Two Myths of Insect Flight
(This column was first published in the March 25, 2002 Buffalo News.)
To achieve stature in the sciences, mathematics or engineering requires not only intelligence but also a major commitment of time and effort. Few are willing to make the required sacrifices and to delay the gratification that a scientific life ultimately provides.
The rest of us have ambivalent attitudes toward scientists. We hold their achievements in awe — most notably spectacular technological accomplishments like space flight, heart transplants and atomic bombs. But we caricature the working scientist as an oddball in a lab coat wearing thick lenses and the inevitable plastic pocket protector. We also retail stories about scientists’ inability to cope with the “real world.”
Perhaps the most famous of these stories is the one about the aeronautical engineer who proved with geometric logic (to use Captain Queeg’s famous phrase) that the bumblebee cannot fly.
Boeing engineer John McMasters sought out the source of this story. His search took him back to the 1930s and finally to a Swiss professor famous for work in supersonic gas dynamics. McMaster’s account continues, “The aerodynamicist was engaged one evening in light dinner-table conversation with a biologist, who asked in passing for enlightenment about the aerodynamic capabilities of the wings of bees and wasps. Intrigued by the question, the aerodynamicist did some preliminary calculations based on the assumption that the wings were more-or-less smooth, flat plates. The resulting calculations ‘proved’ the bee to be incapable of flight....
“The assumptions were almost wildly wrong, and the aerodynamicist himself later discovered part of his error by examining a bee’s wing under a microscope — but not, alas, before the myth was born in the hands of overeager journalists.”
McMaster and others have since studied insect wing structure and have found it to be “if not optimum aerodynamically, certainly...a good shot at the problem in a very difficult flow regime.” In less technical terms insects can fly. Indeed they solved the problem of flight some 350 million years before we did.
A less well known insect flight myth was picked up by many newspapers including The New York Times as well as books recording world records. They reported a deer botfly with a speed of over 800 miles per hour. The source of this myth was a report in the Journal of the New York Entomological Society: “On 12,000 foot summits in New Mexico I have seen pass me at incredible velocity what were certainly [botflies.] As closely as I can estimate, their speed must have approximated 400 yards per second.” (That is equivalent to 800 miles per hour.)
Nobel Prize winning chemist Irving Langmuir examined the report with some care. He (and later McMasters) discovered some problems. At that altitude 800 miles per hour is faster than the speed of sound yet the entomologist reported no sonic boom. To maintain that speed the fly would have to consume more than its own weight of food each second. And finally, McMasters wrote, “Botflies tend not to be very graceful fliers, even running into things on occasion while zipping around — deer and people, for example. Langmuir calculated that the impact of a 0.3-gram botfly traveling at Mach 1.1 would produce a wound equivalent to that of a large-caliber pistol bullet, making hiking on the ‘summits in New Mexico’ a somewhat risky business.”
Using the original report as a basis, Langmuir performed experiments that corrected the insects’ speed to 25 miles per hour, a rather substantial change.
We can laugh at these scientists’ bloopers, but it is important to notice that scientists themselves made the corrections. Most of the rest of us do not have the necessary intellectual tools.-- Gerry Rising