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MD-11 Fuel Burn Lower That The 777-200  
User currently offlineEjaymd11 From United States of America, joined Feb 2001, 193 posts, RR: 0
Posted (12 years 7 months 1 week 1 day 18 hours ago) and read 9936 times:

The numbers are for the standard version.

Under these conditions fuel burn for the MD-11 standard version is as follows.
Mach .84
Temp -30
TAS 477.2
T/O weight max (602,500)
Range 4,500 (I used the range chart I found on Boeing)
Flight time would be 9:25:48
Burn 27,435.9 ponds per hour

I used a flight calculator to get the TAS, flight time, and FPH. I know the MD-11's cruise Mach is around Mach .83 but I was told I should even the playing field.

Under these conditions fuel burn for the 777-200 standard version is as follows.
Mach .84
Temp -30
TAS 477.2
T/O weight max (545,000)
Range 3,300 nm (I used the range chart I found on Boeing)
Flight time would be 6:54:55
Burn 30,034.9 ponds per hour

I used a flight calculator to get the TAS, flight time, and FPH.

Are my numbers correct if not let me know where I messed up.

Ejay MD-11

Let me know if you need the charts

25 replies: All unread, showing first 25:
 
User currently offlineLuisca From , joined Dec 1969, posts, RR:
Reply 1, posted (12 years 7 months 1 week 1 day 16 hours ago) and read 9721 times:

what are u smoking... the fuel burn of a 777 is around 12000 pounds per hour as to my knowledge. correct me if I am wrong.

User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 2, posted (12 years 7 months 1 week 1 day 16 hours ago) and read 9694 times:

T/O weight max (545,000)
Range 3,300 nm


Way, way off.

And work in metric Smile


User currently offlineMr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 22
Reply 3, posted (12 years 7 months 1 week 1 day 14 hours ago) and read 9633 times:

The B777 burns an average of 7 tons an hour.


Boeing747 万岁!
User currently offlineBlatantEcho From United States of America, joined Sep 2000, 1922 posts, RR: 1
Reply 4, posted (12 years 7 months 1 week 1 day 13 hours ago) and read 9580 times:

7 tons = 14,000 lbs and hour for you math wizzes.

unfortunetly, Ejay MD-11, I think your numbers, range, fuel burn are pretty far off to allow for any good calculations of fuel burn.

Maybe someone else will have good numbers for you.

BlatantEcho



They're not handing trophies out today
User currently offlineFDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 34
Reply 5, posted (12 years 7 months 1 week 1 day 12 hours ago) and read 9542 times:

The MGTOW for an MD11F is 630,500lbs.


You're only as good as your last departure.
User currently offlineEjaymd11 From United States of America, joined Feb 2001, 193 posts, RR: 0
Reply 6, posted (12 years 7 months 1 week 1 day 11 hours ago) and read 9514 times:

Okay you wish the 777-200 burned 12,000 ponds an hour. My info comes from Boeing check it out. The take off weight of the standard MD-11 is 602,500 lbs. One more thing before you say the info do your research and tell me why my numbers are wrong.

For the 777-200
http://www.boeing.com/assocproducts/aircompat/777sec3.pdf

For the MD-11
http://www.boeing.com/assocproducts/aircompat/11-3-0.pdf

Ejay


User currently offlineBen88 From United States of America, joined Dec 1999, 1093 posts, RR: 2
Reply 7, posted (12 years 7 months 1 week 1 day 11 hours ago) and read 9491 times:

Your numbers are way off. You're telling me the 777 burns 15 tons an hour? LOL that's more than our 747-400's burn at M.85. Get your figures straight before posting messages.

User currently offlineDelta737 From United States of America, joined Jun 1999, 516 posts, RR: 11
Reply 8, posted (12 years 7 months 1 week 1 day 11 hours ago) and read 9489 times:

I wouldn't get too wrapped up in interpolating information from the Boeing website. You may also have to convert your temperature into ISA and then look at an actual performance chart.

I really don't think engine performance is all that linear.

I'm not sure what the 777 and MD-11 burn per hour, but I'm sure it's not that much by far.

That would be like saying that the 777 burns 10x more gas than a 737-200 with those wonderfully inefficient low-bypass turbojets.

Doug Taylor
Former 727 SO
Former 737 FO
Current MD-88/-90 FO


User currently offlineLMP737 From , joined Dec 1969, posts, RR:
Reply 9, posted (12 years 7 months 1 week 1 day 6 hours ago) and read 9394 times:

I'll be the first to say that the MD-11 is a fine looking aircraft. I know, I worked on it a little while with Boeing. However, it's kind of a moot point comparing the fuel burn of the MD-11 to the 777. We all know which one was successful in the market place and which one was not.

If you look at the chart on the MD-11 you will also notice the disclaimer "Not To Be Used For Flight Planning Purposes". The only way to get an accurate idea of fuel burn is to look at the flight test data. Boeing is not in the habit of making it's flight test data public however.

For the sake of argument lets say the MD-11 has a better fuel burn than the 777. While fuel burn is important there are other factors to consider. Such as, which airplane can carry the most passengers the farthest. The 777 is the winner in this area. Maintenance is another important area. Two engines are cheaper to maintain in terms of manpower and material (spare parts) than three. It is also less time consuming (time is $$$$$$ in the airline industry). You have a problem with the number two on a 777 you pop open the cowling or TR and take a look. On the MD-11 you have to crawl up the tail compartment, open the patio and THEN open the engine.

That my take on the subject.


User currently offlineTsentsan From Singapore, joined Jan 2002, 2016 posts, RR: 15
Reply 10, posted (12 years 7 months 1 week 1 day 4 hours ago) and read 9342 times:

From what I've witnessed and heard from both fuel loaders and pilots, the 777 burns about 8-9 tons an hour at MTOW, and as it gets lighter, about 6.5-7.5 tons an hr.

I've heard a fuel load for a SIN-AMS 777 being 110tons of fuel. Considering that journey is about 13 hours, that gives a fuel consumption of 8.46tons (18600 lbs per hr) if all the fuel was used, bearing in mind that these long haul jets dont get high altitudes until about 1/2 way through the journey.

From what I've read and heard, the Md-11 is a good a/c but apparently the range was a problem in the first few production models so thats why it wasnt tooo popular initially. I'm no expert in MD-11/777 characteristics, but its just what I've heard in life.

Thanks
Tsentsan



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User currently offlineSAS23 From , joined Dec 1969, posts, RR:
Reply 11, posted (12 years 7 months 1 week 1 day 3 hours ago) and read 9333 times:

On the other hand, the L1011-500 burns between 7 and 8 tonnes per hour!

User currently offlineTimz From United States of America, joined Sep 1999, 6902 posts, RR: 7
Reply 12, posted (12 years 7 months 1 week 1 day ago) and read 9289 times:

Okay, Ejaymd11, look again at the Boeing graph for the 777. You got a range of 3300 nm at MTOW 545,000 lb-- but that's at a zero-fuel weight of 420,000 lb. So the 777 is supposed to do 3300 nm on 125,000 lb (including reserves) instead of the 207,700 lb you apparently assumed.

By the way: why did you assume temp -30? And where did you assume that, anyway?


User currently offlineAreopagus From United States of America, joined Sep 2001, 1373 posts, RR: 1
Reply 13, posted (12 years 7 months 1 week 22 hours ago) and read 9232 times:

bearing in mind that these long haul jets dont get high altitudes until about 1/2 way through the journey.

I don't believe that. The 747s that I rode on my last long trip (4 stages of >5000 miles each) were at 35,000 feet in 35 minutes.


User currently offlineKAL_LM From United States of America, joined Jun 2001, 497 posts, RR: 0
Reply 14, posted (12 years 7 months 1 week 21 hours ago) and read 9210 times:

Just for the argument...

Aircraft Type: MD-11F
Route: PDX-ICN
Planned Fuel Burn: 208,000Lbs.
Flight Time: 11hrs 20min
Approx. fuel consumption/hr : 18,352Lbs.
MTOW: 618,000Lbs.
TOW: 615,800Lbs.
Engine Type: PW4460
Clmb to 330/M.82, Crz M.83

According to the manual I've got, average fuel burn on a 777-200 (PW4090 equipped) is 15,100Lbs/hr, so your numbers really don't match up


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At any rate though, we know who won the battle. Besides, whether or not an aircraft is successful (if that is what you're trying to get at) is not totally dependent on fuel consumption. It is other factors like seat cost per mile, cargo/pax capacity, mx costs, reliability of dispatch etc....

Just my two cents worth.

regards,
Tom



is that a light at the end of the tunnel or just a train?
User currently offlineTsentsan From Singapore, joined Jan 2002, 2016 posts, RR: 15
Reply 15, posted (12 years 7 months 1 week 22 hours ago) and read 9190 times:

Areopagus,

ATC requirements. KL/BKK Atc only gives FL280 for SIN-Europe flights.



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User currently offlineEjaymd11 From United States of America, joined Feb 2001, 193 posts, RR: 0
Reply 16, posted (12 years 7 months 1 week 20 hours ago) and read 9179 times:

Timz I just picked -30 degrees, my flight instructor said to subtract 2 degrees every thousand feet from sea level from the standard temp of 15 degrees Celsius but the number I thought the number was too low, also the zero fuel weight includes payload but if you look at the end of the chart is says 31,000 US gallons. If that is wrong let me know. Thanks for you response.

Delta737 A 777 would burn more fuel than a 737-200, is it 10 times more I don't know.

Ben88 I'm not telling you how much a 777-200 burns I'm showing you what I got from the info I gathered, I didn't hear you explaining why my info is wrong.

Thanks I got some major points from a lot of you, that is the type of response I was looking for. One more thing I not trying to offend anyone, just trying to receive, and make a point.

Ejay MD-11


User currently offlineDelta737 From United States of America, joined Jun 1999, 516 posts, RR: 11
Reply 17, posted (12 years 7 months 1 week 17 hours ago) and read 9122 times:

Of course I know a 777 burns more fuel than a 737. An MD 90 burns less fuel than an MD 88 too. :p

I really wouldn't try and use any of that data to make any type of assumptions about performance of an airplane.

Fuel consumption on a jet airliner is a fairly complex thing.

Doug Taylor
jetcareers.com


User currently offlineTimz From United States of America, joined Sep 1999, 6902 posts, RR: 7
Reply 18, posted (12 years 7 months 6 days 22 hours ago) and read 9024 times:

...say the MD11 with a zero-fuel weight of 400,000 lb can make a 5100+ nm trip (at MTOW of 618,000 lb). So, with a payload of 112,400 lb they need 218,000 lb of fuel including reserves. The baseline 777 carries a payload of about 120,000 lb; the 3300-nm trip calls for 125,000 lb of fuel including reserves.

The "31,000 US gallons" refers to the tail-end of the graph (beyond 6500 nm), which is the only part that assumes full fuel.

I still don't see where the temperature got into your calculation, but standard temperature is -50 degrees Celsius at 10 km altitude.


User currently offlineAreopagus From United States of America, joined Sep 2001, 1373 posts, RR: 1
Reply 19, posted (12 years 7 months 6 days 20 hours ago) and read 8993 times:

ATC requirements. KL/BKK Atc only gives FL280 for SIN-Europe flights.

OK, thanks for the clarification, Tsentsan. I am a little puzzled, though. I thought I read that SQ selected the 777 for its ability to get to full cruising altitude before entering KL/BKK airspace, and they would let it stay there. I guess I missed something.

Regards


User currently offlineSailorOrion From Germany, joined Feb 2001, 2058 posts, RR: 6
Reply 20, posted (12 years 7 months 6 days 5 hours ago) and read 8936 times:

huh ... sorry ...
but the MTOM is not 100% fuel, is it?

simple maths:
777-200
flight time: 7 hours
fuel: 64 tons
mean fuel flow: 9,14 tons / hour

MD11:
flight time: 9,5 hours
fuel: 99 tons
mean fuel flow: 10,4 tons / hour

SailorOrion


User currently offlineEjaymd11 From United States of America, joined Feb 2001, 193 posts, RR: 0
Reply 21, posted (12 years 7 months 5 days 11 hours ago) and read 8898 times:

Timz Read my response, I said I just chose that number. I've figured outwhere I went wrong, the MD-11 or the 777-200 canot take-off with full payload and full fuel, it excedes MTOW. So when I get the new numbers I'll post them.

Ejay MD-11


User currently offlineKonstantinos From Greece, joined Jun 2001, 389 posts, RR: 0
Reply 22, posted (12 years 7 months 4 days 19 hours ago) and read 8836 times:

MD-11's and 777, they are the same to me.
A 777 is an MD-11 without the 3rd engine and winglets.
Even if the MD11 was more fuel efficient than the 777, do you think
that Boeing would let you now this? How do we know that the
777 was not developed from the MD11 and how do we know
that Douglas's next aircraft wasn't going to be a 777 type?

We'll never know, will we ?


User currently offlineDonder10 From Canada, joined Oct 2001, 6660 posts, RR: 21
Reply 23, posted (12 years 7 months 4 days 17 hours ago) and read 8816 times:

Actually I remember that Douglas' next aircraft was a bit like the A380.

User currently offlineEjaymd11 From United States of America, joined Feb 2001, 193 posts, RR: 0
Reply 24, posted (12 years 7 months 4 days 12 hours ago) and read 8794 times:

Douglas's next type would have been the MD-12 which was a stretched version. I saw a picture in a book, it was sweet.

Ejay


User currently offlineSAS23 From , joined Dec 1969, posts, RR:
Reply 25, posted (12 years 7 months 4 days 4 hours ago) and read 8760 times:

The temperatures referred to for planning purposes are the field temperatures, NOT the altitude temperatures! You use them to determine whether or not you are likely to be WAT limited on take-off.

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