Quiet Spike

Quiet Spike was a collaborative program between Gulfstream Aerospace and NASA's Dryden Flight Research Center to investigate the suppression of sonic booms. The patent was published with the United States Patent and Trademark Office in 2004 and is owned by Gulfstream Aerospace.

The program was intended to develop technology that may allow next generation supersonic transports to overfly populated areas at above Mach 1 (1225.0 km/h) without the high intensity of sonic boom that proved problematic for first generation supersonic transports such as Concorde (c.f. Operation Bongo).

The boom caused by Concorde generated substantial public opposition in the United States and eventually in other countries around the world with airspace the aircraft was supposed to fly through. This opposition made it impossible for Concorde to be a commercial success. The sonic boom issue was also a significant factor in the eventual cancellation of the Boeing 2707.

Shock waves develop around aircraft as they near Mach 1 (1225.0 km/h). At ground level, these are perceived as a loud double boom or bang. Their intensity varies due to factors such as weather, refraction from different layers of atmospheric density, and size of the aircraft, but in general, from a supersonic aircraft of the size of a civilian airliner, the overpressure created at ground level is enough to rattle windows.

For example, the sonic boom from the Concorde traveling at a speed of Mach 2 (2450 km/h) was about 9.76 kg/m² (2.00 lb/sq ft)

Because of sonic boom intensity, many countries now prohibit supersonic overflight over land or population centres. The FAA prohibits supersonic flight over land, except in special military flight corridors. The Quiet Spike is able to suppress sonic booms a little, but a Quiet Spike alone isn't effective enough to circumvent the current ban on supersonic overflight.

Various structural approaches have been proposed to mitigate sonic booms, mainly focusing around changes to aircraft noses, the use of chines, changes in aircraft planform and even creating pathways through the aircraft structure to mitigate parasitic drag that leads to shock waves.

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