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The numbers in the table comparing these aircraft aren't consistent with each other. Each line of the table expresses the same underlying idea: fuel per passenger-distance. Therefore on each line, the ratio of the number in the left- and right-hand columns should be the same (or the inverse of that ratio in the 3rd line). But they aren't. There's something wrong here but I don't know what. Macboff ( talk) 16:57, 15 January 2013 (UTC)
(This discussion is moved here from a user-talk page, to be more than a two-person discussion):
Hello, thank you for your contributions to the Fuel economy in aircraft#Example Values section. Albeit enlightening, the car and buses comparisons do generate problems :
An apples to apples comparison with only aircrafts would be easier to maintain and expand. I would put a comparison table in the generic Fuel efficiency article between modes at a whole : air transport / rail / marine / car ... If that's okay with you I will transfer it later today. -- Marc Lacoste ( talk) 09:09, 17 July 2014 (UTC)
Marc, I think our discussion is best moved to the article's talk page. First, I really like the way you have broken the big table down into a series of smaller ones based on haul-length each model is intended for. Also, putting the comparison to other modes in sentence-form below the tables makes good sense.
Regarding the French study (I missed that link before), I don't read French so can't utilize that. What kind of trips (distance) are its pax load factors for? Is the data just for France, or is it EU wide, and do you know if comparable data is available for the US for long-distance highway travel? Concerning speed, I continue to think that is an issue apart from the topic of the article and table. If speed were relevant here, there is another angle to that. It is well-established through social research that travelers' sense of distance tends to be time dependent, with faster modes of transit leading to longer trips that are possible within personal time available. Thus in terms of fuel efficiency per holiday (instead of per mile), you can see where this perspective would lead. So, I suggest leaving speed out of this discussion, and leaving the focus of the article on the capabilities of the hardware.
The tables give both a sense of average aircraft performance as well as that of the current champion (Boeing 787). So, as I previously suggested, show the average auto (configured arbitrarily as a four-seater) and the Prius as the champion. Readers can do the simple arithmetic concerning their personal load factors to trips of comparable distance to the table data for the appropriate travel distance. The point is not to favor one mode of travel over another, but to provide perspective on what do these aircraft data mean. I am adding the average auto data to the concluding sentence, in hopes that this will help. Coastwise ( talk) 20:08, 18 July 2014 (UTC)
The last column, fuel-efficiency per seat, gives metric L/km, but then gives English-units as mpg. (And if using mpg, it should be seat-miles per gallon.) The metric versions should be converted to km/L (so that high numbers mean high efficiency). Less clear, though, would be changing the column-name: while "fuel efficiency per seat" makes good intuitive sense at first, it doesn't match the unit-analysis, which is confusing. Should the title be "seat-fuel efficiency", or is that too unclear? — Preceding unsigned comment added by Not-just-yeti ( talk • contribs) 16:05, 22 April 2016 (UTC)
Where are the MC-21-200/300/400 jets? Where is the Comac C919? Where is the Sukhoi 130? Where is the Comac ARJ21? Where is the Mitsubishi MRJ 70/90? Where is the Embraer ERJ 135/140/145? — Preceding unsigned comment added by 2601:44:4200:1AB8:3444:C699:3A6F:E6CA ( talk) 10:46, 15 December 2015 (UTC)
In this expression, referring to flight above Mach 0.85: "Above that speed, air begins to become incompressible"
That's backwards, it should read as compressible, not incompressible. — Preceding unsigned comment added by 173.247.202.130 ( talk) 18:11, 17 December 2015 (UTC)
I find the tables to be mind-numbing in the amount of data presented, and have come to realize that much of the difficulty with them is the limited sorting capability of the table framework. However, if instead the following static sort is used, all of a sudden it all makes sense. Sort the list first by distance, and within each band of distance then sort by seat capacity. Apart from choice of aircraft, these are the factors that mainly affect economy. When the lists are sorted this way (I tried it in a spreadsheet), all of a sudden the data makes a LOT of sense instead of being a blizzard.
By static sort, I mean that sorting would be hard wired. Since it would be a double sort (distance and seat configuration), sorting by clicking the header would just mess things up, and it would not be possible to get back to the original sort.
I also advocate dropping the Fuel Burn column (lb/km) since the column to the right of it is the more important information for lay readers. It would also be good to add a column at the far right, Fuel Used Per Pax. (i.e. liters and gallons for the trip). The addition of this column is part of the reason that with the above manual sorting, the data finally speaks clearly. With this and the new sorting, the relationship of aircraft, distance and seating configuration to fuel economy becomes immediately apparent. Redoing the tables would be a lot of work, but I could help with it.
An alternative way to clearly show these relationships would be to combine all tables into one, sorted by aircraft model and seating configuration. There would be columns for each distance in the existing columns, with each of those cells holding the fuel burned (liters & gallons) for the trip. An accompanying table could be similar, but with l/100-km in the cells. However, these tables would likely be too wide for a web page. Coastwise ( talk) 10:08, 16 February 2016 (UTC)
I tried to illustrate the article which was quite dry before. The main picture still is problematic : it shows more contrails than fuel consumption. I tried to change it for a refuelling picture, but user:Ahunt put it back rightfully it's not illustrating very well the subject either, and the plane isn't identifiable for sure. But illustrating aircraft fuel consumption is hard: fuel burn is invisible! Better contrails pictures could be used :
But contrails are misleading, as they didn't show fuel burn. It could be more metaphorical :
Any ideas? -- Marc Lacoste ( talk) 07:59, 12 December 2016 (UTC)
Not too far from transparent exhaust, high BP modern airliners? The first NASA convair seems the most striking. -- Marc Lacoste ( talk) 06:43, 13 December 2016 (UTC)
Our efforts to select a good, illustrative pic are noted : it was used to illustrate an article in Aviation Week's BCA : Simulators Help Cut Emissions By Reducing Real-Time Training (pic only in the newsletter, the article is behind a paywall). This isn't the first time AvWeek uses a wikimedia picture, and I'm glad it's the case.-- Marc Lacoste ( talk) 16:01, 29 September 2017 (UTC)
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Marc, here is why I have undone your reversion to my edit that "jets have a cruise speed about 40 percent higher than" the fastest 1950s piston powered airliners. While you cite the L-1649 Constellation as having "250kts" cruise speed, several models cruised faster than that, and the L-749 had a cruise speed of 345 kts. The DC-7 had a cruise speed of 359 kts. Additionally, although some airliners have a maximum cruise speed of your cited 0.85 Mach, an operational cruise speed of 0.78 to 0.80 (515 to 529 kts) is common, due to fuel cost. Using those Mach-related speeds and the L-749 and DC-7 cruise speeds, jets commonly are operated at speeds in the range of 37% to 41% greater than those aircraft. Coastwise ( talk) 09:04, 1 February 2017 (UTC)
Another consideration is the Republic Rainbow (XF-12 / RC-2), which was a highly advanced late WW-II photo-recon plane, for which an airliner variant was intended. It never reached production for reasons explained in the WP article; however, the military version had a cruise speed of 363 kts, and the airliner was expected to have a cruise of 393 kts for which jets commonly cruise only 24-26% faster. That shows the relative potential piston aircraft would have had in terms of speed. For the aerodynamic and cooling/exhaust advances described in the article, it is likely that this aircraft would have been more fuel efficient than its contemporaries as well as current airliners; but I have seen no data. Without data this isn't for the article, but is a point to think about - particularly since structural advances of recent decades of course were not implemented. Coastwise ( talk) 09:04, 1 February 2017 (UTC)
Marc, I have reverted your recent edit to what I had previously ('Nonetheless, jets cruise 40-80% faster than their predecessors'), which paraphrases a direct statement in a reference we have both used (Peeters et al. 2005). The reason you provided with your edit was, "I saw this too, but as detailed in the talk page, it's comparing the speed of the less efficient DC7, not the L1049 with comparable efficiency". This amounts to substituting your own judgment in place of a clear statement by the source, "serv[ing] to reach or imply a conclusion not stated by the sources" ( WP:OR), and with a substantial upward rounding that is not "almost". Contrary to your reasoning, the 40-80% is not specific to the model you stated, but obviously to a range of aircraft. The four piston aircraft models referenced in Peeters et al. (2005) are tightly grouped in the paper's charts in terms of energy consumed per available seat kilometer (ASK), at a low level in relation to the curve for improvement in jet fuel consumption over the years. This tight grouping is more clearly shown in Fig 13.1 of Peeters et al. (2009), "Technical and Management Reduction Potentials", in: Gossling & Upham, "Climate change and aviation: Issues, challenges and solutions". Peeters et al.(2005)'s "40-80%" covers the relative speed of this well-performing group of aircraft in relation to the first sentence of the subject paragraph in the WP article. Coastwise ( talk) 23:53, 9 February 2017 (UTC)
In twice reverting my recent edits, Marc LaCoste said in the respective reverts: (1) "reverted to pre 13 march rev : please provide detailed edit summaries for each change, thanks"; and (2) "if it's impossible to detail the changes, present them in the talk page per WP:EPTALK".
Below I will walk through the changes, and to folllow along open three browser tabs with the following content: A. The track changes; B. The original text; and C. My edits of 3/12.
The edits are listed by paragraph, in the order they occur on the track-changes page.
1. The intro paragraph is reworded and has some additional info.
2. The next changed paragraph (beginning "Each model of aircraft ... ) is reworded.
3. The next changed paragraph (beginning "Aircraft weight ...") is reworded.
4. The next changed paragraph (beginning "Flight altitude ...") is reworded and includes merges the paragraph that followed it in the original article.
5. The next series of changes merge the sections "Changes in commercial aircraft fuel economy since the 1950" and "Jet aircraft efficiency", and add information resulting in addtional information and subsections.
6. An intro paragraph was added to the section "Changes in commercial aircraft fuel economy since the 1950", foretelling topics of fuel economy from the individual aircraft model and the fleet perspectives; the latter is a new subtopic.
7. The content under the newly added subheading "The individual aircraft perspective" is the original topic, with edits. The photo was changed from the Comet to the B707 to match the thrust of the discussions in the document cited in both versions.
8. An original paragraph beginning "Today's turboprop airliners ..." was inadvertently lost in the editing and should be worked in somewhere.
9. Next encountered is the old heading "Jet aircraft efficiency". As mentioned above, the content was merged into the section being dicussed so the heading does not exist in the new version.
10. The heading "The aircraft fleet perspective" is added as a new topic. The old content to the left has been worked into to the sections on efficiencies of individual aircraft or the fleet, as appropriate.
11. Information on the Concorde was left out but if considered important could be added somewhere, in the subsection on individual aircraft. Information in the same paragraph on the A380, B747-400ER and B777-300ER is confusing in its detail and too focused on one part of the spectrum of airliners. It seems better left to the material in the tables at the end of the article, or if replaced in the section discussed here needs editing to be concise and demonstrate an important, broad point. As it is, I believe it detracts.
12. The added material about fleet fuel economy continues for a few more paragraphs in the track changes.
13. A subsection is added, "The effect of operations on fleet fuel economy", with underlying sections on tankering and operational factors.
14. Next a structural change was made, adding a major heading "==Technologies for improving fuel economy==", under which the original section on "Weight effect" follows, but renamed "===Weight reduction===" (i.e. as a technological matter).
15. Next, the subsection "====Aerodynamics====" was renamed "===Other technology potentials===" because it includes propulsion as well as aerodynamics. The section on "Fuel consumption factors" is renamed "Operational potentials", as a better description of the content and because fuel consumption factors are well discussed elsewhere in the article. The actual content of these sections was not changed.
16. No changes were made to the balance of the article. Follow three "Next Edit" entries in the track changes for minor edits and references corrections that I made minutes after posting the edit described here. Coastwise ( talk) 05:30, 17 March 2017 (UTC)
I'm afraid this new section gives too much coverage to the Peeters 2005 reference and doesn't fairly represent all significant viewpoints that have been published by reliable sources, in proportion to the prominence of each viewpoint in the published, reliable sources. Its main point is to remind post WW2 piston airliners were already very efficient, that the early jetliners were a step back and the mainstream idea that jetliner efficiency is growing is concealing that earlier technology was already efficient, in counterpoint to ICCT view. I think this as a counterpoint is a good thing and is noted "#Jet aircraft efficiency". But this new section is mainly paraphrasing multiple times the same idea, and as such renders the article as a difficult read in addition to giving it too much coverage. It also eludes the fact that jet airliners took over because they make more sense economically, as they replaced brand new piston airliners in less than a decade. I thus removed this sectin, which could be reinstated if it is resumed to one paragraph.-- Marc Lacoste ( talk) 13:40, 26 March 2017 (UTC)
As the article structure isn't very clear and doesn't facilitate its reading, I propose an updated layout based on 3 main sections :
I've done a draft in User:Marc Lacoste/sandbox/Fuel economy in aircraft, with the same material and additions for flight theory-- Marc Lacoste ( talk) 08:30, 28 March 2017 (UTC)
Marc, I think most of your reorganization is good, and I had been thinking along a similar line. Here are my thoughts on taking it a step further and addressing a still on-going matter:
1. Rename the "Aircraft" section, "Basic physics of flight efficiency"
2. Rename the "Aerodynamics" section, "Aerodynamics and speed" and move the "Speed" section to there. Both are the same topic.
3. Rename the "Range" section, "The effect of flight distance". Most people likely think of range as a maximum for a particular aircraft, whereas flight distance is a variable among routes or city pairs (e.g. affected by necessary fuel load) and is what is represented in the chart.
4. Move the "Altitude" section to be a subsection under "Propulsive efficiency". They are parts of the same topic.
5. Delete the "Airlines" section, as being far too detailed. This material is covered in your series of tables at the end of the article, and in a different, appropriately general way in material I cover next.
6. Rename the "History" section, "Efficiency of airliners and fleets", and replace the "Past" subsection with my sections that you have been deleting. (This "Efficiency ..." heading would also replace the "...1950s" heading at the top of those sections of mine.)
7. Move the "Operations" section to be a subsection at the end of that "Efficiency ..." section. Coastwise ( talk) 08:17, 4 April 2017 (UTC)
{{
cite web}}
: CS1 maint: date format (
link){{
cite web}}
: CS1 maint: date format (
link){{
cite web}}
: CS1 maint: date format (
link)-- Marc Lacoste ( talk) 10:06, 11 April 2017 (UTC)
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The current statement "The maximum range speed is when the ratio between velocity and drag is minimal, while maximum endurance is attained at the best lift/drag ratio." is obviously incorrect: it doesn't account for the engine efficiency. A classic example is Concorde, which was more efficient at M2 despite higher overall drag. Moreover, maximum endurance in the plain (not airline-specific) sense is attained simply at the minimum (absolute) fuel burn where the aircraft is still flyable.
But going into more details here may overload the section, and the correct effects are mentioned elsewhere. How to rephrase it at keep brief? Sergey Khantsis ( talk) 23:59, 22 February 2018 (UTC)
The Climate Change section seems to me to be referenced but off topic. Users expecting to read about fuel economy do not expect to read about Climate Change. Does every wikipedia aticle that talks about any sort of fuel usage now require a Climate Change section? My vote is to remove this section. Climate Change and Air Transport can be discussed somewhere else. — Preceding unsigned comment added by Trustdays ( talk • contribs) 02:43, 20 October 2018 (UTC)
Fuel burn is referencing the present source: https://leehamnews.com/2014/02/03/updating-the-a380-the-prospect-of-a-neo-version-and-whats-involved/ however, this is inaccurate due to a typo. Please see "leehamnet" comment on February 4, 2014:
"Thanks for the interest in the analysis and for checking our figures. We have re-checked everything and indeed the 777-9X trip fuel burn is incorrect. Our model was fine, it was rather a fault when the table was made. The 777-9X trip fuel was taken as 120.5t, should have been 102.5t. Here the correct values for the 777-9X:
– Trip fuel tonnes: 102.5
– Fuel cost per seat mile: $ 0.041 – Fuel per seat and 100km: 2.42 l – Fuel consumption per seat: 74,0%.
Another fault which has been spotted is the LD3 positions for A380 and 748, shall be 38.
The changed figures for the 777-9X does not change the conclusions but it does make a A380neo more pressing come 2020." — Preceding unsigned comment added by 81.170.80.115 ( talk) 19:24, 27 January 2020 (UTC)
How about the fuel economy of cargo aircraft, specifically fuel per kg of payload? Jsekamane ( talk) 09:34, 23 April 2020 (UTC)
I have for a long time wondered about the fuelburn numbers. In widebodies usually the passengerwheight is less than the bellyfreight. To only give fuelburn per seat is false. Seniorsag ( talk) 14:40, 3 June 2020 (UTC)
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The numbers in the table comparing these aircraft aren't consistent with each other. Each line of the table expresses the same underlying idea: fuel per passenger-distance. Therefore on each line, the ratio of the number in the left- and right-hand columns should be the same (or the inverse of that ratio in the 3rd line). But they aren't. There's something wrong here but I don't know what. Macboff ( talk) 16:57, 15 January 2013 (UTC)
(This discussion is moved here from a user-talk page, to be more than a two-person discussion):
Hello, thank you for your contributions to the Fuel economy in aircraft#Example Values section. Albeit enlightening, the car and buses comparisons do generate problems :
An apples to apples comparison with only aircrafts would be easier to maintain and expand. I would put a comparison table in the generic Fuel efficiency article between modes at a whole : air transport / rail / marine / car ... If that's okay with you I will transfer it later today. -- Marc Lacoste ( talk) 09:09, 17 July 2014 (UTC)
Marc, I think our discussion is best moved to the article's talk page. First, I really like the way you have broken the big table down into a series of smaller ones based on haul-length each model is intended for. Also, putting the comparison to other modes in sentence-form below the tables makes good sense.
Regarding the French study (I missed that link before), I don't read French so can't utilize that. What kind of trips (distance) are its pax load factors for? Is the data just for France, or is it EU wide, and do you know if comparable data is available for the US for long-distance highway travel? Concerning speed, I continue to think that is an issue apart from the topic of the article and table. If speed were relevant here, there is another angle to that. It is well-established through social research that travelers' sense of distance tends to be time dependent, with faster modes of transit leading to longer trips that are possible within personal time available. Thus in terms of fuel efficiency per holiday (instead of per mile), you can see where this perspective would lead. So, I suggest leaving speed out of this discussion, and leaving the focus of the article on the capabilities of the hardware.
The tables give both a sense of average aircraft performance as well as that of the current champion (Boeing 787). So, as I previously suggested, show the average auto (configured arbitrarily as a four-seater) and the Prius as the champion. Readers can do the simple arithmetic concerning their personal load factors to trips of comparable distance to the table data for the appropriate travel distance. The point is not to favor one mode of travel over another, but to provide perspective on what do these aircraft data mean. I am adding the average auto data to the concluding sentence, in hopes that this will help. Coastwise ( talk) 20:08, 18 July 2014 (UTC)
The last column, fuel-efficiency per seat, gives metric L/km, but then gives English-units as mpg. (And if using mpg, it should be seat-miles per gallon.) The metric versions should be converted to km/L (so that high numbers mean high efficiency). Less clear, though, would be changing the column-name: while "fuel efficiency per seat" makes good intuitive sense at first, it doesn't match the unit-analysis, which is confusing. Should the title be "seat-fuel efficiency", or is that too unclear? — Preceding unsigned comment added by Not-just-yeti ( talk • contribs) 16:05, 22 April 2016 (UTC)
Where are the MC-21-200/300/400 jets? Where is the Comac C919? Where is the Sukhoi 130? Where is the Comac ARJ21? Where is the Mitsubishi MRJ 70/90? Where is the Embraer ERJ 135/140/145? — Preceding unsigned comment added by 2601:44:4200:1AB8:3444:C699:3A6F:E6CA ( talk) 10:46, 15 December 2015 (UTC)
In this expression, referring to flight above Mach 0.85: "Above that speed, air begins to become incompressible"
That's backwards, it should read as compressible, not incompressible. — Preceding unsigned comment added by 173.247.202.130 ( talk) 18:11, 17 December 2015 (UTC)
I find the tables to be mind-numbing in the amount of data presented, and have come to realize that much of the difficulty with them is the limited sorting capability of the table framework. However, if instead the following static sort is used, all of a sudden it all makes sense. Sort the list first by distance, and within each band of distance then sort by seat capacity. Apart from choice of aircraft, these are the factors that mainly affect economy. When the lists are sorted this way (I tried it in a spreadsheet), all of a sudden the data makes a LOT of sense instead of being a blizzard.
By static sort, I mean that sorting would be hard wired. Since it would be a double sort (distance and seat configuration), sorting by clicking the header would just mess things up, and it would not be possible to get back to the original sort.
I also advocate dropping the Fuel Burn column (lb/km) since the column to the right of it is the more important information for lay readers. It would also be good to add a column at the far right, Fuel Used Per Pax. (i.e. liters and gallons for the trip). The addition of this column is part of the reason that with the above manual sorting, the data finally speaks clearly. With this and the new sorting, the relationship of aircraft, distance and seating configuration to fuel economy becomes immediately apparent. Redoing the tables would be a lot of work, but I could help with it.
An alternative way to clearly show these relationships would be to combine all tables into one, sorted by aircraft model and seating configuration. There would be columns for each distance in the existing columns, with each of those cells holding the fuel burned (liters & gallons) for the trip. An accompanying table could be similar, but with l/100-km in the cells. However, these tables would likely be too wide for a web page. Coastwise ( talk) 10:08, 16 February 2016 (UTC)
I tried to illustrate the article which was quite dry before. The main picture still is problematic : it shows more contrails than fuel consumption. I tried to change it for a refuelling picture, but user:Ahunt put it back rightfully it's not illustrating very well the subject either, and the plane isn't identifiable for sure. But illustrating aircraft fuel consumption is hard: fuel burn is invisible! Better contrails pictures could be used :
But contrails are misleading, as they didn't show fuel burn. It could be more metaphorical :
Any ideas? -- Marc Lacoste ( talk) 07:59, 12 December 2016 (UTC)
Not too far from transparent exhaust, high BP modern airliners? The first NASA convair seems the most striking. -- Marc Lacoste ( talk) 06:43, 13 December 2016 (UTC)
Our efforts to select a good, illustrative pic are noted : it was used to illustrate an article in Aviation Week's BCA : Simulators Help Cut Emissions By Reducing Real-Time Training (pic only in the newsletter, the article is behind a paywall). This isn't the first time AvWeek uses a wikimedia picture, and I'm glad it's the case.-- Marc Lacoste ( talk) 16:01, 29 September 2017 (UTC)
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Marc, here is why I have undone your reversion to my edit that "jets have a cruise speed about 40 percent higher than" the fastest 1950s piston powered airliners. While you cite the L-1649 Constellation as having "250kts" cruise speed, several models cruised faster than that, and the L-749 had a cruise speed of 345 kts. The DC-7 had a cruise speed of 359 kts. Additionally, although some airliners have a maximum cruise speed of your cited 0.85 Mach, an operational cruise speed of 0.78 to 0.80 (515 to 529 kts) is common, due to fuel cost. Using those Mach-related speeds and the L-749 and DC-7 cruise speeds, jets commonly are operated at speeds in the range of 37% to 41% greater than those aircraft. Coastwise ( talk) 09:04, 1 February 2017 (UTC)
Another consideration is the Republic Rainbow (XF-12 / RC-2), which was a highly advanced late WW-II photo-recon plane, for which an airliner variant was intended. It never reached production for reasons explained in the WP article; however, the military version had a cruise speed of 363 kts, and the airliner was expected to have a cruise of 393 kts for which jets commonly cruise only 24-26% faster. That shows the relative potential piston aircraft would have had in terms of speed. For the aerodynamic and cooling/exhaust advances described in the article, it is likely that this aircraft would have been more fuel efficient than its contemporaries as well as current airliners; but I have seen no data. Without data this isn't for the article, but is a point to think about - particularly since structural advances of recent decades of course were not implemented. Coastwise ( talk) 09:04, 1 February 2017 (UTC)
Marc, I have reverted your recent edit to what I had previously ('Nonetheless, jets cruise 40-80% faster than their predecessors'), which paraphrases a direct statement in a reference we have both used (Peeters et al. 2005). The reason you provided with your edit was, "I saw this too, but as detailed in the talk page, it's comparing the speed of the less efficient DC7, not the L1049 with comparable efficiency". This amounts to substituting your own judgment in place of a clear statement by the source, "serv[ing] to reach or imply a conclusion not stated by the sources" ( WP:OR), and with a substantial upward rounding that is not "almost". Contrary to your reasoning, the 40-80% is not specific to the model you stated, but obviously to a range of aircraft. The four piston aircraft models referenced in Peeters et al. (2005) are tightly grouped in the paper's charts in terms of energy consumed per available seat kilometer (ASK), at a low level in relation to the curve for improvement in jet fuel consumption over the years. This tight grouping is more clearly shown in Fig 13.1 of Peeters et al. (2009), "Technical and Management Reduction Potentials", in: Gossling & Upham, "Climate change and aviation: Issues, challenges and solutions". Peeters et al.(2005)'s "40-80%" covers the relative speed of this well-performing group of aircraft in relation to the first sentence of the subject paragraph in the WP article. Coastwise ( talk) 23:53, 9 February 2017 (UTC)
In twice reverting my recent edits, Marc LaCoste said in the respective reverts: (1) "reverted to pre 13 march rev : please provide detailed edit summaries for each change, thanks"; and (2) "if it's impossible to detail the changes, present them in the talk page per WP:EPTALK".
Below I will walk through the changes, and to folllow along open three browser tabs with the following content: A. The track changes; B. The original text; and C. My edits of 3/12.
The edits are listed by paragraph, in the order they occur on the track-changes page.
1. The intro paragraph is reworded and has some additional info.
2. The next changed paragraph (beginning "Each model of aircraft ... ) is reworded.
3. The next changed paragraph (beginning "Aircraft weight ...") is reworded.
4. The next changed paragraph (beginning "Flight altitude ...") is reworded and includes merges the paragraph that followed it in the original article.
5. The next series of changes merge the sections "Changes in commercial aircraft fuel economy since the 1950" and "Jet aircraft efficiency", and add information resulting in addtional information and subsections.
6. An intro paragraph was added to the section "Changes in commercial aircraft fuel economy since the 1950", foretelling topics of fuel economy from the individual aircraft model and the fleet perspectives; the latter is a new subtopic.
7. The content under the newly added subheading "The individual aircraft perspective" is the original topic, with edits. The photo was changed from the Comet to the B707 to match the thrust of the discussions in the document cited in both versions.
8. An original paragraph beginning "Today's turboprop airliners ..." was inadvertently lost in the editing and should be worked in somewhere.
9. Next encountered is the old heading "Jet aircraft efficiency". As mentioned above, the content was merged into the section being dicussed so the heading does not exist in the new version.
10. The heading "The aircraft fleet perspective" is added as a new topic. The old content to the left has been worked into to the sections on efficiencies of individual aircraft or the fleet, as appropriate.
11. Information on the Concorde was left out but if considered important could be added somewhere, in the subsection on individual aircraft. Information in the same paragraph on the A380, B747-400ER and B777-300ER is confusing in its detail and too focused on one part of the spectrum of airliners. It seems better left to the material in the tables at the end of the article, or if replaced in the section discussed here needs editing to be concise and demonstrate an important, broad point. As it is, I believe it detracts.
12. The added material about fleet fuel economy continues for a few more paragraphs in the track changes.
13. A subsection is added, "The effect of operations on fleet fuel economy", with underlying sections on tankering and operational factors.
14. Next a structural change was made, adding a major heading "==Technologies for improving fuel economy==", under which the original section on "Weight effect" follows, but renamed "===Weight reduction===" (i.e. as a technological matter).
15. Next, the subsection "====Aerodynamics====" was renamed "===Other technology potentials===" because it includes propulsion as well as aerodynamics. The section on "Fuel consumption factors" is renamed "Operational potentials", as a better description of the content and because fuel consumption factors are well discussed elsewhere in the article. The actual content of these sections was not changed.
16. No changes were made to the balance of the article. Follow three "Next Edit" entries in the track changes for minor edits and references corrections that I made minutes after posting the edit described here. Coastwise ( talk) 05:30, 17 March 2017 (UTC)
I'm afraid this new section gives too much coverage to the Peeters 2005 reference and doesn't fairly represent all significant viewpoints that have been published by reliable sources, in proportion to the prominence of each viewpoint in the published, reliable sources. Its main point is to remind post WW2 piston airliners were already very efficient, that the early jetliners were a step back and the mainstream idea that jetliner efficiency is growing is concealing that earlier technology was already efficient, in counterpoint to ICCT view. I think this as a counterpoint is a good thing and is noted "#Jet aircraft efficiency". But this new section is mainly paraphrasing multiple times the same idea, and as such renders the article as a difficult read in addition to giving it too much coverage. It also eludes the fact that jet airliners took over because they make more sense economically, as they replaced brand new piston airliners in less than a decade. I thus removed this sectin, which could be reinstated if it is resumed to one paragraph.-- Marc Lacoste ( talk) 13:40, 26 March 2017 (UTC)
As the article structure isn't very clear and doesn't facilitate its reading, I propose an updated layout based on 3 main sections :
I've done a draft in User:Marc Lacoste/sandbox/Fuel economy in aircraft, with the same material and additions for flight theory-- Marc Lacoste ( talk) 08:30, 28 March 2017 (UTC)
Marc, I think most of your reorganization is good, and I had been thinking along a similar line. Here are my thoughts on taking it a step further and addressing a still on-going matter:
1. Rename the "Aircraft" section, "Basic physics of flight efficiency"
2. Rename the "Aerodynamics" section, "Aerodynamics and speed" and move the "Speed" section to there. Both are the same topic.
3. Rename the "Range" section, "The effect of flight distance". Most people likely think of range as a maximum for a particular aircraft, whereas flight distance is a variable among routes or city pairs (e.g. affected by necessary fuel load) and is what is represented in the chart.
4. Move the "Altitude" section to be a subsection under "Propulsive efficiency". They are parts of the same topic.
5. Delete the "Airlines" section, as being far too detailed. This material is covered in your series of tables at the end of the article, and in a different, appropriately general way in material I cover next.
6. Rename the "History" section, "Efficiency of airliners and fleets", and replace the "Past" subsection with my sections that you have been deleting. (This "Efficiency ..." heading would also replace the "...1950s" heading at the top of those sections of mine.)
7. Move the "Operations" section to be a subsection at the end of that "Efficiency ..." section. Coastwise ( talk) 08:17, 4 April 2017 (UTC)
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link)-- Marc Lacoste ( talk) 10:06, 11 April 2017 (UTC)
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The current statement "The maximum range speed is when the ratio between velocity and drag is minimal, while maximum endurance is attained at the best lift/drag ratio." is obviously incorrect: it doesn't account for the engine efficiency. A classic example is Concorde, which was more efficient at M2 despite higher overall drag. Moreover, maximum endurance in the plain (not airline-specific) sense is attained simply at the minimum (absolute) fuel burn where the aircraft is still flyable.
But going into more details here may overload the section, and the correct effects are mentioned elsewhere. How to rephrase it at keep brief? Sergey Khantsis ( talk) 23:59, 22 February 2018 (UTC)
The Climate Change section seems to me to be referenced but off topic. Users expecting to read about fuel economy do not expect to read about Climate Change. Does every wikipedia aticle that talks about any sort of fuel usage now require a Climate Change section? My vote is to remove this section. Climate Change and Air Transport can be discussed somewhere else. — Preceding unsigned comment added by Trustdays ( talk • contribs) 02:43, 20 October 2018 (UTC)
Fuel burn is referencing the present source: https://leehamnews.com/2014/02/03/updating-the-a380-the-prospect-of-a-neo-version-and-whats-involved/ however, this is inaccurate due to a typo. Please see "leehamnet" comment on February 4, 2014:
"Thanks for the interest in the analysis and for checking our figures. We have re-checked everything and indeed the 777-9X trip fuel burn is incorrect. Our model was fine, it was rather a fault when the table was made. The 777-9X trip fuel was taken as 120.5t, should have been 102.5t. Here the correct values for the 777-9X:
– Trip fuel tonnes: 102.5
– Fuel cost per seat mile: $ 0.041 – Fuel per seat and 100km: 2.42 l – Fuel consumption per seat: 74,0%.
Another fault which has been spotted is the LD3 positions for A380 and 748, shall be 38.
The changed figures for the 777-9X does not change the conclusions but it does make a A380neo more pressing come 2020." — Preceding unsigned comment added by 81.170.80.115 ( talk) 19:24, 27 January 2020 (UTC)
How about the fuel economy of cargo aircraft, specifically fuel per kg of payload? Jsekamane ( talk) 09:34, 23 April 2020 (UTC)
I have for a long time wondered about the fuelburn numbers. In widebodies usually the passengerwheight is less than the bellyfreight. To only give fuelburn per seat is false. Seniorsag ( talk) 14:40, 3 June 2020 (UTC)