Aman777
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Why An Upper Deck For The 747?

Mon Sep 12, 2005 4:13 am

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?
 
b6sea
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 4:19 am

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
 
trex8
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 4:22 am

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.
 
jdwfloyd
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 4:25 am

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.
 
ckfred
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 4:25 am

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.
 
SATL382G
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 4:27 am

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....
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HA_DC9
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 4:28 am

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.
 
pilottim747
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 4:31 am

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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Mainliner
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 4:37 am

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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wdleiser
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 5:19 am

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.
 
Glom
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 5:20 am

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.
 
ha763
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 10:38 am

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.
 
lincoln
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 11:12 am

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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dazeflight
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 11:18 am

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
 
FriendlySkies
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 11:24 am

I think the F models have a ladder that swings down to allow the passage of freight.
 
lorm
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 11:29 am

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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ha763
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 11:31 am

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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AR385
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 7:26 pm

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.
 
trex8
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 8:15 pm

Quoting Ha763 (Reply 11):
That is incorrect.

thats strange, they should stop the guides at Boeing tours telling that story then!
 
hailstone
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 9:04 pm

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
 
tockeyhockey
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 10:21 pm

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.
 
YYZYYT
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RE: Why An Upper Deck For The 747?

Mon Sep 12, 2005 11:18 pm

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)
 
Tod
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 12:10 am

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
 
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AirPacific747
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 1:35 am

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
 
Tod
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 1:47 am

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
 
flanker
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 2:14 am

Quoting AR385 (Reply 17):

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

yep tahts what ive herd also
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flanker
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 2:15 am

Quoting AR385 (Reply 17):

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

yep tahts what ive herd also
Calling an illegal alien an 'undocumented immigrant' is like calling a drug dealer an unlicensed pharmacist
 
747Loadmaster
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 2:29 am

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.
 
Okie
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 4:07 am

Quoting Ha763 (Reply 11):
That is incorrect. True, Boeing lost the CX-HLS competiton,

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 who was on the selection committee from a southern state where Lockheed had production facilities twisted a few arms and the Lockheed version was chosen.
This allowed Boeing to concentrate on commercial applications and Lockheed on military. While there were some teething problems with the 747, the C-5 had many problems from the start, the kneeling landing gear and wing cracks come to mind.

Okie
 
ual747den
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 4:08 am

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 orders from PanAm Boeing set out to design a special aircraft only for PanAm. The original design was two 707's stacked. During the design Boeing thought that air transport was going the direction of SST so in an effort to have a design that might attract others they looked at how many cargo containers would fit into it. Obviously they couldn't put any on top so it would not have been a very attractive aircraft to cargo airlines. One of the designers made a design that would be large enough to put 2 cargo containers side by side (The widebody was born) Now that Boeing had an aircraft that would work to carry the cargo they had to find a way to get it in. If it was also going to fly as a pax aircraft there was no way the tail could open so the nose was left therefore they needed to raise the cockpit. They put the cockpit on the second level and built the mockup. Behind the cockpit was empty space just there for aerodynamics. PanAm was still attached to the idea of a double decker so Boeing was forced to make 2 mockups. 1 was 2 707's on top of eachother, it had a very small scary dark looking staircase to the top deck, the mockup had no windows and Boeing told PanAm during the tour that they were still trying to see if the plane could have windows on the bottom deck. (They had just not had anyone look at it before the tour, some say it was a purpose mistake)
Setting right next to the plane PanAm wanted was the other mockup. After the tour Boeing officials asked Juan if he would like to see what they thought would be a better plane for his needs. They showed him the widebody and the last part of the tour was the cockpit, Juan wasn't sure and they started walking out of the cockpit where he saw the extra room. Juan asked what this area was going to be used for, Boeing officials said they could use it for a crew rest area or just extra storage area. Juan told them to make to into a pax area by the next time he came back and they would have a sale......

So the 747 was born........
/// UNITED AIRLINES
 
smokescreen
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 4:16 am

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 empty?
Next, given that the 747 arose (indirectly) from a requirement for a military transport, do any militaries around the world use 74F's in that role? Does anyone know the advantages/disadvantages of a cargo 747 over buying a dedicated airlifter like the c-141?
Thanks in advance for your info!
 
Tod
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 4:23 am

Quoting Smokescreen (Reply 30):
what, if anything, is done with the upper deck on cargo 747's

Galley, lav and seating for supernumeraries.
The new 744SF has a fairly normal u/d until you get back to the doors.

Tod
 
smokescreen
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 4:57 am

Quoting Tod (Reply 31):
Galley, lav and seating for supernumeraries.
The new 744SF has a fairly normal u/d until you get back to the doors.

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 airline geeks, but if it is possible then I see a chance to fly a DC-8 once again!
 
Alessandro
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 5:02 am

I think the limitation of ramp-space as well played a role?
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Tod
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 6:55 am

Quoting Smokescreen (Reply 32):
Are the "supernumeraries" you mention non-rev's, or is it possible to book seats on a freighter?

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't know, but I sure others here do.
Unfortunately, I've only been involved with the design and have never had a chance to ride on a freighter.

Tod
 
DarthRandall
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 7:56 am

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 stay the same, eh?

Quoting Okie (Reply 28):
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 who was on the selection committee from a southern state where Lockheed had production facilities twisted a few arms and the Lockheed version was chosen.

Knowing what we know now about the relative reliability of the C-5 and the 747, one has to imagine that some airmen are just a bit perturbed with the senator in question.
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gearup
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 11:16 pm

Ah, you guys have it all wrong! The hump on the 747 was put there so as the pilots could sit on their wallets!!!  Big grin
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RayChuang
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RE: Why An Upper Deck For The 747?

Tue Sep 13, 2005 11:31 pm

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 borrowed from that design competition but the fuselage design owed nothing to the Boeing CX-HLS proposal. Originally designed as a double-decker, the 747 became a single-deck plane because airlines wanted more lower deck cargo carrying capacity with LD3 containers and also because of interest from a number of airlines for a true freighter version with a swing-up front loading door to load and unload outsized cargo. Indeed, the 747 freighter versions literally transformed the world of air cargo during the 1970's, tremendously increasing the amount of air cargo carried.

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