Thursday, March 17, 2011

Flying with Finesse

One of my students suggested a book I'd never read, Henk Tennekes The Simple Science of Flight (MIT Press, 1996). My heart sank a little when he lent me his copy. "This is a book I'd like to write," I sighed.

Tennekes has the audacity to apply the basics of Aeronautical Engineering to all flying creatures, "from insects to jumbo jets." The discussion is clear and gentle. He puts all of the material together -- and I mean all of the material. For example, study The Great Gliding Diagram, which shows the polar curves for 10 flying objects: the cabbage white, the Gossamer Albatross, a typical sailplane, a swift (the bird, not the Globe-Temco beauty), a real albatross, a budgerigar, an ultralight, the Fokker Friendship, a pheasant, and the Boeing 747. You can compare the performance requirements directly, and there are many interesting consequences about wing loading, wing shape, power requirements, and the like.

Apparently the French call "L/D," the ratio of lift to drag, the finesse. I will now use this term forever. By the way, we owe the concept of the polar graph that shows vertical speed versus horizontal speed to another French engineer, Gustave Eiffel, of "Tour d'Eiffel" fame.

My current aeronautical thinking is that everything depends on two parameters: energy, which I wrote about in this post, and L/D, which I wrote about here. Those posts are just the beginning, of course, hence my idea to write a book explaining every maneuver and performance calculation in terms of these two.

But it would be a nerdy book, full of equations and tables. Tennekes does not shy away from equations (Stephen Hawking claims that every equation reduces the sales of a book by a factor of two), but his gentle prose and simple ink drawings really evoke the beauty of these simple ideas. Perhaps with Tennekes's inspiration I can write something with a little more finesse, too.

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At March 17, 2011 at 9:23 PM , Blogger Dale said...

Jim - Glad you are enjoying the book. I think your blog entry has finesse. - Dale


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