art
Topic Author
Posts: 2736
Joined: Tue Feb 08, 2005 11:46 am

Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 8:46 am

FlightGlobal reports an increase in 748 MTOW.

"Boeing has increased the maximum takeoff weight (MTOW) of its 747-8 Intercontinental and 747-8 freighter after its flight loads survey revealed additional structural margin available to customers."

http://www.flightglobal.com/news/art...eases-747-8-family-weights-367030/

Nice to realise that you can increase fuel/payload by several tons without spending a penny on weight loss to get it!
 
Ruscoe
Posts: 1605
Joined: Sun Aug 22, 1999 5:41 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 9:37 am

So does this translate to 60 xtra pax flown the same distance, or same number flown further, or xtra freight?.

I don'y know enough to put this in it's proper perspective, but it does seeem significant.

Cheers

Ruscoe
 
XT6Wagon
Posts: 2647
Joined: Tue Feb 13, 2007 4:06 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 11:46 am

Quoting Ruscoe (Reply 1):

So does this translate to 60 xtra pax flown the same distance, or same number flown further, or xtra freight?.

I don'y know enough to put this in it's proper perspective, but it does seeem significant.

More range and/or payload wieght. I doubt the 748 as spec'd before would be used on route where the number of seats is greater than the allowed passengers due to wieght. The 772LR/773ER would be better for those routes, as would a A388. This certainly will open up higher cargo wieghts on long flights, and some longer flights. Mostly I bet these early customers will look at it as bonus ability to deal with extreme weather conditions that might otherwise cause a tech stop.

The 748F is a different story and for the general frieght companies this is a fairly huge jump in performance for them. Package companies like FX will again be limited to gaining range or reduced tech stops since they will tend to run out of volume to stuff boxes long before they run out of payload capacity.
 
ebbuk
Posts: 844
Joined: Thu May 11, 2006 6:47 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 12:09 pm

An extra 6tons seems a lot. Tim Clark was talking about the A380 shedding 4 tons and taking 4yrs to do it, Boeing managed to find an extra 6 tons in less than a month according to article. How?

Way out of my knowledge orbit, I won't even try and speculate.
 
art
Topic Author
Posts: 2736
Joined: Tue Feb 08, 2005 11:46 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 12:31 pm

Quoting ebbuk (Reply 3):
Boeing managed to find an extra 6 tons in less than a month according to article. How?

Sounds to me that they realised they had over-engineered the aircraft (loads on the structure turned out to be less than anticipated and/or the structure turned out to be good for higher loads than anticipated).
 
sunrisevalley
Posts: 5302
Joined: Tue Jul 06, 2004 3:26 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 12:48 pm

I believe it is all to do with the OEW being higher than what was planned , thus allowing the operators to increase payload and or fuel load.
 
r2rho
Posts: 2546
Joined: Tue Feb 27, 2007 10:13 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 12:50 pm

6t gained "for free" without any reinforcements or thrust uprates is great news, specially for freighter operators. Then there is still a 2.7% fuel burn shortfall on the GEnx-2B to address via PIPs, not before 2013. So if Boeing can manage in the short-term to iron out some of the shortfalls thanks to in-service experience like this case, all the better for the program.
 
aa1818
Posts: 1523
Joined: Sat Feb 04, 2006 2:03 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 12:52 pm

Quoting ebbuk (Reply 3):

An extra 6tons seems a lot. Tim Clark was talking about the A380 shedding 4 tons and taking 4yrs to do it, Boeing managed to find an extra 6 tons in less than a month according to article. How?

Over-engineering?...or perhaps that is not the best term.
I don't recall the 748i and 748f having the same sort of issues as the A380 that would cause it to gain weight.
If the project goes smoothly a la 777, it seems Boeing can always pull a rabbit out of a hat. On the other hand, the 787 and A380 need/ needed serious diets after all the alterations and variations were completed.

AA1818
“The moment you doubt whether you can fly, you cease for ever to be able to do it.” J.M. Barrie (Peter Pan)
 
User avatar
Stitch
Posts: 23885
Joined: Wed Jul 06, 2005 4:26 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 1:45 pm

Yes, I noticed the new weights with the latest ACAP updates. Interesting, even with the new higher MTOW, range for the 747-8 Intercontinental is actually less than before - now about 5900nm vs 6250.
 
User avatar
seabosdca
Posts: 5161
Joined: Sat Sep 01, 2007 8:33 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 1:52 pm

Quoting Stitch (Reply 8):
Interesting, even with the new higher MTOW, range for the 747-8 Intercontinental is actually less than before - now about 5900nm vs 6250.

That would make sense if MZFW went up along with MTOW. Did it? I don't have the old ACAPS to check.
 
User avatar
Stitch
Posts: 23885
Joined: Wed Jul 06, 2005 4:26 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 1:55 pm

Quoting seabosdca (Reply 9):
That would make sense if MZFW went up along with MTOW. Did it?

Yes. MZFW is now 651,000lb / 295,289kg compared to 642,000lb / 291,206kg.
 
User avatar
bikerthai
Posts: 2246
Joined: Wed Apr 28, 2010 1:45 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 1:58 pm

Quoting AA1818 (Reply 7):

Over-engineering?...or perhaps that is not the best term.

I would agree. 6 tons represent about 1% of the aircraft weight. Which is well within the error margin analysis. I would say the designer is almost dead on on the evaluations.


bikerthai
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
kc135topboom
Posts: 11031
Joined: Sun Jan 30, 2005 2:26 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 2:12 pm

Quoting Stitch (Reply 8):
Interesting, even with the new higher MTOW, range for the 747-8 Intercontinental is actually less than before - now about 5900nm vs 6250.

???? How is that, Stitch? I just looked at the Boeing site (it has not been updated with the new MTOW or fuel capacity) and they still list the B-747-8I as having an 8,000 nm range at 975,000 lb TOW.

http://www.boeing.com/commercial/747family/747-8_fact_sheet.html

By my calulations, on the "I" model, if all the extrat weight capacity were just fuel (another 13,000 lbs of fuel), that would increase the cruising range by 30-45 minutes, or (at cruise speed) up to 8500 nm. That would make the B-747-8I capable of JFK-SIN (8250 nm) with max cargo and 469 pax, or even SYD-LHR (9200 nm) with a restricted load of about 350-375 pax.

A max range of just 5900 nm would kill the B-748I. I doubt Boeing would do that.
 
ebbuk
Posts: 844
Joined: Thu May 11, 2006 6:47 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 2:21 pm

Quoting bikerthai (Reply 11):
Quoting AA1818 (Reply 7):

Over-engineering?...or perhaps that is not the best term.

I would agree. 6 tons represent about 1% of the aircraft weight. Which is well within the error margin analysis. I would say the designer is almost dead on on the evaluations.

It actually sounds like quite the opposite. According to the ACAP figures highlighted by Stitch....

Quoting Stitch (Reply 8):
even with the new higher MTOW, range for the 747-8 Intercontinental is actually less than before - now about 5900nm vs 6250.

.

Oh dear!
 
rheinwaldner
Posts: 1305
Joined: Wed Jan 02, 2008 4:58 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 2:48 pm

Quoting Stitch (Reply 10):
Quoting seabosdca (Reply 9):
That would make sense if MZFW went up along with MTOW. Did it?

Yes. MZFW is now 651,000lb / 295,289kg compared to 642,000lb / 291,206kg.

So the opportunity to have a higher MTOW (because of margins in the structure) actually was the last resort to win back heavy losses in other areas. And still the originally projected range is not reached? What factor would cause this massive shortfall?
 
B777LRF
Posts: 1631
Joined: Sun Nov 02, 2008 4:23 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 3:02 pm

Quoting sunrisevalley (Reply 5):
I believe it is all to do with the OEW being higher than what was planned , thus allowing the operators to increase payload and or fuel load.

Exactly. This is an exercise done to restore the advertised payload, which fell short owing to the aircraft being overweight, nothing more. Boeing will of course spin it otherwise, but that's marketing for you.

And as Stitch noted, it's still short on range.
From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
 
User avatar
seabosdca
Posts: 5161
Joined: Sat Sep 01, 2007 8:33 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 3:27 pm

Quoting KC135TopBoom (Reply 12):
???? How is that, Stitch? I just looked at the Boeing site (it has not been updated with the new MTOW or fuel capacity) and they still list the B-747-8I as having an 8,000 nm range at 975,000 lb TOW.

He is talking about MZFW range, not pax payload range.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 3:46 pm

Quoting ebbuk (Reply 3):
Boeing managed to find an extra 6 tons in less than a month according to article. How?

Initial design weights are all based on what the expected stresses are. They got more data from actual testing to discover the true stresses and found out they had room.

Quoting rheinwaldner (Reply 14):

So the opportunity to have a higher MTOW (because of margins in the structure) actually was the last resort to win back heavy losses in other areas.

They'd still be working all the other areas, so this isn't the last resort, but it's certainly one of the fastest and easiest to implement.

Quoting rheinwaldner (Reply 14):
And still the originally projected range is not reached?

It is, just at a different payload.

Quoting rheinwaldner (Reply 14):
What factor would cause this massive shortfall?

MZFW went up too...you can use the extra weight to carry the original payload farther or more payload. With the way the structural margins worked out, if you go up to the new (higher) MZFW you can't carry enough fuel to recover the range hit so the range at MZFW went down...this doesn't represent a loss of capability since you can still carry the original MZFW farther than you could before.

Tom.
 
PlaneAdmirer
Posts: 254
Joined: Mon Jul 06, 2009 8:39 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 3:59 pm

Does this open or reopen any competitions for the 747-8i?
 
User avatar
bikerthai
Posts: 2246
Joined: Wed Apr 28, 2010 1:45 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 4:16 pm

Quoting ebbuk (Reply 13):
It actually sounds like quite the opposite. According to the ACAP figures highlighted by Stitch....

I think we are talking different efficiencies here. The 6 tons gain was due to the structure capabilities, probably primarily in the wings. Where as the short fall as Stitch have noted may be due to other deficiencies (engine fuel burn, weight penalty from other systems etc.)

But the result would be the same. You can't really take advantage of the extra capability in the wing if your fuel burn is high or the extra wing capability is taken up by extra weight penalty elsewhere.

My comment was primarily in the strength analysis of the wing.

bikerthai
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
Daysleeper
Posts: 565
Joined: Sun Dec 20, 2009 3:33 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 4:21 pm

Quoting PlaneAdmirer (Reply 18):
Does this open or reopen any competitions for the 747-8i?

As someone mentioned earlier in the thread its highly unlikely it will make any difference to the I as it would be space rather than weight limited.
 
User avatar
zeke
Posts: 10775
Joined: Thu Dec 14, 2006 1:42 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 4:22 pm

Quoting Stitch (Reply 8):
Interesting, even with the new higher MTOW, range for the 747-8 Intercontinental is actually less than before - now about 5900nm vs 6250.

I seem to recall posting that last year .....

Quoting KC135TopBoom (Reply 12):

By my calulations, on the "I" model, if all the extrat weight capacity were just fuel (another 13,000 lbs of fuel), that would increase the cruising range by 30-45 minutes, or (at cruise speed) up to 8500 nm.

The 747-8i does not TAS at 1000 kts (which is Mach 1.74 at FL360), no way would 30 min give you 500 nm....

Quoting KC135TopBoom (Reply 12):
That would make the B-747-8I capable of JFK-SIN (8250 nm) with max cargo and 469 pax, or even SYD-LHR (9200 nm) with a restricted load of about 350-375 pax.

The marketing range given by Boeing for any aircraft with their marketing passenger loads, in this case 467 pax is for passengers only and no cargo. If you want to fly max cargo and passengers, you would be up at MZFW, and yes the range would be only around 6000 nm, which would make it unable to do LAX-HKG, LAX-SYD etc.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
ferpe
Posts: 2651
Joined: Tue Nov 30, 2010 7:44 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 4:45 pm

Re payload and range capability of the 748, if the airframe is heavier then planned and your wing stays as planned you will have higher mission drag due to lifting this higher mass (induced drag and maybe also transonic drag increases slightly).

MTOW increase
I you can raise the MTOW you can regain range by the higher MTOW allowing to to get more fuel on board (until the tanks are the limit) but you can never regain efficiency = fuel burn cost.

MZFW
If you can raise the MZFW to come back to original payload you are carrying your original payload in a heavier frame which has higher drag = less efficiency = higher fuel cost.


So once the OEW goes up the business plan for the frame goes south even if you regain the MSP with a higher MZFW and range with a higher MTOW (all other things being equal  ).
Non French in France
 
User avatar
tistpaa727
Posts: 118
Joined: Sat May 05, 2007 5:23 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 5:08 pm

Quoting tdscanuck (Reply 17):
MZFW went up too...you can use the extra weight to carry the original payload farther or more payload. With the way the structural margins worked out, if you go up to the new (higher) MZFW you can't carry enough fuel to recover the range hit so the range at MZFW went down...this doesn't represent a loss of capability since you can still carry the original MZFW farther than you could before.

Thanks Tom. Your explanation makes perfect sense.
Don't sweat the little things.
 
User avatar
seabosdca
Posts: 5161
Joined: Sat Sep 01, 2007 8:33 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 5:15 pm

Quoting ferpe (Reply 22):
f the airframe is heavier then planned and your wing stays as planned you will have higher mission drag due to lifting this higher mass

My understanding is that the performance effect of the weight overage was largely made up by better-than-expected performance of the reprofiled wing. What is really killing the 748 right now is the fuel burn miss on the GEnX-2B.
 
GCPET
Posts: 202
Joined: Fri Jan 13, 2012 12:43 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 5:18 pm

Good to see this, might mean some more orders come in now!

GCPET
If it's not Boeing, I'm not going!
 
User avatar
zeke
Posts: 10775
Joined: Thu Dec 14, 2006 1:42 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 5:41 pm

Quoting ferpe (Reply 22):

So once the OEW goes up the business plan for the frame goes south even if you regain the MSP with a higher MZFW and range with a higher MTOW (all other things being equal ).

The in service fuel burn we are seeing on the 747-8F are almost identical to that of the 744ERF, and for range we are only carrying a 744ERF load (around 125t).
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
cosmofly
Posts: 195
Joined: Tue May 05, 2009 3:36 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 6:49 pm

Quoting zeke (Reply 26):
The in service fuel burn we are seeing on the 747-8F are almost identical to that of the 744ERF, and for range we are only carrying a 744ERF load (around 125t).

Same fuel, same load, what advantages the 748F has over the ERF other than volume?

[Edited 2012-01-18 10:49:27]
 
ebbuk
Posts: 844
Joined: Thu May 11, 2006 6:47 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 6:50 pm

Once upon a time a place to get in depth analysis was the Flight international magazine. I remember evey week going to the newsagents to read all the news and also the analysis of it. I was a poor student at the time couldn't afford to subscribe.

Now, however, we have Jon Ostrower, a decent enough chap I'm sure, regurgitating data from a publication but without comment, no angle on implications for the change and crucially missing is industry comment. Jon is not a journalist and basically the journalism is gone at Flightglobal. I have to come to sites like this to get a handle on what the figures mean.

A real pity.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 7:12 pm

Quoting zeke (Reply 26):
The in service fuel burn we are seeing on the 747-8F are almost identical to that of the 744ERF, and for range we are only carrying a 744ERF load (around 125t).

That sounds about right...you're moving the same payload with a larger/heavier aircraft yet not burning any more fuel. Put another way, the 747-8F is basically more efficient enough that you can carry your -400ERF cargo *plus* the extra weight of the 747-8F itself with no fuel burn penalty.

Quoting cosmofly (Reply 27):
Same fuel, same load, what advantages the 748F has over the ERF other than volume?

Payload...the 747-8F can carry both more weight and more volume. Zeke's talking about running the 747-8F with -400ERF payload...if you're only going to carry -400ERF payload at -400ERF ranges the -8F doesn't have much advantage for you because the plane itself is larger but you're not using any of that capability.

It would be like trying to fly the same group of people on an A318 or an A321 on the same city-pair...same payload, same range, similar fuel burn. The A321 would have no advantage in that case because you're not using any of the additional capability.

Tom.
 
User avatar
Stitch
Posts: 23885
Joined: Wed Jul 06, 2005 4:26 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 7:15 pm

Quoting B777LRF (Reply 15):
This is an exercise done to restore the advertised payload, which fell short owing to the aircraft being overweight, nothing more.

Maximum Structural Payload also went up by 5t - it is now 82t.


Quoting cosmofly (Reply 27):
Same fuel, same load, what advantages the 748F has over the ERF other than volume?

The 747-8F can take a heavier load than the 747-400ERF can - upwards of 139t with the new MTOW/MZFW bump. The 747-400ERF can lift 126t with reduced range, or 113t for longer missions.
 
User avatar
kc135topboom
Posts: 11031
Joined: Sun Jan 30, 2005 2:26 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 9:59 pm

Quoting seabosdca (Reply 16):
Quoting KC135TopBoom (Reply 12):
???? How is that, Stitch? I just looked at the Boeing site (it has not been updated with the new MTOW or fuel capacity) and they still list the B-747-8I as having an 8,000 nm range at 975,000 lb TOW.

He is talking about MZFW range, not pax payload range.

.

Thanks, I should have known that

Quoting zeke (Reply 21):
Quoting KC135TopBoom (Reply 12):

By my calulations, on the "I" model, if all the extrat weight capacity were just fuel (another 13,000 lbs of fuel), that would increase the cruising range by 30-45 minutes, or (at cruise speed) up to 8500 nm.

The 747-8i does not TAS at 1000 kts (which is Mach 1.74 at FL360), no way would 30 min give you 500 nm....

I did say at cruise speed (about 450 TAS, a conservitive true air speed), and I did say "up to 500nm". Over 30-45 minutes does give a range increase at 450 TAS gives you another 225-338 nm (no wind), meaning the GS is 450 knots.

But, of course the B-747-8I cruises at M.855, which at FL-350 (M1.0 at 35,000' is about 660 MPH) is about 505 knots TAS (no wind). So that extra 30-45 minutes of fuel would increase the range by about 250-380 nm. So, my "up to 500 nm" is not that far off, about 120 nms.
 
ghifty
Posts: 892
Joined: Sun Jul 25, 2010 9:12 pm

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 10:57 pm

Wow. 6.5 tonnes is no paperweight.. 1.3% MTOW increase!

I'm sorry to ask such a silly question, but how hard would it be for Boeing to fudge the old official MTOW, so that they could later shave off 6.5 tonnes? Just wondering..
Fly Delta (Wid)Jets
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Boeing Raises 748F Mtow By 13000lb

Wed Jan 18, 2012 11:31 pm

Quoting ghifty (Reply 33):
I'm sorry to ask such a silly question, but how hard would it be for Boeing to fudge the old official MTOW, so that they could later shave off 6.5 tonnes?

Not technically difficult to do a lower MTOW...if the data supports the higher MTOW then it obviously supports a lower one so the regulator doesn't care. Lots of airlines purchase "paper derates" so their aircraft has a lower certified MTOW to lower their landing fees in situations where they don't need maximum weight. However, that's a dangerous game to play during development, since you can't sell the thing based on your "future-to-be-unfudged" number...so you're jerking your customer around for pretty dubious gain.

To fudge a higher MTOW than you really have would be nearly impossible because none of your test data would support it.

Tom.
 
ikramerica
Posts: 14141
Joined: Mon May 23, 2005 9:33 am

RE: Boeing Raises 748F Mtow By 13000lb

Thu Jan 19, 2012 12:22 am

Quoting tdscanuck (Reply 17):
MZFW went up too...you can use the extra weight to carry the original payload farther or more payload. With the way the structural margins worked out, if you go up to the new (higher) MZFW you can't carry enough fuel to recover the range hit so the range at MZFW went down...this doesn't represent a loss of capability since you can still carry the original MZFW farther than you could before.

Tom, or anyone else, so where would the lines cross? What ZFW would the new spec 748i be able to carry the exact same distance as the old spec at MZFW.

Also, how much further can the new spec carry the original MZFW than the old?

Quoting cosmofly (Reply 27):
Same fuel, same load, what advantages the 748F has over the ERF other than volume?

More payload when needed, or ability to take less dense cargo (but still charge the same dimensional weight as on the 744) meaning more profit. Or being able to offer a slightly lower rate at no additional cost to the flight meaning more business. Win-win.

At some lower capacity though, carrying the extra dead weight of the 748 over the 744 is a negative, but one assumes that at that point, you should be using a 77F or MD11F rather than the 744 or the 748 anyway.

Quoting tdscanuck (Reply 29):
Payload...the 747-8F can carry both more weight and more volume. Zeke's talking about running the 747-8F with -400ERF payload...if you're only going to carry -400ERF payload at -400ERF ranges the -8F doesn't have much advantage for you because the plane itself is larger but you're not using any of that capability.

But he sure did make it sound like a bad thing.

Remember, this kind of performance is what made airlines choose the 738 over the 73G once it was learned to be the case for that family. Same payload, same city pair, same costs even though the airframe was larger, which meant that they could profit greatly by putting the aircraft on a route with 20-40 seats to fill at very high margin. If it's true for the 748, will convince some on the fence to go with the 748 in the future, especially once the PIP makes the performance even better.
Of all the things to worry about... the Wookie has no pants.
 
cosmofly
Posts: 195
Joined: Tue May 05, 2009 3:36 pm

RE: Boeing Raises 748F Mtow By 13000lb

Thu Jan 19, 2012 12:40 am

Quoting ikramerica (Reply 35):
But he sure did make it sound like a bad thing.
Quoting zeke (Reply 26):
and for range we are only carrying a 744ERF load

I assume Zeke implies that in order to achieve the desired range, CX can only carry the 744ERF load. My reading was therefore in his opinion the 748F has no advantage over ERF for CX.
 
User avatar
seabosdca
Posts: 5161
Joined: Sat Sep 01, 2007 8:33 am

RE: Boeing Raises 748F Mtow By 13000lb

Thu Jan 19, 2012 12:42 am

Quoting ikramerica (Reply 35):
But he sure did make it sound like a bad thing.

Zeke? Make the performance of a Boeing aircraft sound like a bad thing? Never!  

Still, if they are limited to 744ERF-ish loads because of range, it seems like they should use the 748F on slightly shorter routes (unless they don't have any). Then they would be carrying 10% or so more payload than the 744ERF with similar (or slightly better, given Zeke's wording) trip costs.

It was clear from the beginning that the 748, compared with the 744ERF, was going to have a much higher payload but slightly lower range when carrying all of that payload.

Quoting ikramerica (Reply 35):
Tom, or anyone else, so where would the lines cross? What ZFW would the new spec 748i be able to carry the exact same distance as the old spec at MZFW.

The payload/range lines (I assume you're talking about the previous and new ACAPs) don't cross. For any given ZFW, you can load more fuel and fly farther; for any given range beyond MZFW range, you can load more payload.
 
User avatar
flylku
Posts: 595
Joined: Sat Apr 08, 2006 10:44 pm

RE: Boeing Raises 748F Mtow By 13000lb

Thu Jan 19, 2012 1:37 am

Quoting PlaneAdmirer (Reply 18):
Does this open or reopen any competitions for the 747-8i?

Indeed. The billion dollar question. So what do you all think? Does this breath life into the program or will it end up being 767-400 or 747-SP.
...are we there yet?
 
User avatar
Stitch
Posts: 23885
Joined: Wed Jul 06, 2005 4:26 am

RE: Boeing Raises 748F Mtow By 13000lb

Thu Jan 19, 2012 1:40 am

With a 126t load, range for a 747-400ERF should be around 5100km.

At the same load, range for the 747-8F (at 448t TOW) should be 8300km. 5100km at that load would be around a 395t TOW.
 
Max Q
Posts: 5834
Joined: Wed May 09, 2001 12:40 pm

RE: Boeing Raises 748F Mtow By 13000lb

Thu Jan 19, 2012 6:53 am

Quoting cosmofly (Reply 36):

I assume Zeke implies that in order to achieve the desired range, CX can only carry the 744ERF load. My reading was therefore in his opinion the 748F has no advantage over ERF for CX.

I think what he means is the 8F can carry it's maximum payload with the fuel burn of an ERF at it's maximum payload.


That is a significant increase in payload for the same burn.


This is what is indicated on a CX site on another forum.
The best contribution to safety is a competent Pilot.
 
User avatar
zeke
Posts: 10775
Joined: Thu Dec 14, 2006 1:42 pm

RE: Boeing Raises 748F Mtow By 13000lb

Thu Jan 19, 2012 7:52 am

Quoting tdscanuck (Reply 29):

That sounds about right...you're moving the same payload with a larger/heavier aircraft yet not burning any more fuel.

The 747-8F is burning slightly more fuel, but close enough for me to think of it as being the same. Just looking at around couple of extra tonnes of fuel over a 10 hr sector. Divide that up over 4 engines, you would hardly notice it on the fuel flows.

Quoting KC135TopBoom (Reply 32):

But, of course the B-747-8I cruises at M.855, which at FL-350 (M1.0 at 35,000' is about 660 MPH) is about 505 knots TAS (no wind). So that extra 30-45 minutes of fuel would increase the range by about 250-380 nm. So, my "up to 500 nm" is not that far off, about 120 nms.

Airlines do not operate aircraft these days at constant Mach, we use the ECON speed generated by the FMC. At the end of a HKG-ANC flight a 747-8F would be up around FL370 and flying with an ECON speed of M0.83 with our cost index, that is a TAS of 478 Kt.

M1.0@ FL360 is 660 mph/573 kts, I have no idea where your 505 kts TAS comes from.

Quoting cosmofly (Reply 36):
I assume Zeke implies that in order to achieve the desired range, CX can only carry the 744ERF load. My reading was therefore in his opinion the 748F has no advantage over ERF for CX.

No, it is the difference between academic numbers and real life. For a HKG-ANC flight we need to file an alternate, and that would normally be something like Fairbanks. Fairbanks is about an hour away, it would cost about 11t of fuel to get there, plus the mandatory we need to have in the tanks on landing, call it 16t total on arrival to ANC. The marketing numbers often just work on a 200 nm alternate, so you need to take some of the payload away to put fuel on to achieve the marketing range. The "ERF load" I was referring to was around 125t to put a number on it, a couple of tonne below the ERF maximum capability.

Quoting seabosdca (Reply 37):
Still, if they are limited to 744ERF-ish loads because of range, it seems like they should use the 748F on slightly shorter routes (unless they don't have any).

The -8F was purchased to do HKG-ANC with a full load as that is where it has the greatest benefit in economics, we were told about 2 years ago that this would more than like not be possible as the airframe/engine combination was not at its target. MTOW was increased to recover some of that lost payload, however it comes at a higher operational cost.

It is still early days, give it 12 months and we would have had time to play with different CG positions, cost index etc, might be able to recover some of the fuel burn just with simple changes in the way it is operated. It is being operated at the moment like it is a 742F/744F/744ERF, however, I think we need to get the mentality that it is a different with the wing/engine combination.

Quoting Max Q (Reply 39):

I think what he means is the 8F can carry it's maximum payload with the fuel burn of an ERF at it's maximum payload.

I am not aware that we have carried loads over 130t on the -8F, most of the loads seem to be about 10-20t below max payload.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
User avatar
flylku
Posts: 595
Joined: Sat Apr 08, 2006 10:44 pm

RE: Boeing Raises 748F Mtow By 13000lb

Sun Jan 22, 2012 9:10 pm

In aviation is, for example, 100t referring to tons (short tons) or tonnes (long / metric tonnes)?
...are we there yet?
 
User avatar
zeke
Posts: 10775
Joined: Thu Dec 14, 2006 1:42 pm

RE: Boeing Raises 748F Mtow By 13000lb

Sun Jan 22, 2012 9:14 pm

Quoting flylku (Reply 41):

tonnes, i.e. 1000 kg.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
shankly
Posts: 1240
Joined: Tue Jan 11, 2000 10:42 pm

RE: Boeing Raises 748F Mtow By 13000lb

Sun Jan 22, 2012 10:08 pm

Quoting zeke (Reply 40):
It is still early days, give it 12 months and we would have had time to play with different CG positions, cost index etc, might be able to recover some of the fuel burn just with simple changes in the way it is operated. It is being operated at the moment like it is a 742F/744F/744ERF, however, I think we need to get the mentality that it is a different with the wing/engine combination


Zeke, your posts above are a masterclass in factual reporting on the 748 and your summary nicely reflects the operating issues you face with such a new type. Subjective writing in an objective manner, not easy to do
L1011 - P F M

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos