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Slug71
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Re: A340-300 BLADE makes first flight

Wed Sep 27, 2017 2:51 pm

Eyad89 wrote:
It is big news indeed. Airbus claims this would reduce drag by 8% and eventually would save 5% on fuel consumption. The question is, when are we going to see it first on any airliner? A360? Or A322? I know it is still too early for this as it has just made its first flight.

If this blade project makes it into service around the same time as the ultra fan engine, we would have a deadly combination.


Sounds like it is geared toward a narrow body. My guess is that this could be testing for the A320 family replacement.
The test campaign is expected to go through next year with a total of 120 to 150 hours.
See the link below.

mjoelnir wrote:
This are trials. The piece tested is the outer part only. It is thought for a commuter sized frame flying slower at cruise than the A340.


And that outer part is designed to be 2/3rds the size of a narrow body wing.
See article below.

godsbeloved wrote:
I don't see this technique being applied on a commercial product just yet, since maximum velocity is around mach .70 if I am correct


The speed will increase as the test campaign progresses.
This is a very informative article that KarelXWB shared in the other thread.

https://www.aerosociety.com/news/blade- ... me-to-fly/
 
WIederling
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Re: A340-300 BLADE makes first flight

Wed Sep 27, 2017 4:02 pm

CHI87LG wrote:
ugly planes for cleaner skies and cheaper flying seems like a good bargain to me. and let's not kid around - that is a horrible looking device. but looks ain't everything.


The attached elements are 2/3 scaled wings for an A320 size NB plane.

Unsurprising it looks "stuckoed on" here.
Murphy is an optimist
 
pugman211
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Re: A340-300 BLADE makes first flight

Wed Sep 27, 2017 4:08 pm

There is another topic about this in tech ops. More information and pics too.
 
VSMUT
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Re: A340-300 BLADE makes first flight

Wed Sep 27, 2017 5:38 pm

CHI87LG wrote:
ugly planes for cleaner skies and cheaper flying seems like a good bargain to me. and let's not kid around - that is a horrible looking device. but looks ain't everything.


It's only a small segment of a wing concept to test/demonstrate it. The final product will most probably look very similar to this:

Image
 
redcap1962
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Re: A340-300 BLADE makes first flight

Wed Sep 27, 2017 6:07 pm

CHI87LG wrote:
ugly planes for cleaner skies and cheaper flying seems like a good bargain to me. and let's not kid around - that is a horrible looking device. but looks ain't everything.


If may look stupid, but if it works it ain' stupid!
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Re: A340-300 BLADE makes first flight

Wed Sep 27, 2017 6:24 pm

parapente wrote:
I think this is pretty big news.I wonder what (assuming its successful) the timeline would be before this technology sees commercial use,As stated above it's clearly a radical change considering the wingsweep relative to conventional wings.
One must assume Boeing is also researching this (with NASA?) as it is game changing technology if it works.
The nearest I ever got to this was back in the days I flew sail planes.Huge aspect ratio's with laminar flow wings (and amazing glide angles).
However....
On a summers day if there were a lot of insects the laminar flow was easily broken .Worse (for commercial aircraft) was (can you believe it) rain droplets.They too made the wings performance deteriorate.They will of course already know this stuff and have found a solution of some sort.


Really interesting to hear real world experience with similar techniques...I was curious about what the impact of de-icing fluid would be (or maybe the future control surfaces will have the need for de-icing fluid engineered out somehow...)
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed Sep 27, 2017 7:05 pm

Anyone interested in laminar flow might find the earlier tech-ops thread ( viewtopic.php?t=776637 ) to be interesting. It was one of the more interesting tech-op threads in recent years.

KarelXWB wrote:
Here's a pretty good story on the BLADE project:

The Clean Sky 2 BLADE (Breakthrough Laminar Aircraft Demonstrator in Europe) demonstrator, was rolled out of its hangar in Tarbes in the south of France at the start of September. BLADE is a highly-modified Airbus A340 airliner and the culmination of nearly ten years of research, planning and ground tests by Airbus and its industrial and academic partners on this pan-European aerospace project. With its outer wings removed and replaced by two new panels packed with sensors, BLADE is set to study laminar flow in flight to a level of detail never seen before.

If successful, its flight tests could lead to the way to a step-change in NLF aerodynamics for civil airliners with up to 8% drag reduction for a short-range airliner. This would translate into 5% block fuel burn saving on a typical 800nm single-aisle mission. Given that millions are invested each year to improve engine fuel efficiency by an average of 1%, exploiting NLF represents a tantalising goal for the industry in helping to meeting the challeng environmental targets set by Europe’s ACARE 2020.


Full article
https://www.aerosociety.com/news/blade- ... me-to-fly/


Exactly why they say 'short-range airliner' is explained below:

Sharp-eyed observers will notice that the wing sweep of the outer test NLF wings are around 20degs, compared with 30degs for the rest of the swept wing. The reason highlights a tricky compromise for future airliner designers – optimise a wing with (shallower sweep) that maintains laminar flow at around Mach 0.75 and save fuel, or fly faster at the usual cruising speed of Mach 0.82-0.85 and see boundary layer separation as the aircraft goes faster. One solution might be hybrid laminar-flow, either passive or active, to 'suck' the airflow to the wing and keep the drag down at higher speeds. A slower, but more fuel efficient, straighter wing thus means that the first applications could be in narrowbody airliners on short-haul routes, where slower cruise speeds may not make too much of a difference compared to long-haul.


So the higher speed applications still seems to be off in the future.
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Re: A340-300 BLADE makes first flight

Wed Sep 27, 2017 11:33 pm

CHI87LG wrote:
ugly planes for cleaner skies and cheaper flying seems like a good bargain to me. and let's not kid around - that is a horrible looking device. but looks ain't everything.


A production wing wouldn't look anything like that. The tests are carried out on grafted-on outer wing sections. Everything inside the outer pylon is plain vanilla A340. The reason for the weird look is because the wing sections don't match as they would on a production aircraft.
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Sep 28, 2017 12:15 am

I'm not a huge Airbus fan, but that demonstrator looks pretty cool! The different angles of the wing, with the less swept part outside, is definitely something I wouldn't mind seeing. (Yes, I know...is nothing but a demonstrator aircraft.)
 
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Re: A340-300 BLADE makes first flight

Thu Sep 28, 2017 12:41 am

Boeing also has their "Muppet" concepts from a decade ago for low noise and low fuel use. Something like the "Honeydew" blended delta-wing widebody was designed for very low fuel burn due to high aerodynamic efficiency.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Sep 28, 2017 5:05 am

Karel's article was very interesting article indeed. thanks.
 
WIederling
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Re: A340-300 BLADE makes first flight

Thu Sep 28, 2017 7:23 pm

Stitch wrote:
Boeing also has their "Muppet" concepts from a decade ago for low noise and low fuel use. Something like the "Honeydew" blended delta-wing widebody was designed for very low fuel burn due to high aerodynamic efficiency.


Anything "real" ? :-)
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Re: A340-300 BLADE makes first flight

Thu Sep 28, 2017 7:33 pm

WIederling wrote:
Stitch wrote:
Boeing also has their "Muppet" concepts from a decade ago for low noise and low fuel use. Something like the "Honeydew" blended delta-wing widebody was designed for very low fuel burn due to high aerodynamic efficiency.


Anything "real" ? :-)


No more or less "real" than the stuff VSMUT and keesje have been posting. ;)
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Sep 28, 2017 8:02 pm

I recall a Boeing engineer telling me of a similar laminar wing test campaign on the 757 or 767 carried out many years ago. Anyone know as to what came of it?
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Sep 28, 2017 8:07 pm

Chaostheory wrote:
I recall a Boeing engineer telling me of a similar laminar wing test campaign on the 757 or 767 carried out many years ago. Anyone know as to what came of it?


That was part of the 757 EcoDemo program: http://aviationweek.com/technology/757- ... ctive-flow
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Sep 28, 2017 8:23 pm

Stitch wrote:
Chaostheory wrote:
I recall a Boeing engineer telling me of a similar laminar wing test campaign on the 757 or 767 carried out many years ago. Anyone know as to what came of it?


That was part of the 757 EcoDemo program: http://aviationweek.com/technology/757- ... ctive-flow


I had the '90s, possibly '80s time frame in mind. I'm probably mistaken.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Sat Sep 30, 2017 5:34 am

I wonder how they will get over the issue of having to install control surfaces, given that the tiniest surface irregularity will disrupt the laminar flow. Not a trivial barrier to commercial application.
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Sat Sep 30, 2017 12:45 pm

Any preliminary results from A's rumour mill?...a rough estimate of actual drag reduction perhaps?...

I wonder if the aircraft will investigate stall behaviour...according to Lightsaber in a previous thread, stall handling is laminar flow's one big Achilles' heel...very very delicate proposition to control stall behaviour it seems...


Faro
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Sat Sep 30, 2017 1:21 pm

DocLightning wrote:
I wonder how they will get over the issue of having to install control surfaces, given that the tiniest surface irregularity will disrupt the laminar flow. Not a trivial barrier to commercial application.


control surfaces are at the rear.
if your laminar flow actually stays stable as far as the rear of the profile ...
you have a "luxury of a problem"

major Issue is high lift. me thinks.
You could go for BAe's Jumbolino solution : no high lift at the front :-)

next is going for variable camber at the front. i.e. bending the nose down
without hinges?
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Sat Sep 30, 2017 2:47 pm

Faro wrote:
Any preliminary results from A's rumour mill?...a rough estimate of actual drag reduction perhaps?...

I wonder if the aircraft will investigate stall behaviour...according to Lightsaber in a previous thread, stall handling is laminar flow's one big Achilles' heel...very very delicate proposition to control stall behaviour it seems...

Faro

Perhaps you're thinking of the discussion on page 1 of this thread?
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Sat Sep 30, 2017 4:25 pm

Yes indeed...had the impression it was nestled somewhere else...


Faro
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Sat Sep 30, 2017 5:03 pm

WIederling wrote:
major Issue is high lift. me thinks.
You could go for BAe's Jumbolino solution : no high lift at the front :-)


Seems this is the approach being used, no?

Image

Ref: https://www.ainonline.com/aviation-news ... st-flights

Image

Ref: https://www.ainonline.com/aviation-news ... st-flights
Wake up to find out that you are the eyes of the world
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Tue Oct 31, 2017 4:13 pm

Just caught it going up for a test flight.

https://www.flightradar24.com/AIB83AI/f631d7f
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Fri Feb 09, 2018 9:01 am

Chaostheory wrote:
Stitch wrote:
Chaostheory wrote:
I recall a Boeing engineer telling me of a similar laminar wing test campaign on the 757 or 767 carried out many years ago. Anyone know as to what came of it?


That was part of the 757 EcoDemo program: http://aviationweek.com/technology/757- ... ctive-flow


I had the '90s, possibly '80s time frame in mind. I'm probably mistaken.

Is this what you had in mind?

http://www.nytimes.com/1990/09/11/scien ... -fuel.html
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Fri Feb 09, 2018 4:30 pm

CowAnon wrote:
Chaostheory wrote:
Stitch wrote:

That was part of the 757 EcoDemo program: http://aviationweek.com/technology/757- ... ctive-flow


I had the '90s, possibly '80s time frame in mind. I'm probably mistaken.

Is this what you had in mind?

http://www.nytimes.com/1990/09/11/scien ... -fuel.html


That was with suction applied.

This here solution is microforming the surface to "hold" laminar flow.
Murphy is an optimist
 
kurtverbose
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Apr 26, 2018 12:17 pm

Flight reporting a 10% drag reduction, 5% fuel reduction over an 800nm stage length, and can maintain this at mach 0.79, not 0.75 as previously thought.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Apr 26, 2018 1:31 pm

And they said they could be ready to build such a wing for a new NB aircraft from the late 2020's ie a decade away.That might tie in nicely with an A 320 family replacement.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Apr 26, 2018 2:00 pm

Some ways to go yet before its mature enough for program.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Apr 26, 2018 3:46 pm

parapente wrote:
That might tie in nicely with an A 320 family replacement.


Or re-winging.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Fri Apr 27, 2018 6:33 am

kurtverbose wrote:
parapente wrote:
That might tie in nicely with an A 320 family replacement.


Or re-winging.


If they can get it grandfathered. Boeing tried giving the 747 a new wing with a reduced sweep angle several times, but wasn't allowed to do it without certifying it as a new aircraft. If that is the case, I could see Airbus going for a clean sheet design.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Fri Apr 27, 2018 7:09 am

VSMUT wrote:
kurtverbose wrote:
parapente wrote:
That might tie in nicely with an A 320 family replacement.


Or re-winging.


If they can get it grandfathered. Boeing tried giving the 747 a new wing with a reduced sweep angle several times, but wasn't allowed to do it without certifying it as a new aircraft. If that is the case, I could see Airbus going for a clean sheet design.


The 777X has a new wing. Has that gone through the whole certification process?
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Fri Apr 27, 2018 7:42 am

It would certainly (to me) be surprising if either Airbus or Boeing chose to replace their 2NB aircaft with 'conventional' wings. With this technology nearing maturity.
At a guess both companies have an existing backlog of 5 years+ with their existing NB orders with no doubt plenty more to come.Whilst we don't know for sure it's looking quite likely that Boeing will be tied up for the next decade with the Midrange 797.
Since Airbus are doing just fine with their A320 family it is more than likely that the replacement battle will commence in circa a decade.
As such I have no doubt that (part)laminar wings will form part of this project for both companies.

As stated earlier my only experience in laminar flow wings comes from Sailplanes.As I recall they maintained laminar flow to about 50% back on the upper surface (if it was clean and dry).I can't see how it stays laminar after that unless you mechanically suck the air down.
I do recall that you have to be a little careful how you fly these wings as the air is not attached very strongly (odd phrase).The point being that you could create a large flow breakaway -and thus lift -if you operated out of the correct flying peramiters.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Fri Apr 27, 2018 8:23 am

kurtverbose wrote:
VSMUT wrote:
kurtverbose wrote:

Or re-winging.


If they can get it grandfathered. Boeing tried giving the 747 a new wing with a reduced sweep angle several times, but wasn't allowed to do it without certifying it as a new aircraft. If that is the case, I could see Airbus going for a clean sheet design.


The 777X has a new wing. Has that gone through the whole certification process?


No, not a completely new wing. They had to keep the wing-box and the sweep angle the same. This goes for the 747-8 too. Even the 737MAX has an inner-wing section that is more or less identical to that of the 737-100 for the same reason.
If part of this new technology is to reduce the sweep angle and make changes to the wing box, then grandfathering is most likely out of the window, and Airbus might as well just design a new plane from scratch.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Fri Apr 27, 2018 3:47 pm

kurtverbose wrote:
The 777X has a new wing. Has that gone through the whole certification process?


No, because a wing has not been produced yet. Boeing is working on assembling the static test frame enclosure so the testing will be done eventually.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Tue May 01, 2018 7:49 pm

Sounds like the wing will be incredibly sensitive to contamination of any kind. If they're concerned about insects and such, what is going to happen if there's even a minute amount of ice contamination of ANY kind, at ANY location.

What's the behavior of contamination on laminar wings anyways? Does it simply turn into turbulent flow, or is a substantial percentage of overall lift lost, with drag increasing? Sounds like you might net decent efficiency in a perfect world, but could turn into a dramatic hit if anything happens.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed May 02, 2018 12:36 am

estorilm wrote:
Sounds like the wing will be incredibly sensitive to contamination of any kind. If they're concerned about insects and such, what is going to happen if there's even a minute amount of ice contamination of ANY kind, at ANY location.

What's the behavior of contamination on laminar wings anyways? Does it simply turn into turbulent flow, or is a substantial percentage of overall lift lost, with drag increasing? Sounds like you might net decent efficiency in a perfect world, but could turn into a dramatic hit if anything happens.

Any object has some inherent surface roughness. The flow remains laminar initially despite those perturbations because the disturbance of the flow is not sufficient to overcome the stability of the boundary layer. The further you move down the wing and the closer you get to the natural transition from laminar to turbulent flow, the easier it becomes to initiate that transition by these disturbances, but the smaller the overall effect on drag is. Note that bugs are a sufficiently large disturbance to create the transition anywhere on currently used laminar profiles. However, the effects are limited to just downstream of the disturbance, so one bug on the wing will not affect the whole wing. The more bugs you catch or dirt you have, the larger the effects, of course. A fully contaminated wing may have double the drag of a clean wing. Similarly, operating the wing outside of its design parameters, i. e. above a certain AoA, can increase drag substantially as well, maybe by 50% to give you an idea.

You can see the effect of a single bug in this image. A turbulent region spreads within the generally laminar section of the wing and eventually merges with the turbulent section found downstream.
Image
Keep in mind that this is for "conventional" subsonic laminar airfoils, typically found on gliders and other small aircraft. I have little knowledge about the transsonic profile used by Airbus.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed May 02, 2018 4:16 pm

mxaxai wrote:
estorilm wrote:
Sounds like the wing will be incredibly sensitive to contamination of any kind. If they're concerned about insects and such, what is going to happen if there's even a minute amount of ice contamination of ANY kind, at ANY location.

What's the behavior of contamination on laminar wings anyways? Does it simply turn into turbulent flow, or is a substantial percentage of overall lift lost, with drag increasing? Sounds like you might net decent efficiency in a perfect world, but could turn into a dramatic hit if anything happens.

Any object has some inherent surface roughness. The flow remains laminar initially despite those perturbations because the disturbance of the flow is not sufficient to overcome the stability of the boundary layer. The further you move down the wing and the closer you get to the natural transition from laminar to turbulent flow, the easier it becomes to initiate that transition by these disturbances, but the smaller the overall effect on drag is. Note that bugs are a sufficiently large disturbance to create the transition anywhere on currently used laminar profiles. However, the effects are limited to just downstream of the disturbance, so one bug on the wing will not affect the whole wing. The more bugs you catch or dirt you have, the larger the effects, of course. A fully contaminated wing may have double the drag of a clean wing. Similarly, operating the wing outside of its design parameters, i. e. above a certain AoA, can increase drag substantially as well, maybe by 50% to give you an idea.

You can see the effect of a single bug in this image. A turbulent region spreads within the generally laminar section of the wing and eventually merges with the turbulent section found downstream.
Image
Keep in mind that this is for "conventional" subsonic laminar airfoils, typically found on gliders and other small aircraft. I have little knowledge about the transsonic profile used by Airbus.

Thanks for the information - I think you answered my questions but now I have even more haha.

This sounds like it has great potential for efficiency, but how reliable can the wing's performance be on aircraft that need to remain profitable on short turn-arounds almost constantly? Construction and maintenance on the wing sounds expensive as well, and would ground crews need to clean the leading edge prior to each departure?

AoA is interesting as well, presumably Airbus' FBW systems would be easily-programmed to make the wing behavior seem more conventional and safe, but I'd guess that once you achieve flow-separation, it may be more dramatic than a conventional wing/airfoil. I'm guessing certification would require portions of the wing to remain un-stalled?
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed May 02, 2018 4:50 pm

I think that whatever the potential drawbacks are for laminar flow (and there are some),the fact is Airbus have clearly declared themselves very pleased so whatever they have done works it appears.
It may (may) be perhaps more appropriate to say that it is 'more' laminar rather than laminar.But as they say at Tesco 'every little helps'!
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed May 02, 2018 5:20 pm

estorilm wrote:
Sounds like the wing will be incredibly sensitive to contamination of any kind. If they're concerned about insects and such, what is going to happen if there's even a minute amount of ice contamination of ANY kind, at ANY location.

I think learning more about that is the a major part of this exercise.

Early in this thread ( Pg 1, Reply #21 ) I gave some references that had some pretty amazing requirements:

To provide the geometric and surface quality required for laminar flow, assembly tooling tolerance is ±0.04 mm. Rivet height is reduced to ±0.04 mm from ±0.1 mm for a conventional wing, an acceptable step to +0.07/-0.26 mm from ±0.5mm, aerodynamic accuracy to 0.8 mm from 1.5 mm, and surface waviness to 0.3 mm from 1 mm over a 100 mm length.

Those references talk to the amazing amount of instrumentation going on to the aircraft. I think it's for the exact thing you question: figuring out what kind of impact real world contamination has on laminar flow.
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mxaxai
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed May 02, 2018 5:41 pm

estorilm wrote:
mxaxai wrote:
estorilm wrote:
Sounds like the wing will be incredibly sensitive to contamination of any kind. If they're concerned about insects and such, what is going to happen if there's even a minute amount of ice contamination of ANY kind, at ANY location.

What's the behavior of contamination on laminar wings anyways? Does it simply turn into turbulent flow, or is a substantial percentage of overall lift lost, with drag increasing? Sounds like you might net decent efficiency in a perfect world, but could turn into a dramatic hit if anything happens.

Any object has some inherent surface roughness. The flow remains laminar initially despite those perturbations because the disturbance of the flow is not sufficient to overcome the stability of the boundary layer. The further you move down the wing and the closer you get to the natural transition from laminar to turbulent flow, the easier it becomes to initiate that transition by these disturbances, but the smaller the overall effect on drag is. Note that bugs are a sufficiently large disturbance to create the transition anywhere on currently used laminar profiles. However, the effects are limited to just downstream of the disturbance, so one bug on the wing will not affect the whole wing. The more bugs you catch or dirt you have, the larger the effects, of course. A fully contaminated wing may have double the drag of a clean wing. Similarly, operating the wing outside of its design parameters, i. e. above a certain AoA, can increase drag substantially as well, maybe by 50% to give you an idea.

You can see the effect of a single bug in this image. A turbulent region spreads within the generally laminar section of the wing and eventually merges with the turbulent section found downstream.
Image
Keep in mind that this is for "conventional" subsonic laminar airfoils, typically found on gliders and other small aircraft. I have little knowledge about the transsonic profile used by Airbus.

Thanks for the information - I think you answered my questions but now I have even more haha.

This sounds like it has great potential for efficiency, but how reliable can the wing's performance be on aircraft that need to remain profitable on short turn-arounds almost constantly? Construction and maintenance on the wing sounds expensive as well, and would ground crews need to clean the leading edge prior to each departure?

AoA is interesting as well, presumably Airbus' FBW systems would be easily-programmed to make the wing behavior seem more conventional and safe, but I'd guess that once you achieve flow-separation, it may be more dramatic than a conventional wing/airfoil. I'm guessing certification would require portions of the wing to remain un-stalled?

There seems to be a slight mix-up of stall and turbulent flow. A laminar wing has a certain range of AoA (or rather, lift coefficients) where the flow does not change much. But once you pass a certain AoA the transition from laminar to turbulent flow quickly moves towards the leading edge. The wing is still producing lift, very much actually, but you're paying for that increase in lift with a very significant increase in drag.

Laminar flow can separate but will typically transition to turbulent flow quickly. The wing does not experience a stall, though drag is increased compared to a smooth transition without separation. Only when the turbulent flow separates from a sufficient portion of the wing is a stall noticeable. Stall onset behaviour has been an old problem of laminar airfoils, not necessarily due to the laminar flow itself but due to the specific wing geometry that came with it. Perhaps Airbus has found a way to control some problems.
 
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Revelation
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed Jul 11, 2018 11:41 am

Interesting update at https://www.flightglobal.com/news/artic ... xt-448911/ ( free reg required )

Flaig says laminar flow could be observed from the aircraft's first flight and that the team was "surprised" at the stability of the flow. A key objective of the BLADE project is to assess the robustness of the flow while the wing flexes and becomes distorted in flight, and to find the sweet spot of a wing profile that ensures sustainable laminar flow in airline operations while delivering notable savings.

The tests showed that Airbus can "relax the shape" of the wing and allow for "slightly larger tolerances" than previously thought, Flaig says. Furthermore, the team learned that aerodynamic benefits could be sustained during the flight tests at Mach 0.78 – a typical cruise speed for A320-family jets – where Airbus had previously predicted that an aircraft would need to fly at M0.75 to deliver the fuel savings.

And:

Flaig says it has not yet been decided which of the manufacturing concepts Airbus would adopt for a laminar-flow wing. He asserts, however, that tests have shown "the door is wide open" for the technology to be employed on a potential next-generation single-aisle aircraft from the late 2020s, and that the manufacturer is "very confident" the BLADE project will achieve "more than we targeted".

The time frame seems to line up well with A and B's plans to replace the current single aisle aircraft.
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Amiga500
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed Jul 11, 2018 2:33 pm

Revelation wrote:
The time frame seems to line up well with A and B's plans to replace the current single aisle aircraft.


Its also something that cannot be neutralised with just a re-engine.

There won't be a further 737 iteration.
 
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Matt6461
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed Jul 11, 2018 7:45 pm

Is NASA working on something similar? Or has Trump defunded it to pay for kidnapping children or something?
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed Jul 11, 2018 7:53 pm

NASA does or at least did have some laminar flow testbeds using an F-15 and F-16.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Wed Jul 11, 2018 10:34 pm

Matt6461 wrote:
Is NASA working on something similar? Or has Trump defunded it to pay for kidnapping children or something?


There has been loads of work done on this on both sides of the Atlantic for decades. Its not a new idea.

Its just that implementing most of it has been utterly impractical, indeed for all the research done now, it might just have slid down that scale from "utterly" to "quite". No point in designing an airframe that burns 1% less fuel but costs 5 times as much to build [made up numbers just to illustrate the point].
 
mxaxai
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Jul 12, 2018 9:37 am

Revelation wrote:
Interesting update at https://www.flightglobal.com/news/artic ... xt-448911/ ( free reg required )


The tests showed that Airbus can "relax the shape" of the wing and allow for "slightly larger tolerances" than previously thought, Flaig says. Furthermore, the team learned that aerodynamic benefits could be sustained during the flight tests at Mach 0.78 – a typical cruise speed for A320-family jets – where Airbus had previously predicted that an aircraft would need to fly at M0.75 to deliver the fuel savings.

Out of curiosity: Why is the change from M0.75 to M0.8 or M0.85 (widebody cruise speed) so significant? Is it due to transsonic effects, where the flow becomes supersonic above the wing and needs to go through some weak shocks to decelerate again in front of the trailing edge, which turns the laminar flow into turbulent flow?
 
Amiga500
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Thu Jul 12, 2018 1:45 pm

mxaxai wrote:
Revelation wrote:
Interesting update at https://www.flightglobal.com/news/artic ... xt-448911/ ( free reg required )


The tests showed that Airbus can "relax the shape" of the wing and allow for "slightly larger tolerances" than previously thought, Flaig says. Furthermore, the team learned that aerodynamic benefits could be sustained during the flight tests at Mach 0.78 – a typical cruise speed for A320-family jets – where Airbus had previously predicted that an aircraft would need to fly at M0.75 to deliver the fuel savings.

Out of curiosity: Why is the change from M0.75 to M0.8 or M0.85 (widebody cruise speed) so significant? Is it due to transsonic effects, where the flow becomes supersonic above the wing and needs to go through some weak shocks to decelerate again in front of the trailing edge, which turns the laminar flow into turbulent flow?


A laminar boundary layer is more prone to shock induced separation - so inducing those several weak shocks you speak of becomes more challenging - it'd tend to have one strong shock with significant drag instead.

But it would seem that with this, Airbus have found either a way around it, or that maybe it isn't as pronounced as on previous aerofoil sections.
 
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Fri Jul 13, 2018 3:11 am

Amiga500 wrote:
Its also something that cannot be neutralised with just a re-engine.

Yes, and it's even worse, according to the article:

efforts to reduce wing drag through conventional aerodynamic tweaks have largely been exhausted, in the view of Airbus senior vice-president of research and technology Axel Flaig

So there's no help from aero tweaks either, once you've gotten to a modern high a/r cfrp wing.

Amiga500 wrote:
There won't be a further 737 iteration.

Yes, I agree.

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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Tue Jul 17, 2018 7:09 am

Revelation wrote:
Flaig says it has not yet been decided which of the manufacturing concepts Airbus would adopt for a laminar-flow wing. He asserts, however, that tests have shown "the door is wide open" for the technology to be employed on a potential next-generation single-aisle aircraft from the late 2020s, and that the manufacturer is "very confident" the BLADE project will achieve "more than we targeted".

The time frame seems to line up well with A and B's plans to replace the current single aisle aircraft.


Also interesting in relation to the 797 EIS timing. Or any A320 rewing for that matter. You don't some lainching and have this tech enter service a few years later.

On the current A320 rewing debate that might imply that waiting too long with a conventional design now might make the time to return on investment too short.
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mxaxai
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Re: Airbus A340 Laminar Flow Demonstrator To Fly In 2017

Tue Jul 17, 2018 12:34 pm

Taxi645 wrote:
Also interesting in relation to the 797 EIS timing. Or any A320 rewing for that matter. You don't some lainching and have this tech enter service a few years later.

On the current A320 rewing debate that might imply that waiting too long with a conventional design now might make the time to return on investment too short.

Boeing has just pushed back a firm decision on the 797 until 2019 - 2020, EIS no earlier than 2025 - 2026. Should give Airbus and Boeing more time to do the necessary research and development, in line with the schedule outlined for the laminar flow wing and the upcoming RR ultrafan. (I'm sure that Boeing's aero department isn't sitting idly by either.)

https://www.flightglobal.com/news/artic ... -y-450239/

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