Boomerang Book page 15


WARNING: Complicated Math Stuff Ahead! (Skip this part if math gives you a headache.) If it’s enough for you to just know that a boomerang creates lift the same way an airplane wing creates lift, great. You’ve got an idea about how boomerangs work. If that’s not enough for you, if you want to understand how a wing creates lift...well, that means you need to read lots of books by people much smarter than me. It means digging into the physics of aerodynamics, and it gets complicated. The common explanation of how a wing creates lift is based on something called the Bernoulli effect. A good example of this explanation is in The Way Things Work [Macaulay 1988].

	The cross-section of a wing has a shape called an airfoil. As the wing moves through the air, the air divides to pass around the wing. The airfoil is curved so that air passing above the wing moves faster than air passing beneath. Fast-moving air has a lower pressure than slow-moving air. The pressure of the air is therefore greater beneath the wing than above it. This difference in air pressure forces the wing upward. The force is called lift.

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Aerodynamics:
Even Einstein got it wrong!

Don’t feel bad if you have a hard time getting your head around explanations of aerodynamics.

It has confused some very smart people. Even Albert Einstein got it wrong. Before his E=MC2 days, he once tried to design a new wing shape, based on the commonly held principles of aerodynamics. It didn’t work.

Jšrgen Skogh wrote, “During the First World War Albert Einstein was for a time hired by the LVG (Luft-Verkehrs-Gesellshaft) as a consultant. At LVG he designed an airfoil with a pronounced mid-chord hump, an innovation intended to enhance lift.

The airfoil was tested in the Gšttingen wind tunnel and also on an actual aircraft and found, in both cases, to be a flop.” In 1954 Einstein wrote “Although it is probably true that the principle of flight can be most simply explained in this [Bernoullian] way it by no means is wise to construct a wing in such a manner!”

Skogh, Jšrgen. Einstein’s Folly and The Area of a Rectangle.


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