How planes fly: what really keeps them in the air
Equal transit time: the famous explanation of how wings lift is wrong
Many of us learned at school why planes fly: the air over the curved top of a wing has a longer path, so it must hurry to meet the air below. Wind tunnels tell a different story.
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1
Your friend Miva is the captain of your flight to the coast today. Your friend Rono is coming too, and he is afraid of flying. He wants to know what will hold this huge plane up.
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2
Rono opens his old textbook and reads the answer from school. The top of a wing is curved, so the way over it is longer. So the air that goes over the top must hurry, to meet the air that went under at the back. Faster air has lower pressure, and that pushes the wing up. This upward push is called lift.
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3
Engineers tested it in wind tunnels. They let out a row of smoke puffs, all at the same moment. The puffs over the top reached the back of the wing long before the puffs below. They never met again.
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4
And you can test it right here. You fold a paper plane from a flat page. Its wing has no longer side at all. Still, it glides all the way across the gate.
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5
Stunt planes even fly upside down, with the curved side of the wing at the bottom. If the longer path were the reason for lift, they could never fly like this.
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6
So the story has a name, equal transit time, and it is wrong. Something real still holds the plane up. Rono shuts his textbook. Boarding starts.
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Go further
Two names that go with the story.