Sokes
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Think outside the 35 m box

Tue Aug 27, 2019 8:58 am

From “Any leaks, ideas, or otherwise: What is Airbus’ new clean-sheet aircraft?, post #155 :
viewtopic.php?f=3&t=1429207&p=21613937#p21613937


TObound wrote:
keesje wrote:
TObound wrote:

An A330 sized MOM wouldn't fit into a narrowbody gate. That will be an issue.

Span around 44 m, Code D gates, like 757 and 767.


Yes. But it needs to fit a Code C gate to really sell. How many airlines around the the world do you think would be happy paying higher fees to use a Code D gate for short haul? And how do you think airports would deal with a sudden shift in traffic from Code C to Code D gates (in many places often reserved for international service)?


While I’m afraid that TObound is right, it reminds me of the nose and the glasses:

“It is demonstrable," said he, "that things cannot be otherwise than as they are; for as all things have been created for some end, they must necessarily be created for the best end. Observe, for instance, the nose is formed for spectacles, therefore we wear spectacles. The legs are visibly designed for stockings, accordingly we wear stockings. Stones were made to be hewn and to construct castles, therefore My Lord has a magnificent castle; for the greatest baron in the province ought to be the best lodged. Swine were intended to be eaten, therefore we eat pork all the year round: and they, who assert that everything is right, do not express themselves correctly; they should say that everything is best.”
Voltaire, “Candide”

Embraer’s E190-E2 has a MTOW of 56,4 t. It’s Al-Li wing spans 33,7m
Embraer’s E195-E2 has a MTOW of 61,5 t. It’s Al-Li wing spans 35,1m.

Thoughts?
Why can't the world be a little bit more autistic?
 
flipdewaf
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Re: Think outside the 35 m box

Tue Aug 27, 2019 9:30 am

I'm not sure really what the question/problem is? Are we talking about the problem/cost of the incumbent? i.e. VHS vs betamax or inefficient qwerty keyboards from the days of typewriters?

Code C is what we have and therefore what we will aim for? I think in that scenario there are also plenty of CODE D gates around and where the airport/airline is used to dealing with the code D aircraft (757/767/A300/A310) and a change for them to be code C gates would either be useless (1:1 gets you nothing) or expensive; 5 x code D gates -> 7x code C gates would be a fair amount of reshuffling in an airport.

Maintaining continuity for a carrier is probably an important factor but depending on what market a particular aircraft might be chasing will have a large bearing on if the span is important to airfield ops.

Fred
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Armadillo1
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Re: Think outside the 35 m box

Tue Aug 27, 2019 9:40 am

yep, please define topic in direct statements
 
Armadillo1
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Re: Think outside the 35 m box

Tue Aug 27, 2019 9:50 am

if you ask to drop class C gates - it is possible, but planes for class C still will have advantages.

and still many ways to improve airliners , include for fit them in class C.
MS-21 wing close to CS300 in span and area. wingtips can help in some ways.
still ways to change airfil and area inflight.

for more radical solutions, avanti-style triplane can have less span.
 
Sokes
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Re: Think outside the 35 m box

Tue Aug 27, 2019 10:46 am

Voltaire is known for irony and sarcasm.
"Observe that the nose is formed for spectacles." That is of course rubbish. The spectacles are formed according to the nose, not the other way round.
Should planes be designed according to gates or gates according to planes?
When were gate sizes defined? What was the engine power at that time, how much is engine power now? I have more questions in mind, but let's see what ideas other people have.
Why can't the world be a little bit more autistic?
 
TObound
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Re: Think outside the 35 m box

Tue Aug 27, 2019 11:46 am

You're debating philosophy when this is a question of finance. Replacing existing infrastructure is expensive. Airlines won't pay for it. Simple as that.

In newer airports, there maybe more D gates which airlines can use. Tough sell for airlines that operate from older airports.
 
Sokes
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Re: Think outside the 35 m box

Tue Aug 27, 2019 12:09 pm

TObound wrote:
You're debating philosophy when this is a question of finance. Replacing existing infrastructure is expensive. Airlines won't pay for it. Simple as that.

In newer airports, there maybe more D gates which airlines can use. Tough sell for airlines that operate from older airports.


To remain philosophical:
What was first, the egg or the chicken?

That apart, as I said in the OP, I'm afraid you are right.
Why can't the world be a little bit more autistic?
 
TObound
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Re: Think outside the 35 m box

Tue Aug 27, 2019 1:58 pm

Sokes wrote:
TObound wrote:
You're debating philosophy when this is a question of finance. Replacing existing infrastructure is expensive. Airlines won't pay for it. Simple as that.

In newer airports, there maybe more D gates which airlines can use. Tough sell for airlines that operate from older airports.


To remain philosophical:
What was first, the egg or the chicken?


More a history question than anything. Jetbridges weren't a thing until the late 1950s. Around the time that ICAO was really starting to get rolling on standardization. I think once airports started installing jetbridges, ICAO probably started codifying aircraft gate sizes along those lines. This is how I would guess the process happened.

At this point though, history is all but irrelevant. The existing gates and terminals are a massive sunk cost. Re-arranging them would not be trivial. We are not talking making a gate or two compatible for A380 service. We are talking about the bulk of gates at most airports.
 
Turnhouse1
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Re: Think outside the 35 m box

Tue Aug 27, 2019 8:12 pm

TObound wrote:
Sokes wrote:
TObound wrote:
You're debating philosophy when this is a question of finance. Replacing existing infrastructure is expensive. Airlines won't pay for it. Simple as that.

In newer airports, there maybe more D gates which airlines can use. Tough sell for airlines that operate from older airports.


To remain philosophical:
What was first, the egg or the chicken?


More a history question than anything. Jetbridges weren't a thing until the late 1950s. Around the time that ICAO was really starting to get rolling on standardization. I think once airports started installing jetbridges, ICAO probably started codifying aircraft gate sizes along those lines. This is how I would guess the process happened.

At this point though, history is all but irrelevant. The existing gates and terminals are a massive sunk cost. Re-arranging them would not be trivial. We are not talking making a gate or two compatible for A380 service. We are talking about the bulk of gates at most airports.


Which basically means, unless the D sized replacement is a LOT better economically than what can be built as a code C (folding wings etc) it simply isn't happening. I'm not sure any combination of tube-wing-2turbofans will make that difference, it will really need to be a step change, and even then the question of, 'can't you make a 34.99m version of that?' will rightly be asked.
 
Kno
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Re: Think outside the 35 m box

Fri Aug 30, 2019 10:54 am

How strictly are these guidelines followed? The 757 is often parked at gates that can’t fit an a310 or 767.

My question is, isn’t the gate sized up to a specific planes wing span rather than a code?
 
flipdewaf
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Re: Think outside the 35 m box

Fri Aug 30, 2019 11:19 am

Kno wrote:
How strictly are these guidelines followed? The 757 is often parked at gates that can’t fit an a310 or 767.

My question is, isn’t the gate sized up to a specific planes wing span rather than a code?


In the spirit of a somewhat philosophical thread, any rule written by man can surely be unwritten by man.

Fred
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Sokes
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Re: Think outside the 35 m box

Fri Aug 30, 2019 4:17 pm

Kno wrote:
How strictly are these guidelines followed? The 757 is often parked at gates that can’t fit an a310 or 767.

My question is, isn’t the gate sized up to a specific planes wing span rather than a code?


I think I read once that an airline short of place who had an own terminal redesigned the gates to fit their fleet and not some norm.

flipdewaf wrote:

In the spirit of a somewhat philosophical thread, any rule written by man can surely be unwritten by man.

Fred


Cool! Now we have a discussion. I was laughing when I read your post.

It's actually not really a philosophical topic. I find it ridiculous that planes are designed according to gates and not the other way round.
I started with Voltaire because I thought the nose and the glasses make for a nice joke.

What was first, the chicken or the egg?
It means: 35m gate > 35 m plane > 35 m gate > 35 m plane > 35 m gate > 35 m plane ....
A lot of airports were built the last years. Anybody knows which is the popular gate size in Istanbul or new Chinese airports? Is it 36m?
So when is the right time to reconsider gate sizes: 20 years ago, 10 years ago, now, in 10 years, in 30 years, in 100 years?

I add two more planes to the discussion:

ATR 72-600: .......................... wingspan: 27,1 m, OEW 13,5 t, MTOW: 23,0 t, passengers: 70 @ 30', speed: 510 km/ h
De Havilland Canada Dash 8: wingspan: 28,4 m, OEW 17,8 t, MTOW 30,5 t, passengers: 82 @ 30', speed: 556-667 km/ h

So if we think outside the 35 m (and 52 m) box, we may as well think about speed.

I believe a long as there are only 36 m and 52 m gates, there will be no new 6-abreast narrow-bodies from Airbus or Boeing any time soon.
Why can't the world be a little bit more autistic?
 
WIederling
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Re: Think outside the 35 m box

Sat Aug 31, 2019 11:38 am

Sokes wrote:
To remain philosophical:
What was first, the egg or the chicken?


Dinos :-)
Murphy is an optimist
 
tomcat
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Re: Think outside the 35 m box

Sat Aug 31, 2019 3:33 pm

I would have thought that at a time when the average airline fleets are getting bigger due to market growth and concentration, and considering that the overall air travel market is getting bigger, there would have been an incentive for a having a greater number of aircraft models, each model having a specialized role. It seems that the incentive for fairly specialized sub-fleets is smaller than the possible economies of scale coming from operating identical aircraft across the board and more importantly, than the incentive for the OEMs to maximize the output of existing models while avoiding investments in new models. As a result, the gate size hasn't really been so far a serious constrain for the NB, since there hasn't been any clean sheet design that would have been constrained by this limit. Nevertheless, it appears that the gate constrains will be dealt with by means of folding wingtips on the expected clean sheet designs.

This being said, with the progress of automation, sensors and AI, I'm wondering if the way forward couldn't be reduced gates and taxi clearances rather than adding the weight and the complexity of folding wingtips. Any stupid car will soon look much smarter than the most advanced airliners when it comes to taxiing and parking.
 
Sokes
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Re: Think outside the 35 m box

Tue Sep 10, 2019 10:26 am

tomcat wrote:
...
It seems that the incentive for fairly specialized sub-fleets is smaller than the possible economies of scale coming from operating identical aircraft across the board and more importantly, than the incentive for the OEMs to maximize the output of existing models while avoiding investments in new models. As a result, the gate size hasn't really been so far a serious constrain for the NB, since there hasn't been any clean sheet design that would have been constrained by this limit. Nevertheless, it appears that the gate constrains will be dealt with by means of folding wingtips on the expected clean sheet designs.

This being said, with the progress of automation, sensors and AI, I'm wondering if the way forward couldn't be reduced gates and taxi clearances rather than adding the weight and the complexity of folding wingtips. Any stupid car will soon look much smarter than the most advanced airliners when it comes to taxiing and parking.


I also tend to believe that folding wingtips is not the way forward. Wind turbine manufacturer Enercon tried blades which were divided in two for better transport.
E.g. E141: 16,2 m inner blade section, 50,5 m outer blade section. The turbines with divided blades were discontinued after a short time. However to install a huge wind turbine at a remote place may have more logistic problems beside the blades. Maybe other components were too expensive?
However later designs of theirs were full blade again. I'm not aware any other wind turbine manufacturer tried divided blades. So I believe divided blades are rather not cost effective.

"the incentives for OEMs..."
The supply chain can't keep up anyway. However it will not be forever a seller's market. I hope once offer and demand balances the OEMs will ask what are the appropriate designs for the available technology.
Why they didn't do it 20 years ago? I assume
a) it was more important to focus on wide-bodies / twins with good range at reasonable capacity
b) airport infrastructure was unsuitable for a 45 m wing narrow-body. Which brings us back to the chicken and egg problem.

Why are turboprops so economical? Because they push a lot of air with medium speed as opposed to less air at high speed.
There seems to be a majority opinion on a.net that the B737 MAX is limited by the space under the wings. While it is true for high MTOW versions, is it true for the vast majority of narrow-bodies? Let's assume Boeing's software will be fine once they provide redundancy.

CFM 56-5B series (A 320 family): Bypass ratio 5,5-6,0 / Overall pressure ratio 32,6 - 35,4 : 1
CFM 56-7 series (B737NG family): Bypass ratio 5,1-5,5 / Overall pressure ratio 32,7 : 1
IAE V2500 (A321) : Bypass ratio 4,5:1 / Overall pressure ratio 35:1

Leap 1A (for A320 Neo family): Bypass ratio 11:1 / Overall pressure ratio: 40:1
Leap 1B (for B737 Max family): Bypass ratio 9:1 / " : 40:1

PW1100G (for A320 family): Bypass ratio: 12,5:1 / Overall pressure ratio: ?

Why can the A320 Neo not profit (or profit more) from it’s bigger engine diameter at common MTOWs?
Why can't the world be a little bit more autistic?
 
Sokes
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Re: Think outside the 35 m box

Tue Sep 10, 2019 3:01 pm

From "A350 Neo - ULR Redundant" :
viewtopic.php?f=5&t=1430475

Revelation wrote:
Second, I would not pencil in BLADE improvements for A350neo.

As https://en.wikipedia.org/wiki/Breakthro ... _in_Europe says:

Its wing sweep is around 20° for a Mach 0.75 cruise instead of 30° for Mach 0.82-0.84, laminar flow is expected along 50% of chord length instead of just aft of the leading edge, halving the wing friction drag, reducing the overall aircraft drag by 8% and saving up to 5% in fuel on an 800nm (1,480km) sector.[1]
...
The aerodynamic benefits could be sustained at Mach 0.78 up from M0.75 and next-generation single-aisles could use from the late 2020s.

The A350's wing has a 31.9° sweep angle for a Mach 0.85 cruise speed ( ref: https://en.wikipedia.org/wiki/Airbus_A350_XWB ).

The BLADE results are very good, but really only meaningful for a single aisle where cruise speed is not commercially significant.

Also BLADE only works when one holds extremely high manufacturing tolerances, which adds a lot of cost to build and maintain so you'd only use it when it paid for itself.

A350neo would need an all-new wing with redesign of the wingbox for different sweep angle and accept a slower cruise speed to benefit from BLADE.



Anybody knows more about speeds and laminar flow?
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WIederling
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Re: Think outside the 35 m box

Sun Sep 15, 2019 1:33 pm

Sokes wrote:
I also tend to believe that folding wingtips is not the way forward. Wind turbine manufacturer Enercon tried blades which were divided in two for better transport.
E.g. E141: 16,2 m inner blade section, 50,5 m outer blade section. The turbines with divided blades were discontinued after a short time. However to install a huge wind turbine at a remote place may have more logistic problems beside the blades. Maybe other components were too expensive?
However later designs of theirs were full blade again. I'm not aware any other wind turbine manufacturer tried divided blades. So I believe divided blades are rather not cost effective.


Returning to single piece blades was enabled by self propelled low boy designs that can now operate in environmental conditions that would disallow a tractor pulled one ( improved traction ).

And I'd guess that improved (G->C)FRP production techniques made continuous blades more attractive.
Having to accomodate a flange in the heavy (inner) part of the blade is a PITA.
Murphy is an optimist
 
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trpmb6
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Re: Think outside the 35 m box

Mon Sep 16, 2019 3:26 pm

What is most interesting to me is that the economical costs of reconfiguring the world's airports far outweighs the costs (both economical and safety) of folding wingtips. Imagine, being told early on that you should introduce an extra mechanism, an extra component that can fail, something that adds more weight than would a conventional design, all because of a seemingly trivial gate requirement.

All of those requirements, plus the added hurdle of certifying the design, and yet its still more cost effective than reconfiguring gates. Of course the safety issue is minimal, the 777x folding wing tips are akin to wingtips, merely increasing aspect ratio and not critical to normal operation - still plenty of lift generated.

It's really a neat case study for students to study in how requirements come about and influence the design of aircraft. Imagine, if you will, 2 thousand years from now they are studying the design of the 777x and have no background knowledge of the folding wing tips and why they were there. It would surely be puzzling to those scholars.

I believe going forward that airports will have to begin considering that we are moving towards higher efficiency (higher aspect ratio) wings and that gates should be sized appropriately during remodel. Anyone involved in the upgrades underway at DFW (just to pick an airport where I know a new terminal is in the works)? Any idea on gate allocations? Was pretty sure there was a powerpoint floating around about this very topic.

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