There is reasons to believe this article is essentially correct, if so this is exciting stuff . Increasing the laminar flow partion on the wings have been the desire since the P58 Mustang laminar flow profiled wing, yet it has not been introduced into mainline airliners to date IIRC.
The elegance of the B system is that the suction comes from parts of the wing which has low static pressure, ie no active parts .
I know there are test with increasing laminar flow on test wings for A in the 2015 time frame, is this similar technology? (It can only be similar as B have patented their implementation).
747classic From Netherlands, joined Aug 2009, 1789 posts, RR: 11 Reply 1, posted (1 year 11 months 1 week 5 days 13 hours ago) and read 7921 times:
The hybrid laminar flow control (HLFC) modification is installed on test aircraft ZA003 in a limited area on the leading edge of the Boeing-built vertical stabiliser, one-quarter to one-half of the way up the fin, estimated to be positioned on the adjacent forward panels between ribs 3 and 7, and below the HF antenna.
But from the Wiki article I actually get the impression that all wings have laminar flow, or am I wrong on this? Also; what's so special about the implementation on the 787 that it couldn't be done on previous airliners? And why the apparant gap between the P-51 and the 787?
Autothrust From Switzerland, joined Jun 2006, 1480 posts, RR: 8 Reply 3, posted (1 year 11 months 1 week 5 days 12 hours ago) and read 7868 times:
Quoting ferpe (Thread starter): Boeing have now started the tests with laminar flow improvement technology on the 787 tail:
What the news, that Boeing is second as always? Airbus has tested laminar flow on the A320 already in the year 1998!!
Quote: Airbus Industrie has begun flight testing its A320 development aircraft, equipped with a newly developed vertical tailfin, which incorporates laminar flow technology to reduce air friction and significantly reduce fuel consumption.
474218 From United States of America, joined Oct 2005, 6340 posts, RR: 10 Reply 5, posted (1 year 11 months 1 week 5 days 12 hours ago) and read 7851 times:
BMI727 From United States of America, joined Feb 2009, 14355 posts, RR: 26 Reply 8, posted (1 year 11 months 1 week 5 days 6 hours ago) and read 7652 times:
Quoting ferpe (Thread starter): yet it has not been introduced into mainline airliners to date IIRC.
The Honda Jet is set to use a natural laminar flow wing.
Quoting travelavnut (Reply 2): Could somebody explain laminar flow, and its advantages, in laymens terms? I get the concept, I think, from Wikipedia;
Having laminar flow reduces the skin friction from the air flow. Of course, the mixing of a turbulent boundary layer introduces more energy to delay flow separation so while airliner engineers are seeking to retain more laminar flow, engineers designing smaller aircraft often seek to make the flow turbulent. Airliners sometimes utilize vortex generators to get a similar effect.
Quoting travelavnut (Reply 2): But from the Wiki article I actually get the impression that all wings have laminar flow, or am I wrong on this?
They do, for a little while. Just using rough calculations, the flow over an airliner moving at 500 mph is laminar for about 3 cm.
Quoting travelavnut (Reply 2): And why the apparant gap between the P-51 and the 787?
Reynolds number. Airliners will work at a higher Reynolds number range than a P-51, mostly because they are bigger but are also a bit faster as well.
Why do Aerospace Engineering students have to turn things in on time?
David L From United Kingdom, joined May 1999, 9219 posts, RR: 42 Reply 9, posted (1 year 11 months 1 week 4 days 16 hours ago) and read 7435 times:
Quoting 474218 (Reply 5): I wish people would use the proper terminology! It is the "VERTICAL STABILIZER".
I suspect the "proper terminology" can vary from place to place. I've seen "tailfin" and "tailplane" (horizontal stabiliser) used in technical articles in the UK over the years. There are similar differences in car terminology, e.g. trunk/boot, hood/bonnet, turn-signals/indicators.
ferpe From France, joined Nov 2010, 1785 posts, RR: 57 Reply 10, posted (1 year 11 months 1 week 21 hours ago) and read 7079 times:
As written in the Civil Avition forum I expect B to apply this technology in full on the 797 NSA project, this will be the technology that gives B a distinct advantage over the A320NEO. One can only speculate on how much drag reduction one can achieve when applied on wings and tail but 5% should be achievable IMHO, which is quite a feat.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 11, posted (1 year 11 months 6 days 21 hours ago) and read 6849 times:
Quoting travelavnut (Reply 2): Could somebody explain laminar flow, and its advantages, in laymens terms?
Smooth, rather than erratic flow. Turn your water faucet on low...you'll get a nice smooth "glassy" stream for some distance (laminar) that will be come all wiggly and jagged (turbulent). Laminar flow has lower skin friction, hence lower drag.
Quoting travelavnut (Reply 2): But from the Wiki article I actually get the impression that all wings have laminar flow, or am I wrong on this?
All airliner wings are turbulent (right now). They're too large and fast to be laminar over more than a small fraction of the wing. People often confuse turbulent with separated...they're very different.
Quoting Autothrust (Reply 3): What the news, that Boeing is second as always? Airbus has tested laminar flow on the A320 already in the year 1998!!
Nice try...Boeing did it on a 757 in 1985 (http://www.nasa.gov/centers/dryden/pdf/88792main_Laminar.pdf). Not to say that Boeing did it *first*...it's a far older idea than that, but let's keep the revisionist history to a minimum.
ferpe From France, joined Nov 2010, 1785 posts, RR: 57 Reply 12, posted (1 year 11 months 5 days 20 hours ago) and read 6703 times:
From an intervju wiht J Leahy at Paris Airshow:
"If they (B) built an all-new airframe, it would be about up to 3% better on the airframe side. We did the studies before we did the NEO that an all-new, clean-sheet airplane aerodynamically could save us about 3% in fuel burn. Everything has to come from the engines."
He is clearly not counting on the application of laminar flow technology, once again I think this is what B has up the sleeve for the 797 and is the real reason why they want to go clean sheet. B want to exploit the technology now before the competition works out their own good and tested solutions to the problem and the advantage would be void.
travelavnut From Netherlands, joined May 2010, 1381 posts, RR: 5 Reply 14, posted (1 year 11 months 5 days 11 hours ago) and read 6654 times:
Quoting tdscanuck (Reply 11): Smooth, rather than erratic flow. Turn your water faucet on low...you'll get a nice smooth "glassy" stream for some distance (laminar) that will be come all wiggly and jagged (turbulent). Laminar flow has lower skin friction, hence lower drag.
Thanks a lot Tds!
Quoting tdscanuck (Reply 11): All airliner wings are turbulent (right now). They're too large and fast to be laminar over more than a small fraction of the wing. People often confuse turbulent with separated...they're very different.
So what kind of changes are made to the 787 vertical stabilizer to generate this flow?
Also from your explanation I gather laminar flow over the entire wing of an airliner is impossible to achieve due to the size of the wing?
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 15, posted (1 year 11 months 5 days 11 hours ago) and read 6636 times:
Quoting travelavnut (Reply 14): Quoting tdscanuck (Reply 11):
All airliner wings are turbulent (right now). They're too large and fast to be laminar over more than a small fraction of the wing. People often confuse turbulent with separated...they're very different.
So what kind of changes are made to the 787 vertical stabilizer to generate this flow?
Unfortunately, I can't talk about that. NASA has a good paper on the history of laminar flow control that's a good read to give you some ideas of the techniques: www.nasa.gov/centers/dryden/pdf/88792main_Laminar.pdf
Quoting travelavnut (Reply 14): Also from your explanation I gather laminar flow over the entire wing of an airliner is impossible to achieve due to the size of the wing?
It's impossible if you don't do anything to control the boundary layer. The boundary layer is the slow moving layer of air right next to a surface. The longer the air stays there (the bigger the surface) or the faster the surface is going, the more energy the boundary layer picks up and, eventually, it goes turbulent. To prevent turbulent flow you either need to prevent energy from going into the boundary layer in the first place (natural laminar flow airfoils) or actively remove energy as you go. The latter is where most of the suction-based laminar flow control ideas come from...they use some kind of system to remove energy from the boundary layer. With active boundary layer control, you can keep the flow laminar over arbitrarily large surfaces at arbitrarily large speeds.
Thanks again Tds, got something to read this weekend
Quoting tdscanuck (Reply 15): The latter is where most of the suction-based laminar flow control ideas come from...they use some kind of system to remove energy from the boundary layer. With active boundary layer control, you can keep the flow laminar over arbitrarily large surfaces at arbitrarily large speeds
Ok, I think I'm starting to get this, complicated stuf though.
ferpe From France, joined Nov 2010, 1785 posts, RR: 57 Reply 19, posted (1 year 11 months 4 days 22 hours ago) and read 6458 times:
@Tom
I guess one could also allply this technology to the body surfaces and they should be quite effective there as well, why does one focus on a wings low pressure side? Because the air travels faster there or that boundry layer slows down because of the pressure gradient?
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 20, posted (1 year 11 months 4 days 21 hours ago) and read 6455 times:
Quoting ferpe (Reply 19): I guess one could also allply this technology to the body surfaces and they should be quite effective there as well,
In principle, yes. However, given that the body surfaces are (usually) also the pressure vessel, the logistics of putting a bazillion little holes or vents or scoops or what-have-you in the body surfaces are more complicated.
Quoting ferpe (Reply 19): why does one focus on a wings low pressure side? Because the air travels faster there or that boundry layer slows down because of the pressure gradient?
I'm not sure on the history on that one...in principle, it would work on either side. There may be stall benefits (delayed separation) to doing in on the upper surface though.
BMI727 From United States of America, joined Feb 2009, 14355 posts, RR: 26 Reply 21, posted (1 year 11 months 4 days 21 hours ago) and read 6446 times:
Quoting ferpe (Reply 19): Because the air travels faster there or that boundry layer slows down because of the pressure gradient?
My guess would be that active boundary layer control might be able to reduce the adverse pressure gradient on the rear portion of the wing, which would delay separation.
Theoretically, I would think that if one could utilize the system on both sides of the wing, it could be linked and controlled in such a way to route air from the bottom to the top in certain (likely high alpha) situations almost like having a slotted flap.
Why do Aerospace Engineering students have to turn things in on time?
ferpe From France, joined Nov 2010, 1785 posts, RR: 57 Reply 22, posted (1 year 11 months 4 days 20 hours ago) and read 6423 times:
Quoting tdscanuck (Reply 20): In principle, yes. However, given that the body surfaces are (usually) also the pressure vessel, the logistics of putting a bazillion little holes or vents or scoops or what-have-you in the body surfaces are more complicated.
Thanks Tom, actually this was my conclusion as well. Re practical implementation, I would assume laminar flow goes well with electrical de-ice as you need the slats natural plenum for your suction (instead of for bleed-air deice).
Quoting BMI727 (Reply 21): Theoretically, I would think that if one could utilize the system on both sides of the wing, it could be linked and controlled in such a way to route air from the bottom to the top in certain (likely high alpha) situations almost like having a slotted flap.
I think you need air with much higher pressure differential then you get from those many small holes, any blown flaps or sorts need pretty high energy air. I would assume the air is not that high energy that you get in those laminar flow plenums.
CARST From Germany, joined Jul 2006, 706 posts, RR: 1 Reply 23, posted (1 year 11 months 4 days 12 hours ago) and read 6360 times:
Is such a system prone to icing? If a lot of water gets into the "holes" before departure and while climbing, couldn't this water freeze inside the system? Not only making it loose its advantage, but damaging the (passive) system, too and adding some pounds of weight? Or is the system heated?
Quite an informative article, my assumption on a drag gain of about 5% seems to not be that far of
Non French in France
25 faro: My money is on super-smooth airframe coatings for the hardened wing/tailplane leading edges. May have something to do with the 787 nacelle leading ed
26 jetmech: Perhaps. Boundary layer suction schemes generally aim to endow the boundary layer with additional momentum to penetrate further against a given adver
27 tommytoyz: Another issue with laminar flow is that you need clean surfaces. If an airline doesn't keep their places clean enough, it might significantly interfer
28 tdscanuck: It depends if you're doing it for drag reduction or lift performance. The former is more popular and less dangerous. The change between laminar and t
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. Increasing the laminar flow partion on the wings have been the desire since the P58 Mustang laminar flow profiled wing, yet it has not been introduced into mainline airliners to date IIRC.
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