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Questionable B737MAX Field Performance  
User currently offlineeaa3 From United States of America, joined Sep 2007, 1014 posts, RR: 0
Posted (2 years 1 week 3 days 8 hours ago) and read 8216 times:

According to Air Insight the B737-8 and 9 will really struggle with field performance given the increased weight of the aircraft without increased thrust. This will cause the -8 but especially -9 to require well over 10,000 ft. of runway to takeoff at MTOW and therefore the aircraft won't be able to take of at MTOW from such airports as Minneapolis and Boston.

From Air Insight:

"As an example, according to Boeing, a B737-8MAX will be unable to take off from Minneapolis at MTOW. Minneapolis is at 800 ft but its longest runway is 11,000 ft. This makes you wonder about the -9MAX. Will it need 11-12,000+ ft at sea level? The -900ER already needs almost 10,000ft at sea level on a standard day.”"

http://airinsight.com/2012/08/22/assessing-the-max-story/

Also does anyone know what the field performance will be for the A320NEO and A321NEO.

32 replies: All unread, showing first 25:
 
User currently offlinezeke From Hong Kong, joined Dec 2006, 9041 posts, RR: 75
Reply 1, posted (2 years 1 week 3 days 4 hours ago) and read 8155 times:

I have raised this before and it was stated it was possible by those who claim to be in the know.

Time will tell, most of the improvements seem to already available on existing 737s with options like the performance kit and carbon brakes.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineCM From , joined Dec 1969, posts, RR:
Reply 2, posted (2 years 1 week 2 days 21 hours ago) and read 7995 times:

The problem with the Air Insight analysis is in the absence of data from the OEM, they have assumed the MAX will operate at the same thrusts as the NG. Boeing and CFM have not yet announced the engine thrust offerings for the 737 MAX, which could have a huge impact on the analysis in the Air Insight article. A very minor thrust bump (let's say 500 lbs on the 737-8) is equivalent to 20% more thrust than what is available today on the 737-800. This would more than erase any field length impact of an added 5000 lbs (which is less than 3% MTOW growth from the NG). Also, assuming the new winglets offer the same benefits to the MAX that the blended winglets offered to the NG (albeit in a smaller increment), then this change also should help with takeoff field length.

I would not put much stock in the "data" Air Insight has provided until you know how much thrust the MAX airplanes will have.


User currently onlineRoseflyer From United States of America, joined Feb 2004, 9618 posts, RR: 52
Reply 3, posted (2 years 1 week 2 days 20 hours ago) and read 7972 times:

Takeoff and landing performance on the MAX is likely to get worse. They are increasing weights, which lengthens the takeoff roll. The higher weights also increase braking distance, which is made worse by the taller nose gear which translates to less weight on the main tires when the nose touches down on landing.

For airlines wanting short field performance, the MAX-7 will be the airplane. For those wanting lower CASM and higher capacity, there is the -8 and -9. You can’t get the best performance and the lowest CASM at the same time. Boeing and Airbus trying to optimize the family of airplanes to suit what each airline needs.

The same is true for the NEO and Airbus is facing the same problems of increased TOW. The 737-800 can operate out of shorter runways than the A320 can when it has the optional short field performance package that was created for GOL in 2005 so that the 738 could land at SDU whereas previously only the 73G & A319 could use SDU. That likely means that Boeing can give up a bit more on the MAX and remain competitive with the NEO.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineha763 From United States of America, joined Jan 2003, 3657 posts, RR: 5
Reply 4, posted (2 years 1 week 2 days 19 hours ago) and read 7947 times:
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Has Boeing mentioned or published takeoff performance numbers? The article didn't provide a link to a source.

Boeing shows the increase in MTOW for the -7 as 5000 lbs and for the -8/-9 as 7000 lbs. This is roughly a 3% increase for the -7 and 4% for the -8/-9 over the NGs.

http://boeing.mediaroom.com/index.php?s=43&item=2327

CFM gives a range for the LEAP-1B of 20000-28000 lbs of thrust compared to 18500-27300 lbs of thrust for the CFM56-7B. This is an increase of 8% on the low end and 3% on the top end.

http://www.cfmaeroengines.com/engines/leap
http://www.cfmaeroengines.com/engines/cfm56-7b

Add in the new winglet and other aerodynamic tweaks, I'd say we really need to wait until the 737MAX design is firmed up more.


User currently offlineCM From , joined Dec 1969, posts, RR:
Reply 5, posted (2 years 1 week 2 days 19 hours ago) and read 7945 times:

Quoting Roseflyer (Reply 3):
also increase braking distance

This is one area which does impact minimum takeoff field length, regardless of any thrust changes Boeing decides on. Even if the winglet performance could negate any change in Vref (unlikely), the added average operating weight from any increase in OEW will impact how much remaining runway you need to perform an RTO. This, of course, assumes Boeing is not doing other things to the MAX which improve low speed and braking performance.


User currently offlinemandala499 From Indonesia, joined Aug 2001, 6849 posts, RR: 75
Reply 6, posted (2 years 1 week 2 days 15 hours ago) and read 7834 times:

This doesn't look good... but, for the 900ER...
that MTOW of 85Tons or so, if you fill it up to MZFW (67.7 tons), and plan to land at MLW (71.3 tons), you can still carry 14 tons of fuel, that gives... err... 2200NM trip range... and on dry runway, 14C, sea level, on a flap 5 you need 10,000ft, not 11,000ft (that's for 30C)...

The question is, are you going to need to fill it up to MTOW often? The guys here flying it fills it to MZFW often in 30C conditions... and you can count the number of 3000m runways here with both hands....

So, MTOW for a narrowbody needing 10000ft over sounds bad... but look at the MTOW growth over the past 30 years for the 737!

Anyways, that article is aimed at "disappointing runway performance as a 757 replacement"... yeah, well, fuel burn and engine maintenance costs anyone? You get what you paid for, and pax wants cheap cheap cheap...

Sure the A321 gives better runway performance, but again, the fuel burn ain't so rosy comparing with the rest of the family, and comparing it with the 737-900ER, it's dismal.

We'll see what the MAX and NEO can come up with the runway performance numbers and certified for use fuel burn numbers... it'll surely be interesting...

But if it ends up as sacrificing runway performance for trip fuel burn... won't be surprised either.



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently onlineRoseflyer From United States of America, joined Feb 2004, 9618 posts, RR: 52
Reply 7, posted (2 years 1 week 2 days 14 hours ago) and read 7790 times:

Quoting mandala499 (Reply 6):
We'll see what the MAX and NEO can come up with the runway performance numbers and certified for use fuel burn numbers... it'll surely be interesting...

The vast majority of airlines are not flying the existing 737NG or A320 at MTOW or even near it. For the majority of operators, it does not matter what a MTOW 737-MAX9 requires for takeoff, because they want to see how it is used in normal operations. Normal operations is not US - Hawaii or transcon in the winter or LHR-IKA. Normal operations is a flight of 800-900 miles with quick turns and 7-9,000ft runways.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinezeke From Hong Kong, joined Dec 2006, 9041 posts, RR: 75
Reply 8, posted (2 years 1 week 2 days 11 hours ago) and read 7715 times:

Quoting CM (Reply 2):
A very minor thrust bump (let's say 500 lbs on the 737-8) is equivalent to 20% more thrust than what is available today on the 737-800.

Did you mean 2% ? or 5000 lb ?



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Reply 9, posted (2 years 1 week 2 days 8 hours ago) and read 7660 times:

Quoting Roseflyer (Reply 7):
The vast majority of airlines are not flying the existing 737NG or A320 at MTOW or even near it. For the majority of operators, it does not matter what a MTOW 737-MAX9 requires for takeoff, because they want to see how it is used in normal operations. Normal operations is not US - Hawaii or transcon in the winter or LHR-IKA. Normal operations is a flight of 800-900 miles with quick turns and 7-9,000ft runways.

I do have a question, maybe someone can answer. MTOW takes into consideration that you're operating in a 1-class configuration, correct?



What gets measured gets done.
User currently offlineCM From , joined Dec 1969, posts, RR:
Reply 10, posted (2 years 1 week 2 days 7 hours ago) and read 7650 times:

Quoting zeke (Reply 8):
Did you mean 2%

Yes. Sorry for the confusion.

Quoting FlyASAGuy2005 (Reply 9):
MTOW takes into consideration that you're operating in a 1-class configuration, correct?

MTOW simply is the maximum certified weight for takeoff... it is an all-inclusive weight (airplane, passengers, bags, fuel, etc) and does vary with the cabin configuration of the airplane.


User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Reply 11, posted (2 years 1 week 2 days 7 hours ago) and read 7638 times:

Quoting CM (Reply 10):
MTOW simply is the maximum certified weight for takeoff... it is an all-inclusive weight (airplane, passengers, bags, fuel, etc) and does vary with the cabin configuration of the airplane.

Well that's really where i'm getting at. The assumed pax weight is going to be whatever the certified limit is, correct? (as far as the MTOW is concerned).

The point i'm getting at is most airlines will save quite a bit of weight due to the fact that most a/c are operating in a 2-class config. So DL would have a max of 160 pax (minus crew) on a 738 but the gross seating for the 738 is certified to 189 (or whatever it is). For MTOW purposes, i'm assuming that's taking into account 189 pax. Is my thinking correct here?



What gets measured gets done.
User currently offlinemandala499 From Indonesia, joined Aug 2001, 6849 posts, RR: 75
Reply 12, posted (2 years 1 week 2 days 6 hours ago) and read 7617 times:

Quoting FlyASAGuy2005 (Reply 11):
For MTOW purposes, i'm assuming that's taking into account 189 pax. Is my thinking correct here?

Aircraft, crew, food, pax, bags, cargo, and fuel!
MTOW, and MZFW do not take consideration the configuration. Your TOW and ZFW yes, but not the limits.

Quoting Roseflyer (Reply 7):
The vast majority of airlines are not flying the existing 737NG or A320 at MTOW or even near it. For the majority of operators, it does not matter what a MTOW 737-MAX9 requires for takeoff, because they want to see how it is used in normal operations.

Exactly my point ! Most of the time, these aircraft will be operating on routes less than 1500NM... so they won't be anywhere near the highest MTOW... The 737-900ER for example rarely operate at its MTOW of 85tons... for 1500NM, they operate at the 72 to 75 ton range (75 ton being the lower MTOW version), which need only 8600ft runway...

The Max-9 will suffer from "bad runway performance numbers" for MTOW, but the majority of the market won't need to use that MTOW. But most of the market would want good fuel burn numbers instead of the TO Field Length Requirement at MTOW.



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlinesweair From Sweden, joined Nov 2011, 1821 posts, RR: 0
Reply 13, posted (2 years 1 week 2 days 2 hours ago) and read 7568 times:

IMO the MAX would need more thrust than the NG, but as I see it will have the exact same thrust engines. The 739ER has a lousy field performance.

User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Reply 14, posted (2 years 1 week 1 day 20 hours ago) and read 7441 times:

Quoting mandala499 (Reply 12):
Aircraft, crew, food, pax, bags, cargo, and fuel!
MTOW, and MZFW do not take consideration the configuration. Your TOW and ZFW yes, but not the limits.

I think my wording is being lost some how. I get that the configuration can be different. That's pretty obvious. The MTOW will not change because an airline chooses to fly it in an all busines class config.

To my original point, for WARM BODIES (excluding crew) what # does Boeing go off of to come up with their "people weight" so to speak in the MTOW calculations. I can only assume it's whatever the certified limit is, correct (plus crew/babies, etc.).



What gets measured gets done.
User currently onlineRoseflyer From United States of America, joined Feb 2004, 9618 posts, RR: 52
Reply 15, posted (2 years 1 week 1 day 17 hours ago) and read 7368 times:

Quoting FlyASAGuy2005 (Reply 14):
To my original point, for WARM BODIES (excluding crew) what # does Boeing go off of to come up with their "people weight" so to speak in the MTOW calculations. I can only assume it's whatever the certified limit is, correct (plus crew/babies, etc.).

These are the weights used for analysis and loads: 190lbs for summer or 195lbs for winter per passenger including carry on luggage and 30lbs for each checked bag.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineFabo From Slovakia, joined Aug 2005, 1219 posts, RR: 1
Reply 16, posted (2 years 1 week 1 day 12 hours ago) and read 7277 times:

Quoting FlyASAGuy2005 (Reply 14):
To my original point, for WARM BODIES (excluding crew) what # does Boeing go off of to come up with their "people weight" so to speak in the MTOW calculations. I can only assume it's whatever the certified limit is, correct (plus crew/babies, etc.).

What the market wants, I suppose. It is not that easy to see in narrowbodies, but quite easy in widebodies - you can either have so much payload for full fuel or so much fuel for full payload, or somewhere in between... and they try and find the sweet spot for the airlines.

What could be more interesting for you in narrowbodies would be MZFM maybe. e.g. how much load will Boeing let airlines to cram into a 737. In widebodies, cargo is a concern, in narrowbodies, I suppose less so. (And once you have MZFM, you tweak MTOW to get as much fuel in as you want there)



The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
User currently offlineMax Q From United States of America, joined May 2001, 4472 posts, RR: 19
Reply 17, posted (2 years 1 week 1 day 4 hours ago) and read 7157 times:

This is the Achilles heel of Boeing's minimum change philosophy for the 'Max'


A large part of the poor field performance on the long body NG's and even more so on the Max is the geometry limits of the short main landing gear which Boeing is not changing for the new Aircraft.


The Aircraft is geometrically limited for rotation because of this and it has to run up the take off speeds artificially to ensure adequate tail clearance at the higher weights.


Boeing recognized this as a problem when they stretched the 767 from the -300 to the -400 model. But they extended the landing gear 18 inches, added winglets and more power. Even then the take off and landing speeds had to be raised but it's field performance is acceptable.


It's time for Boeing to bite the bullet and extend the main landing gear. The performance potential of the Aircraft would be vastly increased. In fact they could increase the gross weight further, in combination with a more powerful engine and finally get that transatlantic performance some operators want.



The best contribution to safety is a competent Pilot.
User currently offlineFabo From Slovakia, joined Aug 2005, 1219 posts, RR: 1
Reply 18, posted (2 years 1 week 21 hours ago) and read 7044 times:

Quoting Max Q (Reply 17):
It's time for Boeing to bite the bullet and extend the main landing gear.

Some would say it is time for Boeing to bite the bullet and go for all-new narrowbody, and I agree, with MAX EIS in 2017, it is about time to start something serious regarding all-new narrowbody.



The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
User currently onlinecatdaddy63 From United States of America, joined Apr 2007, 301 posts, RR: 0
Reply 19, posted (2 years 1 week 16 hours ago) and read 6955 times:
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Quoting Fabo (Reply 18):
Some would say it is time for Boeing to bite the bullet and go for all-new narrowbody, and I agree, with MAX EIS in 2017, it is about time to start something serious regarding all-new narrowbody.

Barring a huge leap in engine technology, Boeing wont replace the MAX family before 2025. The order book is already pretty strong for the MAX, and it will only get better. With the 787-10 and the 777 upgrades that haven't even been formally offered yet the all new narrowbody will take a back seat for now.


User currently onlineRoseflyer From United States of America, joined Feb 2004, 9618 posts, RR: 52
Reply 20, posted (2 years 6 days 19 hours ago) and read 6787 times:

Quoting Max Q (Reply 17):


It's time for Boeing to bite the bullet and extend the main landing gear. The performance potential of the Aircraft would be vastly increased. In fact they could increase the gross weight further, in combination with a more powerful engine and finally get that transatlantic performance some operators want.

I don't disagree with your point. However I do disagree that there is evidence that Boeing should extend the landing gear.

There are a few airlines that would benefit from a 738 or 739 with increased payload. However the majority of airlines would not benefit. The majority of flights do not push the takeoff performance of the airplane. It's only a few select airlines that operate the 737NG near MTOW on a regular basis.

The majority of the flights are shorter in duration than 5-6 hour MTOW flights. The average flight of a 737NG is less than 2 hours. By not changing the main landing gear, the OEW does not go up as much for the MAX which means more efficiency. Airlines are crying for any point of fuel burn improvement that they can get. That's what is selling this airplane. Increase performance is not.

Keeping costs and maintenance low is also desirable. Minimum change keeps the price of the airplane and potential program delays in check. It also reduces maintenance costs since the same spares inventory can be kept

For airlines that want better performance, they can go down in size as the 73G has great short field performance and with engine options can have the same or better takeoff performance as a 757. It also has more range. The consequence is CASM.

Another factor to keep weight down, is that Boeing is seeing competition from below. The E195, C-Series and other projects are going to eat away at the bottom end of the 737 market. By continuously increasing TOW, the airplane becomes less efficient at operating short segments and airlines are more likely to consider the smaller alternatives. On the other hand there is no competition above the 739 & A321. Airlines are cross shopping the 739 with the A321 or the 788. With the 788 being such a huge jump up, airlines are forced to take some compromises.

So while I agree that Boeing could get more performance out of taller gear, I can fully understand the reason not to do it. Launch customers like Southwest will be screaming to keep OEW down down down. The result is slightly worse takeoff performance, which is a compromise that airlines are willing to take with today's fuel prices.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineMax Q From United States of America, joined May 2001, 4472 posts, RR: 19
Reply 21, posted (2 years 6 days 13 hours ago) and read 6682 times:

Quoting Roseflyer (Reply 20):

I don't disagree with your point. However I do disagree that there is evidence that Boeing should extend the landing gear.

There are a few airlines that would benefit from a 738 or 739 with increased payload. However the majority of airlines would not benefit. The majority of flights do not push the takeoff performance of the airplane. It's only a few select airlines that operate the 737NG near MTOW on a regular basis.

The majority of the flights are shorter in duration than 5-6 hour MTOW flights. The average flight of a 737NG is less than 2 hours. By not changing the main landing gear, the OEW does not go up as much for the MAX which means more efficiency. Airlines are crying for any point of fuel burn improvement that they can get. That's what is selling this airplane. Increase performance is not.

Keeping costs and maintenance low is also desirable. Minimum change keeps the price of the airplane and potential program delays in check. It also reduces maintenance costs since the same spares inventory can be kept

For airlines that want better performance, they can go down in size as the 73G has great short field performance and with engine options can have the same or better takeoff performance as a 757. It also has more range. The consequence is CASM.

Another factor to keep weight down, is that Boeing is seeing competition from below. The E195, C-Series and other projects are going to eat away at the bottom end of the 737 market. By continuously increasing TOW, the airplane becomes less efficient at operating short segments and airlines are more likely to consider the smaller alternatives. On the other hand there is no competition above the 739 & A321. Airlines are cross shopping the 739 with the A321 or the 788. With the 788 being such a huge jump up, airlines are forced to take some compromises.

So while I agree that Boeing could get more performance out of taller gear, I can fully understand the reason not to do it. Launch customers like Southwest will be screaming to keep OEW down down down. The result is slight

I disagree.



Boeing is limiting the potential of the Aircraft for no good reason.



The best contribution to safety is a competent Pilot.
User currently offlineStitch From United States of America, joined Jul 2005, 30922 posts, RR: 87
Reply 22, posted (2 years 6 days 13 hours ago) and read 6678 times:
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Quoting Max Q (Reply 21):
Boeing is limiting the potential of the Aircraft for no good reason.

So making the plane heavier so it will burn more fuel for some 95% of it's missions is a "good reason"?  


User currently offlineMax Q From United States of America, joined May 2001, 4472 posts, RR: 19
Reply 23, posted (2 years 6 days 11 hours ago) and read 6635 times:

Quoting Stitch (Reply 22):

So making the plane heavier so it will burn more fuel for some 95% of it's missions is a "good reason"?

Talk about a leading question !


Ridiculous assertion anyway. A taller landing gear would not only allow better field performance but it would also enable Boeing to put a larger fan on the Max, easily negating any weight penalty.



The best contribution to safety is a competent Pilot.
User currently offlineContnlEliteCMH From United States of America, joined Mar 2005, 1458 posts, RR: 44
Reply 24, posted (2 years 6 days 10 hours ago) and read 6589 times:

Quoting Max Q (Reply 23):
A taller landing gear would not only allow better field performance but it would also enable Boeing to put a larger fan on the Max, easily negating any weight penalty.

Since it is a good assumption that you are not presenting a tradeoff that Boeing has not studied in detail, where do you think they have erred?



Christianity. Islam. Hinduism. Anthropogenic Global Warming. All are matters of faith!
25 tdscanuck : Limiting the potential on certain factors so you can gain on others *that the customers tell you they want you to do* is a good reason. Taller gear m
26 mandala499 : Raising the landing gear would improve field performance due to larger fan. Raising the landing gear would also affect the aircraft in other ways: 1.
27 Post contains images astuteman : IIRC, the NEO MTOW's will be going up a whole 1 tonne from the CEO A320's, and it too is receiving winglet (sharklet) treatment. The sharklet treatme
28 Brenintw : Discussing the landing gear length, I recall reading on here the observation that the current MLG allows Boeing to certify the overwing exits without
29 Post contains images ferpe : It would mean a substantial redesign of the whole aircraft, IIRC the MLG are meeting at the center of the aircraft right now, make them longer and yo
30 packsonflight : The problem with messing with the MLG is certification I think. If they start to change the wing MLG attachment points and modifying the center wing
31 tdscanuck : It's unlikely to break the original certification; the wing and gear got changed for the 737NG without that problem. However, it would greatly expand
32 Post contains images ferpe : Just to illustrate the problematic of the 737-8MAX start case, here how the drag of the frame looks at it's V2 (stable climb point at 15ft with OEI )
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