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737 MAX: A Few Basic Layman Questions  
User currently onlinequestions From Australia, joined Sep 2011, 672 posts, RR: 1
Posted (1 year 7 months 2 weeks 5 days 23 hours ago) and read 16512 times:

I have a few questions.

1) Is the 737 MAX a completely redesigned 737 variant? The rear portion of the fuselage under the tail (pardon my lack of understanding about plane components) looks more Airbus-like (gasp) than Boeing. By that I mean the top line of the fuselage on an Airbus aircraft typical follows a somewhat horizontal line while Boeing's design trails downward.

2) If it is a new design, why was the vertical, triangular portion in front of the tail edge kept? No other Boeing aircraft has this and it seems to be a signature design element of the 737.

3) Why does the 737 MAX sit so low to the ground like other 737s? Does this pose a problem with engine design? Would a higher clearance, a la the 757, allow for larger engines in the future or for some other operational advantage?

4) What will passengers notice that may be different from other narrow body aircraft? For example, other than the Sky Interior, will the narrow body feel wider?

44 replies: All unread, showing first 25:
 
User currently offline757gb From Uruguay, joined Feb 2009, 676 posts, RR: 1
Reply 1, posted (1 year 7 months 2 weeks 5 days 23 hours ago) and read 16467 times:

There are a lot of people here that know a lot more than I do, but I'll try to give you a few answers.

No, the 737 MAX is not a completely redesigned 737. It is Boeing's alternative to an all new 737 replacement, given the market pressure present by the A32X-NEO being available to order now, with excellent number of orders so far.

That means that many parts of the airplane remain the same and easily recognizable. The most important change relates to the new engines. Now the 737 has always had the "disadvantage" (depending on one's viewpoint) of sitting too close to the ground, and that means that you cannot hang just any available engine applicable to the size, as you would be able to do to the A32X. The landing gear is being partially lengthened to accommodate the new engines, but you can only go so far before doing a major redesign, which was not part of the idea.

I am not sure as to how different the 737 will feel to the passenger. Cabin size is the same, and I am assuming Sky interior, but that is already available on the 737NG.



God is The Alpha and The Omega. We come from God. We go towards God. What an Amazing Journey...
User currently offlinequiet1 From Thailand, joined Apr 2010, 345 posts, RR: 0
Reply 2, posted (1 year 7 months 2 weeks 5 days 23 hours ago) and read 16394 times:

Quoting 757gb (Reply 1):
The landing gear is being partially lengthened to accommodate the new engines, but you can only go so far before doing a major redesign, which was not part of the idea.

If I've been following the threads correctly, the nose gear is a little longer on the MAX to accommodate a slightly larger engine under the wing.

On another thread I was surprised to read that the A330 main landing gear strut collapses on retraction to fit in the bay (and re-extends, of course, on extension for landing.) Was that not an option for the MAX? Couldn't they jack the fuselage up to a 757 height by adding a self-collapsing gear and attach some really large engines?


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 3, posted (1 year 7 months 2 weeks 5 days 23 hours ago) and read 16399 times:

Quoting questions (Thread starter):
1) Is the 737 MAX a completely redesigned 737 variant?

No.

Quoting questions (Thread starter):
The rear portion of the fuselage under the tail (pardon my lack of understanding about plane components) looks more Airbus-like (gasp) than Boeing.

Yes. The whole tail cone is new.

Quoting questions (Thread starter):
2) If it is a new design, why was the vertical, triangular portion in front of the tail edge kept?

It's not a new design; they're keeping the fin to reduce changes and not mess up the lateral stability too much.

Quoting questions (Thread starter):
No other Boeing aircraft has this and it seems to be a signature design element of the 737.

The 707 has it, as does the 727 (in the form of the part under the center inlet). They didn't figure out how to get rid of it until the 747.

Quoting questions (Thread starter):
3) Why does the 737 MAX sit so low to the ground like other 737s?

Since it's a low-change derivative, they want to keep as much as they can. That includes the landing gear length, the maintenance tooling, and the ability to keep the engines close to the ground for easy servicing.

Quoting questions (Thread starter):
Does this pose a problem with engine design?

Yes. It restricts the fan size and makes the nacelle and strut design more difficult.

Quoting questions (Thread starter):
Would a higher clearance, a la the 757, allow for larger engines in the future or for some other operational advantage?

Yes.

Quoting questions (Thread starter):
4) What will passengers notice that may be different from other narrow body aircraft?

Very little. It will be quieter but probably not in a way that passengers will really notice.

Tom.


User currently offlineStitch From United States of America, joined Jul 2005, 29690 posts, RR: 84
Reply 4, posted (1 year 7 months 2 weeks 5 days 23 hours ago) and read 16389 times:
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Quoting questions (Thread starter):
Is the 737 MAX a completely redesigned 737 variant?

No. It's a 737 Next Generation with new engines, a taller nose gear, a re-profiled aft section, some Fly-By-Wire (I believe), new winglets and updated avionics.

Quoting questions (Thread starter):
Why does the 737 MAX sit so low to the ground like other 737s?

Because it's a 737.  
Quoting questions (Thread starter):
Does this pose a problem with engine design?

Yes, but the 737 MAX will have larger engines than the 737 Next Generation.

Quoting questions (Thread starter):
Would a higher clearance, a la the 757, allow for larger engines in the future or for some other operational advantage?

Yes, but it would require new main gear and that would probably require changes to the wings, wingbox and such.

Quoting questions (Thread starter):
What will passengers notice that may be different from other narrow body aircraft? For example, other than the Sky Interior, will the narrow body feel wider?

I expect the MAX will use the Sky Interior, perhaps with some minor tweaks.


User currently offlineairliner371 From United States of America, joined Aug 2012, 1280 posts, RR: 1
Reply 5, posted (1 year 7 months 2 weeks 5 days 22 hours ago) and read 16342 times:

Quote:
I expect the MAX will use the Sky Interior, perhaps with some minor tweaks.

I believe, but don't quote me, Boeing will offer the MAX with the sky interior only.



You will either love or hate the airline industry. If you love it, it will get in your blood and it will never leave.
User currently offlinedlednicer From United States of America, joined May 2005, 531 posts, RR: 7
Reply 6, posted (1 year 7 months 2 weeks 5 days 22 hours ago) and read 16229 times:
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Quoting tdscanuck (Reply 3):
Quoting questions (Thread starter):
2) If it is a new design, why was the vertical, triangular portion in front of the tail edge kept?

It's not a new design; they're keeping the fin to reduce changes and not mess up the lateral stability too much.

Actually, the dorsal fin was increased in size going from the 737 Initial models (-100 and -200) to the Classic models (-300, -400 and -500). Usually, dorsal fins are used to prevent rudder lock (a lesson learned the hard way on the Boeing 307).


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The changes to the tail cone were the results of lessons learned on the 757, 767, 777 and 787. My question is: has the APU inlet been improved (ala 757, 767, etc.) and is the bicycle seat still there?


User currently offlineAA737-823 From United States of America, joined Mar 2000, 5639 posts, RR: 11
Reply 7, posted (1 year 7 months 2 weeks 5 days 20 hours ago) and read 16015 times:

Quoting tdscanuck (Reply 3):
The 707 has it, as does the 727 (in the form of the part under the center inlet). They didn't figure out how to get rid of it until the 747.

Come on man, you're losing your edge. The 737 didn't even HAVE the vertical fin forward extension he's talking about until the -300 series. And the 707 certainly doesn't have one. No clue what you're talking about with the 727- there's an engine inlet there...


User currently offlineghifty From United States of America, joined Jul 2010, 841 posts, RR: 0
Reply 8, posted (1 year 7 months 2 weeks 5 days 18 hours ago) and read 15551 times:

Quoting AA737-823 (Reply 7):
there's an engine inlet there...

The part *under* it. If you look in pictures there's a little vertical structure.. it appears to be a support structure for the #2 engine, but I guess it's not just that.



Fly Delta Jets
User currently onlinequestions From Australia, joined Sep 2011, 672 posts, RR: 1
Reply 9, posted (1 year 7 months 2 weeks 5 days 16 hours ago) and read 14843 times:

Thanks for all the replies.

User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 10, posted (1 year 7 months 2 weeks 5 days 13 hours ago) and read 13337 times:

Quoting dlednicer (Reply 6):
My question is: has the APU inlet been improved (ala 757, 767, etc.) and is the bicycle seat still there?

Dear lord, I hope so.

Quoting AA737-823 (Reply 7):
Come on man, you're losing your edge. The 737 didn't even HAVE the vertical fin forward extension he's talking about until the -300 series.

The dorsal fin is a lateral stability fix. They didn't need it until they increased the size & thrust with the -300.

Quoting AA737-823 (Reply 7):
And the 707 certainly doesn't have one.

Not all, but some. The UK CAA made them add it to some models.
Everything you could care to know is here: Ventral And Dorsal Fins. (by Tg 747-300 Jul 25 2006 in Tech Ops)

Quoting AA737-823 (Reply 7):
No clue what you're talking about with the 727- there's an engine inlet there...

I specifically said *under* the center inlet. They didn't need to connect that part up for structural support.

Tom.


User currently offlineEPA001 From Netherlands, joined Sep 2006, 4593 posts, RR: 38
Reply 11, posted (1 year 7 months 2 weeks 5 days 10 hours ago) and read 12135 times:
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Quoting tdscanuck (Reply 3):
It will be quieter but probably not in a way that passengers will really notice.

This is an area of the next generation narrow-bodies where I would expect that much advancements in design and manufacturing that also the passengers will note this (hopefully) quite easily.

But time will tell.  


User currently offlinef4f3a From United Kingdom, joined Jul 2004, 246 posts, RR: 0
Reply 12, posted (1 year 7 months 2 weeks 5 days 9 hours ago) and read 11352 times:

Will the flight deck be revised . Ie will it have eicas/ ecam rather
Than the 707 style ovhd panel / recall .

It's a shame it's not a total redesign the 737 cockpit is
Rather too small when compared with other Boeing / airbus.


User currently offlinefpetrutiu From United States of America, joined Aug 2007, 866 posts, RR: 0
Reply 13, posted (1 year 7 months 2 weeks 5 days 8 hours ago) and read 10671 times:

Quoting f4f3a (Reply 12):

It's a shame it's not a total redesign the 737 cockpit is
Rather too small when compared with other Boeing / airbus.

I am not sure what you mean, the NG cockpit is very functional when it comes to flying it. It really does not need to be any bigger.


User currently offlinef4f3a From United Kingdom, joined Jul 2004, 246 posts, RR: 0
Reply 14, posted (1 year 7 months 2 weeks 5 days 7 hours ago) and read 9961 times:

Mmm yes it does, when you have to do 12 hour days
In it . It is much smaller than the a320 . You step into the a320
You have to climb into the ng .

As for functionality the way the systems are represented is from the 1950s
Even old when compared with 767 757flight deck and 747.

There is no integration between the systems. The Ovhd
Panel should be like that of other boeings and have push button
Switches in a clean layout.

The ng itself should have been much better and updated but
The huge order from southwest put an end to that.
The 737 is a great aeroplane but it should be brought
Into line and upto the same standard as 777 family.
In fact I believe sales would be better if 737neo 787 had
Same commonality as a320/330


User currently offlineJAAlbert From United States of America, joined Jan 2006, 1492 posts, RR: 1
Reply 15, posted (1 year 7 months 2 weeks 5 days 3 hours ago) and read 8051 times:

Quoting dlednicer (Reply 6):
My question is: has the APU inlet been improved (ala 757, 767, etc.) and is the bicycle seat still there?

What's the bicycle seat and what function does it play?


User currently offlineJAAlbert From United States of America, joined Jan 2006, 1492 posts, RR: 1
Reply 16, posted (1 year 7 months 2 weeks 5 days 3 hours ago) and read 7851 times:

And another question, related to the original post...

The 737-MAX tail will feature a cone. Why not the screwdriver like on the 777? Is the 777 the only Boeing with a screwdriver tail? I know some of the MDs have them, but it seems a rather unique feature not often repeated. Why is that?


User currently offline817Dreamliiner From Montserrat, joined Jul 2008, 2077 posts, RR: 1
Reply 17, posted (1 year 7 months 2 weeks 5 days 3 hours ago) and read 7794 times:

Quoting JAAlbert (Reply 16):

I think the new tail cone was adopted from the 787.



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User currently offlinepeterinlisbon From Portugal, joined Jan 2006, 396 posts, RR: 0
Reply 18, posted (1 year 7 months 2 weeks 5 days 3 hours ago) and read 7705 times:

I'm just wondering why it seems that long-haul aircraft need to be redesigned every 10-20 days from scratch (eg. 707>747>757/767>777>787 whereas short-haul aircraft like the 737 can stick around for 50 years with minor changes.

User currently offlinedlednicer From United States of America, joined May 2005, 531 posts, RR: 7
Reply 19, posted (1 year 7 months 2 weeks 5 days 2 hours ago) and read 7614 times:
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Quoting JAAlbert (Reply 15):
What's the bicycle seat and what function does it play?

The bicycle seat has a little trailing edge flap that deflects to help feed the inlet during in-flight use of the APU.

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Later model Boeings have a scoop that opens up during APU operation.

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User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 20, posted (1 year 7 months 2 weeks 5 days ago) and read 6431 times:

Quoting f4f3a (Reply 12):
Will the flight deck be revised . Ie will it have eicas/ ecam rather

I certainly hope not; it would break crew commonality with the other 737's and blow the training and staffing plans out of the water.

Quoting f4f3a (Reply 14):
In fact I believe sales would be better if 737neo 787 had
Same commonality as a320/330

How so? Who's out there that would be running common crew across a 737 and a 787?

Quoting JAAlbert (Reply 15):
What's the bicycle seat and what function does it play?

The tail closure of the 737, to put it delicately, sucks. The boundary layer is thick and there's separation. As a result, the APU has a hard time getting enough clean air in under certain conditions. The bicycle seat sticks out to capture higher energy air and keep the inlet functioning properly.

Quoting JAAlbert (Reply 16):
The 737-MAX tail will feature a cone. Why not the screwdriver like on the 777?

The 777 tailcone is a bit of a maintenance headache with regard to the bend in the APU exhaust. It does have better drag but, judging by the 787, they've either decided it's not worth it or they've figured out how to get sufficiently low drag with a round closure.

Quoting JAAlbert (Reply 16):
Is the 777 the only Boeing with a screwdriver tail? I know some of the MDs have them, but it seems a rather unique feature not often repeated. Why is that?

The MD's didn't run the APU exhaust through the screwdriver.

Quoting peterinlisbon (Reply 18):
I'm just wondering why it seems that long-haul aircraft need to be redesigned every 10-20 days from scratch (eg. 707>747>757/767>777>787 whereas short-haul aircraft like the 737 can stick around for 50 years with minor changes.

The 747 is going to make 50 years, no problem, with changes of about the same magnitude as the 737.

It's not that long-hauls need to be redesigned every 10-20 years, it's that the OEM's have to launch a new aircraft whenever the market demands a product that isn't filled by an existing type. The narrowbody market hasn't changed enough in 50 years to require an all new type.

Tom.


User currently offlinedlednicer From United States of America, joined May 2005, 531 posts, RR: 7
Reply 21, posted (1 year 7 months 2 weeks 4 days 22 hours ago) and read 5884 times:
AIRLINERS.NET CREW
DATABASE EDITOR

Quoting tdscanuck (Reply 20):
The 777 tailcone is a bit of a maintenance headache with regard to the bend in the APU exhaust. It does have better drag but, judging by the 787, they've either decided it's not worth it or they've figured out how to get sufficiently low drag with a round closure.

I've heard that the APU exhaust on the 777 creates a lot of ramp noise when the APU is running.

BTW, I designed the new tail stinger and oil cooler boil-off exit on Rare Bear by telling the crew chief to "make it look like a 777 tail cone".


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User currently offlineDocLightning From United States of America, joined Nov 2005, 18704 posts, RR: 58
Reply 22, posted (1 year 7 months 2 weeks 4 days 22 hours ago) and read 5874 times:

Quoting questions (Thread starter):
1) Is the 737 MAX a completely redesigned 737 variant? The rear portion of the fuselage under the tail (pardon my lack of understanding about plane components) looks more Airbus-like (gasp) than Boeing. By that I mean the top line of the fuselage on an Airbus aircraft typical follows a somewhat horizontal line while Boeing's design trails downward.

No. It is mostly re-engined. AFAIK, it has the same airfoil as the current 737 (albeit with different wingtip devices), new engines, a few aerodynamic changes, and not much else. Boeing is trying to keep this model as minimal of a change as si necessary to compete with the A320-NEO family.

Quoting questions (Thread starter):
2) If it is a new design, why was the vertical, triangular portion in front of the tail edge kept? No other Boeing aircraft has this and it seems to be a signature design element of the 737.

No idea.

Quoting questions (Thread starter):
3) Why does the 737 MAX sit so low to the ground like other 737s? Does this pose a problem with engine design? Would a higher clearance, a la the 757, allow for larger engines in the future or for some other operational advantage?

The 737 was designed a long time ago for a very different mission than it serves today. Up until the development of the first small jets (Caravelle, DC-9, etc.), jets were only mainline aircraft that served major markets. With the development of the smaller jet, it was very likely that some of these smaller communities would have only limited infrastructure available at their airports. The 737 had to be low to the ground to facilitate loading/unloading and maintenance at stations where even airstairs might not be available. The 727 was designed with similar considerations in mind, but the need for the third engine necessitated rear placement.

At the time, the decision to put the engines under the wing was unique. Nobody else (SUD, BAC, McD) had gone with under-wing engines because rear-mounted engines offered better ground clearance for operations on semi-prepared runways and gave the option of a "power back." The 737 design wound up being more structurally and operationally efficient, though, and to date the 727 is the only Boeing airliner designed with rear-mounted engines.

Today, of course, the rules have changed a bit. 737's are now flying longer missions and rarely have flight times shorter than 45 minutes. Any airport large enough to support a 737 will have at least airstairs, a tug, and a baggage loader.

Quoting questions (Thread starter):
4) What will passengers notice that may be different from other narrow body aircraft? For example, other than the Sky Interior, will the narrow body feel wider?

It will offer the Sky Interior, AFAIK.

Quoting f4f3a (Reply 14):

Mmm yes it does, when you have to do 12 hour days
In it . It is much smaller than the a320 . You step into the a320
You have to climb into the ng .

I have noticed no significant difference between the two cabins.

The cross-sections are very similar where it counts.


User currently offlineneutrino From Singapore, joined May 2012, 588 posts, RR: 0
Reply 23, posted (1 year 7 months 2 weeks 4 days 12 hours ago) and read 5470 times:

Quoting DocLightning (Reply 22):
Quoting f4f3a (Reply 14):

Mmm yes it does, when you have to do 12 hour days
In it . It is much smaller than the a320 . You step into the a320
You have to climb into the ng .

I have noticed no significant difference between the two cabins.

He's talking about the cockpit.



Potestatem obscuri lateris nescitis
User currently offlineDarkSnowyNight From United States of America, joined Jan 2012, 1281 posts, RR: 3
Reply 24, posted (1 year 7 months 2 weeks 4 days 11 hours ago) and read 5396 times:

Quoting peterinlisbon (Reply 18):

I'm just wondering why it seems that long-haul aircraft need to be redesigned every 10-20 days from scratch (eg. 707>747>757/767>777>787

Every ten to twenty days?? Man, those engineers' hands must be exhausted!

Quoting tdscanuck (Reply 20):

How so? Who's out there that would be running common crew across a 737 and a 787?

Who would be running common crew between an A319 & an A333? I agree it seems a bit overblown to get all hyped up over commonality, but apparently enough folks like it enough to make a big deal of it. For the record, I'm 100% sure (barring some massive 787esque delay) that the 737MAX sales will be similar enough to the A32XNEO regardless.

Quoting tdscanuck (Reply 20):

The MD's didn't run the APU exhaust through the screwdriver.

Can't say too much about the MD-80 family, but I know that on the Scud doesn't seem any less MX intensive than the 777 here.

Quoting dlednicer (Reply 21):

I've heard that the APU exhaust on the 777 creates a lot of ramp noise when the APU is running.

Probably. But so do a lot of planes (The aforementioned MD-11, for example, dumps its APU exhaust sideways like the 777, but also downward too. It can can actually get quite dangerously hot under that, to say nothing of the noise.

I don't think that OEMs & Operators take ramp noise into very serious consideration when coming up with or approving these things. They may look into it, but if another operational consideration trumps that, there you go.



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User currently offlinelightsaber From United States of America, joined Jan 2005, 12428 posts, RR: 100
Reply 25, posted (1 year 7 months 2 weeks 4 days 7 hours ago) and read 5349 times:
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Quoting tdscanuck (Reply 3):
They didn't figure out how to get rid of it until the 747.

Nitpick, the low appendage to the tail is always a fix to lateral stability. The design came out of North American when they converted the P-51 from a 'Razorback' to a 'bubble canopy.' Since the P-51 had always had lateral stability issues, in particular with engine thrust increases/decreases, they came up with the 'extra triangle' to help.

The cleaner solution is a taller vertical stabilizer (e.g., A318, A332), but that is a far more expensive fix due to the extend of the required structural changes.

Quoting DocLightning (Reply 22):
Any airport large enough to support a 737 will have at least airstairs, a tug, and a baggage loader.

I have had the pleasure of flying into airports that only had the baggage loader. Even then, during the 'rush,' not every aircraft receives *any* of your listed services.    Ok, as a fraction of today's services... very few. But still some.   

FWIW, I just helped my folks book travel and I didn't realize how difficult it was to travel economically to small cities! It is more costly than TCON in business class to fly an hour flight (in coach)! They chose to skip the one hour flight and drive 3 hours from a nearby major airport. So I expect the fraction that benefit from the 'rough field' options of the 737 will diminish.

Quoting tdscanuck (Reply 3):
Yes. It restricts the fan size and makes the nacelle and strut design more difficult.

To quantify, it is about a 3% to 4% fuel burn penalty on TCON missions with a ~45 minute flight being the break even (on the MAX) where the smaller engines burn as much fuel as the desired fan diameter. In general, one now design for a minimum 'break even' fuel burn at the hour mission. Widebodies tend to have the engines optimized, naturally, for longer missions (typically at 6 to 8 hours or about half their maximum mission).

Lightsaber



I've posted how many times?!?
User currently offlineAADC10 From United States of America, joined Nov 2004, 2016 posts, RR: 0
Reply 26, posted (1 year 7 months 2 weeks 4 days 6 hours ago) and read 5231 times:

Quoting DocLightning (Reply 22):
I have noticed no significant difference between the two cabins.

A 7" cabin width difference is quite a bit in a narrowbody. A320 series seats are often 1/2" to 1" wider than the 737 seats and the aisles are slightly wider as well. Not a night and day difference but noticeable.


User currently offlineMountainFlyer From United States of America, joined Jul 2005, 473 posts, RR: 0
Reply 27, posted (1 year 7 months 2 weeks 4 days 6 hours ago) and read 5281 times:

Quoting DocLightning (Reply 22):
The 737 was designed a long time ago for a very different mission than it serves today. Up until the development of the first small jets (Caravelle, DC-9, etc.), jets were only mainline aircraft that served major markets. With the development of the smaller jet, it was very likely that some of these smaller communities would have only limited infrastructure available at their airports. The 737 had to be low to the ground to facilitate loading/unloading and maintenance at stations where even airstairs might not be available. The 727 was designed with similar considerations in mind, but the need for the third engine necessitated rear placement.

Also, the turbojet engines at the time had a much smaller diameter, so the lower wings weren't a problem until the much larger turbofans came around.

Quoting lightsaber (Reply 25):
FWIW, I just helped my folks book travel and I didn't realize how difficult it was to travel economically to small cities! It is more costly than TCON in business class to fly an hour flight (in coach)! They chose to skip the one hour flight and drive 3 hours from a nearby major airport. So I expect the fraction that benefit from the 'rough field' options of the 737 will diminish.

From what I understand, nearly all of the "rough field operations" done by 737s today is in very remote parts of Canada and Alaska. Most of them don't really have a choice to drive three hours to a larger airport. I'm interested to see what will take their place in the future.



SA-227; B1900; Q200; Q400; CRJ-2,7,9; 717; 727-2; 737-3,4,5,7,8,9; 747-2; 757-2,3; 767-3,4; MD-90; A319, 320; DC-9; DC-1
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 28, posted (1 year 7 months 2 weeks 4 days 6 hours ago) and read 5242 times:

Quoting dlednicer (Reply 21):
BTW, I designed the new tail stinger and oil cooler boil-off exit on Rare Bear by telling the crew chief to "make it look like a 777 tail cone".

That may be the best reverse-engineering story I've ever heard.

Quoting lightsaber (Reply 25):
Quoting tdscanuck (Reply 3):
They didn't figure out how to get rid of it until the 747.

Nitpick, the low appendage to the tail is always a fix to lateral stability. The design came out of North American when they converted the P-51 from a 'Razorback' to a 'bubble canopy.' Since the P-51 had always had lateral stability issues, in particular with engine thrust increases/decreases, they came up with the 'extra triangle' to help.

I should have phrased that more clearly. I agree with you that the dorsal is always a fix. For whatever, reason, several manufacturers were bad at predicting rudder effectiveness at high beta and ended up having to stick dorsal extensions on to repair the issue without incurring the huge redesign penalty of a whole new fin. The 747 was the point when Boeing appears to have sorted out their analysis and not had to do a dorsal extension on a new jetliner type.

Tom.


User currently offlineRwy04LGA From United States of America, joined Jul 2005, 3140 posts, RR: 8
Reply 29, posted (1 year 7 months 2 weeks 4 days 4 hours ago) and read 5094 times:

Quoting tdscanuck (Reply 10):
clue what you're talking about with the 727- there's an engine inlet there...

I specifically said *under* the center inlet. They didn't need to connect that part up for structural support.

The L-1011-500 has a little thingy under the #2 inlet.

Quoting tdscanuck (Reply 20):
10-20 days

DAYS??? Wow!



Just accept that some days, you're the pigeon, and other days the statue
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 30, posted (1 year 7 months 2 weeks 4 days 1 hour ago) and read 4952 times:

Quoting Rwy04LGA (Reply 29):
Quoting tdscanuck (Reply 20):
10-20 days

DAYS??? Wow!

Don't put that quote on me. It came from Reply 18.

Tom.


User currently offlineikramerica From United States of America, joined May 2005, 21417 posts, RR: 60
Reply 31, posted (1 year 7 months 2 weeks 4 days 1 hour ago) and read 4929 times:

Quoting questions (Thread starter):
By that I mean the top line of the fuselage on an Airbus aircraft typical follows a somewhat horizontal line while Boeing's design trails downward

737 and 747 have always had a tail cone that followed the horizontal of the upper fuselage, while the 757, 767, 777 and 787 have a more evenly tapered shape (the 777 to a spade, the others to a cone). The 737 and 747 cones are more stubby though, not as pointy as the Airbus, so the 737MAX is going pointy with a similar cone design to the 787, but otherwise keeping the same lines as the current 737.

Quoting DocLightning (Reply 22):
The cross-sections are very similar where it counts.

Mostly, but the foot space for window pax on the 737 is pretty cramped, not as cramped as an ERJ, but still not the best for longer flights. The A320 is much more comfortable in that respect.

Quoting AADC10 (Reply 26):
A 7" cabin width difference is quite a bit in a narrowbody. A320 series seats are often 1/2" to 1" wider than the 737 seats and the aisles are slightly wider as well. Not a night and day difference but noticeable.

Define often?



Of all the things to worry about... the Wookie has no pants.
User currently offlinedlednicer From United States of America, joined May 2005, 531 posts, RR: 7
Reply 32, posted (1 year 7 months 2 weeks 4 days 1 hour ago) and read 4903 times:
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Quoting lightsaber (Reply 25):
Nitpick, the low appendage to the tail is always a fix to lateral stability. The design came out of North American when they converted the P-51 from a 'Razorback' to a 'bubble canopy.' Since the P-51 had always had lateral stability issues, in particular with engine thrust increases/decreases, they came up with the 'extra triangle' to help.

Nope, it pre-dates that. The first use of a dorsal fin I can find is on the Boeing 307, after the prototype crashed, on March 18, 1939. The accident happened when the 307's performance with two engines inoperative on one wing was being demonstrated. When the engines were shut down, the pilot went to maximum deflection to counter the resulting yaw. The Stratoliner then experienced rudder lock, where the hinge moments prevented the rudder from being re-centered. As a result, the 307 went into a spin and crashed. The 10 people aboard, including KLM test pilot Albert von Baumhauer, Boeing test pilot Julius Barr, Boeing Chief Aerodynamcist Ralph Cram, Boeing Chief Engineer Earl Ferguson, and a TWA representative were killed.

George Schairer was hired away from Consolidated by Boeing to replace Cram. One of his first tasks was to figure out what happened and then fix the 307. Wind tunnel testing showed that the addition of a dorsal fin prevented rudder lock from happening. This was incorporated into the 307, and was also incorporated into the B-17, starting at the E model.

I have a copy of Schairer's paper "Directional Stability and Vertical Surface Stalling", presented at Institute of Aeronautical Sciences Aerodynamics session, Ninth Annual Meeting in New York on January 31 1941. My copy was made from Schairer's personal copy, now in the archives at the Museum of Flight.

http://www.air-and-space.com/Boeing%20307/NC19903%20pre-Pan%20Am%20left%20side%20Dave%20Davis%20l.jpg
http://www.air-and-space.com/Boeing%20307/Boeing%2012329B%20N19903%20left%20side%20l.jpg


User currently offlinelightsaber From United States of America, joined Jan 2005, 12428 posts, RR: 100
Reply 33, posted (1 year 7 months 2 weeks 3 days 23 hours ago) and read 4776 times:
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Quoting dlednicer (Reply 32):
The first use of a dorsal fin I can find is on the Boeing 307

Nice find. Thank you.

Lightsaber



I've posted how many times?!?
User currently offlineN766UA From United States of America, joined Jul 1999, 8094 posts, RR: 24
Reply 34, posted (1 year 7 months 2 weeks 3 days 23 hours ago) and read 4738 times:

Quoting questions (Thread starter):
1) Is the 737 MAX a completely redesigned 737 variant?

Nope.

Quoting questions (Thread starter):
2) If it is a new design, why was the vertical, triangular portion in front of the tail edge kept? No other Boeing aircraft has this and it seems to be a signature design element of the 737.

Because it's not a completely new design.

Quoting questions (Thread starter):
3) Why does the 737 MAX sit so low to the ground like other 737s? Does this pose a problem with engine design? Would a higher clearance, a la the 757, allow for larger engines in the future or for some other operational advantage?

See above. Putting the airplane higher in the air like a 757 would require completely redesigning key elements of the aircraft, and that was not the goal here.

Quoting questions (Thread starter):
4) What will passengers notice that may be different from other narrow body aircraft? For example, other than the Sky Interior, will the narrow body feel wider?

Nope. It will likely be quieter, certainly, but unless you're wearing goofy fish-eye lenses there's nothing mortal man can do to make a finite space feel bigger. Same ole 737 dimensions.



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User currently offlineCM From , joined Dec 1969, posts, RR:
Reply 35, posted (1 year 7 months 2 weeks 3 days 22 hours ago) and read 4631 times:

In response to the earlier question about the APU inlet: the MAX has an all new inlet for the APU. The NACA inlet with the bicycle seat is gone, replaced by a retractable (RAID) style door, similar to Boeing widebodies. This is part of the aero cleanup at the tail end of the airplane.

Quoting AADC10 (Reply 26):
A320 series seats are often 1/2" to 1" wider than the 737 seats and the aisles are slightly wider as well.

Close, but not quite as generous as you describe. The A320 cabin width permits 1" wider seats with a slightly narrower aisle than the 737 or (more commonly) seats which are about 0.5" wider with a wider aisle as well. I'm not a huge guy (6'2" / 200 lbs), but I can notice that difference. On the other hand, I don't think it makes any real comfort difference. I certainly dont seek out A320 flights so I can get my extra half inch of seat bottom.

Quoting N766UA (Reply 34):
there's nothing mortal man can do to make a finite space feel bigger.

Hmmm, architects have been doing just this with light, color and geometry for a couple of millennia. Call any interior designer and ask them if they can make a cramped room feel bigger and they will say yes.


User currently offlineinfiniti329 From United States of America, joined Jul 2012, 469 posts, RR: 0
Reply 36, posted (1 year 7 months 2 weeks 3 days 21 hours ago) and read 4597 times:

Quoting dlednicer (Reply 21):
I've heard that the APU exhaust on the 777 creates a lot of ramp noise when the APU is running.

What apu dosent?

Quoting DocLightning (Reply 22):
I have noticed no significant difference between the two cabins

The A320 has bigger feel to it from a passengers point of view


User currently offlineDocLightning From United States of America, joined Nov 2005, 18704 posts, RR: 58
Reply 37, posted (1 year 7 months 2 weeks 3 days 21 hours ago) and read 4546 times:

Quoting MountainFlyer (Reply 27):
Also, the turbojet engines at the time had a much smaller diameter, so the lower wings weren't a problem until the much larger turbofans came around.

The 731 and 732 were powered by PW JT8D turbofans, not turbojets. The only boeing jetliner to use turbojets was the 707 and even then only a few examples were built before turbofans were substituted.

Quoting infiniti329 (Reply 36):

The A320 has bigger feel to it from a passengers point of view

I contend that it really does not.


User currently offlinePITingres From United States of America, joined Dec 2007, 1087 posts, RR: 13
Reply 38, posted (1 year 7 months 2 weeks 3 days 18 hours ago) and read 4385 times:

Quoting infiniti329 (Reply 36):
The A320 has bigger feel to it from a passengers point of view

Gah. Please. This is one of those eternal A.net arguments and it has no place on this thread.

FWIW I disagree 100%. For me the extra 1/2 inch (or inch, even) of width is completely irrelevant and there are lots of people shaped just like me. If you want to talk up the extra miniscule width advantage of the A32x has for you, feel free, but please don't fool yourself into thinking that everyone notices. Because I sure don't and I doubt that I am unique.



Fly, you fools! Fly!
User currently offlineferpe From France, joined Nov 2010, 2792 posts, RR: 59
Reply 39, posted (1 year 7 months 2 weeks 3 days 10 hours ago) and read 4162 times:

Re the dorsal fin and it's function. IIRC it is not only put there to add vertical surface ie increase the available directional stability force, it's placement and shape also changes the fins yaw angle vs force characteristic.

To explain it, turn the whole thing 90° and you have a wing with a strake added. The strake has exactly the function it has on the F16 and F18, it ads a vortex when the alfa (yaw) increases which delays the separation of the flow on the wing (rudder) close to the fuselage. Therefore not only the centering force gets augmented but also the angle until it starts to tail of (pun intended  ) gets increased.

So one might say that the straked straight wing was invented on the VTP of the 307, long before the YF16 and 17.

[Edited 2012-09-05 08:39:14]


Non French in France
User currently offlineiahmark From United States of America, joined Nov 2007, 47 posts, RR: 0
Reply 40, posted (1 year 7 months 2 weeks 3 days 10 hours ago) and read 4054 times:

Cabin wise both - A320 and B737 are really the same, the diff is in the cargo bay where the A320 can carry LD containerized cargo and the 737 does not.

Still… I like the shape of the 737 better; the A319/20/21 look kind of out of balance specially the blunt noses….


User currently offlineDocLightning From United States of America, joined Nov 2005, 18704 posts, RR: 58
Reply 41, posted (1 year 7 months 2 weeks 3 days 8 hours ago) and read 3928 times:

Quoting neutrino (Reply 23):
He's talking about the cockpit.

Fair enough. I've heard a lot of pilots complain about the 737 cockpit. After all, the exterior mold lines were developed for the 707. In fact, the 707, 727, and 737 all share the same nose with only very minor differences. I've heard pilots complain that it is loud, unergonomic, and that there are a bunch of protuberances that seem optimally placed to cause you to hit your head.

Unfortunately, what pilots think of flying the aircraft is low on the list of considerations an airline has when choosing between the A320 and 737.


User currently onlinequestions From Australia, joined Sep 2011, 672 posts, RR: 1
Reply 42, posted (1 year 7 months 2 weeks 3 days 7 hours ago) and read 3813 times:

Quoting DocLightning (Reply 41):
protuberances

pro·tu·ber·ance   [proh-too-ber-uhns, -tyoo-, pruh-]
noun
1. the condition, state, or quality of being protuberant.
2. a protuberant part or thing; projection or bulge.


User currently offlineAesma From France, joined Nov 2009, 6114 posts, RR: 9
Reply 43, posted (1 year 7 months 2 weeks 3 days 5 hours ago) and read 3720 times:

Quoting iahmark (Reply 40):
Still… I like the shape of the 737 better; the A319/20/21 look kind of out of balance specially the blunt noses….

What 737 ? I think the jurassics look good and very "sixties", however I can't get over the deformed nacelles and dorsal fin of the 737 classic/NG/max, and I hate the huge winglets.

Contrary to you I find the A320 very balanced, exactly how you would expect a modern NB to look like (maybe in a few years the CSeries will be the new benchmark in looks), meaning it's also kind of boring. I'm not sold on the new winglets, so it's not against Boeing, small winglets like on the 744 and A33/40 are good looking however.



New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
User currently offlineTWA772LR From United States of America, joined Nov 2011, 1164 posts, RR: 1
Reply 44, posted (1 year 7 months 2 weeks 3 days 5 hours ago) and read 3668 times:

Quoting f4f3a (Reply 14):
As for functionality the way the systems are represented is from the 1950s

Thats because it's supposed to share commonality to all 737s. The 100s and 200s were designed in the late 50s early 60s and then the 300/400/500 have upgraded cockpits from the originals but still have similarities. Same when you compare the NG to the classics. So it's safe to say the MAX won't have a completely different cockpit, but would instead have similarity to the NG, which has similarity to the classics, which has similarity to the original 737s.



Я говорю по-русский. :)
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