Why does speed lose out to capacity?
Which means, roughly 5 times more passengers can be accommodated by compromising half of the top speed. So, why does speed loses out so much to capacity that it ultimately becomes unfeasible to operate a supersonic airliner?


I think you are asking, "why do supersonic aircraft have such low capacity"?

To travel faster than the speed of sound you need to have a very sharp nose and minimal area exposed to the forward direction, to minimize the generation of shockwaves. Shockwaves are bad for people on the ground (the 'sonic boom' effect) and they are terrible for fuel efficiency. Second you really do not want to trap air on flat surfaces facing forwards, because the air will get squashed in the supersonic flow and heat up a lot (like when you blow up a bicycle tyre or a football it is warm afterwards, or when the space shuttle re-enters the atmosphere). Again this is an enormous drag and having hot air flowing around your aircraft causes problems with the structure (Concorde used to grow by 300 mm during flight because of the heat).

Since you cannot be wide and you cannot be tall (without being aerodynamically inefficient), you need to be very long if you want lots of people. And then you have other problems.

The design and construction of Concorde was never a commercial project, it was funded by two governments almost as a vanity project, as a prototype or as an experiment. Then it was given for free to two airlines to use as they wanted.

So unlike the A380 and the B747, no one has ever said "now we try to maximize the economics and the capacity of our design": that never happened. All they ever asked was "How do we make this work!?"

Whereas the subsonic aircraft get a lot of time, money and thought spent on how to make them more economical to use by filling them with more passengers.

For more information I recommend this interview with a former Concorde pilot: http://omegataupodcast.net/2015/02/166-flying-the-concorde/


  Also, Concorde was developed 40 years ago. Are some more efficient supersonic Airliners possible today?


I am sure that these days a far more fuel efficient supersonic engine could be built for passenger operations. And I do believe there would be a market for it on say LON-NYC or even maybe LON-DXB. But designing supersonic aircraft is quite different to designing subsonic ones; and then you have all the difficulty of modern safety regulations without being able to demonstrate you are relying on old, proven designs; and then there are very few routes where it could work profitably so you have very high development and maintenance costs spread over a small number of airframes.

Basically, it isn't worth the risk to anyone to make it.