One of the things that we frequently report on in this column, consists of something scientists have discovered by copying what they have seen in nature. In the August 2005 issue of AOPA Pilot, a magazine for aircraft owners and pilots, there is an interesting report on the work of scientists at Duke University and Chester University in their studies of the physics of fluids.

When you see humpback whales, one of the things that you will notice is that their flippers have bumps on them called tubercles. Most of us have assumed that these bumps were just random variations in the growth of the fins and had no function. What researchers have done is to compare what happens with a bumpy flipper and a smooth flipper under the same conditions.

The data shows that the bumpy flipper produces eight percent more lift and 32 percent less drag than the smooth flipper, and stalls at a 40 percent steeper angle. Researchers say that the tubercles cause swirling vortices which break up pressure gradients against the leading edge of the flippers, and that this channels the water into the valleys between the tubercles producing the desirable effects. The mathematics of this discovery is complex, but the implications are staggering.

Not only will the application of this research make better wings on planes, but will improve helicopter rotors, airplane propellers and even centerboards on sailboats and rudders on all kinds of ships. Like a lot of other things we see in nature, the tubercles are carefully designed features which improve the function of the organism in fluids. Wherever man ventures, he finds a wonder working hand has gone before. Our thanks to Jerry Miller for this material

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