Aman777 From Canada, joined Aug 2005, 13 posts, RR: 0 Posted (9 years 5 days 1 hour ago) and read 12327 times:
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 From United States of America, joined Aug 2005, 340 posts, RR: 0
Reply 1, posted (9 years 5 days 1 hour ago) and read 12290 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.
Trex8 From United States of America, joined Nov 2002, 4768 posts, RR: 14
Reply 2, posted (9 years 5 days 1 hour ago) and read 12276 times:
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.
Ckfred From United States of America, joined Apr 2001, 5234 posts, RR: 1
Reply 4, posted (9 years 5 days 1 hour ago) and read 12242 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.
SATL382G From , joined Dec 1969, posts, RR:
Reply 5, posted (9 years 5 days 1 hour ago) and read 12230 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..
HA_DC9 From United States of America, joined Jul 1999, 653 posts, RR: 1
Reply 6, posted (9 years 5 days 1 hour ago) and read 12218 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.
Pilottim747 From United States of America, joined Jul 2001, 1607 posts, RR: 5
Reply 7, posted (9 years 5 days 1 hour ago) and read 12197 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.
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Mainliner From United States of America, joined Aug 2005, 412 posts, RR: 0
Reply 8, posted (9 years 5 days ago) and read 12166 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.
Glom From United Kingdom, joined Apr 2005, 2818 posts, RR: 10
Reply 10, posted (9 years 5 days ago) and read 12023 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.
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 From United States of America, joined Nov 2004, 3887 posts, RR: 8
Reply 12, posted (9 years 4 days 18 hours ago) and read 11592 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 . AFAIK, the upper deck doors on the 747 are intended for emergency exit only.
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Dazeflight From Germany, joined Jun 1999, 580 posts, RR: 2
Reply 13, posted (9 years 4 days 18 hours ago) and read 11577 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 ...
Ha763 From United States of America, joined Jan 2003, 3657 posts, RR: 5
Reply 16, posted (9 years 4 days 17 hours ago) and read 11538 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
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.
Tockeyhockey From United States of America, joined Feb 2005, 950 posts, RR: 0
Reply 20, posted (9 years 4 days 7 hours ago) and read 9985 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.
YYZYYT From Canada, joined Apr 2005, 954 posts, RR: 0
Reply 21, posted (9 years 4 days 6 hours ago) and read 9578 times:
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:
AirPacific747 From Denmark, joined May 2008, 2404 posts, RR: 24
Reply 23, posted (9 years 4 days 3 hours ago) and read 8332 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.
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