naca foil datas
 

Does anybody know that where i can get the standard lift & drag coefficient of naca 4 digit series foils? i can find the shape information, but is there any standard lift and drag information database? Thanks

RE: naca foil datas
 

The original NACA report is here,

http://naca.central.cranfield.ac.uk/report.php?NID=1087

RE: naca foil datas
 

I have a book called "Handbook of Airfoil Sections for Light Aircraft" that has a lot of them. You might find a copy at a used book dealer. Note that the data is for a Reynold's Number at full-size aircraft dimensions.
In my opinion, but I'm not an aeronautical engineer, there is not a significant difference between them. I use the NACA 2315 because the high and low points are both at 30% which makes for clean design of the spars and a D-tube wing.
Chuck
EDIT
I just looked at the link Wellss gave and it is the same graphical data as in the book I have.

RE: naca foil datas
 

For model speeds and sizes you'd be better off paying to unlock the Xfoil portion of Profili 2 or run the NACA shapes through the free version of Xfoil and develop your own lift-drag curves. Most of the orginal NACA report shows a low Re that is more like the high end Re's that we modellers use.

RE: naca foil datas
 

Thank you guys for all of this great information. Does the lift and drag coefficient in air vary much with the size of the foil? What I am trying to do is to do the CFD model, but I am not sure if my lift and drag results will be correct. That is why i want to compare my results to a relatively standard value. Thank you again.



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EDIT-Sorry, hit the wrong button- BMatthews

RE: naca foil datas
 

Bear in mind that the lift and drag coefficients of airfoils vary considerably with Reynolds number. I have a lot of old wind tunnel-derived information on various airfoils that does not state the Reynolds number that the airfoils were tested at, and thus the information is useful as a rough guide only.

For example, the NACA 0015 airfoil, very commonly used for aerobatic models, shows peak lift coefficient ranging all the way from 0.83 at Reynolds number 43,000, up to 1.55 (87 percent higher) at Reynolds number 3,300,000.

RE: naca foil datas
 

It is higher drag that causes lower maximum lift at low Rn. Why the drag is higher....I believe is due to the boundary layer not scaling and so is thicker, relative to a smaller airfoil.

RE: naca foil datas
 

CFD = Computational Flow Dynamics? Or is this something else?

As noted by the others already airfoil performance varies greatly as the Reynolds number falls. More importantly at the very slow or very small region is that the flow dynamics tends to collapse at the extreme low Re's. Xfoil, being designed and written to closely model the flow behaviour noted by Eppler and Selig, does a fairly decent job of indicating the range of size and speed where the flow becomes unpredictable. If you run Xfoil and lay in numbers in the 10K to 100K range you'll see that the lower ones all look like jagged broken glass. Then at some point there'll be one curve that looks semi normal and for numbers higher than that they smoothen out and look like siblings just like you'd expect to see from higher numbers. The jagged results of the lower Re's are indicative of the unstable back and forth separation bubble behaviour that can occur at the very low reynolds numbers such as found on smaller and slower models.

RE: naca foil datas
 

XFLR5, read the manual, use it.