posted on May, 7 2013 @ 03:28 PM
NASA is moving towards their goal of flying the first "quiet sonic boom" aircraft by the end of the decade. This would prove windtunnel tests, and
would have the ultimate goal of the FAA removing the supersonic flight restriction over populated areas.
Both Boeing, and Lockheed Skunk Works are moving forward with designs for a Concorde sized airliner, that would have a sine waved shaped sonic boom on
the ground, with an 80 PLdB rating as opposed to 105 PLdB from the Concorde.
By altering the shape of the boom into a sine wave shape (through fuselage shaping and other techniques), people on the ground will hear a quiet
swoosh sound, as opposed to the double boom heard by the classic N shaped waves from the traditional sonic boom.
Phase 2 of the program will look at how inlets, exhaust, and other features affect the shockwave. Boeing has produced a 1.79% scale model for
windtunnel testing that is rather interesting looking.
NASA continues to make steady progress towards the possible launch of a low-boom supersonic demonstrator program* later this decade. This would
take boom-shaping techniques proved in the windtunnel and test them in the real world to gauge the public acceptance of shaped booms.
The goal is to reduce boom annoyance to a level where regulators can be persuaded to lift the ban on supersonic flight over land. Previous windtunnel
work has shown that careful shaping of the aircraft can get the sonic boom for a small supersonic airliner down to what NASA believes is the threshold
Under Phase 2 of the so-called N+2 system-level experimental validation program, Boeing and Lockheed Martin’s Skunk Works are continuing work on
small airliner concepts that are about the capacity and range of Concorde, but with dramatically quieter sonic booms – around 80 PLdB versus 105
And the shockwave signature observed on the ground would be more of a sine wave, resulting in a muted whoosh rather than the traditional double bang
generated by the classic N-wave boom signature, with its sharp pressure rises caused by the powerful bow and tail shocks.