Boeing4ever
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Commercial Airliner Naca Airfoil Sections

Sun Apr 16, 2006 9:54 am

I'm curious as to what are some typically used NACA airfoil sections for commercial aircraft. In particular, what kind of airfoil sections for the 747, Concorde, A380, 777, and the C-5 or C-17 use? What are the lift curve slopes for these aircraft airfoils assuming flaps up?? Zero-lift angle of attack assuming flaps up?

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2H4
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 16, 2006 11:10 am

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Boeing4ever
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 16, 2006 11:18 am

Now that is awesome. Interesting to note that some manufacturers seem to have come up with their own "personalized" airfoil designs. For example, the 747's root airfoil(s) are a BAC 463 to a BAC 468. Shame the A380's airfoil data isn't there. I was hoping to get the lift curve slope and zero lift angle of attack to plug into a MATLAB script I wrote for my Aero class hmwk that takes that data, plus things like wing sweep, aspect ratio, Mach number, etc to plot Lift/Drag plots. It's tough looking for out of the way specs on aircraft over an enthusiast's internet.

Thank you very much though! This is a treasure trove!

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L-188
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 16, 2006 12:29 pm

Well it gets better then that.

A lot of these commercial aircraft will have an airfoil section that will change as it starts at the root and moves out to the tip.
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aeroweanie
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 16, 2006 2:20 pm

2H4:
Interesting - that site you point to is a rip-off of the real Incomplete Guide To Airfoil Usage, located at: http://www.ae.uiuc.edu/m-selig/ads/aircraft.html

Most modern (post 1980) airliner wings are designed as full 3D surfaces and don't have discrete airfoils with designations. Hence, there will be no listing for the A330, A340, A380, 777 or 787.
 
2H4
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 16, 2006 2:40 pm




Quoting AeroWeanie (Reply 4):
Interesting - that site you point to is a rip-off of the real Incomplete Guide To Airfoil Usage

Wow, it fooled me...I couldn't find the link I was originally provided, so I had to Google some keywords to find that one. Thanks for the link!




2H4


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Boeing4ever
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 16, 2006 10:08 pm

Quoting AeroWeanie (Reply 4):
Most modern (post 1980) airliner wings are designed as full 3D surfaces and don't have discrete airfoils with designations. Hence, there will be no listing for the A330, A340, A380, 777 or 787.

Interesting. So how do they obtain data on the wing's lift and drag coefficients? The lift curve slope? The zero-lift angle of attack? Is it all done by CFD now?

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Starlionblue
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 16, 2006 11:23 pm

Interesting to not how Mr Rutan has no "conventional aircraft" listing here!

http://agert.homelinux.org/~fredrik/flyg/aircraft.html
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aeroweanie
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RE: Commercial Airliner Naca Airfoil Sections

Mon Apr 17, 2006 3:09 am

Quoting Starlionblue (Reply 7):
Interesting to not how Mr Rutan has no "conventional aircraft" listing here!

Look again:
Rutan 158 Pond Racer Roncz Airfoil Roncz Airfoil
Rutan 191 Roncz Airfoil Roncz Airfoil
Rutan 202 Boomerang Roncz Airfoil Roncz Airfoil
Rutan 226 Raptor Roncz RQW17B Roncz RQW17B
Rutan 247/Visionaire Vantage Roncz Airfoil (14.7%) Roncz Airfoil (14.7%)
Rutan 309/Adam Aircraft M-309 Hatfield SC-309-0119 Hatfield SC-309-0117
Rutan 311 Global Flyer Roncz CAP15 Roncz CAPTIP5
Rutan 316 SpaceShipOne Rutan Airfoil Rutan Airfoil
Rutan 318 White Knight Hatfield Airfoil Hatfield Airfoil
 
aeroweanie
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RE: Commercial Airliner Naca Airfoil Sections

Mon Apr 17, 2006 3:11 am

Quoting Boeing4ever (Reply 6):
Interesting. So how do they obtain data on the wing's lift and drag coefficients? The lift curve slope? The zero-lift angle of attack? Is it all done by CFD now?

Transport aircraft wings are designed using CFD and wind tunnel tests are later performed to confirm the predictions. The old days of going into the wind tunnel with a half-dozen or more candidate wing designs are gone.
 
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RE: Commercial Airliner Naca Airfoil Sections

Mon Apr 17, 2006 4:14 am

Quoting AeroWeanie (Reply 9):
Transport aircraft wings are designed using CFD and wind tunnel tests are later performed to confirm the predictions. The old days of going into the wind tunnel with a half-dozen or more candidate wing designs are gone.

So is it fair to say that the NACA airfoils will now collect dust? This is pretty interesting to me, as my sophomore Aero Design class spent a portion of time on 2-D aerodynamics involving airfoils. I suppose the term airfoil will now be more educational than design oriented since the concept at least helps in aeronautical instruction.

I guess now it'd be a stretch to ask if the zero-lift angle of attack and lift curve slopes for mordern wings are available anywhere as I suppose companies will be a bit more secretive a la "secret sauce". (Let's just hope in that case it really doesn't turn out to just be maynaise left in the sun!)

I guess I have to wait to Senior year before my courses start teaching me the modern stuff...or is it true what they say...that the stuff you learn in college is outdated anyway? Oh well, the degree and the insight gained will get me in...I'll learn more as I go along.

But what to do with my kick ass MATLAB script, lol!

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Starlionblue
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RE: Commercial Airliner Naca Airfoil Sections

Mon Apr 17, 2006 4:34 am

Quoting AeroWeanie (Reply 8):
Quoting Starlionblue (Reply 7):
Interesting to not how Mr Rutan has no "conventional aircraft" listing here!

Look again:

Oops!
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aeroweanie
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RE: Commercial Airliner Naca Airfoil Sections

Mon Apr 17, 2006 4:52 am

Quoting Boeing4ever (Reply 10):
So is it fair to say that the NACA airfoils will now collect dust? This is pretty interesting to me, as my sophomore Aero Design class spent a portion of time on 2-D aerodynamics involving airfoils. I suppose the term airfoil will now be more educational than design oriented since the concept at least helps in aeronautical instruction.

Airfoils are alive and well! Piston and turboprop powered aircraft wings are designed using discrete airfoils. Helicopter rotor blades also have discrete airfoils - I have a patent on one that is used on two different current production helicopters. Propeller blades are another example of something with discrete airfoils. Its just airliner wings that don't have discrete airfoils. Some business jet wings do, some don't - it depends on the design philosophy of the company.
 
lehpron
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 23, 2006 6:04 am

For some reason I keep thinking in terms of patented ideas, that if a company took used ideas, they would have to refer them. But organizations like NASA, which I hope still do airfoil research, would do them for the purposes of being used by other companies. But then if say Boeing does their own airfoil research, do they not run the risk of another company figuring out what foils they use and compete (though not completely) using the same foils on the same kinda of wing?

BTW, How can I figure out what an airfoil of a NACA 5-digit or 6-digit airfoil looks like?
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chksix
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 23, 2006 4:23 pm

You can use Javafoil to generate a plot.

http://www.mh-aerotools.de/airfoils/javafoil.htm
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keta
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RE: Commercial Airliner Naca Airfoil Sections

Sun Apr 23, 2006 5:46 pm

Modern airliners use custom-made airfoils. They don't resemble much to usual sections, they use supercritical airfoils that will change from root to tip.

In the following page you have a lot of airfoils and plots. In the B you have some used for the 707 and 737 (not for the most modern versions I believe):

http://www.ae.uiuc.edu/m-selig/ads/coord_database.html
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aeroweanie
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RE: Commercial Airliner Naca Airfoil Sections

Mon Apr 24, 2006 4:06 pm

Quoting Lehpron (Reply 13):
For some reason I keep thinking in terms of patented ideas, that if a company took used ideas, they would have to refer them. But organizations like NASA, which I hope still do airfoil research, would do them for the purposes of being used by other companies. But then if say Boeing does their own airfoil research, do they not run the risk of another company figuring out what foils they use and compete (though not completely) using the same foils on the same kinda of wing?

NASA doesn't do much airfoil work any more (they hardly do ANY aeronautics work any more). Their aim has been to demonstrate a level of technology that other people can either use or improve upon. Boeing does their own airfoil research and they have patented some of the airfoils they have developed. The trend is to not patent an actual wing design and to instead hold it as a trade secret. However, a $20,000 laser scan job can reveal all the secrets of a wing design.
 
oly720man
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RE: Commercial Airliner Naca Airfoil Sections

Mon Apr 24, 2006 6:25 pm

NACA airfoil sections were great when aircraft had unswept constant chord wings and it made it easier to predict behaviour. Now, any large commercial aircraft wing is swept, tapered and twisted so a particular section across the whole span is just not suitable, or efficient.

Quoting AeroWeanie (Reply 9):
Transport aircraft wings are designed using CFD and wind tunnel tests are later performed to confirm the predictions.

The B777 never went near a wind tunnel, AFAIK. It was designed on computer all the way. These days, CFD predictions are getting better than wind tunnel tests for cruise, at least. And that's if your computer is big enough and fast enough to create the massive grids and do all the calculations.
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aeroweanie
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RE: Commercial Airliner Naca Airfoil Sections

Mon Apr 24, 2006 11:56 pm

Quoting Oly720man (Reply 17):
NACA airfoil sections were great when aircraft had unswept constant chord wings and it made it easier to predict behaviour. Now, any large commercial aircraft wing is swept, tapered and twisted so a particular section across the whole span is just not suitable, or efficient.

Actually, the NACA 6-series airfoils were found to work very well on swept wings and thus were used on many swept wing aircraft. The NACA 64A010 is very common in such applications. The wing of the 707 uses NACA 6-series airfoils, with modified camber lines.

Quoting Oly720man (Reply 17):
The B777 never went near a wind tunnel, AFAIK. It was designed on computer all the way. These days, CFD predictions are getting better than wind tunnel tests for cruise, at least. And that's if your computer is big enough and fast enough to create the massive grids and do all the calculations.

Not true! While there was a lot of CFD work done on the 777, it also was heavily wind tunnel tested. This testing was done in the Boeing Transonic Wind Tunnel (BTWT), the NASA Ames 11' Unitary tunnel, the NASA Langley National Transonic Facility (NTF) and the RAE Pressure Tunnel. Risk reduction is everything in the development of an airliner and the wind tunnel serves as a risk reduction tool.
 
lehpron
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RE: Commercial Airliner Naca Airfoil Sections

Tue Apr 25, 2006 6:04 am

Quoting AeroWeanie (Reply 18):
Not true! While there was a lot of CFD work done on the 777, it also was heavily wind tunnel tested

I agree! When I was in wind tunnel lab, our professor told us a story that Boeing was embarrased to find out that their 777 in flight had a 0.01 Mach increase in cruise compared to CFD solutions. This was primarily due to not having the Reynold's number high enough. IIRC, the air didn't circulate properly underneth a critical portion of the wing. I'd like it if someone could verify that story, it's been a few years.

Quoting AeroWeanie (Reply 16):
Their aim has been to demonstrate a level of technology that other people can either use or improve upon. Boeing does their own airfoil research and they have patented some of the airfoils they have developed.

...in which there a so few companies big enough to really use those ideas, in terms of investing in those ideas. Pretty soon, those large companies become like customers and to satisfy them, NASA would have to cater to them. But if Boeing does more research privately, the burden of cost goes to the smaller companies and soon NASA may cancel projects due to no one using/affording the ideas. For that, if NASA wants to give up on aeronautics, IMO, they should drop the the first 'A'...

I've had beef with NASA and Boeing for 8+ years; IMO, those making the decisions are only interested in ROI. I don't think business has any right to have a place in research.

Quoting AeroWeanie (Reply 16):
The trend is to not patent an actual wing design and to instead hold it as a trade secret.

While I agree if the technology was at the edge of the envelope, had NASA done the research, then the costs for Boeing would be less (hence less break-even, etc), be it publically available knowledge.

Quoting AeroWeanie (Reply 16):
However, a $20,000 laser scan job can reveal all the secrets of a wing design.

I wonder, if any, A380 engineers did that with 747's wing... Big grin
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