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Why No Double Decker 747?  
User currently offlineRuscoe From Australia, joined Aug 1999, 1562 posts, RR: 2
Posted (11 years 9 months 9 hours ago) and read 2644 times:

It seems like such an obvious thing to do to increase capacity in the 747 that I figure their must be some pretty good reason why Boeing don't simply stretch the upper deck all the way back.

Does anyone know the reason why?

Ruscoe

7 replies: All unread, jump to last
 
User currently offlineThadocta From Australia, joined Aug 2001, 397 posts, RR: 2
Reply 1, posted (11 years 9 months 8 hours ago) and read 2629 times:

Two words - "unfavourable aerodynamics" - which is another way of saying "loss maker".

Dave


User currently offlineRayChuang From United States of America, joined Jun 2000, 8005 posts, RR: 5
Reply 2, posted (11 years 9 months 7 hours ago) and read 2603 times:

Actually, when Boeing was in the development stage of the 747 they did seriously look at a full double-deck configuration. They dropped it because a full double-deck configuration would have sacrificed too much carrying capacity for the LD-3 containers and also would not have been the right structural configuration for a pure freighter, hence the reason why the original 747 came out with a single deck configuration with a small upper deck for the cockpit and a small lounge/seating area just right behind the cockpit.

In a way, the final 747-100 configuration was essentially a heavily modified version of the Boeing C-5 proposal, but with wings mounted on the bottom of the fuselage and still maintaining the ability to incorporate a fold-up nose on the freighter versions.


User currently offlineBackfire From Germany, joined Oct 2006, 0 posts, RR: 0
Reply 3, posted (11 years 9 months 7 hours ago) and read 2587 times:

There were certainly models built of a twin-deck 747 back in the development days. But you can't simply stretch the present upper deck rearwards and hope that it won't seriously alter the aircraft's economic characteristics. The 747's airframe is designed to accommodate the forward twin-deck only; extending it would, at the very least, add a fair amount of weight to the rear of the aircraft which would then upset the aerodynamics. It might fly, but as Thadocta pointed out, it won't necessarily fly economically even with the additional capacity -- and with airline margins as they are, an uneconomical aircraft won't sell.

User currently offlineAvObserver From United States of America, joined Apr 2002, 2472 posts, RR: 9
Reply 4, posted (11 years 8 months 4 weeks 22 hours ago) and read 2386 times:

The original 747 project leader, Joseph Sutter, said himself that a full double deck on the 747 would be structurally inefficient due to added weight. Expect the upper deck to be stretched only slightly in any future 747 stretch proposals.

User currently offlineFlyingbronco05 From United States of America, joined May 2002, 3840 posts, RR: 2
Reply 5, posted (11 years 8 months 4 weeks 22 hours ago) and read 2377 times:

If there are so many negatives, then why is Airbus building the A380?

I personally think the A380 is going to be a flop!



Never Trust Your Fuel Gauge
User currently offlineBrons2 From United States of America, joined Sep 2001, 3013 posts, RR: 4
Reply 6, posted (11 years 8 months 4 weeks 22 hours ago) and read 2374 times:

If you go to Boeing's site and look at the 742's Airport Planning guide, there is a section where it discusses possible future variants of the 747. One of which is a version where the upper deck goes all the way back. Such a variant would have seated 700 passengers, according to the web page.


Firings, if well done, are good for employee morale.
User currently offlineKlaus From Germany, joined Jul 2001, 21442 posts, RR: 53
Reply 7, posted (11 years 8 months 4 weeks 19 hours ago) and read 2339 times:

Flyingbronco05: If there are so many negatives, then why is Airbus building the A380?

The A380 differs in many aspects...
- The upper deck is substantially wider.
- The cargo hold makes much better use of the available space.
- There is considerably less "wasted space" than in the 747 (which was designed in different times with much different priorities and matched those very well - but times have changed since then).
- The entire aerodynamic package for the A380 is designed for the full-length twin-dual-aisle-deck configuration - with room for a stretch.


Flyingbronco05: I personally think the A380 is going to be a flop!

With the already existent pre-orders it doesn´t look a lot like that. But we´ll see.

The point is, there´s a huge difference between trying to modify an existent design and starting from scratch. Superficial outward similarities don´t have all that much weight.


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