NASA Aims to Quiet Sonic Booms

On Oct. 14, 1947, Chuck Yeager flew into aviation history by piloting a Bell XS-1 research plane to supersonic speeds of more than 700 mph. These days, NASA is flying unmanned aircrafts at Mach 10 velocity.

A sonic boom is created by shock waves that form on the front and rear of the aircraft flying faster than the speed of sound. The boom loudness is related to the strength of the shock waves. Supersonic flights over land generally is prohibited because of annoyances caused by the loud booms.

Now, NASA is concluding a series of flight tests to measure shock waves generated by an F-15 jet, in an effort to validate computer models that could be used in designing quieter supersonic aircraft.

The Lift and Nozzle Change Effects on Tail Shock, or Lancets, project aims to enable the developmental of commercial aircraft that can fly faster than the speed of sound without the loud sonic booms.

During the flight tests at NASA’s Dryden Flight Research Center in Edwards, Calif., one of two F-15s generally followed 100 feet to 500 feet below and behind the other, measuring the strength of the leading aircraft’s shock waves at various distances with special instruments. Global Positioning System relative positioning was used to guide the pilot of the probing aircraft to the test position and for accurate reporting of measurement locations.

A second NASA F-15B was the probing aircraft. It was fitted with a special nose spike for taking shock strength measurements.

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One Response

  1. From my understanding of sonic booms, the annoyance factor of a sonic boom can be greatly reduced if the time of the overpressure rise is made longer. This has the effect of reducing its loudness, especially for those where sonic booms are over land.

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