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Old Mar 06, 2014, 09:48 AM
flying since 2000
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Winterthur ZH, Switzerland
Joined Mar 2009
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Profile question

Hi there,

Does anyone have the possibility (Profili?) to find out what profile that is in the attachment? I took a picture of the root rib (unbuilt kit) and converted it to black and white as good as possible.

I'd really appreciate a tip!

Stefan
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Old Mar 06, 2014, 11:58 AM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
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There's simply no way to spot it other than to compare overlays. I'd start off by measuring the point of maximum thickness. Then use Profili to draw out airfoils that look close and lay the rib over the printout to see which fits the best.

You might be better off to tell us what the model is and perhaps someone familiar with that particular design will know what the profile is supposed to be.

To start you off I'd going to suggest you look at the Eppler 201 and similar "200" family airfoils. It looks a little like those. Other family options are the Quabek airfoils in the 12 to 15% thickness range and the Selig 4233. Other than these starting points you'll simply have to shop down the airfoil aisle and pick out stuff that looks close and print it out. The bad news is that it'll take you a good hour or two to step through the whole library. The good news is that there will only be around 10 to 12 airfoils that are similar for you to print. So you won't use up too much paper.... But start with determining the thickness percentate. Then look at any option which is within 1% of that measurement and which appears to have the right shape.
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Old Mar 06, 2014, 02:19 PM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
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Also have a look through these to see if anything looks similar --

https://www.google.com/search?q=airf...w=1346&bih=655
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Old Mar 06, 2014, 10:34 PM
Grad student in aeronautics
United States, GA, Atlanta
Joined Oct 2010
444 Posts
One thing that might help is this digitizer program:
http://digitizer.sourceforge.net/
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Old Mar 06, 2014, 11:14 PM
A witty saying proves nothing.
kcaldwel's Avatar
Joined Jan 2007
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Here are some airfoils Profili came up with as being close to yours. I called your airfoil "Test airfoil".

Kevin
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Old Mar 07, 2014, 06:21 AM
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Canada, ON, St. Catharines
Joined Apr 2004
26 Posts
What is the kit? That may also help to identify it. Maybe contact the designer or is there a construction article somewhere?
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Old Mar 07, 2014, 07:31 AM
tau
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Joined Aug 2006
42 Posts
Gents,

there is a quite handy web application tool that will search through its entire database for similar airfoils.

It is woth while remembering and saving this bookmark!

Regards, Tunc
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Old Mar 07, 2014, 03:14 PM
flying since 2000
sfluck's Avatar
Winterthur ZH, Switzerland
Joined Mar 2009
513 Posts
Hi guys,

I'm building a K8 after a kit from Modellbaustudio Liening (hobby-land.de), which i think is a new edition of the Flair K8.

Thanks for the tips all!

Thanks Kevin for your comparing sheet! Thats really cool! It looks like the NA63A513 probably is the closest fit...
Tunc, i tried using this tool, but it wont let me although i have the newest version of the software needed... Weird.
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Old Mar 07, 2014, 03:19 PM
flying since 2000
sfluck's Avatar
Winterthur ZH, Switzerland
Joined Mar 2009
513 Posts
Oh gosh me again...

Silly me, I only googled for "Modellbaustudio K 8 airfoil"...
When i search for Flair K8, theres the info thats a HQ3.5/14. and judging by eye, that's probably it...

Shame on me, sorry guys!
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Old Mar 07, 2014, 03:21 PM
A witty saying proves nothing.
kcaldwel's Avatar
Joined Jan 2007
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Hmm. Your posted image file doesn't match very well with the HQ3.5/14.

Kevin
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Old Mar 07, 2014, 08:50 PM
B for Bruce
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The 'Wack, BC, Canada
Joined Oct 2002
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And HQ3.5/12 perhaps? Or it may simply be yet one more kit maker's slightly butchered version of the "proper" airfoil. Lots of places where a little distortion could take place between the coordinates and the cutting.
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Old Mar 07, 2014, 09:03 PM
A witty saying proves nothing.
kcaldwel's Avatar
Joined Jan 2007
3,569 Posts
I checked it against all the other HQ3.5 thickness forms, and they don't fit any better. If the image file is anywhere near close, and it is supposed to be an HQ3.5, there is a lot more "distortion" than I'd want to pay money for.

Kevin
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Old Mar 08, 2014, 03:50 AM
hul
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Switzerland
Joined Mar 2003
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Profili reckons HQ2.5/12 is the best fit (second best...)

Hans
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Old Mar 12, 2014, 03:55 PM
flying since 2000
sfluck's Avatar
Winterthur ZH, Switzerland
Joined Mar 2009
513 Posts
Just got a message from the producer of the kit, and it's a HQ 2.5/12.
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Old Mar 12, 2014, 04:16 PM
hul
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Switzerland
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I win
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