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The Straight Dope



When I was in college, not so many eons ago, it was pretty much an article of faith among us intellectual iconoclasts that, though we could put a man on the moon, we still had no idea how a bumblebee could fly. Do we? --Keith Hanson, Silver Spring, Maryland

Of course. You think this is on a par with quantum mechanics or something? The basic principles of bumblebee flight, and insect flight generally, have been pretty well understood for maybe 40 years. Somehow, though, the idea that bees "violate aerodynamic theory" got embedded in folklore. It probably sprang from a faulty analogy between bees and conventional fixed-wing aircraft. Bees' wings are small relative to their bodies; if an airplane were built the same way, it'd never get off the ground. But bees aren't like airplanes, they're like helicopters. Their wings work on the same principle as helicopter blades--to be precise, "reverse-pitch semirotary helicopter blades," to quote one authority. A moving airfoil, whether it's a helicopter blade or a bee wing, generates a lot more lift than a stationary one.

The real challenge with bees wasn't figuring out the aerodynamics but the mechanics: specifically, how bees can move their wings so fast--roughly 200 beats per second, which is 10 or 20 times the firing rate of the nervous system. The trick apparently is that the bee's wing muscles (thorax muscles, actually) don't expand and contract so much as vibrate, like a rubber band. A nerve impulse comes along and twangs the muscle, much as you might pluck a guitar string, and it vibrates the wing up and down a few times until the next impulse comes along. Cecil is aware he is sliding over a few subtleties here, but hey, nobody ever said science for the masses was pretty.

Do you know anything about broadcast power? This has nothing to do with radio or TV. As I understand it, broadcast power involves turning electricity into a signal which is transmitted and then converted back into electricity by a special device fitted to any common appliance. I saw a demonstration of this in college about 12 years ago, when a visiting artist was using these devices in his kinetic sculptures. Could broadcast power be used for non-polluting electric vehicles? Do you know of any experts who could speak knowledgeably on this subject who would not be biased in favor of the oil companies? --Rodney Franko, Madison, Wisconsin

You've been spending too much time reading Popular Science, Flash. Also, I don't know that I'd place much faith in the technological insight of kinetic sculptors--most of those guys barely know how to operate a can opener. It's possible to transmit power through space using a microwave beam, but that's not "broadcast" power in the sense you mean. True broadcast power would involve incredible waste and probably kill everybody besides. Scientists nowadays worry about the possible injurious effects of the electric fields around wires--imagine what might happen if the juice was just poured into the air.

Most likely you heard something about the satellite power system (SPS), one of the wilder ideas to float around the federal bureaucracy in the late 70s. The plan was to build a giant array of solar cells the size of Manhattan in orbit around the earth, beam the collected solar power via microwave to a giant receiving dish on earth, convert it into standard juice, and feed it into the regular power system.

Several government agencies looked into SPS and concluded it was every bit as crazy as it sounded. The complete system would cost three trillion dollars, roughly the size of the gross national product and many times what we spend on conventional power technology. A mere demonstration project might cost 40 to 100 billion dollars. The National Research Council declared that further study was pointless and the project died a quiet death. Proponents haven't totally given up; one brainstorm they had was to build a solar-cell factory in the low-gravity environment of the moon to save on rocket-fuel costs. (Supposedly this would save money over shipping parts from the earth.) Very ingenious, boys. Now go play outside.

Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.

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