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  1. #1

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    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.

  2. #2
    All Day Dan's Avatar
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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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    Dan

  3. #3
    ByLoudDesign's Avatar
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    It is listed as a USA 35B
    Kits: F11C-2 1:4, Do-24T 1:8, P-3 1:10, Howard 500 1:5, XFY-1 1:4, SR-9 1:4, V-22 1:6, B-25J 1:4, F+W C3603 1:5, B314 1:11, DHC-4 1:10

  4. #4
    ByLoudDesign's Avatar
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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
    Kits: F11C-2 1:4, Do-24T 1:8, P-3 1:10, Howard 500 1:5, XFY-1 1:4, SR-9 1:4, V-22 1:6, B-25J 1:4, F+W C3603 1:5, B314 1:11, DHC-4 1:10

  5. #5

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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
    Last edited by fritzke; 09-26-2013 at 09:19 AM. Reason: Added Quotes.

  6. #6

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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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    Last edited by Hashem; 09-25-2013 at 11:09 AM.

  7. #7
    All Day Dan's Avatar
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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.
    Dan

  8. #8
    ByLoudDesign's Avatar
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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".
    Kits: F11C-2 1:4, Do-24T 1:8, P-3 1:10, Howard 500 1:5, XFY-1 1:4, SR-9 1:4, V-22 1:6, B-25J 1:4, F+W C3603 1:5, B314 1:11, DHC-4 1:10

  9. #9
    All Day Dan's Avatar
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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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    Dan

  10. #10

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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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    Last edited by Hashem; 09-25-2013 at 10:14 PM.

  11. #11
    All Day Dan's Avatar
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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.
    Dan

  12. #12

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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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  13. #13
    All Day Dan's Avatar
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    Good news. You're on your way. Start a design-build thread so we all can watch your progress. Dan.
    Dan


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