New designs, however, are pioneering so-called low-boom technology. For this reason, Concorde only flew routes that were largely over water. This means that in most countries, routine supersonic flight is banned over land, severely limiting the potential routes of a civilian supersonic plane. In some cases these booms can cause damage to buildings and supersonic military jets flying over land have even been known to break windows. An approaching supersonic aircraft is inaudible, but when it crosses the observer, they get hit by a sudden, boom-like sound of concentrated sound waves that is quite uncomfortable. This leads to its soundwaves trailing behind the aircraft in a cone-like shape, similar to the waves trailing behind a boat. When an aeroplane goes supersonic, however, it moves ahead of the sound it produces. If they were visible to the naked eye, these waves would look similar to what happens when a stone is dropped in a pond, with little waves spreading in concentric circles.
When an immobile object, such as a stereo, produces sound, its sound waves spread in all directions. One important boost behind the resurgence of civilian supersonic aircraft is that they could produce less noise and reduce the problem of a sonic boom. ‘This is not just a dream anymore,’ said Professor Nicole Viola of the Polytechnic University of Torino in Italy, where she works on supersonic airliners. And Aerion, in cooperation with Boeing, is developing a supersonic business jet, which could fly by 2025. NASA has pioneered the X-59, an experimental supersonic aircraft that lowers noise levels of the infamous sonic boom. The US company Boom wants to fly a scale model of its supersonic airliner, called the Overture, in 2021, and has already raised $196 million to do it. New technological advances allow designs to succeed where Concorde failed and a range of companies and research institutes are heavily investing in a new generation of civilian supersonic aircraft. Now, however, almost 20 years later, we might be returning to that supersonic dream. The futuristic dream of a three-hour flight between London and New York, that Concorde offered, seemed shattered. Since then no commercial supersonic airliners have operated – the regulatory, technological and commercial problems being too much to overcome. On that day Concorde, the legendary supersonic airliner, made its final commercial flight, flying from London Heathrow to New York City’s John F.