ejaymd11
Posts: 180
Joined: Thu Feb 22, 2001 8:04 am

MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 5:13 am

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
 
luisca
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RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 7:03 am

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.
If it ain't Boeing (or Embraer ;-)) I ain't Going!
 
777236ER
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RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 7:12 am

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


Way, way off.

And work in metric Smile
Your bone's got a little machine
 
Mr.BA
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RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 8:36 am

The B777 burns an average of 7 tons an hour.
Boeing747 万岁!
 
BlatantEcho
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RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 10:00 am

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
 
FDXmech
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RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 11:00 am

The MGTOW for an MD11F is 630,500lbs.
You're only as good as your last departure.
 
ejaymd11
Posts: 180
Joined: Thu Feb 22, 2001 8:04 am

RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 11:43 am

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
 
ben88
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Joined: Fri Dec 31, 1999 4:49 pm

RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 12:03 pm

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.
 
Delta737
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RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 12:07 pm

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
 
LMP737
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RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 4:35 pm

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.
Never take financial advice from co-workers.
 
tsentsan
Posts: 1921
Joined: Mon Jan 28, 2002 10:48 pm

RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 7:09 pm

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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Guest

RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 7:36 pm

On the other hand, the L1011-500 burns between 7 and 8 tonnes per hour!
 
timz
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RE: MD-11 Fuel Burn Lower That The 777-200

Thu May 16, 2002 10:54 pm

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?
 
Areopagus
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RE: MD-11 Fuel Burn Lower That The 777-200

Fri May 17, 2002 1:06 am

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.
 
tsentsan
Posts: 1921
Joined: Mon Jan 28, 2002 10:48 pm

RE: MD-11 Fuel Burn Lower That The 777-200

Fri May 17, 2002 1:14 am

Areopagus,

ATC requirements. KL/BKK Atc only gives FL280 for SIN-Europe flights.
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KAL_LM
Posts: 492
Joined: Fri Jun 29, 2001 8:58 am

RE: MD-11 Fuel Burn Lower That The 777-200

Fri May 17, 2002 2:00 am

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?
 
ejaymd11
Posts: 180
Joined: Thu Feb 22, 2001 8:04 am

RE: MD-11 Fuel Burn Lower That The 777-200

Fri May 17, 2002 2:44 am

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
 
Delta737
Posts: 469
Joined: Sat Jun 05, 1999 11:23 am

RE: MD-11 Fuel Burn Lower That The 777-200

Fri May 17, 2002 6:14 am

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
 
timz
Posts: 6081
Joined: Fri Sep 17, 1999 7:43 am

The Boeing Graphs...

Sat May 18, 2002 12:40 am

...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.
 
Areopagus
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Joined: Thu Sep 20, 2001 12:31 pm

RE: MD-11 Fuel Burn Lower That The 777-200

Sat May 18, 2002 2:44 am

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
 
SailorOrion
Posts: 1959
Joined: Tue Feb 06, 2001 5:56 pm

RE: MD-11 Fuel Burn Lower That The 777-200

Sat May 18, 2002 5:38 pm

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
 
ejaymd11
Posts: 180
Joined: Thu Feb 22, 2001 8:04 am

RE: MD-11 Fuel Burn Lower That The 777-200

Sun May 19, 2002 11:41 am

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
 
Konstantinos
Posts: 364
Joined: Mon Jun 25, 2001 5:29 am

RE: MD-11 Fuel Burn Lower That The 777-200

Mon May 20, 2002 3:47 am

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 ?
 
donder10
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Joined: Sun Oct 21, 2001 5:29 am

RE: MD-11 Fuel Burn Lower That The 777-200

Mon May 20, 2002 6:14 am

Actually I remember that Douglas' next aircraft was a bit like the A380.
 
ejaymd11
Posts: 180
Joined: Thu Feb 22, 2001 8:04 am

RE: MD-11 Fuel Burn Lower That The 777-200

Mon May 20, 2002 10:26 am

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
 
Guest

RE: MD-11 Fuel Burn Lower That The 777-200

Mon May 20, 2002 6:34 pm

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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