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NASA To Test 'Quiet' Supersonic Flights Over Texas (cnn.com)
NASA announced it will publicly demonstrate a quiet supersonic aircraft near the coastal resort city of Galveston, Texas, to ensure that its prototype really will be barely audible when it crosses the sound barrier. CNN reports: If NASA's experimental project -- formerly known as the X-plane or "Low-Flight Flight Demonstrator" but recently renamed X-59 QueSST -- works, it should help make supersonic flight more economical. From November, NASA will use supersonic F/A-18 Hornet jets over Galveston to mimic the sonic profile of the X-59 while a group of around 500 residents document the noise levels -- if there are any. By performing dives at the speed of sound, the jets will produce two types of sonic boom in order to truly determine the sound they produce on the ground.
According to NASA, Galveston was chosen as the testing area as it's located near the Gulf of Mexico, allowing the fighter jets keep louder sonic booms out to sea, while hurling quieter sonic "thumps" into the city. The secret to the plane's noise-reducing ability is its uniquely shaped structure, designed so that supersonic shockwaves don't build up into powerful sonic booms.
According to NASA, Galveston was chosen as the testing area as it's located near the Gulf of Mexico, allowing the fighter jets keep louder sonic booms out to sea, while hurling quieter sonic "thumps" into the city. The secret to the plane's noise-reducing ability is its uniquely shaped structure, designed so that supersonic shockwaves don't build up into powerful sonic booms.
You should read the articles. They give some more insight.
Looks like the modified F/A-18 are able to produce the needed effect only performing dives, not in normal straight flight. They are anyway modified fighters, and the modification looks quite expensive it's common for a prototype to cost way more than the final product it's being used to test).
The final object will allow testing in straight flight and pose basis for further development towards applying the technology to actual transportation airplanes, which are much bigger than a fighter jet and cost relatively less.
I'd add that it looks like this technology requires costs to be cut down also using economies of scale, which, past history proves, is difficult for supersonic flights, since most people don't actually need such fast transfers. The few that actually need them can pay the premium. Most probably it will be applied to corporate jets and specialised military transports before big airliners.
That's not exactly a fair comparison. A 1970's era subsonic airliner would use a lot more fuel than the 787 as well.
This report puts Concorde per passenger fuel consumption at about twice a 707, four times a contemporary 747, essentially the same as a business jet and a lot better than a train.
One of the reasons why Concorde was so expensive was that there were only a few built, to fly very specific routes that were mostly over water, and even so, there were generally fairly long subsonic legs at the beginning and end. Those are expensive because supersonic aircraft tend to drink fuel when flying subsonic, and if you have to do it at the end of your flight you have to carry all that extra fuel all the way.
Opening up more routes to supersonic aircraft would make them a LOT more economical. Barring some groundbreaking innovation, supersonic would still be more expensive than subsonic, but not by nearly as much as the Concorde was.