“In order to make the market viable for supersonics you have to make it feasible to fly overland faster than sound – which is currently against the law. We don't think there is a viable market until you change that” Scott Neal, Gulfstream senior VP marketer.

The Gulfstream X-54 was a cancelled supersonic business jet connected to Gulfstream's "Sonic Whisper" program, using an extremely long nose called the "Quiet Spike" which enabled the bizjet to break the sound barrier without letting out a sonic boom.

It uses variable sweep wings to help it break the sound barrier and two Rolls-Royce Tay medium-bypass turbofans with a supersonic nacelle to enable the aircraft to fly at Mach 1.4, fairly slower than the competing Aerion SBJ.