[credit_guy]

It’s not a matter of physics.

All things being equal, it takes a lot more energy to slice through the air at Mach 2 than at Mach 0.85. But all things are not equal: Concorde flew about twice as high as regular subsonic planes. At that altitude, the air is about half as dense, so it takes less energy to move it out of the way.

In the end what matters is the lift to drag ratio and the speed ratio. In cruise mode, a regular commercial jet has a L/D ratio of about 17, and Concorde of 7 [1], i.e. about 2.4 lower. So each minute it spends cruising, Concorde will burn 2.4 times more fuel than a subsonic jet of equal mass. But Concorde flies faster, so it spends less time to cover the same distance. How much less? About 2/0.85 = 2.35. In other words, to cover the same distance Concorde burns about the same amount of fuel as a subsonic jet, while in cruise mode. Concorde’s fuel economy was horrible at takeoff though due to a triple whammy: L/D ratio of only 4, need to use the (very inefficient) afterburners, and the tyranny of the rocket equation.

But if someone can solve these issues, there is nothing that prevents a supersonic to be as fuel efficient as a subsonic jet.

[1] https://en.wikipedia.org/wiki/Lift-to-drag_ratio#Supersonic/...

[throwaway00127]

>It’s not a matter of physics.

It is, and you're misunderstanding some of the basics of supersonic flight.

"As speeds approach the speed of sound, the additional phenomenon of wave drag appears. This is a powerful form of drag that begins at transonic speeds (around Mach 0.88). Around Mach 1, the peak coefficient of drag is four times that of subsonic drag. Above the transonic range, the coefficient drops drastically again, although remains 20% higher by Mach 2.5 than at subsonic speeds. Supersonic aircraft must have considerably more power than subsonic aircraft require to overcome this wave drag, and although cruising performance above transonic speed is more efficient, it is still less efficient than flying subsonically."[1]

Factoring in that supersonic airplanes are significantly heavier, have lower L/D, must spend more fuel getting to higher altitudes, still have to fly subsonic a considerable amount of the flight time/path, etc. means that it's a matter of physics.

[1] https://en.m.wikipedia.org/wiki/Supersonic_transport

[credit_guy]

A few lines down in your link you have this: "At about Mach 2, a typical wing design will cut its L/D ratio in half (e.g., Concorde managed a ratio of 7.14, whereas the subsonic Boeing 747 has an L/D ratio of 17)".

Sure, at trans-sonic speeds the coefficient of drag is horrible, but a supersonic commercial jet doesn't spend more than the minimum time necessary in that speed range.

What's more, improvements are possible even for the trans-sonic range. The planned Concorde B was projected to have dramatic fuel consumption improvement of 25% at Mach 1.2 [1]. This projection was made around 1980. In the 40 years since, computers have advanced a bit, so there's a chance the Boom guys know what they are talking about.

[1] http://www.concordesst.com/concordeb.html

[throwaway00127]

>A few lines down in your link you have this: "At about Mach 2, a typical wing design will cut its L/D ratio in half (e.g., Concorde managed a ratio of 7.14, whereas the subsonic Boeing 747 has an L/D ratio of 17)".

That is literally proving my point. Thanks for agreeing with me?

>Sure, at trans-sonic speeds the coefficient of drag is horrible, but a supersonic commercial jet doesn't spend more than the minimum time necessary in that speed range.

And the wave drag is still bad even at supersonic speeds. The planes still have to spend a significant amount of time subsonic (take off, approach, landing, etc.) even if it's minimalized, it's still a significant amount.

>What's more, improvements are possible even for the trans-sonic range. The planned Concorde B was projected to have dramatic fuel consumption improvement of 25% at Mach 1.2 [1].

Still worse than subsonic at that time. Since then, subsonic, high bypass engine design has made that gap even wider.

So still, no, it's a matter of physics.