> The reason for that is that the concorde used afterburners (basically, pump fuel into the high speed exhaust for extra thrust) which are incredibly inefficient.

Concorde didn't use afterburners "at speed". The afterburners were used for takeoff, and to go through the mach wall.

Concorde burned insane amounts of fuel on the ground because turbojets are very inefficient at low-speed. Not unlike the SR-71's really (though the SR-71 also had such extreme high-speed bypass it was basically using ramjets at speed).

I never said anything about concorde using afterburners "at speed"/in cruise flight. But the mere use of afterburners in the early stages accounted for an extraordinary amount of fuel consumption.

Didn't SR-71's also leak fuel when on the ground?

Yes but that's a separate concern. The engines were not efficient at slow speed / ground levels even ignoring the "leaks until it gets hot enough to seal the pipes" issue, the blackbird was designed to hit peak efficiency above Mach 3 (generally speaking all jets are designed to hit peak efficiency at their cruising speed, and the blackbird was designed for a cruising altitude of mach 3.2).

That's only because they decided to not use tanks inside the wings. The wings themselves contained the fuel. You can certainly build a non leaking SR-71 if a higher weight is acceptable.

> That's only because they decided to not use tanks inside the wings.

It's not only that. It's because they didn't have alloys which would handle the thermal constraints without significant expansion, so they had to design for that expansion. And in the same way rail tracks handle expansion by leaving gaps, that's what they did.

Furthermore, due to limited room and systems able to handle the temperature gradients, the fuel acted not just as fuel but also coolant, heat sink and even hydraulic fluid for some propulsion components (e.g. the afterburner nozzles and inlet guide vanes used JP7 as hydraulic fluid).

Expected fuel burn per passenger is minimum 3x a ‘normal’ business class seat on a modern plane: https://theicct.org/news/reviving-supersonic-flight-signific...

Either way, it’s fairly obscene.

While fuel cost is minor part of total flight cost (most is staff + depreciation), I wonder how much will be saved by a good satellite network. Being able to work on a plane at some point starts to pay itself off.

Fuel costs accounted for 23.7% of airline operating expenses in 2019 [1], I think that's more than a minor part - especially if you triple it.

1: https://www.iata.org/contentassets/ebdba50e57194019930d72722...

Concorde itself could have been much more efficient, there were plans for a "Concorde B" with high-bypass engines that would have carried a larger payload with additional range at higher efficiency.

https://www.heritageconcorde.com/concorde-b

The Mk622 engine was still a turbojet, albeit improved. Primarily its gains came from a more efficient compressor, providing more oxygen to the combustion chamber.

Warning: That page contains a background animation that cannot be disabled, even when disabling page styles. I had to open it in W3M, which I'm glad I did as it was very informative.

Running this in the browser console worked for me:

  $('video').remove()

(There aren't any other video elements.)

The Concorde B was a bandaid on a massive gaping wound.

Concorde had afterburners, but only used them for take-off and breaking through Mach 1. And they were optional for both.

> The reason for that is that the concorde used afterburners (basically, pump fuel into the high speed exhaust for extra thrust) which are incredibly inefficient.

To put things in perspective, Concorde was using two Olympus engines designed originally in the 50s.

It was already a marvel that they can run for such a range at Mach 2.0 when designed 70 years ago.

A lot of things improved since. Most fighter jets can supercruise at supersonic speed without afterburners nowadays.

Concorde used four engines. Two engine ETOPS over water wasn't a thing back then, first real relaxation of that rule was in '76.

see: https://en.wikipedia.org/wiki/ETOPS

Of course four. My apologies, too quick to type.