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A revelation
When I was in high school (and dinosaurs walked the earth) a science museum in my home town held a paper airplane contest. One of the events was a duration aloft contest, which was conducted by launching the planes off of a second-floor balcony that overlooked the museum's atrium. One day while pondering the contest I happened to drop a check. Instead of just falling to the floor, it started spinning along its long axis and flew quite a distance, and, more to the point, stayed aloft quite a while. I decided to use this serendipitous discovery as the basis of my entry in the paper airplane contest. I cut out a simple check-sized rectangle of notebook paper, put a little S-shaped camber into it so that it would tend to start and keep spinning, and just dropped it off the balcony. I won, and not just by a little bit. My entry completely obliterated the more traditionally designed competition. (If memory serves, mine stayed aloft about thirty seconds, versus about ten for the second place entry.) Of course, everyone thought I was cheating, so the next year they changed the rules to say that entries "must conform to recognized aerodynamic principles." That, of course, led to a big argument over what that meant exactly. That year my strip of notebook paper took second place. The "winning" entry (I put it in quotes because it was actually disqualified on the basis of the new rule) was a little cross-shaped scrap of rice paper about the size of a quarter. It pretty much just floated away on a thermal and never landed at all. :-) So they changed the rules again, and this time they got very clever: all entries in the time-aloft contest had to carry a penny as a payload. So I built a large (two-foot wingspan) version of my spinning check out of computer punch cards (I told you this was back in the Jurassic) taped together. I wrote "Piloted by Abe Lincoln" next to the penny, and won another commanding victory. But there was still a lot of grumbling and complaining that my entry was somehow "cheating", and I was not entirely convinced that I wasn't. (That was my senior year, and I have no idea what they did after that. Probably just breathed a big sigh of relief that I was gone.) Now, years later, I ran across this: http://www.av8n.com/how/htm/airfoils.html#sec-spinners Finally I understand why the thing flew! It really was flying! Thanks, John Denker! BTW, Denker's book is for my money the finest introductory text about flying ever written, bar none. It is extraordinary that he has made it freely available on the Internet. It should be required reading for all pilots IMHO. rg |
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On Tue, 28 Dec 2004 08:53:20 -0800, Ron Garret
wrote in :: it started spinning along its long axis and flew quite a distance, and, more to the point, stayed aloft quite a while. Many thanks for a provocative subject and a well told story. I can recall (from my youth, probably Precambrian by comparison) vendors selling "kites" on the southern California coast that operated on this principle. As I recall, they were about 24" long with vanes about 3" wide and had endplate disks that extended beyond the vanes. There was a tube through the long axis, and a string bridle connected to the ends of a rod that ran through the tube. I seem to recall them as being reflective. The vendor would set up shop with a dozen or so flying. |
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