide. But when it is flapping its wings, we're into a whole new ball game for how air moves around it.

Maybe all those nice bumblebee sermons could be revised to have nice moral lessons about the need to 'keep flapping', lest we go tumbling end over end.... just a thought.