Wing Tips

Discussion in 'Pitts Model 12' started by scottly, Jan 12, 2010.

Help Support Biplane Forum by donating using the link above.
  1. Jan 12, 2010 #1

    scottly

    scottly

    scottly

    Well-Known Member

    Joined:
    Sep 13, 2006
    Messages:
    1,640
    Likes Received:
    4
    Model 12 fiberglass wingtips....are they one layer of glass cloth? How flexable are they?


    Are they polyseter resin layups?




    I'm trying to make some for a Skybolt....if you can help, I'd appreciate it.
     
  2. Jan 12, 2010 #2

    Neil

    Neil

    Neil

    Well-Known Member Lifetime Supporter

    Joined:
    Nov 10, 2006
    Messages:
    6,102
    Likes Received:
    884
    Gender:
    Male
    Location:
    Monroe, Louisiana
    The tips we make for the Legend are 6 layers with epoxy. These are molded tips. You can use 4, but I find that to be a little too flexible. If they are attached with screws you need a few more layers around the edge, but if you bond them on and cover with fabric they are fine. You can use poly, vinyl or epoxy resin, but the epoxy tips will bond to the wing with epoxy better than the others.

    If you are making tips by bonding foam to the end of the wing and shaping to suit, one layer of cloth might be enough. Two would be better.



     
  3. Jan 12, 2010 #3

    scottly

    scottly

    scottly

    Well-Known Member

    Joined:
    Sep 13, 2006
    Messages:
    1,640
    Likes Received:
    4
    I made plugs then female molds. I was going to do the layup with fiberglass and have a picture of the Model 12 tips, but can't tell how many layers they are.
    I guess I could save weight with carbon fiber and do fewer layers? I will bond them to the wings then cover with fabric.
     
  4. Jan 12, 2010 #4

    Neil

    Neil

    Neil

    Well-Known Member Lifetime Supporter

    Joined:
    Nov 10, 2006
    Messages:
    6,102
    Likes Received:
    884
    Gender:
    Male
    Location:
    Monroe, Louisiana
    Not a big fan of carbon fiber. You can't tear it, but a screw driver will poke a hole in it like it was paper. Hard to tell if you've worked all the air out and the stuff is pricey too. The greatest weight savings with carbon is when it is used with a foam core. Resin weight is the same as with glass. It might however be practical to use a single layer of CF with a few layers of glass cloth. Four layers may be good enough like this.

    Another thing about Carbon. It blocks radio signals.

    Are you making traditional style tips or something smaller?



     
  5. Jan 12, 2010 #5

    scottly

    scottly

    scottly

    Well-Known Member

    Joined:
    Sep 13, 2006
    Messages:
    1,640
    Likes Received:
    4
    [​IMG]Well, i don't know what you mean by "traditional", but they will start on the last rib (which is smaller) and make a nice taper around, evenly, the airfoil....kinda like this:



     
  6. Jan 12, 2010 #6

    Neil

    Neil

    Neil

    Well-Known Member Lifetime Supporter

    Joined:
    Nov 10, 2006
    Messages:
    6,102
    Likes Received:
    884
    Gender:
    Male
    Location:
    Monroe, Louisiana
    I was thinking standard Skybolt shape. I like these though. Four layers would probably be enough, six would add durability.
     
  7. Jan 12, 2010 #7

    Vilhelm

    Vilhelm

    Vilhelm

    Supporting Member Supporting Member

    Joined:
    Jan 16, 2007
    Messages:
    400
    Likes Received:
    33
    When I madethe wingtipsfor my the Acro Sport, I first made some samples to find out how many layers was needed. I found 3 layers of glass weave to be adequate, so I made them with only 3 layers woven glass cloth and epoxy. When mounted on the wing they are quite stiff, the underside which hasthe leastdouble curvature can be moved a little with finger pressure, but so can the fabric covering on the rest of the wing.

    They are screwed on capstrips glued to the end rib. The 1/4"x1/4" capstrips called for in the plans are totally inadequate for that purpose. I made mine 5/8"X 1/2". They will not bend, so has to bee divided in shorter pieces and shaped to the rib curvature.
     
  8. Jan 12, 2010 #8

    barchiola

    barchiola

    barchiola

    This space available.

    Joined:
    Mar 29, 2008
    Messages:
    404
    Likes Received:
    25


    scottly,
    here are some pics of what I've been working on. mine may be a little different in that they'll wrap around the tip rib at the leading edge and go to the next rib in.
    <a href="http://%20picasaweb.google.com/Barchiola/LowerWingTips#" target="_blank">
    http://picasaweb.google.com/Barchiola/LowerWingTips#</a>

    it sounds like you're at about the same point as i am with a female mold completed but no finished tips yet. I've got carbon fiber and fiberglas and am planning a two layer lay-up vacuumed bagged using regular west epoxy as the resin.

    i'd like to see how yours turn out. how far are you from making the final parts?

    good luck,
    bart

    Edited by: barchiola
     
  9. Jan 13, 2010 #9

    scottly

    scottly

    scottly

    Well-Known Member

    Joined:
    Sep 13, 2006
    Messages:
    1,640
    Likes Received:
    4
    Bart:


    I am waiting for it to get warm. :) No garage heat in Florida....never needed it before.


    I'm not going to vacuum bag....just do a simple layup.


    I like the way you did your mold. I carved my plug free-hand from polystyrene using a coarse wood file. I then coated it with System 3 Silvertip laminating resin. I then used auto body filler to further shape it, covered with glazing compound, primed, painted, and waxed it.


    I used West systems epoxy and lots of layers to make the molds. I followed other's examples fromt he 601 forum.


    When I get it all done, I'll post pics, if any one is interested.

    Edited by: scottly
     

Share This Page