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Old Jul 28, 2006, 01:42 PM
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Originally Posted by flieslikeabeagl
Hey Mal, good to run across one of your posts again! Its the weirdest thing, my wife and I both find ourselves missing Kamloops, even though we've only spent a few days there. We both wish we could be there again!

Back to the propeller, I remember reading about the attempts to make a human-powered airplane back in the late 1970's and early 1980's. The propeller turned out to be crucial - there was barely enough power available from the pilot, and an inefficient propeller would not permit flight at all. The MIT aircraft, Chrysalis, used a propeller designed by an MIT professor, Eugene Larrabee, who came up with the concept of minimum induced loss propellers, and wrote ground-breaking research papers on the topic.

Later Paul Mcready and his team were trying to win the second Kremer prize with his aircraft the Gossamer Albatross, but were not even close to their goal until someone told McReady about Eugene Larrabee and his work on minimum induced loss propellers. A new propeller was designed based on Larrabee's principles, and the human-powered airplane not only flew, but took the Kremer prize.

The same thing happened again the Daedalus, which crossed the Aegean Sea in 1988.

This is why the propellers of all these planes - anything that has barely enough power to fly - tend to look alike. They are all based on Prof. Larrabee's work!

Most of us know that an elliptical wing planform (like the one on the Spitfire) has less drag than any other wing shape. I'm no aerodynamics expert, but my understanding is that Prof. Larrabee was the first to realize that this was no longer true for a propeller - because the tip of a propeller moves faster than the root, the elliptical shape is not the optimum shape. He then figured out what the correct planform for minimum drag on the propeller blades was...and voila, there was the "minimum induced drag" propeller!

Here's a short 'Web article on the man who, as much as anyone, made human powered flight possible:

HA! Great to hear from you too!

I had a grewat time even though my health was not the best. We(Tom chris MR.Callingridge Mom dad and I Still talk about that supper and wonder how you and your wife are doing. I knew you were alive as i saw a post every once in awhile.

Happy to hear from you

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