Tuesday, June 16, 2009

Bernoulli's Principle: Or Why Planes Don't Fall Out Of The Sky

Thanks to things like Facebook and Twitter, several friends have made their aversion to air turbulence known over the last few days. Turbulence is no fun, but it's part of air travel, especially if you're going over the Rocky Mountains. Many years of flying back and forth to San Francisco from the East Coast taught me how to determine how much longer we had until landing based on how the plane shook over Colorado.

On commercial airlines turbulence is unsettling, but mild. If you're going through a storm and it's really bumpy, someone will inevitably pull out a rosary. I've known people who flew military planes and described the turbulence they had to deal with like, "Being tossed about like a pebble in a tin can." And then they still had to complete a mission! In case you didn't know, the U.S. Military also doesn't serve peanuts during flights. Savages!

We all know, at least fundamentally, that planes don't just fall out of the sky. (Well, unless you're on Air France) Turbulence is just speed bumps, waves on an ocean, if you will. Planes stay up thanks to a concept called Bernoulli's Principle, which can be better understood in the short video below.

Here is a longer video from roughly the late 1960s that explains flight in greater detail. Good stuff all around.

This is likely the first and last physics lesson you will ever see on this blog. Now no morning belly aching about turbulence, OK?