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Why An Upper Deck For The 747?  
User currently offlineAman777 From Canada, joined Aug 2005, 13 posts, RR: 0
Posted (9 years 3 months 1 week 6 days 14 hours ago) and read 12580 times:

Hi guyz!

This actually might have been discussed before, but because I am not too sure I like to post it again anyway.

Does any know the reason why the 747 has an upper deck. Why couldn't it have been designed with just one deck. I really can't picture why they would just put an 1/4 of upper deck instead of just perhaps stretching the airplane out few more feet backwards like the 777-300ER

I have heard that the upper deck contributes to the lift capability of the airplane to some extent, could this be the only reason? Or are there other reasons for doing this?

37 replies: All unread, showing first 25:
 
User currently offlineB6sea From United States of America, joined Aug 2005, 340 posts, RR: 0
Reply 1, posted (9 years 3 months 1 week 6 days 14 hours ago) and read 12543 times:

I dont know the technical reasons or anything, but I believe a major reason was just because they could. By putting an extra deck on a plane they could make the plane unique and thus desirable by airlines ie: "Be the first to fly the only double-deck airliner on __your airline here__!". Just my thoughts though.

-Chans


User currently offlineTrex8 From United States of America, joined Nov 2002, 4871 posts, RR: 14
Reply 2, posted (9 years 3 months 1 week 6 days 14 hours ago) and read 12529 times:
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Boeing used its design for the USAF competition for a large airlifter, won by Lockheed with its C5 Galaxy, as the basis for its 747 design. The USAF requirement included a nose cargo door with the cockpit elevated above the main deck. thats how the 747 got to look like the 747.

User currently offlineJdwfloyd From United States of America, joined Feb 2005, 837 posts, RR: 4
Reply 3, posted (9 years 3 months 1 week 6 days 14 hours ago) and read 12498 times:

Like Trex said the 747 was intended to be a cargo only A/C, the pax model was an after thought. The expected the sales to be mainly cargo operators.

User currently offlineCkfred From United States of America, joined Apr 2001, 5310 posts, RR: 1
Reply 4, posted (9 years 3 months 1 week 6 days 14 hours ago) and read 12495 times:

My understanding is that the 747 airframe was originally designed as a cargo plane, which competed against Lockheed's design for the C-5 program. The nose was required to open, so that very large cargo, such as tanks, trucks, etc., could be loaded. This required an upper deck for the flight crew.

When Boeing lost the competition to Lockheed, Boeing then turned the design of the airframe into a widebody passenger plane. Boeing had doubts about using a double-decker design that, in a sense, but two 707 fuselages on top of each other. So the cargo airframe solved the problem.

The upper deck was kept, since Boeing still planned a cargo version of the plane, it gave the pilots a great view, and allowed space for a lounge. The 377 had a lounge on a lower deck.


User currently offlineSATL382G From , joined Dec 1969, posts, RR:
Reply 5, posted (9 years 3 months 1 week 6 days 14 hours ago) and read 12483 times:

Boeing didn't think the 747 would last long as a pax aircraft. The 2707 SST was coming along and Boeing thought the 747 would be delegated to cargo duties. Putting the cockpit on the 2nd deck opened up a lot of potential cargo space. Just cut in a cargo door and you're good to go..

The 2707 got canceled and the rest is history....

regards....


User currently offlineHA_DC9 From United States of America, joined Jul 1999, 656 posts, RR: 1
Reply 6, posted (9 years 3 months 1 week 6 days 14 hours ago) and read 12471 times:

IIRC...When the 747 was being intended as a cargo aircraft, only the flight deck was designed with a small "hump" around the flight deck due to the clearance requirments of the cargo deck and forward-loading cargo door. However, it was discovered to be more aerodynamic for the "hump" to be stretched further back giving the look the 747 is known for today. As a result of the stretched "hump", more space became available creating the upper deck.

User currently offlinePilottim747 From United States of America, joined Jul 2001, 1607 posts, RR: 5
Reply 7, posted (9 years 3 months 1 week 6 days 14 hours ago) and read 12450 times:

According to the PBS program Chasing the Sun which aired in 2003, the upper deck was born because airlines wanted the 747 to be a cargo jet as well as passenger jet (as others above have said). However, this documentary said that Boeing engineers were worried about heavy cargo containers smashing into the cockpit in the event of an accident. So the engineers designed the upper deck to keep the pilots up above the cargo, which could supposedly break loose in an accident.

Initially Boeing had intended the rest of the upper deck to be used for navigation equipment. The PBS documentary gives Juan Trippe (of Pan Am fame) credit for coming up with the idea that the upper deck could be used for passengers. In Pan Am's case it was initially used as a lounge.

pilottim747



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User currently offlineMainliner From United States of America, joined Aug 2005, 421 posts, RR: 0
Reply 8, posted (9 years 3 months 1 week 6 days 14 hours ago) and read 12419 times:

From the beginning Boeing envisioned the 747 to be a freighter. Designers wanted the nose of the aircraft to swing upward to allow the loading of freight, so they placed the cockpit above the main deck to allow this. I read somewhere that Boeing hadn't originally planned to put any passenger seating in the upper deck, but they extended the upper deck to accomodate a first class section at the request of Pan Am.


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User currently offlineWdleiser From United States of America, joined Apr 2004, 962 posts, RR: 3
Reply 9, posted (9 years 3 months 1 week 6 days 13 hours ago) and read 12287 times:

Quoting Pilottim747 (Reply 7):

I saw that too. So yes, I do believe the upper deck was created not only for the nose loading capabilities but also for so if cargo were to shift it could not go crashing into the cockpit.


User currently offlineGlom From United Kingdom, joined Apr 2005, 2821 posts, RR: 10
Reply 10, posted (9 years 3 months 1 week 6 days 13 hours ago) and read 12276 times:

As stated, the 747 was originally Boeing's bid for a USAF air carrier and when it was defeated by the Lockheed C-5, they developed it for commercial use, envisioning it's future mainly in freight as Concorde and the 2707 take over pax travel. The noseloading was an important part of the aircraft's capability. That's how the small hump got to be there. When the 747 unexpectedly became a success in pax travel, Boeing decided to increase capacity for the -300 model by stretching the upper deck, which also had the added benefit of improving aerodynamics, and this carried over onto the -400. The freighters retain the shortened upper deck though because a stretched upper deck causes more problems than it solves for those purposes.

User currently offlineHa763 From United States of America, joined Jan 2003, 3671 posts, RR: 5
Reply 11, posted (9 years 3 months 1 week 6 days 8 hours ago) and read 11920 times:
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Quoting Trex8 (Reply 2):



Quoting Glom (Reply 10):

That is incorrect. True, Boeing lost the CX-HLS competiton, which became the Lockheed C-5, and that the 747 team was made up mostly of the same people who worked on the CX-HLS team. However, Boeing evaluated over 200 different designs, all created after losing the CX-HLS competition, before deciding on the 747 shape that we know today. One design was a full double deck aircraft with a mid-wing design (wing located between the 2 decks). Another design was a single deck with the cockpit lower than the pax deck (similar to Airbus' Beluga). Boeing also looked into having a double decker with a cross-section that would only sit 2-3-2, which was later used for the 767. In fact, most of the designs were full double deckers.


User currently offlineLincoln From United States of America, joined Nov 2004, 3887 posts, RR: 8
Reply 12, posted (9 years 3 months 1 week 6 days 7 hours ago) and read 11845 times:

I had always heard the "Not expected to last as a pax aircraft" explaination, but this leads me to a (potentially stupid) question:

How is (was) the upper deck on nose-loading 747s? Clearly a staircase in the middle of the cabin, as in the pax versions, would sigificantly limit the benefit of having a nose that opens  Smile. AFAIK, the upper deck doors on the 747 are intended for emergency exit only.

Lincoln



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User currently offlineDazeflight From Germany, joined Jun 1999, 580 posts, RR: 2
Reply 13, posted (9 years 3 months 1 week 6 days 7 hours ago) and read 11830 times:

Quoting Lincoln (Reply 12):
How is (was) the upper deck on nose-loading 747s? Clearly a staircase in the middle of the cabin, as in the pax versions, would sigificantly limit the benefit of having a nose that opens Smile. AFAIK, the upper deck doors on the 747 are intended for emergency exit only.

well, it's not like you cannot build in removable stairs or a ladder ...

ciao
Daniel


User currently offlineFriendlySkies From United States of America, joined Aug 2004, 4120 posts, RR: 5
Reply 14, posted (9 years 3 months 1 week 6 days 7 hours ago) and read 11812 times:

I think the F models have a ladder that swings down to allow the passage of freight.

User currently offlineLorM From United States of America, joined Jun 2004, 409 posts, RR: 1
Reply 15, posted (9 years 3 months 1 week 6 days 7 hours ago) and read 11799 times:

The staircase in a 747F are totally different from a passenger 747. It is a retracting ladder, albeit if limited retract. It swings/retracts upward.

The 747 / C-5 development programs also were the first to use the now wonderful high-bypass engines. PW JTD9s on the 747 and the GE TF39s on the C-5.

[Edited 2005-09-12 04:30:45]


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User currently offlineHa763 From United States of America, joined Jan 2003, 3671 posts, RR: 5
Reply 16, posted (9 years 3 months 1 week 6 days 7 hours ago) and read 11791 times:
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Quoting Lincoln (Reply 12):
How is (was) the upper deck on nose-loading 747s? Clearly a staircase in the middle of the cabin, as in the pax versions, would sigificantly limit the benefit of having a nose that opens

All that happens is that you lose 1 loading space. If you look at the loading configuration, you will see that there is only space for one pallet in the 2nd position instead of 2. The other position is where the stair are located.



Here's some pictures of where the stairs are located on a converted pax 742SF and a 744F with the nose door.


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User currently offlineAR385 From Mexico, joined Nov 2003, 6602 posts, RR: 35
Reply 17, posted (9 years 3 months 1 week 5 days 23 hours ago) and read 11436 times:
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Yes to all, it was designed as a cargo plane and Boeing did not worried too much whe loosing the competition to Lockheed, because they knew there would be additional markets for their carga plane

The " hump" also contributes to the aerodynamic efficiency of the aircraft and apparently the longer it is (743, 744) the more contribution.


User currently offlineTrex8 From United States of America, joined Nov 2002, 4871 posts, RR: 14
Reply 18, posted (9 years 3 months 1 week 5 days 22 hours ago) and read 11106 times:
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Quoting Ha763 (Reply 11):
That is incorrect.

thats strange, they should stop the guides at Boeing tours telling that story then!


User currently offlineHailstone From Germany, joined Nov 2000, 410 posts, RR: 0
Reply 19, posted (9 years 3 months 1 week 5 days 21 hours ago) and read 10786 times:

there is a great book out there - get it if you can get your hands on it:"Wide Body - The Making of the 747" by Clive Irving, ISBN 0340534877

User currently offlineTockeyhockey From United States of America, joined Feb 2005, 952 posts, RR: 0
Reply 20, posted (9 years 3 months 1 week 5 days 20 hours ago) and read 10238 times:

as i understand it, the hump is part of what allows the 747 to be the fastest passenger jet in the skies. this has something to do with the "area rule" which, put simply, is that in order for maximum efficiency, an object should have as close to the same amount of surface area along its entire length. the extra surface are created by the hump balances out extra surface area created where the wings intersect with the fuselage.

i'm no aerodynamics expert, so correct me if i'm wrong, but this is the explanation that i've heard.


User currently offlineYYZYYT From Canada, joined Apr 2005, 999 posts, RR: 0
Reply 21, posted (9 years 3 months 1 week 5 days 19 hours ago) and read 9831 times:

I

Quoting Tockeyhockey (Reply 20):
as i understand it, the hump is part of what allows the 747 to be the fastest passenger jet in the skies. this has something to do with the "area rule" which, put simply, is that in order for maximum efficiency, an object should have as close to the same amount of surface area along its entire length. the extra surface are created by the hump balances out extra surface area created where the wings intersect with the fuselage.

i'm no aerodynamics expert, so correct me if i'm wrong, but this is the explanation that i've heard.

I have heard the same thing.

And while I'm no aerodynaic expert, some of the psoters on these former threads are:

747 Cockpit Location Vs. A380 Cockpit Location (by Thrust Jan 22 2005 in Tech Ops)

A380 Aerodynamics (by BAW2198 Jan 31 2005 in Tech Ops)


User currently offlineTod From Denmark, joined Aug 2004, 1729 posts, RR: 3
Reply 22, posted (9 years 3 months 1 week 5 days 18 hours ago) and read 9358 times:

Quoting Ha763 (Reply 16):
All that happens is that you lose 1 loading space

Since the stairs are located just forward of the constant section of the fuselage, it appears as though you would not actually fit a full sized container in that position anyway.

Tod


User currently offlineAirPacific747 From Denmark, joined May 2008, 2477 posts, RR: 24
Reply 23, posted (9 years 3 months 1 week 5 days 17 hours ago) and read 8585 times:

Quoting Tod (Reply 22):
Since the stairs are located just forward of the constant section of the fuselage, it appears as though you would not actually fit a full sized container in that position anyway.

Tod

The stairs must be retractable, and they are in the front, so the pilots dont need to get up in the cockpit that early anyway.. then you dont lose any space


User currently offlineTod From Denmark, joined Aug 2004, 1729 posts, RR: 3
Reply 24, posted (9 years 3 months 1 week 5 days 16 hours ago) and read 8461 times:

Quoting AirPacific747 (Reply 23):
The stairs must be retractable, and they are in the front, so the pilots dont need to get up in the cockpit that early anyway.. then you dont lose any space

But they do like to be able to get out of the aircraft in a timely manner without climbing out the cockpit ceiling hatch and using the excape rope.

Tod


25 Flanker : yep tahts what ive herd also
26 Flanker : yep tahts what ive herd also
27 747Loadmaster : They shout down at you every 10 minutes to put the stairs down and you have to stop everything for them to get up and down.
28 Okie : Well the story I got was that Boeing had pretty much won all aspects of the selection process. Unfortunately for the for the USAF, a certain senator
29 UAL747DEN : This is my favorite of all times questions. As we all know PanAm went to Boeing and said we want a double decker. Because of the large numbers of orde
30 Smokescreen : I have two (possibly dumb) related questions: what, if anything, is done with the upper deck on cargo 747's? Do they use it for smaller items or is it
31 Tod : Galley, lav and seating for supernumeraries. The new 744SF has a fairly normal u/d until you get back to the doors. Tod
32 Smokescreen : Thanks. Are the "supernumeraries" you mention non-rev's, or is it possible to book seats on a freighter? Of course the latter would only appeal to us
33 Alessandro : I think the limitation of ramp-space as well played a role?
34 Tod : Supernumeraries are the people that fly along with their cargo. I am not aware of anyone booking seats on freighters. As far as non-rev travel, I don
35 DarthRandall : So, its primary appeal was as a freighter, and nobody thought that it would take off as a passenger aircraft. The more things change, the more things
36 Post contains images Gearup : Ah, you guys have it all wrong! The hump on the 747 was put there so as the pilots could sit on their wallets!!!
37 RayChuang : People forget that if you look at Boeing's proposal for the CX-HLS, the design strongly resembled what the Antonov An-124 became. As such, the 747 bor
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