The sonic boom really isn't an issue as long as you can fly that part of the route over the sea. Concorde often took longer routes to avoid flying over land, and it was still quicker than a more direct subsonic flight. Or you just fly supersonic over countries you don't care about - flights from London to Bahrain would fly supersonic from the Adriatic Sea crossing the Middle East over land to Bahrain.
The Bahrain route is interesting, as today it is 5.5 hours and Concorde was 4 hours, so not that much difference. I'd rather spend an extra hour and a half on a much more comfortable and bigger aircraft. They also tried routes to Singapore (stopping in Bahrain to refuel), the total flight time was 9 hours, compared to non-stop flights today which are 13 hours. I wonder if developments in reducing the time subsonic aircraft take to reach and descend from cruising altitude could narrow that gap even further.
For power/intensity ratio, 10dB is 10x; for amplitude ratio, 20dB is 10x.
Loudness is typically measured by "sound pressure level" (dB SPL), which uses the latter (amplitude ratio).
Also, it's worth pointing out that while sound perception (like almost all the perceptions people have, Stevens's power law [1]) is logarithmic, its base isn't exactly 10 or 100. [2] claims that every 20dB (10x) in SPL, the perceived loudness is 4x.
Here's an example: https://www.silentium.com/technology-2/quiet-at-the-source/
I’m curious if either shielding the engines, or having a scramjet (like a turbofan but without the blades) could have a similar effect.
I would imagine drag increases linearly or exponentially with speed - not as a step function once you cross the sound barrier.
Or are you saying because it's going to be flying twice as fast?
https://en.wikipedia.org/wiki/Drag-divergence_Mach_number#:~....
[Increasing Mach Number] can cause the drag coefficient to rise to more than ten times its low-speed value.
I only know this because of a number of fluid-dynamics courses that are only required for Mechanical and Aeronautical engineering majors. Barely anyone else is expected to know this information. Mach numbers represent fluid-flow discontinuities. If there is fluid flow in a varying inner-diameter tube and there is a Mach number change from <1 -> >1 at any point in the tube, as long as the Mach discontinuity is there, fluid flow characteristics before and after the discontinuity are decoupled from each other, they no longer influence each other if the Mach discontinuity is present.
I'm super interested to see how quiet their planes are at subsonic. If you ever saw the Concorde flying subsonic, it was unbelievably loud. Nothing to do with being supersonic - their engines were just obnoxiously loud. Came into Cape Town a long time ago and made the whole town rumble on final.
In this blog post: https://blog.boomsupersonic.com/booms-principles-of-sustaina...
..Boom says: "Today’s subsonic commercial aircraft are 80% more fuel efficient than those of the 1960s, and noise footprints have shrunk up to 90% in the last 50 years. This technological progress has fueled Boom’s efforts to design a supersonic airliner that makes economic sense for airlines and their customers. "
However, the innovation that enabled this is high bypass turbofan engines. Turns out if you move more air slower, it's way quieter and more fuel efficient because physics. Boom can't take advantage of this - at least directly, because they have to go supersonic. A high bypass turbofan engine is huge, by it's very nature. At supersonic speeds this presents a lot of drag. That's why I'm super curious how they plan to be quiet and fuel efficient while also being supersonic.