SR-71B Blackbird - wikipedia.org

I was flying last month to attend a graduation and it occurred to me that I was, in fact, flying in a large metal tub with metal flappy bits bolted on.  How do airplanes fly? Well, they have wings.  Duh! But why do wings fly?  What makes a wing a wing?  Can any flat sheet of metal be used?  Why do planes only fly when moving?  This is quite an interesting question indeed.  The answer is quite subtle – subtler than you may think.  It is in fact confusing enough that a lot of high school text books and a good chunk of introductory university physics textbooks explain it incorrectly.  You may have been taught the answer in high school and you have just accepted it without thinking too hard about it.  Read on if you wish to check if you were indeed taught correctly.

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