Since the Concorde was officially retired in 2003 mostly due to the excessive noise and operating costs of the machine (and not because of safety issues, as many still believe), supersonic flight has been sort of a taboo in the civil aviation circles. A number of startups and big players are increasingly rethinking the opportunity of crossing the Mach limit again, with interesting concept projects such as Lockheed-Martin’s new Quiet Supersonic Technology Airliner (QSTA). Based on the X-59 test project that Lockheed is currently building for Nasa, the QSTA would be larger (22m wingspan and 69m length) and have space for a single row of 40 seats. The “quiet” part of the name is what’s really important here, as many country in the past imposed limitation on flight speed of airliners over land to avoid the loud sonic-boom that would be generated by breaking the speed of sound. The X-59, and therefore the QSTA, despite being able to reach speeds of Mach 1.8, would be able to avoid the boom thanks to a design that prevent shockwaves from colliding, therefore creating just a  smaller and way more acceptable “sonic thump”.