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The Concorde was an incredible achievement considering the time it was built and a very beautiful airplane. It was very fuel inefficient, both because at the ti

by _ph_ 10y ago

The Concorde was an incredible achievement considering the time it was built and a very beautiful airplane. It was very fuel inefficient, both because at the time of construction the oil crisis had not happened yet, and the limitations of jet engines back then. However, modern cheap air travel is mostly possible because modern jet engines are so much more efficient than their ancestors from the Concorde times. So it is very unfortunate, that the Concorde was built but that it did not trigger any iterations of the concept, just picking up all the advances in jet engine and body material construction.

trhway 10y ago
> It was very fuel inefficient my understanding is that Concorde engines are among the most efficient built to date - they had something like 70:1 compress ratio. It is juts the nature of high speed flying that you have to burn much more fuel. >modern jet engines are so much more efficient because of high-by-pass. Wouldn't work for supersonic. From https://en.wikipedia.org/wiki/Thrust_specific_fuel_consumption#Significance_of_SFC https://en.wikipedia.org/wiki/Thrust_specific_fuel_consumpti... : "For example, Concorde cruised at Mach 2.05 with its engines giving an SFC of 1.195 lb/(lbf·h) (see below); this is equivalent to an SFC of 0.51 lb/(lbf·h) for an aircraft flying at Mach 0.85, which would be better than even modern engines; the Olympus 593 was the world's most efficient jet engine.[2][3] However, Concorde ultimately has a heavier airframe and, due to being supersonic, is less aerodynamically efficient, i.e., the lift to drag ratio is far lower. In general the total fuel burn of a complete aircraft is of far more importance to the customer."
- WalterBright 10y ago
  I don't remember the exact figure, but the last episode of "Aviation Disasters" was on the Concorde, and mentioned that it burned a major amount of fuel just getting to the runway, and because the delta wing was very inefficient at low speeds, burned another big chunk of fuel just getting off the the ground.
  - cyberferret 10y ago
    It's a common bug bear of all aircraft with swept wings designed for supersonic flight. Terribly inneficient at take off/landing speeds. Which is why most military aircraft have to hook up to a tanker after take off to fill the tanks so they can continue on their mission. Concorde (and other passenger aircraft) don't have this luxury due to the risks involved, so I am thinking that most of the high cost of fuel vs passenger load that is being discussed in this thread is because of the voracious thirst that the plane has in the early stages. Most supersonic aircraft are quite efficient in the cruise stage. The Lockheed SR-71 for instance, derives a fair percentage of thrust just from the shape of the airframe, so the pilots actually throttle back a little once they reach Mach 2+!
    - cknight 10y ago
      It is interesting to hear the SR-71 was so efficient once it got going. Certainly when it was stationary it was possibly the least fuel efficient aircraft ever - its body was designed to leak fuel when on the tarmac. The hot airframe would, once in flight, expand to seal the gaps!
      - Inconel 10y ago
        The SR-71 was an interesting beast. I've read that due to the constant leaking while on the tarmac they would have to immediately rendezvous with a tanker to refuel after takeoff.
        cyberferret 10y ago
        I highly recommend you guys try and grab a copy of "Skunk Works" by Ben Rich which is a fantastic story about Kelly Johnson and the Lockheed facility that built the SR-71, U2 etc. Ben worked alongside Kelly, and said that the guy had an unerring knack for designing aircraft. Ben (an aerodynamics engineer) would spend days designing an intake, and Kelly would come along and take one look at it and say "That is 20% too big", and sure enough, when Ben went back over his calculations, he would find it to be about 18% oversized. Another great book is "Sled Driver" by Brian Shul - probably one of the best aviation books I've read (and I am a former pilot). Sadly, I believe both books are out of print now, but you may be able to find a copy somewhere second hand. I've seen "Sled Driver" on eBay for about $3000 from time to time!!
- _ph_ 10y ago
  Didn't know that it was that efficient - but I guess only when not using the afterburners. Still, if the efficiency of the engine could not be raised much, a modern construction could cut down other operation costs as weight and most importantly maintenance. Also, the whole airframe could be made lighter.
- parados 10y ago
  Some discussion here by the engineers and pilots that worked with the Olympus 593 on this very subject: https://paulross.github.io/pprune-concorde/docs/Olympus_5930.html https://paulross.github.io/pprune-concorde/docs/Olympus_5930... https://paulross.github.io/pprune-concorde/docs/Rolls_Royce0.html https://paulross.github.io/pprune-concorde/docs/Rolls_Royce0...
agumonkey 10y ago
There a british company that changed engines design to decouple front and back blades; 15% fuel savings, 70% noise reduction. Apparently the design is so appealing they expect them to be used next year.

by _ph_ 10y ago

trhway 10y ago

> It was very fuel inefficient my understanding is that Concorde engines are among the most efficient built to date - they had something like 70:1 compress ratio. It is juts the nature of high speed flying that you have to burn much more fuel. >modern jet engines are so much more efficient because of high-by-pass. Wouldn't work for supersonic. From https://en.wikipedia.org/wiki/Thrust_specific_fuel_consumption#Significance_of_SFC https://en.wikipedia.org/wiki/Thrust_specific_fuel_consumpti... : "For example, Concorde cruised at Mach 2.05 with its engines giving an SFC of 1.195 lb/(lbf·h) (see below); this is equivalent to an SFC of 0.51 lb/(lbf·h) for an aircraft flying at Mach 0.85, which would be better than even modern engines; the Olympus 593 was the world's most efficient jet engine.[2][3] However, Concorde ultimately has a heavier airframe and, due to being supersonic, is less aerodynamically efficient, i.e., the lift to drag ratio is far lower. In general the total fuel burn of a complete aircraft is of far more importance to the customer."

WalterBright 10y ago
I don't remember the exact figure, but the last episode of "Aviation Disasters" was on the Concorde, and mentioned that it burned a major amount of fuel just getting to the runway, and because the delta wing was very inefficient at low speeds, burned another big chunk of fuel just getting off the the ground.
- cyberferret 10y ago
  It's a common bug bear of all aircraft with swept wings designed for supersonic flight. Terribly inneficient at take off/landing speeds. Which is why most military aircraft have to hook up to a tanker after take off to fill the tanks so they can continue on their mission. Concorde (and other passenger aircraft) don't have this luxury due to the risks involved, so I am thinking that most of the high cost of fuel vs passenger load that is being discussed in this thread is because of the voracious thirst that the plane has in the early stages. Most supersonic aircraft are quite efficient in the cruise stage. The Lockheed SR-71 for instance, derives a fair percentage of thrust just from the shape of the airframe, so the pilots actually throttle back a little once they reach Mach 2+!
  - cknight 10y ago
    It is interesting to hear the SR-71 was so efficient once it got going. Certainly when it was stationary it was possibly the least fuel efficient aircraft ever - its body was designed to leak fuel when on the tarmac. The hot airframe would, once in flight, expand to seal the gaps!
    - Inconel 10y ago
      The SR-71 was an interesting beast. I've read that due to the constant leaking while on the tarmac they would have to immediately rendezvous with a tanker to refuel after takeoff.
      - cyberferret 10y ago
        I highly recommend you guys try and grab a copy of "Skunk Works" by Ben Rich which is a fantastic story about Kelly Johnson and the Lockheed facility that built the SR-71, U2 etc. Ben worked alongside Kelly, and said that the guy had an unerring knack for designing aircraft. Ben (an aerodynamics engineer) would spend days designing an intake, and Kelly would come along and take one look at it and say "That is 20% too big", and sure enough, when Ben went back over his calculations, he would find it to be about 18% oversized. Another great book is "Sled Driver" by Brian Shul - probably one of the best aviation books I've read (and I am a former pilot). Sadly, I believe both books are out of print now, but you may be able to find a copy somewhere second hand. I've seen "Sled Driver" on eBay for about $3000 from time to time!!
_ph_ 10y ago
Didn't know that it was that efficient - but I guess only when not using the afterburners. Still, if the efficiency of the engine could not be raised much, a modern construction could cut down other operation costs as weight and most importantly maintenance. Also, the whole airframe could be made lighter.
parados 10y ago
Some discussion here by the engineers and pilots that worked with the Olympus 593 on this very subject: https://paulross.github.io/pprune-concorde/docs/Olympus_5930.html https://paulross.github.io/pprune-concorde/docs/Olympus_5930... https://paulross.github.io/pprune-concorde/docs/Rolls_Royce0.html https://paulross.github.io/pprune-concorde/docs/Rolls_Royce0...

agumonkey 10y ago

There a british company that changed engines design to decouple front and back blades; 15% fuel savings, 70% noise reduction. Apparently the design is so appealing they expect them to be used next year.