XT6Wagon From United States of America, joined Feb 2007, 3459 posts, RR: 4
Reply 2, posted (3 years 2 months 1 week 6 days 14 hours ago) and read 15857 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.
art From United Kingdom, joined Feb 2005, 3455 posts, RR: 1
Reply 4, posted (3 years 2 months 1 week 6 days 13 hours ago) and read 15625 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).
r2rho From Spain, joined Feb 2007, 2916 posts, RR: 1
Reply 6, posted (3 years 2 months 1 week 6 days 13 hours ago) and read 15500 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.
AA1818 From Trinidad and Tobago, joined Feb 2006, 3455 posts, RR: 4
Reply 7, posted (3 years 2 months 1 week 6 days 13 hours ago) and read 15488 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.
“The moment you doubt whether you can fly, you cease for ever to be able to do it.” J.M. Barrie (Peter Pan)
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.
rheinwaldner From Switzerland, joined Jan 2008, 2332 posts, RR: 5
Reply 14, posted (3 years 2 months 1 week 6 days 11 hours ago) and read 14786 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?
B777LRF From Luxembourg, joined Nov 2008, 1545 posts, RR: 3
Reply 15, posted (3 years 2 months 1 week 6 days 10 hours ago) and read 14671 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
seabosdca From United States of America, joined Sep 2007, 6238 posts, RR: 7
Reply 16, posted (3 years 2 months 1 week 6 days 10 hours ago) and read 14497 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.
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.
bikerthai From United States of America, joined Apr 2010, 2244 posts, RR: 4
Reply 19, posted (3 years 2 months 1 week 6 days 9 hours ago) and read 13811 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.
zeke From Hong Kong, joined Dec 2006, 9574 posts, RR: 76
Reply 21, posted (3 years 2 months 1 week 6 days 9 hours ago) and read 13688 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
ferpe From France, joined Nov 2010, 2805 posts, RR: 59
Reply 22, posted (3 years 2 months 1 week 6 days 9 hours ago) and read 13269 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).
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.
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 ).
Tistpaa727 From United States of America, joined May 2007, 335 posts, RR: 2
Reply 23, posted (3 years 2 months 1 week 6 days 8 hours ago) and read 12852 times:
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.
seabosdca From United States of America, joined Sep 2007, 6238 posts, RR: 7
Reply 24, posted (3 years 2 months 1 week 6 days 8 hours ago) and read 12753 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.
: Good to see this, might mean some more orders come in now! GCPET
: 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
: Same fuel, same load, what advantages the 748F has over the ERF other than volume?[Edited 2012-01-18 10:49:27]
: 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
: 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
: 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
: . 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
: 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
: 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
: 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
: 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
: 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
: 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.
: 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
: 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
: In aviation is, for example, 100t referring to tons (short tons) or tonnes (long / metric tonnes)?