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Hypothetical B747-9  
User currently offlineZvezda From Lithuania, joined Aug 2004, 10511 posts, RR: 64
Posted (7 years 7 months 1 week 1 day 8 hours ago) and read 1858 times:

Let us consider hypothetically stretching the B747-8 another 7 frames to a length of 79.83 meters.

Let's lengthen the landing gear by, say, 8 to 10 inches in order to avoid tailstrikes and to allow clearance for GEnx engines with the 111 inch fan.

OEW should be roughly 460,000 lbs. Nominal seating would be about 500.

Based on the weight difference, range with a full passenger load would decrease from the 8000nm of the B747-8 to about 7300nm. However, the lower SFC of the larger GEnx engines would reduce fuel burn by perhaps 4%. Range might be close to 7700nm.

Total development and certification cost should be below $1B. Is there a market for such a large aircraft that would justify spending $1B on development?

Obviously, taxiing would be a problem at some airports. Some airlines would want greater range, though it still exceeds the range of the B747-400ER.

What am I missing?

9 replies: All unread, jump to last
 
User currently offlineGunsontheroof From United States of America, joined Jan 2006, 3500 posts, RR: 10
Reply 1, posted (7 years 7 months 1 week 1 day 8 hours ago) and read 1854 times:

Quoting Zvezda (Thread starter):
What am I missing?

Market demand.



Next Flight: 9/17 BFI-BFI
User currently offlineZvezda From Lithuania, joined Aug 2004, 10511 posts, RR: 64
Reply 2, posted (7 years 7 months 1 week 1 day 8 hours ago) and read 1851 times:

Quoting Gunsontheroof (Reply 1):
Market demand.

Because the size is too large or because range is too short?


User currently offlineGunsontheroof From United States of America, joined Jan 2006, 3500 posts, RR: 10
Reply 3, posted (7 years 7 months 1 week 1 day 7 hours ago) and read 1846 times:

Quoting Zvezda (Reply 2):
Because the size is too large or because range is too short?

Probably a combination of both, but I think that the market for VLAs is going to prove to be much to small to accommodate another aircraft besides the A380. Time may prove me wrong of course, but I'd feel fairly comfortable betting that the 747-8 (-ER variants aside if they're even possible) will be the final member of the 747 family.



Next Flight: 9/17 BFI-BFI
User currently offlineZvezda From Lithuania, joined Aug 2004, 10511 posts, RR: 64
Reply 4, posted (7 years 7 months 1 week 1 day 7 hours ago) and read 1834 times:

Gunsontheroof, I agree that the VLA market may be smaller than Airbus and Boeing are publicly predicting. However, the question here for Boeing is how many sales could a B747-9 win that otherwise would be won by Airbus. If the number is greater than 30 or 40 (breakeven sales for a $1B investment), then it would seem to make sense for Boeing to develop a B747-9.

User currently offlineZeke From Hong Kong, joined Dec 2006, 8872 posts, RR: 75
Reply 5, posted (7 years 7 months 1 week 1 day 7 hours ago) and read 1831 times:

Quoting Zvezda (Thread starter):
What am I missing?

What wingspan, takeoff/approach distances/speeds would you estimate ?



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineZvezda From Lithuania, joined Aug 2004, 10511 posts, RR: 64
Reply 6, posted (7 years 7 months 1 week 1 day 6 hours ago) and read 1828 times:

Quoting Zeke (Reply 5):
What wingspan, takeoff/approach distances/speeds would you estimate ?

I don't think it would make sense to change the wing from that of the B747-8 for such a small market (unless perhaps for different wingtip extensions). Obviously, takeoff and landing speeds increase somewhat if MTOW/MLW increase, which they probably should. The airports from which a hypothetical B747-9 might operate generally have very long runways, but any increase in MTOW would also mean slower climb rates, which adversely affect communities with noise issues.

Landing shouldn't be a problem as the MLW for the B747-8F is anyway much higher. Since design range would be limited by fuel weight rather than fuel capacity, the design would have to compromise range and MTOW. Since a lot of airlines have been insisting on 8000nm range, perhaps it makes sense to start from there and figure out what the MTOW would have to be?


User currently offlineEI321 From Iraq, joined Jul 2009, 0 posts, RR: 0
Reply 7, posted (7 years 7 months 1 week 1 day 1 hour ago) and read 1771 times:

Quoting Zvezda (Reply 4):
However, the question here for Boeing is how many sales could a B747-9 win that otherwise would be won by Airbus

Probably less than those that could be won by the 747-8. A it stands now, I cant name any airlines that have outright chose the 748 INSTEAD of the A380.

Of the 44 existing freighter orders, all except Emirates have been ordered by airlines that already operate older 747F fleets, and will use the new aircraft to either replace existing 747s or expand the fleet. Lufthansa will use their 748Is to replace passenger 744s.

So the market for new operators for a 747-9 is small enough to begin with, before even considering teh possible design issues.


User currently offlineGunsontheroof From United States of America, joined Jan 2006, 3500 posts, RR: 10
Reply 8, posted (7 years 7 months 1 week 20 hours ago) and read 1715 times:

Quoting EI321 (Reply 7):
Lufthansa will use their 748Is to replace passenger 744s.

Not completely though...many of LH's B744s are quite young. You'll be seeing both a/c flying with them for quite some time.

Quoting Zvezda (Reply 4):
If the number is greater than 30 or 40 (breakeven sales for a $1B investment), then it would seem to make sense for Boeing to develop a B747-9.

I'd say the number would have to be much greater than that for Boeing to stretch the 747 again. All signs so far indicate that they're perfectly content to cede the limited VLA market to Airbus. Considering the technical problems that are causing the breakeven point to rise continually, I'd say it's the right call.



Next Flight: 9/17 BFI-BFI
User currently offlineEI321 From Iraq, joined Jul 2009, 0 posts, RR: 0
Reply 9, posted (7 years 7 months 6 days 23 hours ago) and read 1629 times:

Quoting Gunsontheroof (Reply 8):
Quoting EI321 (Reply 7):
Lufthansa will use their 748Is to replace passenger 744s.

Not completely though...many of LH's B744s are quite young. You'll be seeing both a/c flying with them for quite some time.

Lufthansa was the first European airline to bring the -400 into service back in '89. The -800s will be delivered between late 2010 and 2013, at which time the initial batch of 17 -400s will be 17 to 21 years in service with the airline, the normal age at which LH replaces its aircraft. With good demand for use -400s in the frighter market, I think LH will convert some for themselves and replace most or all of the remainder of the rest with -800s, the -800s enter service.


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