What If?: Serious Scientific Answers to Absurd Hypothetical Questions by Randall Munroe

Author:Randall Munroe [Munroe, Randall]
Language: eng
Format: epub, azw3
Tags: Humor, Form, Trivia, Science, Physics, General
Publisher: Houghton Mifflin Harcourt
Published: 2014-09-02T05:00:00+00:00

To act as a parachute, a balloon filled with air—rather than helium—would have to be 10 to 20 meters across, far too big to be inflated with portable tanks. A powerful fan could be used to fill it with ambient air, but at that point, you may as well just use a parachute.

Helium

The helium makes things easier.

It doesn’t take too many helium balloons to lift a person. In 1982, Larry Walters flew across Los Angeles in a lawn chair lifted by weather balloons, eventually reaching several miles in altitude. After passing through LAX airspace, he descended by shooting some of the balloons with a pellet gun.

On landing, Walters was arrested, although the authorities had some trouble figuring out what to charge him with. At the time, an FAA safety inspector told the New York Times, “We know he broke some part of the Federal Aviation Act, and as soon as we decide which part it is, some type of charge will be filed.”

A relatively small helium balloon—certainly smaller than a parachute—will suffice to slow your fall, but it still has to be huge by party balloon standards. The biggest consumer rental helium tanks are about 250 cubic feet, and you would need to empty at least ten of them to put enough air in the balloon to support your weight.

You’d have to do it quickly. Compressed helium cylinders are smooth and often quite heavy, which means they have a high terminal velocity. You’ll have only a few minutes to use up all the cylinders. (As soon as you emptied one, you could drop it.)

You can’t get around this problem by moving your starting point higher. As we learned from the steak incident, since the upper atmosphere is pretty thin, anything dropped from the stratosphere or higher will accelerate to very high speeds until it hits the lower atmosphere, then fall slowly the rest of the way. This is true of everything from small meteors1 to Felix Baumgartner.

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