imag
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Can You Have A 748F With A Streched Bubble

Fri Apr 17, 2009 4:47 pm

Hello

If someone wanted a 748F with the stretched upper deck like the 748i, is that possible? Ie have a 748i body with the nose opening? Would there be any restrictions on what can be carried on the upper deck, say extra seating/bedding for pilots or extra carrying capacity?

Obviously there would be extra issues like getting more people up into the bubble up the small ladder, but in theory is this possible?

Thanks
 
B777LRF
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RE: Can You Have A 748F With A Streched Bubble

Fri Apr 17, 2009 5:19 pm

If you threw enough money at Boeing, I'm sure it could be done. But why would you make such a daft move? The standard upper-deck has more than enough space at it is; in fact quite a few B747-400SF conversions have put a bulkhead on the upper-deck as there is no need, at all, for all that space.

Try having a look at the upper-deck of existing B747-400Fs and you'll find most operators have a rather sizeable galley, between 4 and 8 business-class seats + bunks for between 4 to 6 people. Really, what more do you need?

Getting people up the stairs from the main-deck is not any issue, getting them evacuated in case of an emergency would be. But that's not an issue either, as the door (there's only one; the LH one is blocked) is fitted with a slide, which can be used as an inflateable and is, if memory serves me right, certified to carry 20 people - more than any 747F will ever carry.

Your idea is, I'm afraid, not viable.
From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
 
jbernie
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RE: Can You Have A 748F With A Streched Bubble

Fri Apr 17, 2009 6:11 pm

I guess military operators could find potential in such an aircraft as you could carry cargo & the extra space upstairs could be used for troops/technical support in good comfort but I am not sure that the demand would be there, but if you are willing to pay (like QF on their 744ER) then Boeing will accomodate you if the build is in fact possible.
 
413X3
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RE: Can You Have A 748F With A Streched Bubble

Fri Apr 17, 2009 6:15 pm

the whole point of cargo aircraft is to cut down on all unnecessary weight. having that big upper deck just takes away from fuel and cargo loads and thus would hurt your bottom line
 
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litz
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RE: Can You Have A 748F With A Streched Bubble

Fri Apr 17, 2009 6:17 pm

Doesn't the upper deck on a747 intrude into the main deck's airspace (e.g. : the floor of the upper deck is below the crown of the ceiling) ?

If so, it would then restrict the amount of cargo you can put in the nose (and under the upper deck), whereas rearward of that point, you can load full circumference cargo.

Therefore, if you put in a standard upper deck (which, as noted, provides plenty of usable space for crew + pax) you carry more cargo. And when your airplane carries cargo for a living, this is never a bad thing.

- litz
 
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Francoflier
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RE: Can You Have A 748F With A Streched Bubble

Sat Apr 18, 2009 4:00 am



Quoting Litz (Reply 4):
Doesn't the upper deck on a747 intrude into the main deck's airspace (e.g. : the floor of the upper deck is below the crown of the ceiling) ?

You are entirely correct. Freighters make no money carrying people, and the extended upper deck reduces the volume available for freight on the main deck. It is one of the disadvantages of the -400BCF over the straight -400F.

I suppose it could be done, at a cost, but unless for a very specific use, it would be completely useless. Not to mention that the resale value of the aircraft would drop a lot.
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
ha763
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RE: Can You Have A 748F With A Streched Bubble

Sun Apr 19, 2009 10:42 pm

The -400BCF still has the extended hump, but under that the upper deck floor is reduced to allow the same amount of 10ft high pallets as a -200F, but 2 less than a -400F. However, the -400BCF does have the ability to carry 30 pallets, the same as the -400F and 1 more than a -200F. You only lose a small amount of volume compared to the -400F, but still have more volume than the -200F and longer range than the -200F.
 
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DocLightning
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RE: Can You Have A 748F With A Streched Bubble

Sun Apr 19, 2009 11:26 pm

I understand that a benefit of stretching the hump was that it fits better in with the area rule by overlapping with the wings.

However, my guess is that the cost analysis is that the extra weight doesn't merit a section of completely unused space almost the size of a 736 just to help out the aerodynamics a bit.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
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474218
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RE: Can You Have A 748F With A Streched Bubble

Mon Apr 20, 2009 12:12 am



Quoting DocLightning (Reply 7):
I understand that a benefit of stretching the hump was that it fits better in with the area rule by overlapping with the wings.

If there was any aerodynamic advantage to gained with the stretched upper deck, it could be achieved by use of a non-structural fairing in lieu of pressurized mental structure.
 
PGNCS
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RE: Can You Have A 748F With A Streched Bubble

Tue Apr 21, 2009 4:04 pm



Quoting 474218 (Reply 8):
pressurized mental structure

I have never heard this term in connection with a Boeing airplane before, but I like it! Big grin
 
474218
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RE: Can You Have A 748F With A Streched Bubble

Tue Apr 21, 2009 5:52 pm



Quoting PGNCS (Reply 9):
I have never heard this term in connection with a Boeing airplane before, but I like it!

a-net's spell check just doesn't catch those wrong word that are spelled correctly.

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