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Thread: Building a Scratch Built Cub

  1. #161

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    Quote Originally Posted by skywagon8a View Post
    If you place a bead or a bend along the center line of this belly pan it will be stiffer, reducing the possibility of cracking due to vibration.
    t
    and water will say away from the tubes
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  2. #162
    jnorris's Avatar
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    Looks great John. Keep up the great work!!
    Joe

    Fortis Fortuna Adiuvat
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  3. #163

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    The front of the belly pan in the tail usually matches a metal V section on the frame that ties in with the belly stringer. The bend Skywagon8a mentioned makes it work, are you omitting the belly stringer?
    DENNY
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  4. #164
    stknrddr's Avatar
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    Hi Denny and Tempdoug,

    Thanks for the good comments. Yes, I plan to roll two or three beads lengthwise into the belly pan to stiffen it up which is why I haven't drilled the bolt holes in the pan yet. I guess I could drill holes at the end of each bead and/or at the end of the pan for water to exit. I hadn't thought of that.

    I do plan to have a stringer in the belly, however I will have the stringer die into the bottom of the fuselage somewhere ahead of the belly pan.

    thanks,

    john
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  5. #165
    stknrddr's Avatar
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    Hi Skywagon8a and Joe N,

    Thanks for the comments. I appreciate your help.

    john

  6. #166

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    The water issue is a good point. I have a fabric covered belly tail section, but it is open at the lower vertical tubes in the back. I normally have my plane in the hanger all winter, but had a friend in mine doing work so the cub sat through some good snow storms. Pulled it into the IA's hanger for annual and they noted that the tail was now full of water to the top of the tubes. They burned a few holes and all was well with the world.
    DENNY

  7. #167
    stknrddr's Avatar
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    Builders' Update

    Windshield Frames and Wing Spar Hole Drilling for Ailerons

    Click image for larger version. 

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    I sheared, bent and attached the windshield frames as shown here.
    I made both frames the same shape having a flat along the outside
    to the attach the windshield to, then a 90 degree bend along the front
    side. I also have a short bend along the back side of the diagonal
    tube to weld the frame to the fuselage. The frames are shy of the
    longeron so fuel lines can transition from inside the frames to the front
    of the fuselage. I have no plan to put an interior cover on the frames,
    but if I decide to add them, I will probably need to add a couple of
    tabs to attach the covers to. Something to consider when
    scratch building.

    Click image for larger version. 

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    Before welding the frames in place, I clamped straight edges
    along the outside of the upper cockpit as shown. This is to
    ensure that I get the frames aligned flat to the outside of
    the fuselage.

    Click image for larger version. 

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    Here you can see how I controlled the orientation
    of the outside edge of the frame.

    Moving on the Wing Spars

    Click image for larger version. 

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    I am building primarily a scratch built wing with a few
    parts being purchased from Javron. Jay at Javron will sell
    any individual parts. Here, I am laying out the holes to be
    drilled in the rear spar that the aileron attachment
    brackets will be bolted to. I am moving the ailerons
    closer to the tips of the wings, so I can omitt the "short" rib
    which is a different shape than the rest of the ribs. I scratch built all
    of my ribs, so for the sake of simplicity, I did not make the
    "short" rib. The result will be a less rounded wing tip,
    and Jay (at Javron) refers to this as his "square" wing tip.

    When moving the aileron outward, the aileron requires 4 hinges
    instead of the traditional 3 (longer aileron). In the photo above, I have the
    "4 hinge aileron spar" setting to the left of the rear spar. Using the
    original Piper Drawings, I can locate the hole to be drilled
    in the rear spar for the hinge at the control horn on the aileron. I then
    drilled that hole. I bought the 4-hinge aileron spars from Jay, with
    pre-drilled holes for the hinges on the aileron spar. I can now
    align, transfer, measure, locate and drill the 3 remaining holes
    in the rear wing spar. Long story. I could have had Jay drill these
    holes, but at the time when I bought the wing spars, I was unsure
    of my final wing (wing tip) design, and I knew that I could figure this out.

    Click image for larger version. 

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    The aileron spar is setting next to, and aligned to the rear wing spar. I already
    drilled the hole in the rear spar for the hinge bracket. That's the
    aileron control horn attached to the aileron spar. The Piper
    drawing provides a definite location to place the control horn
    location hole in the wing spars.

    Click image for larger version. 

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    Aligning and transferring the aileron hinge locations to the rear spar.
    The remaining 3 hole locations are not on the Piper drawings as this is not
    the stock aileron.

    Click image for larger version. 

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    Locating the vertical position of the spar holes on the
    rear spar as on the original Piper drawings. Having the aileron
    located on the rear spar will allow me to position the wing ribs
    at each end of the aileron.

    Extra Photo

    Click image for larger version. 

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    Dodging a Wisconsin summer pop-up rain storm.

    Thank you for looking folks!

    john
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  8. #168
    skywagon8a's Avatar
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    Quote Originally Posted by stknrddr View Post
    I am moving the ailerons
    closer to the tips of the wings, so I can omitt the "short" rib
    which is a different shape than the rest of the ribs. I scratch built all
    of my ribs, so for the sake of simplicity, I did not make the
    "short" rib. The result will be a less rounded wing tip,
    and Jay (at Javron) refers to this as his "square" wing tip.

    When moving the aileron outward, the aileron requires 4 hinges
    instead of the traditional 3 (longer aileron). In the photo above, I have the
    "4 hinge aileron spar" setting to the left of the rear spar. Using the
    original Piper Drawings, I can locate the hole to be drilled
    in the rear spar for the hinge at the control horn on the aileron. I then
    drilled that hole. I bought the 4-hinge aileron spars from Jay, with
    pre-drilled holes for the hinges on the aileron spar. I can now
    align, transfer, measure, locate and drill the 3 remaining holes
    in the rear wing spar. Long story. I could have had Jay drill these
    holes, but at the time when I bought the wing spars, I was unsure
    of my final wing (wing tip) design, and I knew that I could figure this out.

    john
    This aileron is pushed out to the tip of the wing with a full sized rib at the tip. Notice there are only 3 hinges. The inboard hinge is the same location as Piper's middle hinge and is where the bellcrank and control cables attach. The length of the aileron is shorter than the original since having moved further outboard it is more effective. I have not found any condition where I wished for more aileron. By shortening the inboard end of the aileron there is room to make the flaps even longer. These flaps are 110" and work great. The shiny piece is a 12" extension beyond the tip of the spars.

    N1PA

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