Late in August 2003, a Northrop F-5E swept down a test range at Edwards Air Force Base, California, the same range where Chuck Yeager first broke the sound barrier more than 50 years earlier. As the airplane flew over the dry lake bed, it shook the ground with a resounding boom. Moments later, another F-5E flew the same course at the same speed, but with a vastly different result: The boom from the second flyover was hushed, dramatically quieter than the first. The flights were part of an experiment conducted by the Defense Advanced Research Projects Agency, NASA, and Northrop Grumman. By heavily modifying the shape of an F-5E, called the Shaped Sonic Boom Demonstrator, or SSBD, the three organizations surmised they could dampen the powerful sonic boom that normally accompanies supersonic flight. They were right. "We're going to fix the sound barrier that Chuck Yeager broke," says Roy Martin, a Northrop Grumman test pilot who flew the F-5E demonstrator.
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