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Eppler Airfoils

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plncraze

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I have looked on this this site for some "real world" experience with some of Eppler's airfoil from his book and have not found any. Are there any folks out there using them?
The reason I am asking is that Eppler has both tail less and prop air foils. I am curious about both.
 
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Topaz

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I've done a lot of XFoil investigation with a slightly-increased-camber variant of the Eppler 361 helicopter airfoil. That's not "real world," but it's reasonable results and information. I started exploring this as a low-Cm laminar 'foil for a small motorglider with a low-Reynold's Number requirement, and it's very nice for that.

What is it you're trying to determine? Are his airfoils any good? Quite a few have been used on sailplanes (Eppler 662, for example), with quite good success.
 

fly2kads

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In addition to sailplanes, I think some of the experimental canard aircraft have used Eppler airfoils. I also remember reading an article about someone who used Eppler's prop airfoils for a custom propeller, and it turned out well.

I have experimented with Eppler airfoils in Xfoil, as well. They tend to require a little bit of cleanup as the point distribution isn't that great. Once that's out of the way, they seem to work as advertised.

Other people have used Eppler's airfoil code for the development of their own successful airfoils, as well. For example, at least some of the NASA NLF sections....
 

plncraze

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I was interested in whether his airfoil were close to their promises or if they were just a design exercise. I was thinking about using them on a real aircraft.
 

Grimace

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Is there a rhyme or reason to Eppler's naming conventions? I'm hoping to find a 10% thickness version of his E472 for an ultralight glider tail. I want that one for the reason of simplicity of construction (relatively straight aft of max thickness) and having a rather "forward" max thickness to reduce the size of the d-box.
 

fly2kads

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If there is, I don't know what it is. I don't remember anything of his that meets that exact definition, but it wouldn't be too hard to tweak the E472 down to 10% thickness with XFOIL or XFLR5.
 

Lendo

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Grimace,
I had to read your message a couple of times, I thinking you mean in terms of Vertical tail?, max thickness is usually from 25% to 30% cord of any Airfoil. The max a Rudder is 40% of chord many are 30 to 35% chord.
A Vertical tail like the RV is a good performer (least drag dues to reasons of Sweep). I would look at seep at 25% being no more than 20° and if you want a vertical trailing edge rudder, design it from there.
Otherwise I'm confused about what your saying.
George
 

Retiree

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Eppler numbers his airfoils in series. So a type of airfoil might start at E600. Then the next airfoil in the series would be E601, he might be changing thickness or pitching moment.
He wrote a book with all his airfoils, up to that point. He even put in the parameters he used for the designs. The title of the book is Airfoil Design and Data.
Doug
 

Retiree

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If there is, I don't know what it is. I don't remember anything of his that meets that exact definition, but it wouldn't be too hard to tweak the E472 down to 10% thickness with XFOIL or XFLR5.
You can't be sure that after you "tweak " it, the airfoil will have the same characteristics you want. It will not be an Eppler airfoil anymore.
If you do tweak it, please don't post the airfoil coordinates as an Eppler airfoil.
Doug
 
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