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Even if the noise problem has been fixed, supersonic travel has another huge problem: Fuel consumption. Concorde positively guzzled fuel compared to the jets of
by BorgHunter 10y ago
Even if the noise problem has been fixed, supersonic travel has another huge problem: Fuel consumption. Concorde positively guzzled fuel compared to the jets of its day, and this (among other things) made it uneconomical to operate. The authors of this article never even touched this topic. Has it improved considerably?
- lmm 10y agoConcorde was more-or-less viable for BA (though not for AF). Specialized maintenance for such a small fleet (because it effectively only operated the transatlantic route due to regulations) was the thing that killed it economically.
- mikeash 10y agoIt was viable in that it broke even on its running costs, but towards the end it wouldn't have covered the cost of actually acquiring the aircraft, nor any major expenditures such as upgrades required for safety or compatibility with newer systems. Concorde used to serve a lot more than just the NYC-London/Paris route. It used to serve Bahrain, Rio de Janeiro, Dakar, Caracas, Washington DC, Miami, and Mexico City. Those faded away due to a lack of demand. (Ignoring Dallas and Singapore, as those failed due to restrictions on supersonic flight.) I'm sure a new design could be a lot more economical. Of course, regular airliners have become a lot more economical as well, so it's a tougher bar to clear.
- CaptainZapp 10y agoConcorde was more-or-less viable for BA (though not for AF). Can you elaborate, or direct me to a source? I'm genuinly interested.
- lmm 10y agoThere was an extended forum thread (on pretty much all aspects of Concorde - went on for tens or hundreds of pages) that was linked from here once - afraid I don't have it to hand.
- aterris 10y agoIf this thread is anywhere, I would bet its on flyertalk (awesome air travel forum with great info).
- xioxox 10y agoMaybe this one: http://www.pprune.org/tech-log/423988-concorde-question.html http://www.pprune.org/tech-log/423988-concorde-question.html
- CaptainZapp 10y agoVery interesting. Thank you very much.
- barisser 10y agoYou're right; let's go nuclear: https://en.wikipedia.org/wiki/Nuclear-powered_aircraft https://en.wikipedia.org/wiki/Nuclear-powered_aircraft
- baldfat 10y agoI actually would think that could be done "safely". No sarcasm. I am expecting that if fusion ever becomes a reality we will go with electric motors which will certainly always be sub-sonic.
- zwily 10y ago> electric motors which will certainly always be sub-sonic Why is that?
- skykooler 10y agoElectric motors have a top speed which is governed by the forces generated by induction. At higher speeds they spend more and more torque countering those forces. Contrast this with turbines, where a higher inlet speed translates into a higher output speed - the amount of energy a turbine uses to keep itself spinning is constant rather than proportional to airspeed. This is why electric motors would have issues flying at high speeds.
- sliverstorm 10y agoCan you not simply use overdrive gearing to keep motor speed down?
- kabdib 10y ago... or spin the motor with another motor. It could be motors all the way down . . .
- marcosdumay 10y ago
- fred_is_fred 10y agoThe market can figure that out. If the noise problem is solved (I can't read the article because it says I need to sign in), then allow it and let the airlines decide if they can make money doing it.
- PKop 10y agoClick the "web" link above, under the article title. Sometimes you need to use an incognito window, but not always.
- Reason077 10y agoIt's not so much the cost of fuel that is a concern, but the environmental impact. Unlike power generation and ground transport, global emissions from aviation are increasing rapidly at a time of growing concern about climate change. While increased speed is nice if it can be done efficiently, innovation in aviation needs to remain focused on improving efficiency.
- adrianN 10y agoBanning a particular form of transportation seems a poor method for reducing emissions. Just tax the fuel properly and it will sort itself out. Flying is currently much too cheap compared to its environmental impact imho. How can it be cheaper to fly from Berlin to Munich than taking the car (or the train)?
- codecamper 10y ago"tax it properly" Define properly. We are afraid of possible feedback loops destabilizing ice sheets much earlier than predicted? Maybe the price should be 5x what it current is? If emitting CO2 causes unknown massive harm, then it seems sane to figure out a CO2 neutral method to create these liquid fuels that jets require. That would seem very expensive, with current technology.
- adrianN 10y ago
- vermontdevil 10y agohttp://www.nasa.gov/press-release/nasa-begins-work-to-build-a-quieter-supersonic-passenger-jet http://www.nasa.gov/press-release/nasa-begins-work-to-build-... NASA is working on this - both the sound and the fuel use.
- thearn4 10y agoIn fact, x-plane development is going to be funded by NASA Aeronautics for the production of a number of next-gen flight demonstrators, included a supersonic low-boom demonstrator. Truss-braced wing configuration, hybrid-electric and all-electric are among the other contenders.
- lujim 10y agoSubsonic flight is cutting through cheese with a sharp knife. Supersonic flight is cutting through cheese with a hammer. There is no way it will ever be commercially economical with gas turbine engines and afterburners. Even super cruise without afterburners is incredibly inefficient and has very few uses outside of tactical aviation.
- thescriptkiddie 10y agoDrag in supersonic flight is not nearly as big an issue as you would think. The Concorde was inefficient mostly because it used afterburning turbojets that had poor efficiency at low speed. https://en.wikipedia.org/wiki/File:Qualitive_variation_of_cd_with_mach_number.png https://en.wikipedia.org/wiki/File:Qualitive_variation_of_cd...
- lujim 10y agoThat is coefficient of drag. You have to remember that goes into the drag equation which includes velocity squared. force_of_drag = .5 * mass_density * (velocity^2) * coefficient_drag * area. As that coefficient starts tapering off after transonic drag decreases velocity squared is there to ramp up the drag.
- mchouza 10y agoThat's true, but supersonic planes also travel higher (Concorde -> 18 km, XB-70 -> 22 km). The real problem is that L/D decreases at supersonic speeds. For example, the XB-70 had a L/D of about 7, while the 707 had a L/D over 18...
- Gravityloss 10y agoAs lift is also proportional to density, area and square of velocity, that whole term cancels out from the equation of fuel usage per distance, basically only L/D or cL/cD matters. In practice it might be a bit more complicated. EDIT: indeed here we can see that Concorde had lift to drag ratio of only 7.5 at Mach 2, while Boeing 747 has 17.7 at Mach 0.9 or so. https://en.wikipedia.org/wiki/Lift-to-drag_ratio https://en.wikipedia.org/wiki/Lift-to-drag_ratio
- xlm1717 10y agoThe article does touch on how newer designs could reduce sonic booms by making lighter aircraft. If a new supersonic jet is manufactured that is a fraction of the weight of a Concorde, it could be much more fuel efficient as well.
- ElijahLynn 10y agoThe article does mention that the size of the aircraft affects the size of the boom.
- _ph_ 10y agoThe Concorde had never been optimized for fuel consumption. Even for a jet of its time, it was quite wasteful of fuel. I once was told by someone who had some insight into Boing, that they had a much more efficient supersonic airliner in development in the competition to the Concorde, when the project was cancelled. So yes, supersonic airplanes would use more fuel than subsonic ones, but how much we can't know until someone builds a modern supersonic aircraft.
- JshWright 10y ago> but how much we can't know until someone builds a modern supersonic aircraft. You really think modern aircraft manufacturers are surprised by the fuel consumption (or any other performance characteristic) of their aircraft prior to them actually being built?
- _ph_ 10y agoOh, by the time they start to assemble physical parts they of course know exactly the performance figures, but that is pretty close to the end of the design process. Only after the design process you know these and I don't know how much of that is being done now.
- ghaff 10y agoThat's true but there's enough history of supersonic aircraft design that it's not really much of a mystery what the general numbers are going to look like given speed, range, capacity, etc. targets. Sure, the designers won't know at a detailed level until they actually design the aircraft to some degree. But it's pretty much a certainty that they have (at a minimum) a back of the envelope idea of how things will look.
- elidourado 10y agoYes, the Concorde actually flew with afterburners, which are notoriously fuel-inefficient. Modern engines can do Mach 2.2 without afterburners.
- rleigh 10y agoThis was only for take off and acceleration through the trans-sonic regime. It certainly didn't use them for super-cruise at Mach 2; at this speed the engines were operating at their peak efficiency.
- peteri 10y agoAt supersonic cruise (M2) Concorde used fuel at the same rate as a Jumbo, a quick google search reveals this: "BA said a 747 cost $100,000 to fly each way across the atlantic in wages, fuel, maintenace etc, before fixed costs. At the same time Concorde was costing $120,000". Having read in the past the various Concorde threads on pprune.org, one view was that it was killed of by Airbus who didn't want to keep on supporting it as the manufacturer so helped get rid of the certificate of airworthiness. see this url http://www.concorde-spirit-tours.com/concorde.htm http://www.concorde-spirit-tours.com/concorde.htm for at least one view.
- goodcanadian 10y agoThe 747 carries ~450 passengers. The Concorde carried ~100. So, the Concorde is 4.5 times worse on a per capita basis. EDIT: Actually, ~5.4 times worse if you take into account the 1.2x difference in cost.
- ulfw 10y agoBritish Airways' 747-400 carry between 275 and 345 passengers, depending on configuration. But still. Similar in principle :) http://www.britishairways.com/en-gb/information/about-ba/fleet-facts/boeing747-400 http://www.britishairways.com/en-gb/information/about-ba/fle...
- goodcanadian 10y agoDepends on the airline, I suppose. Air Canada used to fly 747-100s with 400 seats: http://www.aircanada.com/en/about/fleet/historical/b747-100.html http://www.aircanada.com/en/about/fleet/historical/b747-100....
- Roboprog 10y agoIf you are concerned about fuel consumption you are probably not sufficiently wealthy. You probably even drive a Corolla or a Civic instead of a nice Hummer :-)
- jhayward 10y agoGaz guzzling is not a foregone conclusion. For instance, recall that the SR-71 actually got better fuel mileage the faster it flew, due to insightful use of the energy found in the compression wave.