DAYflyer
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Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 1:15 am

Is it possible or practicle for Boeing to replace the venerable 744 with a super-large twin? With the success of the 777 and the advent of the 787 with the new technology, can a twin be made large enough to hold 450 pax?

Could the GE 90-115 engines be uprated to support such an aircraft or would an entirely new engine have to de developed?
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ikramerica
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 1:22 am

The GE90x, using the lighter composite developed for the GEnx, could produce the same power with less weight. So that's 115k, which would be the min thrust needed to lift such a plane if the the other engine fails.

The fuselage, using 787 technology, could be 773+ size with the same weight.

But the length of any such plane would be the limiting factor. Right now the 773 is almost the length of the 346, longer than both the 744 and 380. The 744Adv would be about that length, too.

So is there some rule at airports that says the 346 is as long as it gets?
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aa777flyer
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 1:22 am

Wow, that would be a pretty big twin. I am sure it can be done.
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gigneil
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 1:37 am

Quoting Ikramerica (Reply 1):
So is there some rule at airports that says the 346 is as long as it gets?

The 346 is actually a few meters shy of the limit. Aircraft must fit into an 80m x 80m box.

A twin to replace the 744 would need to be wider (to accomodate 3-4-3 but 3-5-3 would be better) and longer than the 773.

The GE90 could be uprated to 127,000 pounds probably. But the question is, is that enough? No. The 747Adv will have as much as 264,000 pounds of thrust and its a quad with a better engine out profile. A twin would need much, much more power than that.

At this time, it cannot be done, at least not to provide the same range/payload capability.

N
 
na
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 1:42 am

Thinking into the future, I sadly must admit, it can be done. And the projected joint successor of 777-300 and 747 might be a gigantic twin in Boeings planning, though I hope a quad concept will still have a chance.
Thats why I hope the 747 Adv. will become reality.
I hate to think of an aviation world full of aircraft who are all underwing-twinjets, the most common and therefore already now most boring configuaration.
 
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 2:02 am

I feel your pain, but with twins being far more economical to operate, I too fear that the twin is the inevitable successor someday. Perhaps not too soon, but Boeing seems to be going in that direction.
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zvezda
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 2:14 am

If the objective is to replace the B777-300 and B747 with a twin (assuming that a B787-10 replaces the B777-200ER), then we might start with a planned family with fuselage lengths of 60, 70, and 80 meters. A B777 width cabin would not suffice. A circular 270 inch fuselage would accomodate a generous 3-4-3 seating or 3-5-3 at slightly better than B747 comfort levels. The overhead space could accomodate crew rest, passenger bunks, lavs, and galleys -- freeing up main deck space for passenger seating.

As for engines, Boeing would build the 60 meter version first. It would probably weigh less than the B777-300ER, so the GE-90 could be used. Perhaps the 70 meter version could also use a GE-90 (perhaps at 125K lbs thrust). The 80 meter version might need an all new engine or perhaps the GE-90 would rise to the occasion. PW and RR might want to develop all new engines. Quite a bit of progress has already been made in SFC since the GE-90 and more will be made during the time a new engine would be developed.

It seems very clear to me that a twin seating up to 500 could be developed.
 
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 2:21 am

Quoting DAYflyer (Thread starter):
Could the GE 90-115 engines be uprated to support such an aircraft or would an entirely new engine have to de developed?

The catch starts becoming the strength of the engine thrust wake.
As others have noted, the SFC would drop significantly with new designs. But as any graduate of basic propulsion theory knows, the trade off is a larger fan diameter.

What the limit on size comes down to is "will enough runways be widened for the A380 to make a large twin practical." The large engines could be built. They're just going to be pretty far out on the wing to give them the ground clearance they require.

Quoting Zvezda (Reply 6):
PW and RR might want to develop all new engines.

All three manufacturers would want to develop new engines. At 125k+ of thrust, these new engines would logically be geared turbo fans. Ok, I'm biased!  bigthumbsup 

Also, I'm betting that the 80m*80m "box" will be expanded in the next decade. I have no proof, just a hunch.

Lightsaber
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wukka
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 2:34 am

Quoting Lightsaber (Reply 7):
They're just going to be pretty far out on the wing to give them the ground clearance they require.

That was my thought, as well. And the further out they are, the more that asymmetry is noticed, both structurally, and in handling (based on physics and rotation around a vertical axis) in the event of an engine-out. Perhaps some huge tail-mounts... or overhead wings?  biggrin 

Overhead wings might be kinda' cool... then you could look out the window at the huge barn-sized powerplant pushing you through the air.
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 3:23 am

Can Boeing Replace 744 With Larger Twin?

Gosh I hope not!
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zvezda
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RE: Question: Can Boeing Replace 744 With Larger T

Wed Jun 22, 2005 3:39 am

Quoting Lightsaber (Reply 7):
What the limit on size comes down to is "will enough runways be widened for the A380 to make a large twin practical." The large engines could be built. They're just going to be pretty far out on the wing to give them the ground clearance they require.

Huh? We're talking about a twin. There is no way that the engines would be as far out as the outboard engines on a B747 -- or even an A340.

Quoting Lightsaber (Reply 7):
I'm betting that the 80m*80m "box" will be expanded in the next decade. I have no proof, just a hunch.

I would be surprised. Enlarging the 80m*80m box would be extremely expensive and entirely unneeded. No one is even building an 80 meter long airliner yet. The only airliner with an 80 meter wingspan is the WhaleJet. Even the B747Adv would not have an 80 meter wingspan.
 
eatmybologna
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RE: Question: Can Boeing Replace 744 With Larger T

Wed Jun 22, 2005 3:44 am

Why not compromise and go with a tri-engine?
Isn't knowledge more than just the acquisition of information? Shouldn't the acquired information be correct?
 
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tjwgrr
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 4:05 am

Wow!

http://www.cardatabase.net/modifiedairlinerphotos/photos/big/00000911.jpg
Direct KNOBS, maintain 2700' until established on the localizer, cleared ILS runway 26 left approach.
 
Glom
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 4:11 am

What is that? It's insanely long!
 
Blue_Angel
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 4:24 am

Quoting Eatmybologna (Reply 11):

I had the same idea than you  Wink
 
ikramerica
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 4:25 am

Quoting Eatmybologna (Reply 11):
Why not compromise and go with a tri-engine?

maintaining that tail engine and the weight is an issue.

Quoting Zvezda (Reply 6):
A circular 270 inch fuselage would accomodate a generous 3-4-3 seating or 3-5-3 at slightly better than B747 comfort levels.

Heck, at that size, the real luxury would be 2-3-3-2 econ seating (18" wide), 2-2-2-2 business seating (22"), and 1-2-2-1 first suites. Now that would be a luxurious layout.

A frugal airline would do a two class 3-3-3-3, 2-2-2-2. (17"/22") and still provide 747 or better comfort. Or for an airline like VS, the angled upper class suite would be 1-2-2-1.

Also, would the "bubble top" idea need to be dead? Not the same extreme we see it now on the 747, or the full deck of the A380, but just two feet taller in front to be able to put the cockpit above the main cabin with pilot rest/crew rest in the crown space, tapering toward the back, still providing the options Boeing is showing for the 747Adv. Pushing First pax seats forward into the nose like on the 747 really helps with the 80x80 length problem. And it would make this jet a more viable all cargo version, with a swing up/open nose.

There would also be a great economic advantage to developing the GE90x engine, as Boeing would be able to apply it to the 772LR/773ER jets as well. Then the GENx engines would power the midsize planes (and any 747Adv), the GE90x would power the large planes. A GENx variation from the 783 could also be used on the larger two 737/757/762 replacement models, with a next gen CFM for the smaller two 737 replacements. Of course, this also would hold true for RR engines, including if they want to enter the 115k+ market.
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wukka
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RE: Question: Can Boeing Replace 744 With Larger T

Wed Jun 22, 2005 4:44 am

Quoting Zvezda (Reply 10):
Huh? We're talking about a twin. There is no way that the engines would be as far out as the outboard engines on a B747 -- or even an A340.

Right, Zvezda, we're talking about a twin. The 74x and the 34x are quads. It's the overall fan diameter to provide an equal amount of thrust for one engine on one side vs. two distributed engines on one side that makes this an issue. The placement of the center of thrust would certainly bring the larger single engine on a twin closer to the fuse than the furthest outboard of a quad based on equal displacement... but, the diameter of the engine required on the twin becomes an issue with ground clearance. Extended height gear might be an option to keep the cowling from digging into the concrete on an underwing design, but then it becomes a design / torque / structural issue for the gear around the horizontal axis on rotation and landing.
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gigneil
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 5:43 am

Quoting Eatmybologna (Reply 11):
Why not compromise and go with a tri-engine?

Quads are of superior design than trijets. The tail and rear fuselage construction of a tri is so heavy and complex that you ruin any advantages.


I maintain that even a 130,000 pound GE-90 is insufficient to power an aircraft with the range and payload capability of a 747-400.

N
 
flyAUA
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 5:44 am

Although I am no rocket scientist, I think it would be hard to make an aircraft like the B744 with 2 engines that produced 113500 lb of thrust each. Unless you have some kind of new technology to invent big-ass engines that were really powerful.

Quoting Glom (Reply 13):
What is that? It's insanely long!

It's called photoshopping  Wink
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zvezda
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RE: Question: Can Boeing Replace 744 With Larger T

Wed Jun 22, 2005 5:44 am

Quoting Zvezda (Reply 6):
A circular 270 inch fuselage would accomodate a generous 3-4-3 seating or 3-5-3 at slightly better than B747 comfort levels.



Quoting Ikramerica (Reply 15):

Heck, at that size, the real luxury would be 2-3-3-2 econ seating (18" wide), 2-2-2-2 business seating (22"), and 1-2-2-1 first suites. Now that would be a luxurious layout.

The WhaleJet has a 281 inch fuselage width. Because of the inefficiencies of metal in an ovoid fuselage, the interior width would be much nearer. Airbus have not proposed any three aisle seating arrangements and I don't believe they have enough width to do so sensibly. Another 20 or so inches would be required. At 270 inches (exterior diameter), one could fit 3-4-3 or 3-5-3 in Economy, 2-2/2-2 in Business and 1-2-1 First suites in a herringbone arrangement. Aisles would need to be 24 to 30 inches to have reasonable embarcation/debarcation times.

Quoting Ikramerica (Reply 15):
Also, would the "bubble top" idea need to be dead? Not the same extreme we see it now on the 747, or the full deck of the A380, but just two feet taller in front to be able to put the cockpit above the main cabin with pilot rest/crew rest in the crown space, tapering toward the back, still providing the options Boeing is showing for the 747Adv. Pushing First pax seats forward into the nose like on the 747 really helps with the 80x80 length problem. And it would make this jet a more viable all cargo version, with a swing up/open nose.

Good points. Keep in mind that the height of a B747 from the low point of the fuselage to the top of the hump is 309 inches. The change to a composite fuselage could reduce that to about 300 inches with the same interior space.

Quoting Wukka (Reply 16):
It's the overall fan diameter to provide an equal amount of thrust for one engine on one side vs. two distributed engines on one side that makes this an issue.

The question was about airports being able to accomodate the aircraft. There is no way that one would "solve" the ground clearance problem by putting the engines farther out than the outboard engines of existing quads because that would cause other problems including 1) the thrust would be too far from the centerline for single-engine takeoffs and 2) the wings would need to be much stronger and hence heavier. Longer landing gear is the obvious solution to the ground clearance issue.
 
wukka
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 7:43 am

Quoting Zvezda (Reply 19):
There is no way that one would "solve" the ground clearance problem by putting the engines farther out than the outboard engines of existing quads because that would cause other problems including 1) the thrust would be too far from the centerline for single-engine takeoffs and 2) the wings would need to be much stronger and hence heavier.

Not necessarily. Current wing design has +horizontal from the wing root on out from the center, giving them somewhat of a "V" shape. This, over the length of the wing, can give a few more feet of clearance for engine mounting. One also has to account for downward flex based on the weight of the engine, of course.

I don't think that anyone suggested going further off of the midline than the furthest out of the existing quads. If I missed that suggestion, I apologise!
We can agree to disagree.
 
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 8:56 am

Quoting Gigneil (Reply 17):
I maintain that even a 130,000 pound GE-90 is insufficient to power an aircraft with the range and payload capability of a 747-400.

I agree and any twin replacent of that scale is going to have to be wider, not longer. With the 80 meter box, the only way is to increase the cabin width by about 20"-24.
 
zvezda
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 8:56 am

Quoting Wukka (Reply 20):

I don't think that anyone suggested going further off of the midline than the furthest out of the existing quads. If I missed that suggestion, I apologise!



Quoting Lightsaber (Reply 7):

What the limit on size comes down to is "will enough runways be widened for the A380 to make a large twin practical." The large engines could be built. They're just going to be pretty far out on the wing to give them the ground clearance they require.

The only reason runways might need to be widened would be to prevent ingestion of material. There must be concrete or asphalt under the engines which is why a lot of taxiways have been widened to accomodate the WhaleJet.
 
zvezda
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 9:04 am

Quoting Gigneil (Reply 17):
I maintain that even a 130,000 pound GE-90 is insufficient to power an aircraft with the range and payload capability of a 747-400.

Not everyone needs 8000nm range. Might Boeing not choose to offers models with different wings as they have with the B787-3 and B787-8/9? The short range versions could, I believe, be powered by 120K or 125K lbs thrust engines. The long range versions would need 135K to 145K lbs thrust and I don't think the GE-90 can be certified to 145K lbs.
 
ikramerica
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 9:43 am

Quoting Zvezda (Reply 19):
The WhaleJet has a 281 inch fuselage width. Because of the inefficiencies of metal in an ovoid fuselage, the interior width would be much nearer. ... Another 20 or so inches would be required. At 270 inches (exterior diameter), one could fit 3-4-3 or 3-5-3 in Economy, 2-2/2-2 in Business and 1-2-1 First suites in a herringbone arrangement. Aisles would need to be 24 to 30 inches to have reasonable embarcation/debarcation times.

A. I thought he was talking an interior of 270 inches. The A380 has a main cabin interior of 259 in.

B. No it wouldn't need 20 more inches. 270 would be more than enough to fit 2-3-3-2 at 18" seats with 24" aisles, or 17" with 21" aisles in a cattle car configuration. It's more desirable than 3-4-3 or 3-5-3, and holds the same or more people per row.

C. 30" is pretty damn wide for an economy aisle. 24" is fine, and 21" is still workable. With three aisles, the luxury economy seating loads 3.333 seats per row per aisle, and even in the dense economy seating, each aisle only loads 4 seats per row. This would really speed up embarkation, not slow it down, as it would make it among the best ratio jets in the sky. Compare with an ERJ (3 seats per row per aisle), 767 (3.5 seats per row per aisle), CRJ/E170/787/A300/310/330/340/350/380(upper) (4 seats per row per aisle), DC10/MD11/L1011/777 (4.5 seats per row per aisle), MD-80/Fokker/747(main)/A380(main) (5 seats per row per aisle), 707/727/737/757/A320/747(upper) (6 seats per row per aisle).

All you'd need would be a wider door 2 to ease boarding, but a standard door 1 would suffice. Also at this width, the fuselage would likely be ovoid in the wide direction versus the tall, or some sort of "double bubble" design, but not stacked. I know this multiple tube design has been explored at Boeing and other places, even in a flying wing design.
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zvezda
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 10:05 am

A cabin width of 270 inches could just accomodate a three aisle configuration, however, that would require a fuselage diameter of at least 280 inches (assuming circular and composite). If ovoid (in either direction) or metal then the fuselage would be wider -- perhaps 290 inches. Regardless, I expect many airlines would pack in 3-6-3 seating before adding a third aisle.
 
wukka
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 10:10 am

Quoting Zvezda (Reply 22):
The only reason runways might need to be widened would be to prevent ingestion of material. There must be concrete or asphalt under the engines which is why a lot of taxiways have been widened to accomodate the WhaleJet.

I don't think that you're getting what we're saying. Modern wings tend to taper up (higher off the ground) the further away from the fuselage of the plane. A bigger diameter engine hanging under the wing has a finite amount of space to work with. The only way to fit a larger circumference engine under the wing while the plane is on the ground is to lift the entire fuselage higher off the ground, or place the engines further out on a wing that is tapered upward, or a combination of both... unless you move to a tail-mount engine or an overhead wing.
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zvezda
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 10:20 am

Quoting Wukka (Reply 26):
I don't think that you're getting what we're saying. Modern wings tend to taper up (higher off the ground) the further away from the fuselage of the plane. A bigger diameter engine hanging under the wing has a finite amount of space to work with. The only way to fit a larger circumference engine under the wing while the plane is on the ground is to lift the entire fuselage higher off the ground, or place the engines further out on a wing that is tapered upward, or a combination of both...

Of course I get that. Lightsaber was talking about widening runways because the engines would have to be farther out. That's absurd. As I pointed out already, there are compelling reasons not to put the engines farther out. Raising the fuselage higher of the ground is absolutely the better solution and probably necessary anyway to avoid tail strikes with an 80 meter length. Once you're high enough off the ground to avoid tail strikes with an 80 meter airliner, I really don't think you're going to have any ground clearance problems with the engines. Even if you were to, then you just raise the entire fuselage a little higher.
 
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 10:44 pm

I think it is entirely feasable to do this. I think if you upgrade the GE 90 series to 145K of thrust it could be done. Then of course the landing gear would have to be taller (757 style).
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zoom1018
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 10:57 pm

Quoting Eatmybologna (Reply 11):
Why not compromise and go with a tri-engine?

I would also like to have a new 3 holers... a really big trijet would be great!
 
kalakaua
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 11:09 pm

To answer your thread topic question...
Why not keep both? Haha.
Modified Airliner Photos:
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Design © Fu Ling Yu
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Or... Something like this.

Modified Airliner Photos:
Click here for bigger photo!
Design © Fu Ling Yu
Template © Nathan Long

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United Airline
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 11:24 pm

I don't think so. That will be way too long. For super large aircraft like 400+ seats ones you need 4 engines.

But I wonder if Boeing can build a B 747 with 2 engines. That will be cool. Big grin
 
flyAUA
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 11:30 pm

Quoting Kalakaua (Reply 30):
Modified Airliner Photos:

Design © Fu Ling Yu
Template © Curtis Hedlund

I really hope this never happens. At least I would never set foot on it!
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zvezda
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RE: Question: Can Boeing Replace 744 With Larger T

Wed Jun 22, 2005 11:39 pm

Quoting United Airline (Reply 31):

But I wonder if Boeing can build a B 747 with 2 engines.

The reduction of structural weight by using composites facilitates going from four engines to two. Slapping two enormous engines on a B747-400 wouldn't be a good idea. The landing gear would need to be a lot taller for the engines to clear the ground and the wings would have to be stronger in some places and hopefully lighter overall. Once you've replaced the center wing box and wings with all-new carbon fibre designs, you'd might as well replace the fuselage as well. I also doubt the FAA would let Boeing certify such a kluge as a B747 and the fuselage cannot be certified as a new type because it doesn't meet current standards. So, there is no way we're going to see a B747 twin.
 
DAYflyer
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 11:47 pm

Quoting Zvezda (Reply 33):
I also doubt the FAA would let Boeing certify such a kluge as a B747 and the fuselage cannot be certified as a new type because it doesn't meet current standards. So, there is no way we're going to see a B747 twin.

I agree, but I do think a 744 replacement is possible in a twin when composite technology is applied.
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United Airline
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Wed Jun 22, 2005 11:55 pm

When it comes to B 747 replacement we will probably see the B 747-600/700, or an A 380 size aircraft. The BWB is possible too (eventually they will get there)
 
HiFi
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 2:37 am

Quoting Zoom1018 (Reply 29):
Quoting Eatmybologna (Reply 11):
Why not compromise and go with a tri-engine?

I would also like to have a new 3 holers... a really big trijet would be great!

Tri-holers are not really viable these days... besides the already mentioned maintenance and structural reinforcement problems, a truly efficient air inlet for the third engine is very hard to achieve. Efficiency of the fin is also reduced and therefore it has to be bigger... this can become critical when talking about super-sized airliners. Fitting an engine on the top of the fuselage becomes more and more difficult when engines are getting larger and larger due to improved by-pass ratios.

The biggest problem for long range twin aircraft was ETOPs. Now that barriers of ETOPs are expanding (120, 180, and so on), the third engine is not that helpful anymore.
no commercial potential
 
ikramerica
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 3:11 am

Quoting Zvezda (Reply 25):
Regardless, I expect many airlines would pack in 3-6-3 seating before adding a third aisle.

And then during the evacuation certification failures, they might change their mind...

Anyway, a 270" fuselage would allow for 3-3-3-3 tourist seating, so why go for 3-6-3?

Quoting Zvezda (Reply 33):
The landing gear would need to be a lot taller for the engines to clear the ground

They tested the GE90 sized engines on the 747 test bed with standard gear IIRC, but an enlarged GE90 might have clearance problems.

2 larger GE90 class engines would weigh the same as 4 current 744 engines, so that is a wash. But the 875k lb weight of the 744(non-ER), 100k lb more than the 773ER, would require more thrust, though not as much more as one would imagine, to allow the 747 to operate as a twin. No way it would ever happen, but it is soon within the realm of reality for a Twin plane in that size to safely operate.

I would say 2010 such a design could safely be launched with confidence, with EIS as early as 2014.
Of all the things to worry about... the Wookie has no pants.
 
gigneil
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 3:15 am

Quoting Ikramerica (Reply 37):
Anyway, a 270" fuselage would allow for 3-3-3-3 tourist seating, so why go for 3-6-3?

I don't think that a third aisle would get certified.

It poses some exit problems. How do you escape from the middle aisle.

N
 
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Starlionblue
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 3:16 am

With a total thrust of 264k for a four holer (747Adv) you would need each engine on your proposed equivalent twin to be rated at 198k. That's quite a bit more that is even remotely possible today. Why spend all that money on R&D for a very limited market when you can just make a quad.

In twenty years, things may have changed.
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ikramerica
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 3:23 am

same way you "escape" from ANY aisle? at the cross overs/doorways. just like any other plane, there is a minimum distance to an emergency exit for any seat. a third aisle wouldn't change that...

this multiple aisle scenario has been studied by both airbus and boeing for flying wings and such, and they didn't seem to be concerned you'd be trapped. with fewer seats per aisle, it's likely safer. It just requires wider doors at one or two locations, door 2 and door 4?
Of all the things to worry about... the Wookie has no pants.
 
zvezda
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RE: Question: Can Boeing Replace 744 With Larger T

Thu Jun 23, 2005 7:25 am

Quoting Ikramerica (Reply 37):
Anyway, a 270" fuselage would allow for 3-3-3-3 tourist seating, so why go for 3-6-3?

12 seats at 18 inches each is 216 inches plus 3 aisles at 20 inches each comes to a cabin width of 276 inches. There is no way to fit a 276 inch wide cabin in a 270 (or even a 280) inch diameter fuselage. A 285+ inch fuselage would be needed for 3-3-3-3. With 17.5 inch seats, the fuselage could perhaps be as small as 280 inches in diameter. Note that the WhaleJet's fuselage is 281 inches wide and the cabin is 259 inches wide. Anyway, 2-4-4-2 would make a lot more sense than 3-3-3-3.

Quoting Gigneil (Reply 38):
I don't think that a third aisle would get certified.

It poses some exit problems. How do you escape from the middle aisle.

With enough doors and wide enough aisles, evacuation certification can be achieved for any legal seating arrangement -- even 3-6-6-6-3 (e.g. in a BWB).
 
DAYflyer
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 10:55 am

At 280+ inches, it gives new meaning to the term widebody!
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widebodyphotog
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 11:01 am

Quote:
don't think that a third aisle would get certified.

It poses some exit problems. How do you escape from the middle aisle.

Boeing has done several project studies with three isle configurations, on both single deck and double deck aircraft. Most recently on a proposed 747 successor that featured 11abreast in three isles on the main deck and eight abreast on the upper deck...

Single deck aircraft with 12 abreast in three isles with up to 650 seats have been evaluated as well. While these aircraft were not twins, I think they are still relevant to the discussion. I'll try to dig up some of the particulars and post what I can later on.

-widebodyphotog
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gigneil
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 11:09 am

Quoting DAYflyer (Reply 42):
At 280+ inches, it gives new meaning to the term widebody!

The A380 is 281 inches wide.

N
 
widebodyphotog
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 12:41 pm

http://theaviationspecialist.com/NLA_PA797-3I-9_Sec2.JPG

Some details:

Cabin width trim-to-trim: 324 inches
Circular Fuselage diameter: 342 inches
Lower cargo hold height: 98 inches
Length overall: 248 feet 4 inches
Wing Span: 259 feet 10 inches
MTOW: 1,025,000-1,300,000lbs

-widebodyphotog
If you know what's really going on then you'll know what to do
 
zvezda
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 1:32 pm

Widebodyphotog,

Thanks for providing the details on the example above. I infer from the 342 inch circular cross section (three stairways is also a good clue) that there was passenger seating upstairs. Correct? I infer from the 18 inch difference between the cabin width and the fuselage diameter that this study was for an aluminium fuselage. Correct? Also, do you know the OEW?

-Zvezda
 
DfwRevolution
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RE: Question: Can Boeing Replace 744 With Larger T

Thu Jun 23, 2005 1:46 pm

>> Thanks for providing the details on the example above. I infer from the 342 inch circular cross section (three stairways is also a good clue) that there was passenger seating upstairs. Correct?

I was of the understanding that features like passenger bunks and cabins would be located upstairs, as well as virtually all non-revenue areas save for lavs. It's unlikely that Boeing would move part/all of the gally on the 747, 777, or 787 above deck, but with a 342-inch fuselage, it should be doable.





Would Boeing likely keep the quad configuration if this concept were dusted off in the 2015-2020 timeframe?

The article these graphics were from are old, but here's the link nonetheless-

http://www.aerospaceweb.org/question/design/q0108.shtml

---

I just noticed, but if you take a look at the wingspan of this concept, Boeing goes 15 centimeters up to the maximum of the 80-meter box. That's the space between the A and K keys on your keyboard  Wink

[Edited 2005-06-23 06:51:08]
 
United Airline
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 2:02 pm

The BWB will be double deck I guess?

Wonder if they will resurrect the B 747-600/700 concept. The 700 is similar to the design of the A 380.
 
United Airline
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RE: Question: Can Boeing Replace 744 With Larger Twin?

Thu Jun 23, 2005 2:08 pm

Quoting Widebodyphotog (Reply 43):
Boeing has done several project studies with three isle configurations, on both single deck and double deck aircraft. Most recently on a proposed 747 successor that featured 11abreast in three isles on the main deck and eight abreast on the upper deck...

Single deck aircraft with 12 abreast in three isles with up to 650 seats have been evaluated as well. While these aircraft were not twins, I think they are still relevant to the discussion. I'll try to dig up some of the particulars and post what I can later on.

So there is a chance that it will be double. I hope they will keep it double deck. So will the new aircraft be bigger than the B 747? If yes I suppose it will be a super jumbo.

I am sure they can work on a twin size superjumbo/jumbo.

Anyway I suppose the B 747/773 replacement will not take place anytime soon. According to Boeing they plan to keep the B 747 in production for another 30 years. With the B 747 Advanced, I hope it will capture more orders.

The B 777 is too new and they need not be replaced anytime soon

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