Dr. Universe: How do planes fly? -Tahira, 12, India
Planes are very heavy, yet they stay up in the air kind of like a bird in the sky. They can get us across the world in less than a day. Humans went from learning how to fly a plane to putting a man on the moon in a little over 60 years.
But the answer to your question goes even further back. It goes all the way back to the 1700s and actually started not with air, but with water.
That’s what I found out from my friend Michael Allen, a physics and astronomy professor at Washington State University. He thought you asked a great question and was happy to tell me all about how planes can fly.
Around 300 years ago, a scientist from Switzerland named Daniel Bernoulli was experimenting with water pipes, like the ones under your sink at home. When water (or anything) moves through a small space, like the inside of a pipe, it puts pressure on that container (the pipe.)
The more air you push into a smaller space, the greater the pressure. Allen told me that Bernoulli found out that the faster the water moved through the pipe, the less pressure the water put on the pipe.
This idea has come to be known as Bernoulli’s Principle. This principle doesn’t only apply only to water, it also applies to air that passes over the wings on an airplane.
Allen told me that wings on an airplane are flat on the bottom and curved on the top. Allen said that as the wing moves through the air, some air goes over the top of the wing while some goes under the bottom of the wing.
However, the air that goes over the top of the wing has to go over a longer distance than the air under the wing because of the curve. Allen also said the air has to get past the wing at the same time, meaning the air above must travel faster, just like the water moving quickly in the pipe.
Since this air above the wings travel faster, there is less pressure above the wing than below the wing, which pushed the wings and the plan up into the air, causing the plane to fly.
Thanks for your question. It was a great one and I’m happy that you have such a big interest in airplanes. Have you ever thought about becoming a scientist or engineer that works on planes one day? Maybe you could make the next spacecraft that takes a person to the moon or Mars.
Ian Smay and Dr. Universe
Ianb Smay contributed this article. He is a student in the Edward R. Murrow College of Communication at Washington State University.