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B747 Upper Deck  
User currently offlinestevenjehly From , joined Dec 1969, posts, RR:
Posted (4 years 7 months 1 week 5 days 2 hours ago) and read 10464 times:

Greetings all. For quite sometime I have been wondering why Boeing does not extend the upper deck of its 747 the full length of the aircraft. They did it to a small extent with the 747-400 a number of years ago. If they did that it could have about the same seating as the A380 and I believe it would be a legitimate competator. Folks love the 747! It's obvious they opted for the 787 as their next generation but as far as the number of seats, an extended 747 would have a greater capacity. Does anybody know if this was ever discussed at Boeing? Has this ever been a Forum topic? I'm anxious to hear comments from A.netters.

12 replies: All unread, jump to last
 
User currently offlineViscount724 From Switzerland, joined Oct 2006, 26021 posts, RR: 22
Reply 1, posted (4 years 7 months 1 week 5 days 2 hours ago) and read 10388 times:

Quoting stevenjehly (Thread starter):
Has this ever been a Forum topic?

Yes it's been discussed in quite a few threads. Here's one that covers most of the issues.
747 Design: Not A Complete Double Decker? (by CF188A Mar 16 2007 in Civil Aviation)

If the 747 had been designed with a full-length upper deck, it would have been much less useful as a freighter. Without the upper deck in most of the fuselage you can make use of the complete fuselage height for cargo and can thus carry much larger containers. If the upper deck was full length, you would be resticted to the same much lower height that now only affects the area below the cockpit and short upper deck. It would also make the aircraft much heavier, meaning reduced payload and range.


User currently onlinebohica From United States of America, joined Feb 2004, 2751 posts, RR: 0
Reply 2, posted (4 years 7 months 1 week 5 days 1 hour ago) and read 10142 times:

Another problem would be boarding/deplaning. The upper deck doors on a 747 are emergency exits only. They were never designed as normal passenger doors. Also they are hinged at the top which would interfere with jetways. It would take a long time to board a full length upper deck on a 747 through the main deck then go up the stairs.

User currently offlineBMI727 From United States of America, joined Feb 2009, 15840 posts, RR: 27
Reply 3, posted (4 years 7 months 1 week 5 days 1 hour ago) and read 10112 times:

Quoting Viscount724 (Reply 1):

True. As of now, the 747 is a very versatile freighter. Long things can bee loaded through the nose, and tall cargo can be carried in the rear. For that matter, freight carrying ability is how the 747 got its hump in the first place. Combine that with the fact that the VLA market probably isn't big enough to warrant the extra cost and reduced cargo potential, and Boeing probably made the right call.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineZkpilot From New Zealand, joined Mar 2006, 4866 posts, RR: 10
Reply 4, posted (4 years 7 months 1 week 4 days 21 hours ago) and read 9662 times:

Full length upper deck could not be grandfathered... meaning it would have to re-certified which is quite an expensive process. Part of the reason for this would be that the aircraft would require new much larger wings, increased/strengthened landing gear, bigger engines, and possibly a bigger tail. It would be cheaper and easier to just design a clean sheet aircraft. That said, minor stretches to the UD (as on the 748I) do not cause these problems hence why Boeing is doing this.
As others have mentioned, SUD is not good for freighters as it cuts down the usable freight space.



56 types. 38 countries. 24 airlines.
User currently offlinedanimarroquin From Colombia, joined Jan 2005, 450 posts, RR: 0
Reply 5, posted (4 years 7 months 1 week 4 days 21 hours ago) and read 9443 times:

would the 747-8i would be done with a entrance door at the upper deck , or will have just a emergency exit like the 400 ?

User currently offlinePITrules From United States of America, joined Jun 2000, 3256 posts, RR: 6
Reply 6, posted (4 years 7 months 1 week 4 days 20 hours ago) and read 9417 times:

Quoting Viscount724 (Reply 1):
If the 747 had been designed with a full-length upper deck, it would have been much less useful as a freighter. Without the upper deck in most of the fuselage you can make use of the complete fuselage height for cargo and can thus carry much larger containers. If the upper deck was full length, you would be resticted to the same much lower height that now only affects the area below the cockpit and short upper deck. It would also make the aircraft much heavier, meaning reduced payload and range.

But all this would only concern possible future pax to cargo conversions. I'm not sure how much that plays into the overall decision to launch a new passenger version. As far as the pure freighter goes, Boeing has been building 2 different sized upper deck versions of the 747 for a couple decades now, I don't see why that would have to change to launch another passenger version.

Quoting Zkpilot (Reply 4):
meaning it would have to re-certified which is quite an expensive process

But how is this different than the 748? Isn't it undergoing its own certification process?



FLYi
User currently offlineZkpilot From New Zealand, joined Mar 2006, 4866 posts, RR: 10
Reply 7, posted (4 years 7 months 1 week 4 days 20 hours ago) and read 9355 times:

Quoting PITrules (Reply 6):

Quoting Zkpilot (Reply 4):
meaning it would have to re-certified which is quite an expensive process

But how is this different than the 748? Isn't it undergoing its own certification process?

IIRC it is having its new wings recertified and that is about it... because it has grandfathering from previous 747 models. The UD stretch still conforms to standards of distance to the nearest exit.



56 types. 38 countries. 24 airlines.
User currently offlinePITrules From United States of America, joined Jun 2000, 3256 posts, RR: 6
Reply 8, posted (4 years 7 months 1 week 4 days 20 hours ago) and read 9278 times:

Quoting Zkpilot (Reply 7):
IIRC it is having its new wings recertified and that is about it... because it has grandfathering from previous 747 models. The UD stretch still conforms to standards of distance to the nearest exit.

Interesting, I did not know that. But the 748 is much more than new wings. New engines, fuselage plugs, weights to name a few



FLYi
User currently offlineCM767 From Panama, joined Dec 2004, 655 posts, RR: 1
Reply 9, posted (4 years 7 months 1 week 4 days 8 hours ago) and read 8557 times:

The main issue here is, it is needed?

So far sales of VLA prove that the need for higher capacity is so small that will not justify additional investment, for adding capacity. If resources are available, it probably will be better used to reduce operating cost.



But The Best Thing God Has Created Is A New Day
User currently offlineBMI727 From United States of America, joined Feb 2009, 15840 posts, RR: 27
Reply 10, posted (4 years 7 months 1 week 4 days 6 hours ago) and read 6469 times:

Quoting CM767 (Reply 9):
The main issue here is, it is needed?

No. It just isn't worth it for the potential gains. And remember why the upper deck was created in the first place. It wasn't about having extra cabin space up there, it was just about getting the cockpit off the main deck.



Why do Aerospace Engineering students have to turn things in on time?
User currently offlineZkpilot From New Zealand, joined Mar 2006, 4866 posts, RR: 10
Reply 11, posted (4 years 7 months 1 week 4 days ago) and read 2921 times:

Quoting PITrules (Reply 8):
Quoting Zkpilot (Reply 7):
IIRC it is having its new wings recertified and that is about it... because it has grandfathering from previous 747 models. The UD stretch still conforms to standards of distance to the nearest exit.

Interesting, I did not know that. But the 748 is much more than new wings. New engines, fuselage plugs, weights to name a few

The engines are coming from the 787. If the 747 was to have a full UD it would need much larger engines.
Fuselage plugs are pretty simple... think of all the other aircraft variants... ie 762/763, 772/773, A332/A333 etc.



56 types. 38 countries. 24 airlines.
User currently offlineCXB77L From Australia, joined Feb 2009, 2694 posts, RR: 5
Reply 12, posted (4 years 7 months 1 week 3 days 18 hours ago) and read 2496 times:
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Quoting danimarroquin (Reply 5):
would the 747-8i would be done with a entrance door at the upper deck , or will have just a emergency exit like the 400 ?

As far as I'm aware it is still the top hinged emergency exit doors on the upper deck. Main deck doors are also side hinged doors that open outwards, as opposed to the slide-open doors on the 777 and 787.



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