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CARST
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737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 8:29 am

With Boeing updating the 737NG to the 737Max, would it be reasonable for them to offer an 737-10? Nearly every week someone asks why there is no real 757 replacement and we seem to be in agreement that the market is to small for a new aircraft in the 752 / 753 / 762 aircraft-size.

So what about stretching the 739 by 3 or 4 rows and adding another belly-tank? Would that make sense? Would this aircraft have enough range for TATL trips? Or would it be too limited by wingarea and its powerplants? At least it should be a low-cost program enhancing the 737Max line with a 4th aircraft and closing the gap to the 787-8.
 
EGCC777LR
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 8:55 am

Maybe I'm wrong on this, but IIRC this has been discussed before and is a no go option. I think it had something to do with the ground clearance of the fuselage being unable to accept a stretch past where the 900 currently is with the current landing gear. And there is no room in the fuselage to accept longer landing gear struts.

I may be wrong, I'm sure there are many more knowledgeable here who can explain further
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scouseflyer
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 8:57 am

I think that the 737-9 is about as long as you can get with the current landing gear as I believe that they'd run into problems with increased tailstrike risk with the plane being too low to the ground. I'm sure that the 757 had taller gear and a differant centre wingbox which would remove commonality with the rest of the MAX family.
 
Burkhard
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 8:58 am

This would be a major investment ( new gears, new gear box ) for a wing that is far to short for such an MTOW increase. Boeing better concentrates on the economics of the -7, -8 and -9 max.
 
TSS
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 9:00 am

Quoting CARST (Thread starter):
So what about stretching the 739 by 3 or 4 rows and adding another belly-tank? Would that make sense? Would this aircraft have enough range for TATL trips? Or would it be too limited by wingarea and its powerplants?

While the wing area and powerplants might be limiting, the current height of the aircraft and it's effect on rotation angles during takeoff would probably be an equal or even bigger limiting factor, at least as far as runway length requirements go. The longer landing gear/greater ground clearance that so many of us were hoping would be incorporated into the 737MAX upgrade would have solved or at least somewhat mitigated the rotation angle problem as well as allowing larger diameter and more powerful/efficient engines to be fitted, but it doesn't look like taller landing gear will be a part of the upgrade, thus a 737-10 is rendered a non-starter.
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CARST
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 11:19 am

But didn't they solve this rotation / tail-strike-risk problem with a software update on the 773 when they discovered that the same problem exists for the very long fuselage of the 773 in relation to its landing gear height?!


Edit: More about the 777 TSP / trail strike prevention in this article:
http://www.boeing.com/commercial/aer...rticles/qtr_1_07/article_02_5.html

[Edited 2011-09-19 04:23:30]
 
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seabosdca
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 11:21 am

Quoting TSS (Reply 4):
While the wing area and powerplants might be limiting, the current height of the aircraft and it's effect on rotation angles during takeoff would probably be an equal or even bigger limiting factor, at least as far as runway length requirements go.

   The 739 already has terrible runway performance, mostly because of rotation angles. I don't think a 737-10, absent new landing gear, could have realistically usable runway performance.
 
tdscanuck
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 1:57 pm

Quoting CARST (Thread starter):
With Boeing updating the 737NG to the 737Max, would it be reasonable for them to offer an 737-10?

No.

Quoting CARST (Thread starter):
Nearly every week someone asks why there is no real 757 replacement

And every week the answer is the same...the 737-900/A321 cover about 90%+ of the market and what's left isn't economical to design another type.

Quoting CARST (Thread starter):
So what about stretching the 739 by 3 or 4 rows and adding another belly-tank? Would that make sense? Would this aircraft have enough range for TATL trips?

It would not make sense. That much stretch would ruin the rotation angles, the additional weight would curb range and adding a belly tank would not be enough to recover that. A 737-10 as described wouldn't be able to hold range with a 737-900ER.

Quoting CARST (Reply 5):
But didn't they solve this rotation / tail-strike-risk problem with a software update on the 773 when they discovered that the same problem exists for the very long fuselage of the 773 in relation to its landing gear height?!

It wasn't exactly the same problem. The 777-300 uses a semi-levered landing gear to help with clearance (not an option available to the 737) and the problem wasn't as severe as the 737.

Tom.
 
CargoIT
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 2:57 pm

I think a 737-800LR would be more likley. Up the MTOW to about the same as the -900 and add fuel tanks in the belly. Keep in mind that the TATL 757-200s generally have a few less seats than the ones used on domestic routs.
 
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 3:13 pm

Quoting CargoIT (Reply 8):

Sure, but it's not that simple. Just look at the 752 from the inside out and its A LOT different from the 738. Nevermind the huge wing, fuel capacity, and the large engines slung under the wings. Its not just a matter of adding a fuel tank. And upping MTOW. Such an a/c would be severly payload optimized.

We need to come to grips that the current design of the 737 has its limits as far as upgrades and missions.
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ODwyerPW
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 3:44 pm

In the case of the 737-9, the design is already MAXED out. No further growth potential.
learning never stops.
 
TSS
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 4:02 pm

Quoting EGCC777LR (Reply 1):
I think it had something to do with the ground clearance of the fuselage being unable to accept a stretch past where the 900 currently is with the current landing gear.
Quoting scouseflyer (Reply 2):
I think that the 737-9 is about as long as you can get with the current landing gear as I believe that they'd run into problems with increased tailstrike risk with the plane being too low to the ground.
Quoting TSS (Reply 4):
the current height of the aircraft and it's effect on rotation angles during takeoff would probably be an equal or even bigger limiting factor
Quoting CARST (Reply 5):
rotation / tail-strike-risk problem
Quoting seabosdca (Reply 6):
The 739 already has terrible runway performance, mostly because of rotation angles.
Quoting tdscanuck (Reply 7):
That much stretch would ruin the rotation angles

6 out of 10 responses mention exactly the same problem, and 60% is about as close to a full consensus as you're likely to get on Anet.  
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HNL2BOS
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 5:23 pm

If the tailstrike issue were the only reason holding back such a project could the strech be put before the main gear/wings. Imagine a 737 looking CRJ 1000ish.
 
BMI727
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 6:57 pm

Quoting hnl2bos (Reply 12):
If the tailstrike issue were the only reason holding back such a project could the strech be put before the main gear/wings. Imagine a 737 looking CRJ 1000ish.

That would likely mess up CG a bit and make such a plane difficult to load effectively. Not insurmountable but certainly not worth the effort.
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egph
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 9:40 pm

I From a rather uneducated naive mind:

I think the 737-900/ Boeing 737-9 are long enough and really going any longer on that fuselage would just look weird and as people above have stated I doubt it would have a great runway performance.

If Boeing were too look at producing a 757 replacement I think simply taking the Boeing 739 design and making it XtraLR with added tanks or whatever else would need to be done would be the next logical step. However as a committed Airbus man, I think a modified A321 could fit the bill if Airbus had the time/money/economic incentive to develop it.
 
gigneil
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 10:15 pm

An A322, - totally possible.

I doubt the range is as important as the capacity.

NS
 
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seabosdca
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 10:53 pm

Quoting gigneil (Reply 15):
An A322, - totally possible.

Much easier than a 737-10, but I think it would still need a bigger wing to have the range most operators would want. Not many operators would want a plane that big that couldn't at least match the range of the 757-300.
 
gigneil
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RE: 737-10 Max, Reasonable Or Not?

Mon Sep 19, 2011 11:34 pm

I think they could get away with a little wing root extension and transcontinental range, but I agree with you in theory.

NS
 
rwessel
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RE: 737-10 Max, Reasonable Or Not?

Tue Sep 20, 2011 1:11 am

Quoting hnl2bos (Reply 12):
If the tailstrike issue were the only reason holding back such a project could the strech be put before the main gear/wings. Imagine a 737 looking CRJ 1000ish.

Well, I suppose they could fix the CG issues a big extension in front of the wing would cause by adding a forward wing, ala Piaggio Avanti.   

If nothing else, it wouldn’t be another boring tube with wings!

Parking issues alone would probably kill that idea, though.
 
wdleiser
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RE: 737-10 Max, Reasonable Or Not?

Tue Sep 20, 2011 1:24 am

I have always wondered how the 757 would do these days if Boeing restarted the assembly line, updated avionics and strapped on some new RR or GenEx engines.
 
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Stitch
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RE: 737-10 Max, Reasonable Or Not?

Tue Sep 20, 2011 1:38 am

Quoting wdleiser (Reply 19):
I have always wondered how the 757 would do these days if Boeing restarted the assembly line, updated avionics and strapped on some new RR or GenEx engines.

If it sold more than a few score, I'd be shocked.
 
tdscanuck
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RE: 737-10 Max, Reasonable Or Not?

Tue Sep 20, 2011 4:25 am

Quoting hnl2bos (Reply 12):

If the tailstrike issue were the only reason holding back such a project could the strech be put before the main gear/wings.

In addition to what BMI727 said (CG issues), you would reduce yaw stability because you'd be adding destabilizing area ahead of the Cp without any compensating increase in tail volume. It's not impossible but it would be more complex than a simple stretch.

Quoting wdleiser (Reply 19):
I have always wondered how the 757 would do these days if Boeing restarted the assembly line, updated avionics and strapped on some new RR or GenEx engines.

There are no RR or GEnX engines in the right size. Even if such a thing did exist, it wouldn't be competitive against the 737MAX/A320NEO.

Tom.
 
thegeek
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RE: 737-10 Max, Reasonable Or Not?

Tue Sep 20, 2011 4:43 am

Quoting hnl2bos (Reply 12):
If the tailstrike issue were the only reason holding back such a project could the strech be put before the main gear/wings. Imagine a 737 looking CRJ 1000ish.

Wouldn't that also mean very much increased negative lift would be required from the stabiliser, and therefore worse aerodynamic efficiency and fuel consumption. Tail fuel tanks may help a little but doubtful it would be enough.
 
TSS
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RE: 737-10 Max, Reasonable Or Not?

Tue Sep 20, 2011 5:07 am

Quoting gigneil (Reply 17):
I think they could get away with a little wing root extension and transcontinental range

A simple wing root root extension could solve the MLG length problem, provided that the extension takes place in the portion of the wing root between the MLG pivot points and storage bays, which would in turn help alleviate the rotation issue. They'd probably still need to lengthen the nose landing gear, though.
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tdscanuck
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RE: 737-10 Max, Reasonable Or Not?

Tue Sep 20, 2011 1:47 pm

Quoting thegeek (Reply 22):
Wouldn't that also mean very much increased negative lift would be required from the stabiliser, and therefore worse aerodynamic efficiency and fuel consumption.

Yes, if you let the CG go forward.

Quoting thegeek (Reply 22):
Tail fuel tanks may help a little but doubtful it would be enough.

Adding tail fuel tanks to a 737 would be a massive change, not in keeping with a simple stretch at all.

Quoting TSS (Reply 23):
A simple wing root root extension could solve the MLG length problem, provided that the extension takes place in the portion of the wing root between the MLG pivot points and storage bays, which would in turn help alleviate the rotation issue.

A wing root extension may be mechanically simple but it could require massive retesting of all aerodynamics and structure. Again, not keeping with the idea of simple stretch.

Tom.
 
TSS
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RE: 737-10 Max, Reasonable Or Not?

Tue Sep 20, 2011 3:56 pm

Quoting tdscanuck (Reply 24):
A wing root extension may be mechanically simple but it could require massive retesting of all aerodynamics and structure. Again, not keeping with the idea of simple stretch.

Very true. Also, the wing root extension idea would only make sense if it was adopted across the -9, -8, and -7 lines as well because of the ground clearance/engine diameter benefits, and that would in turn lead to gate spacing issues because it would increase the wing span of the whole 737 line. I accept that the 737 line has been refined to the point that there are no more "simple" improvements to make, or at least none that don't involve serious trade-offs, but it's still fun to speculate on "what if's".
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AvObserver
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RE: 737-10 Max, Reasonable Or Not?

Wed Sep 21, 2011 6:38 pm

Quoting odwyerpw (Reply 10):
In the case of the 737-9, the design is already MAXED out. No further growth potential.

This is pretty much what I thought, too but there are some things Boeing can and will do to make it more competitive with the NEO. But the biggest problem I see is the ground clearance issue limiting fan size; keeping the MAX fan diameter as much as 15 inches smaller than one of the NEO options. The 737 legacy design definitely is a problem in this respect.

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