The Debunker: Does a Bumblebee's Flight Defy Physics?

by Ken Jennings

Ah, June. The bees are buzzing, the crickets are chirping, the fireflies are glowing, and the June bugs are—doing whatever June bugs do, I guess? It's their month. In the United Kingdom, the connection between summer and the insect kingdom has been formalized by turning the last week of June into National Insect Week. We're also celebrating our six-legged friends all month, and we've called in Ken Jennings (not an insect, but at least a WASP) as a guest expert. He tells us that our insect knowledge has a few bugs.

The Debunker: Does a Bumblebee's Flight Defy Physics?

In popular culture, the fact that the roly-poly little bumblebee can fly with those flimsy little wings is often used an inspiring bit of motivational puffery. "By the laws of physics, science says that a bumblebee shouldn't even be able to fly!" we are told. "And yet it can." The implication is a little confusing: if I'm not able to accomplish tasks that literally violate physical law, then I'm falling disappointingly short of my full potential? That seems like an awful high bar.

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In the most common version of the story, a mathematician or engineer is startled to discover, over drinks, that the aerodynamics of bumblebees defies every equation of flight he knows. The subject is sometimes named as German physicist Ludwig Prandtl; in another version of the legend, it's a Swiss aeronautics engineer named Jacob Ackeret. There's no documentary evidence attaching either man to the bee story, but there is a 1934 French text called The Flight of Insects, in which zoologist Antoine Magnan notes that he and his assistant both crunched the numbers and, based on the laws of air resistance on bees, "arrived…at the conclusion that their flight is impossible."

If this chance remark is the origin of the legend, then have no fear: decades of more careful work and firsthand study have solved the mystery that bedeviled Magnan. The main difference between a bee and the kind of heavier-than-air flying devices that an engineer usually studies is rigidity: bees flap their little wings in a way that a 747 does not. In the 1970s, a Cambridge professor named Torkel Weis-Fogh was able to model the mechanics of insect flight more accurately. He discovered that insect thrust comes from tiny eddies of air created as the wings rotate. Pockets of low pressure are created above the bee as it lowers its wings, which lift the bee upward. It's the same way most birds and insects take off, and not anything miraculous—except in the more general sense that any living creature who can slip the surly bonds of earth is its own little miracle.

Quick Quiz: "Flight of the Bumblebee," from the opera The Tale of Tsar Saltan, is the best-known work of which Russian composer?

Ken Jennings is the author of eleven books, most recently his Junior Genius Guides, Because I Said So!, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings.