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What's Piper J3-Cub's airfoil NACA number?

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Old 09-25-2013, 07:35 AM
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Hashem
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Default What's Piper J3-Cub's airfoil NACA number?

Im trying to draw piper j3 cub in Autocad. so I dont know the NACA number of piper airfoil.
does anyone know?

I want to search its number and find airfoil coordinates and draw it in autocad.

I will appreciate your help.
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Old 09-25-2013, 07:55 AM
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All Day Dan
 
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I did a Champ a while ago and used an NACA0017 airfoil generated from Compufoil. You don't need a flat bottom airfoil. Flies great. Dan.
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Old 09-25-2013, 08:28 AM
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It is listed as a USA 35B
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Old 09-25-2013, 08:34 AM
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Thought I would look up the data for you, just scrool down or use the "U" link. http://aerospace.illinois.edu/m-seli...atabase.html#U
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Old 09-25-2013, 08:34 AM
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Airfoil database:

http://aerospace.illinois.edu/m-selig/ads/coord_database.html#P


USA35-B

http://www.flyingmag.com/aircraft/pistons/piper-cub


"Taylor chose the lightly loaded USA-35B airfoil for the E-2, a design that provided good low-speed flying qualities — it was reluctant to stall and provided plenty of warning before it did. All Cubs, including the J-3 and Super Cub, have used this same airfoil shape. "


Dave

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Old 09-25-2013, 08:56 AM
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thanks for your kind answers.
I drew the airfoil in autocad.

but leading edge isn't smooth. it seems it is drawn with a few lines. how can I solve this?
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Old 09-25-2013, 10:14 AM
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Use pedit. Select the polyline segments you want to smooth. If they are not polylines enter yes to make them polylines. Enter join. Pick the polylines you want to join. Enter s to smooth them. Dan.
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Old 09-25-2013, 10:55 AM
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Your can also use the arc command "A" is an embedded short cut and using three point form several arcs And then join all the rest of the line segments useing the polyline edit "PE".
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Old 09-25-2013, 11:34 AM
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Here's what a USA 35B airfoil looks like with a ten inch chord. If you send me your email address I can email a .dwg file of it and you can modify as you need. Dan
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Old 09-25-2013, 08:02 PM
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Quote:
Originally Posted by All Day Dan View Post
Here's what a USA 35B airfoil looks like with a ten inch chord. If you send me your email address I can email a .dwg file of it and you can modify as you need. Dan
thanks for your cooperation.
I sent you my email.

I used "pedit" command after seleting the airfoil then I selected the "spline" to smooth the curves.

but I think the curve has some issues, see the image:

the arrows shows two bad smooth curves which I think have affected the airfoil shape.

don't you think the points coordinates for drawing airfoil is few? (33 points)
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Old 09-26-2013, 06:59 AM
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The .dwg file is on the way. There may be some distortion in the one you have. Overlay the two with different colors and see how they compare. I got mine from Compufoil. Dan.
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Old 09-26-2013, 08:56 AM
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Quote:
Originally Posted by All Day Dan View Post
The .dwg file is on the way. There may be some distortion in the one you have. Overlay the two with different colors and see how they compare. I got mine from Compufoil. Dan.
wow, what a difference. I have even smoothen the curves.

compufoil have generated more points. its great. thank you Dan for your help

I have uploaded the compufoil generated airfoil for whom are interested.
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Old 09-26-2013, 12:08 PM
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Good news. You're on your way. Start a design-build thread so we all can watch your progress. Dan.
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