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Holes In Airplane Wings To Save Fuel  
User currently offlineLumberton From United States of America, joined Jul 2005, 4708 posts, RR: 20
Posted (7 years 11 months 2 days 21 hours ago) and read 7379 times:

Short article, title says it all.
http://www.dailymail.co.uk/pages/liv...id=411695&in_page_id=1766&ito=1490

Quote:
Markus Kloker and Ralf Messing, project leaders, told German newspaper "Der Spiegel" that a series of 50-micron-diameter (0.05 mm) holes in the wings reduce swirls and then also advancing resistance.

They are claiming a 15% reduction in fuel consumption!!!


"When all is said and done, more will be said than done".
32 replies: All unread, showing first 25:
 
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 1, posted (7 years 11 months 2 days 21 hours ago) and read 7376 times:

I think you may have the wrong link?

User currently offlineDw747400 From United States of America, joined Aug 2001, 1260 posts, RR: 1
Reply 2, posted (7 years 11 months 2 days 20 hours ago) and read 7340 times:

There have been some studies done about using very small holes to manipulate the boundary layer. I believe most research has shown the systems are not worth their weight and complexity--but maybe that is changing. We do need the actual link of course! (Though I do find the picture of a regional jet in an article about a 777 amusing... not that I expect better from the press.)


CFI--Certfied Freakin Idiot
User currently offlineBobster2 From , joined Dec 1969, posts, RR:
Reply 3, posted (7 years 11 months 2 days 20 hours ago) and read 7343 times:

Found the correct link with Google:

http://www.avionews.com/index.php?co...d=66965&pagina_chiamante=index.php

It says they're talking to Airbus. I bet a 15% fuel reduction on the A380 would be a huge savings.  Smile


User currently offlineFr8Mech From United States of America, joined Sep 2005, 5418 posts, RR: 14
Reply 4, posted (7 years 11 months 2 days 18 hours ago) and read 7294 times:

The problem, as I see it, will be maintenance and related costs. This will probably be a critical contour that won't play well if it is dented, scratched or deformed. I imagine hail will play havoc with the design. Not being a physicist: can water enter these holes and freeze? Will de-ice fluid be able to 'flush' these holes of ice? What will the adhering effects of Type IV do to the fuel burn?

Questions, questions, questions.



When seconds count...the police are minutes away.
User currently offlineKalvado From United States of America, joined Feb 2006, 491 posts, RR: 0
Reply 5, posted (7 years 11 months 2 days 17 hours ago) and read 7281 times:

Very hard to imagine manufacturing of 50-micron holes to be cost-effective whatever fuel saving would be. Even then, they will get clogged with dust very soon - not to mention any paint job.
I suspect, surface grooves were proposed, and idea lost in translation and communication. Patterned surface (some sort of shark-skin) would make some sense for me. But even then, how long are they going to last when exposed to real environment?


User currently offlineRichardPrice From , joined Dec 1969, posts, RR:
Reply 6, posted (7 years 11 months 2 days 12 hours ago) and read 7214 times:

Sounds like a golfball design...

User currently offlineChksix From Sweden, joined Sep 2005, 345 posts, RR: 4
Reply 7, posted (7 years 11 months 2 days 11 hours ago) and read 7203 times:

Isn't this used already in the inlets of jet engines to control the boundary layer?
http://www.airliners.net/open.file/1090718/M/
See the inside of the cowling.

The F4 Phantom also had those "meshes" on the inlet ramps
http://www.airliners.net/open.file/1122681/M/



The conveyor belt plane will fly
User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 4
Reply 8, posted (7 years 11 months 2 days 9 hours ago) and read 7177 times:

Quoting Chksix (Reply 7):
Isn't this used already in the inlets of jet engines to control the boundary layer?
http://www.airliners.net/open.file/1090718/M/
See the inside of the cowling.

The purpose of the holes in the B737 air intake is to reduce noise.

I don´t think they do the same on the good old F4. It must be noisy Big grin!!!



This job sucks!!! I love this job!!!
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17038 posts, RR: 66
Reply 9, posted (7 years 11 months 2 days 9 hours ago) and read 7176 times:

Quoting Kalvado (Reply 5):
I suspect, surface grooves were proposed, and idea lost in translation and communication. Patterned surface (some sort of shark-skin) would make some sense for me. But even then, how long are they going to last when exposed to real environment?

This has been tried on real airliners. I believe CX did some sharkskin experiments. But the cost of the paint job pretty much negated any advantages.

I'm not saying ideas like these should be discouraged, but often the proposals are made by people who know a lot about aerodynamics and not a lot about real world aircraft operations.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineBobster2 From , joined Dec 1969, posts, RR:
Reply 10, posted (7 years 11 months 2 days 5 hours ago) and read 7110 times:

I found another article that explains it better. The key is that they apply vacuum suction to the holes that controls the shape and structure of the boundary layer. So it's not like a golf ball. They admit it's very expensive and would only be practical if fuel costs are high. There are links here to more technical info:

http://www.greencarcongress.com/2006/10/researchers_sta.html


User currently offlineKalvado From United States of America, joined Feb 2006, 491 posts, RR: 0
Reply 11, posted (7 years 11 months 2 days 4 hours ago) and read 7083 times:

Quoting Bobster2 (Reply 10):
The key is that they apply vacuum suction to the holes that controls the shape and structure of the boundary layer. So it's not like a golf ball. They admit it's very expensive and would only be practical if fuel costs are high.

Thanks for the link!
It makes much more sence now. What really confuses me, how would that work with all hardware (pumps, pipes) needed for all that - weight penalty would definitely be non-negligible. Overall, it looks more like some purely scientific research, which got publicity way before it really should.


User currently offlineAeroWeanie From United States of America, joined Dec 2004, 1609 posts, RR: 52
Reply 12, posted (7 years 11 months 2 days 4 hours ago) and read 7076 times:
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This is nothing new. The RAE and NASA have studied hybrid laminar flow control for years (about 50+). One huge problem is in-service maintenance. NASA flew a hybrid laminar flow control glove on a JetStar in simulated airline service to try and get the manufacturers interested, but the demo just showed up all the problems.


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Photo © David Lednicer



User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 13, posted (7 years 11 months 1 day 21 hours ago) and read 7009 times:

Quoting Starlionblue (Reply 9):
people who know a lot about xxxxxxxxxxx and not a lot about real world xxxxxxxxxxx operations.

They're called "middle management" and they usually have business school diplomas.



Todos mis dominós son totalmente pegajosos
User currently offlineLimaNiner From United States of America, joined Oct 2006, 400 posts, RR: 0
Reply 14, posted (7 years 11 months 1 day 18 hours ago) and read 6963 times:

Quoting Kalvado (Reply 5):
Very hard to imagine manufacturing of 50-micron holes to be cost-effective

I wonder if "drilling" these holes with lasers would be practical?

Quoting Kalvado (Reply 5):
they will get clogged with dust very soon

I would imagine positive pressure from the inside (e.g. by blowing in some warm air from the engines) would work (and avoid clogging the holes with freezing water, too), but then I saw that this technique requires *negative* pressure...

Quoting Bobster2 (Reply 10):
The key is that they apply vacuum suction to the holes



Quoting BAe146QT (Reply 13):
They're called "middle management" and they usually have business school diplomas.

Indeed!

I've always wanted to reply to some MBA clown "Hey, since we can replace an engineer with expertise X with an engineer with expertise Y, why can't we replace our CFO (who has an MBA in accounting) with an MBA with HR specialization?"


User currently offlineAeroWeanie From United States of America, joined Dec 2004, 1609 posts, RR: 52
Reply 15, posted (7 years 11 months 1 day 17 hours ago) and read 6953 times:
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Quoting LimaNiner (Reply 14):
I wonder if "drilling" these holes with lasers would be practical?

That's how its done.


User currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 16, posted (7 years 11 months 1 day 15 hours ago) and read 6933 times:

Quoting Starlionblue (Reply 9):
I believe CX did some sharkskin experiments.

G'day Starlionblue  Smile. Was that an experiment only? I seem to remember that the fuselages of Airbus were covered in some sort of "micro-riblet" film  Confused



JetMech split the back of his pants. He can feel the wind in his hair.
User currently offlineChksix From Sweden, joined Sep 2005, 345 posts, RR: 4
Reply 17, posted (7 years 11 months 1 day 11 hours ago) and read 6886 times:

Quoting Troubleshooter (Reply 8):
Quoting Chksix (Reply 7):Isn't this used already in the inlets of jet engines to control the boundary layer?
http://www.airliners.net/open.file/1090718/M/
See the inside of the cowling.
The purpose of the holes in the B737 air intake is to reduce noise.

I don´t think they do the same on the good old F4. It must be noisy !!!

Hi,
I've read that those panels have suction or a low pressure behind them for boundary layer control. It can't be just noise reduction IMO.

I assume that the fan would lose a lot of efficiency if part of the flow was turbulent in the inlet.



The conveyor belt plane will fly
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17038 posts, RR: 66
Reply 18, posted (7 years 11 months 1 day 10 hours ago) and read 6876 times:

Quoting BAe146QT (Reply 13):
Quoting Starlionblue (Reply 9):
people who know a lot about xxxxxxxxxxx and not a lot about real world xxxxxxxxxxx operations.

They're called "middle management" and they usually have business school diplomas.

Hey, you're describing my wife  Wink You'll be glad to hear she works nowhere near the airline/aerospace industry. Big grin

Quoting JetMech (Reply 16):
Quoting Starlionblue (Reply 9):
I believe CX did some sharkskin experiments.

G'day Starlionblue Smile. Was that an experiment only? I seem to remember that the fuselages of Airbus were covered in some sort of "micro-riblet" film

By "experiment" I meant "in service trial". But I have no further info I'm afraid.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 4
Reply 19, posted (7 years 11 months 1 day 9 hours ago) and read 6868 times:

Quoting Chksix (Reply 17):
Hi,
I've read that those panels have suction or a low pressure behind them for boundary layer control. It can't be just noise reduction IMO.

Definately not on the B737! They are "just" acoustic panels. Inside the small holes the airflow creates small vortices thus increasing static pressure resulting in a temperature increase. You can say that noise is transferred into heat. All this happens inside these holes. End of story.

As I wrote earlier I´m not sure if they serve the same purpose on the F4 air intakes. These intakes are designed for mach 2+ and are not comparable to those on the B737.



This job sucks!!! I love this job!!!
User currently offlineAeroWeanie From United States of America, joined Dec 2004, 1609 posts, RR: 52
Reply 20, posted (7 years 11 months 1 day 8 hours ago) and read 6856 times:
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Quoting Troubleshooter (Reply 19):
Definately not on the B737! They are "just" acoustic panels. Inside the small holes the airflow creates small vortices thus increasing static pressure resulting in a temperature increase. You can say that noise is transferred into heat. All this happens inside these holes. End of story.

The holes in the panels on jet engine inlets have tiny cavities behind them, tuned to absorb noise at the frequencies transmitted by the inlets. The cavities are called Helmholtz Resonators.

Quoting Troubleshooter (Reply 19):
As I wrote earlier I´m not sure if they serve the same purpose on the F4 air intakes. These intakes are designed for mach 2+ and are not comparable to those on the B737.

On the F-4 inlet ramps, the air is sucked into the holes to surpress boundary layer separation caused by the shocks used to slow down the flow into the inlets at supersonic speeds.

In the test panels, flown for example on the JetStar, less air is sucked into the holes. The idea there is to stabilize the laminar boundary layer and delay its transition to a much draggier turbulent boundary layer.


User currently offlineChksix From Sweden, joined Sep 2005, 345 posts, RR: 4
Reply 21, posted (7 years 11 months 1 day 8 hours ago) and read 6852 times:

Thanks for those clarifications.


The conveyor belt plane will fly
User currently offlineEatmybologna From France, joined Apr 2005, 412 posts, RR: 0
Reply 22, posted (7 years 10 months 4 weeks 23 hours ago) and read 6667 times:

Dennis Connor did this once with his America's Cup 12 meter racing yacht.

NF 203
October 1993
NASA RIBLETS FOR STARS & STRIPES

America has won an Olympic medal and the America's Cup thanks to the same NASA technology that is saving commercial airlines hundreds of millions of dollars annually.

On February 4, 1987, skipper Dennis Connor and his ten-man crew guided the Stars and Stripes racing yacht past the finish line at Fremantle, Australia, to recapture sailing's most coveted prize, the America's Cup. Representing the San Diego Yacht Club, Connor and Stars and Stripes scored a 4-0 sweep in the best-of-seven finals over Australia's Kookaburra III.

Stars & Stripes
The hull's underside was coated with a "riblet" skin
that helped the craft slide through the sea more smoothly.
(photo credit: Sally Samins - PPL MEDIALINK)

A key piece of NASA technology assisted in the win. Stars and Stripes design coordinator John Marshall disclosed the boat's "secret weapon" as the hull's underside, coated with a "riblet" skin that helped the craft slide through the sea more smoothly.

You can read the rest of it here..

http://www.nasa.gov/centers/langley/news/factsheets/Riblets.html



Isn't knowledge more than just the acquisition of information? Shouldn't the acquired information be correct?
User currently offlinePrebennorholm From Denmark, joined Mar 2000, 6449 posts, RR: 54
Reply 23, posted (7 years 10 months 4 weeks 22 hours ago) and read 6644 times:

50 micron holes for boundary layer suction: Corrosion, crack development, paint, dirt, combine with anti icing heating, no, I don't see it happen.

And as AeroWeanie wrote, the idea is as old as fast flight itself.

NASA tested it on a special transport optimized wing mounted on an F-8 Crusader some 30 or 35 years ago. The results were inconclusive.

If the wing is not perfectly shaped, not polished as a mirror, if it it wet (rain, flying through clouds), if rivets are not completely flush, if the leading edge has collected dead insects, etc. etc... Then it all comes to nothing. Except for the weight penalty for the suction machinery, the vacuum tubing etc.

Anyway, one offspring from the idea has been used during the last 20 years or so with positive effect to energize the boundary layer on practically all competition glider aircrafts: Zig-zag tape mounted where transition from laminar to turbulent flow is expected. That at least minimized the size of separation bubbles.

That can hardly be copied with any effect on transport planes. They operate the wings at much higher Reynolds numbers at which separation bubbles are almost non-existant.



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineAogdesk From United States of America, joined Jun 2004, 935 posts, RR: 3
Reply 24, posted (7 years 10 months 4 weeks 20 hours ago) and read 6623 times:

Got so excited after reading the title of this thread that I ran out and drilled .125" holes all over the wing of a 737. Guess I should have read further huh?  Wink

25 787atPAE : Sounds like y'all are describing the "suck and blow" method of boundary layer control. I heard about this for my BS degree, and the prof let it be kno
26 Post contains images LimaNiner : Yeah, but: AC yachts are basically disposable (they have to last less than a year), and the "riblets" used on Connor's yacht weren't "active", i.e.,
27 Post contains images AeroWeanie : What NASA tested on the F-8 was a wing using the then-new supercritical airfoil. They actually first tested it on a T-2 Buckeye. The supercritical ai
28 Oly720man : Our previous prof was looking at this over a number of years and, yes it works, but it's maintenance intensive as well as being marginal on efficiency
29 BAe146QT : Imagine how much would be saved if they drilled holes all over the plane? Better yet, make it out of chicken wire so we can test the theory about 100,
30 HAWK21M : You'll end up flying it unpressurised then. regds MEL
31 BAe146QT : Just kiddin, Mel. There was a thread (or three) about what would happen to the weight (not mass) of an aircraft it it was full of birds, and all the b
32 Prebennorholm : Thanks AeroWeanie, my bad! I totally mixed up the the NASA F-8 supercritical test aircraft and the Air Force X-21A laminar flow test aircraft. As the
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