Wednesday, April 29, 2009

Flight of the Bumblebee


According to the laws of physics and aerodynamics, there is absolutely no reason or possibility for a bumblebee to be able to fly. Their bodily structure should make it impossible. Yet, they do fly.

If you care to read in detail about Bumblebees check this out from Wikipedia. If not, skip down the bottom. According to 20th century folklore, the laws of aerodynamics prove that the bumblebee should be incapable of flight, as it does not have the capacity (in terms of wing size or beats per second) to achieve flight with the degree of wing loading necessary. Not being aware of scientists 'proving' it cannot fly, the bumblebee succeeds under "the power of its own ignorance". The origin of this myth has been difficult to pin down with any certainty. John McMasters recounted an anecdote about an unnamed Swiss aerodynamicist at a dinner party who performed some rough calculations and concluded, presumably in jest, that according to the equations, bumblebees cannot fly. In later years McMasters has backed away from this origin, suggesting that there could be multiple sources, and that the earliest he has found was a reference in the 1934 French book Le vol des insectes, they had applied the equations of air resistance to insects and found that their flight was impossible, but that "One shouldn't be surprised that the results of the calculations don't square with reality".

Some credit physicist Ludwig Prandtl (1875–1953) of the University of Göttingen in Germany with popularizing the myth. Others say it was Swiss gas dynamicist Jacob Ackeret (1898–1981) who did the calculations.

In 1934, French entomologist Antoine Magnan included the following passage in the introduction to his book Le Vol des Insectes:

Tout d'abord poussé par ce qui fait en aviation, j'ai appliqué aux insectes les lois de la résistance de l'air, et je suis arrivé avec M. SAINTE-LAGUE a cette conclusion que leur vol est impossible.

This means:

First prompted by the fact of aviation, I have applied the laws of the resistance of air to insects, and I arrived, with Mister Sainte-Lague, at the conclusion that their flight is impossible.

Magnan refers to his assistant André Saint-Lagué, who was apparently an engineer.

It is believed that the calculations which purported to show that bumblebees cannot fly are based upon a simplified linear treatment of oscillating aerofoils. The method assumes small amplitude oscillations without flow separation. This ignores the effect of dynamic stall, an airflow separation inducing a large vortex above the wing, which briefly produces several times the lift of the aerofoil in regular flight. More sophisticated aerodynamic analysis shows that the bumblebee can fly because its wings encounter dynamic stall in every oscillation cycle.

Another description of a bee's wing function is that the wings work similarly to helicopter blades, "reverse-pitch semirotary helicopter blades".

Why is it possible for bumblebees to fly? The answer is simple. That’s what God created them to do.

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