Gulfstream X-54
The Gulfstream X-54 is a proposed research and demonstration aircraft, under development in the United States by Gulfstream Aerospace for NASA, that is planned for use in sonic boom and supersonic transport research. == Design == Initiated during 2008, the X-54 project is intended to produce an experimental aircraft capable of supersonic speeds with a formed sonic boom that is acoustically shaped to mitigate noise pollution.