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Boeing Raises 748F Mtow By 13000lb  
User currently offlineart From United Kingdom, joined Feb 2005, 3398 posts, RR: 1
Posted (2 years 11 months 1 week 1 day 14 hours ago) and read 16283 times:

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!

43 replies: All unread, showing first 25:
 
User currently offlineRuscoe From Australia, joined Aug 1999, 1605 posts, RR: 2
Reply 1, posted (2 years 11 months 1 week 1 day 13 hours ago) and read 16092 times:

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


User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3432 posts, RR: 4
Reply 2, posted (2 years 11 months 1 week 1 day 11 hours ago) and read 15717 times:

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.


User currently offlineebbuk From , joined Dec 1969, posts, RR:
Reply 3, posted (2 years 11 months 1 week 1 day 11 hours ago) and read 15588 times:

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.


User currently offlineart From United Kingdom, joined Feb 2005, 3398 posts, RR: 1
Reply 4, posted (2 years 11 months 1 week 1 day 11 hours ago) and read 15485 times:

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).


User currently offlinesunrisevalley From Canada, joined Jul 2004, 5220 posts, RR: 5
Reply 5, posted (2 years 11 months 1 week 1 day 10 hours ago) and read 15374 times:

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.

User currently offliner2rho From Germany, joined Feb 2007, 2776 posts, RR: 1
Reply 6, posted (2 years 11 months 1 week 1 day 10 hours ago) and read 15360 times:

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.

User currently offlineAA1818 From Trinidad and Tobago, joined Feb 2006, 3437 posts, RR: 4
Reply 7, posted (2 years 11 months 1 week 1 day 10 hours ago) and read 15348 times:

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 currently offlineStitch From United States of America, joined Jul 2005, 31420 posts, RR: 85
Reply 8, posted (2 years 11 months 1 week 1 day 9 hours ago) and read 15068 times:
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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 currently offlineseabosdca From United States of America, joined Sep 2007, 5841 posts, RR: 6
Reply 9, posted (2 years 11 months 1 week 1 day 9 hours ago) and read 15016 times:

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 currently offlineStitch From United States of America, joined Jul 2005, 31420 posts, RR: 85
Reply 10, posted (2 years 11 months 1 week 1 day 9 hours ago) and read 15005 times:
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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 currently offlinebikerthai From United States of America, joined Apr 2010, 2197 posts, RR: 4
Reply 11, posted (2 years 11 months 1 week 1 day 9 hours ago) and read 14976 times:

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 currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12181 posts, RR: 51
Reply 12, posted (2 years 11 months 1 week 1 day 9 hours ago) and read 14874 times:

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.


User currently offlineebbuk From , joined Dec 1969, posts, RR:
Reply 13, posted (2 years 11 months 1 week 1 day 9 hours ago) and read 14817 times:

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!


User currently offlinerheinwaldner From Switzerland, joined Jan 2008, 2289 posts, RR: 5
Reply 14, posted (2 years 11 months 1 week 1 day 8 hours ago) and read 14646 times:

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?


User currently offlineB777LRF From Luxembourg, joined Nov 2008, 1466 posts, RR: 3
Reply 15, posted (2 years 11 months 1 week 1 day 8 hours ago) and read 14531 times:

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 currently offlineseabosdca From United States of America, joined Sep 2007, 5841 posts, RR: 6
Reply 16, posted (2 years 11 months 1 week 1 day 8 hours ago) and read 14357 times:

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.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 17, posted (2 years 11 months 1 week 1 day 7 hours ago) and read 14262 times:

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.


User currently offlinePlaneAdmirer From United States of America, joined Jul 2009, 564 posts, RR: 0
Reply 18, posted (2 years 11 months 1 week 1 day 7 hours ago) and read 14002 times:

Does this open or reopen any competitions for the 747-8i?

User currently offlinebikerthai From United States of America, joined Apr 2010, 2197 posts, RR: 4
Reply 19, posted (2 years 11 months 1 week 1 day 7 hours ago) and read 13671 times:

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.
User currently offlineDaysleeper From UK - England, joined Dec 2009, 873 posts, RR: 1
Reply 20, posted (2 years 11 months 1 week 1 day 7 hours ago) and read 13597 times:

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 currently offlinezeke From Hong Kong, joined Dec 2006, 9229 posts, RR: 76
Reply 21, posted (2 years 11 months 1 week 1 day 7 hours ago) and read 13548 times:

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.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineferpe From France, joined Nov 2010, 2805 posts, RR: 59
Reply 22, posted (2 years 11 months 1 week 1 day 6 hours ago) and read 13129 times:

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 currently offlineTistpaa727 From United States of America, joined May 2007, 331 posts, RR: 2
Reply 23, posted (2 years 11 months 1 week 1 day 6 hours ago) and read 12712 times:
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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 currently offlineseabosdca From United States of America, joined Sep 2007, 5841 posts, RR: 6
Reply 24, posted (2 years 11 months 1 week 1 day 6 hours ago) and read 12613 times:

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.


25 GCPET : Good to see this, might mean some more orders come in now! GCPET
26 zeke : 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 (ar
27 cosmofly : Same fuel, same load, what advantages the 748F has over the ERF other than volume?[Edited 2012-01-18 10:49:27]
28 ebbuk : 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
29 tdscanuck : 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
30 Stitch : Maximum Structural Payload also went up by 5t - it is now 82t. The 747-8F can take a heavier load than the 747-400ERF can - upwards of 139t with the
31 KC135TopBoom : . Thanks, I should have known that I did say at cruise speed (about 450 TAS, a conservitive true air speed), and I did say "up to 500nm". Over 30-45
32 ghifty : 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 o
33 tdscanuck : 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 c
34 ikramerica : 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 MZF
35 cosmofly : 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
36 Post contains images seabosdca : 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 se
37 flylku : 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.
38 Stitch : 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 tha
39 Max Q : 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 i
40 zeke : 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
41 flylku : In aviation is, for example, 100t referring to tons (short tons) or tonnes (long / metric tonnes)?
42 zeke : tonnes, i.e. 1000 kg.
43 shankly : 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 n
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