23 October 2008

Soaring, cryptography and nuclear weapons

By Martin Hellman

Let's face it, nuclear weapons are the elephant in the room that no one likes to talk about. So let's approach the issue from the less threatening perspective of the awesome picture of the glider.

The glider looks like it's suspended above the runway, but in reality it's screaming toward the photographer at over 200 kilometers an hour in a maneuver known as a high-speed low pass. The pilot starts about 2,000 feet (609 meters) high and over a kilometer from the runway. He then dives to convert altitude into speed and skims the runway. Next, he does a steep climb to reconvert some of that speed into altitude so he can turn and land.
Given that the glider has no engine, you might wonder how the pilot can be sure he'll gain enough altitude in the climb to safely turn and land. The laws of physics tell us exactly how altitude is traded for speed and vice versa. While there is a loss due to the air resistance of the glider, that is a known quantity which the pilot takes it into account by starting from a higher altitude than needed for the landing phase.

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