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Thread: Hoenshell's Build

  1. #61
    Hoenshell's Avatar
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    Default Re: Hoenshell's Build

    This method of holding my cowlings on, tight and together while still being able to manipulate the positioning is working out pretty good for me so far.


    Shawn
    Building IV Classic

  2. #62
    Administrator DesertFox4's Avatar
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    Default Re: Hoenshell's Build

    Good luck with the cowl fitting Shawn. Looks good. Always liked the smooth cowl look on the Classic 4.


    DesertFox4
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  3. #63
    Senior Member HighWing's Avatar
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    Default Re: Hoenshell's Build

    I was always challenged with the way the IV cowl fit against the door. they seemed to want to bow out right at the horizontal joint with the overlapping Lexan trying to hold it flat but only when the door is closed. First I added some glass that surrounded the vertical tubing about half way at the forward door opening. Covering the vertical tube with clear packing tape makes a perfect separating medium for the epoxy saturated glass. Then, after helping my friend with the Lancair, I decided to go the piano hinge route between upper and lower cowl as he did. And as a a belt and suspenders thing, I added a Hysoled on tab that the hinge pin could run through to give the totally secured look - door open or closed.

    Just some thoughts.
    Attached Images Attached Images
    Last edited by HighWing; 12-03-2018 at 07:02 PM. Reason: Add detail
    Lowell Fitt
    Goodyear, AZ


    My You Tube Channel

  4. #64
    Hoenshell's Avatar
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    Default Re: Hoenshell's Build

    I am working on getting the IV smooth cowling to fit properly and it seems that the few IV smooth cowl builders in the past have had to cut and modify the shape of the cowling around the prop flange. I'm about to perform this operation. I'm unsure what would be the best fiberglass cloth and resin to use on this project. Anyone have some recommendations?


    This top picture is my cowling and the last two are what I'm going to be performing.




    Shawn
    Building IV Classic

  5. #65
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    Default Re: Hoenshell's Build

    I did a lot of fiberglassing on my cowling and wingtips. They were crunched in several places and pieces that were broke out and missing so I had to bridge areas kind of like you're having to do. I used the fiberglass chop strand mat and tore pieces off and built up these areas. You'll have to do it in multiple steps and you'll have to feather back a pretty good ways in both directions from the repair area. I used masking tape to kind of make "forms" for the fiberglass. Also I used a heat gun to form areas of the fiberglass that needed adjustments. On bends and areas that needed strength, after I filled with the chopped strand mat, I would add a piece of the weaved mat on the back side. I attached pics but had to resize them so small that hopefully you can still get an idea.
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  6. #66
    Senior Member efwd's Avatar
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    Default Re: Hoenshell's Build

    Shawn, I assume you hastily placed the spinner plate into the pic. It's backwards. Ive done stuff like that before, just saying. Wouldn't want you to do too much before you turn it around.
    Eddie Forward
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  7. #67
    Hoenshell's Avatar
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    Default Re: Hoenshell's Build

    I did that to measure and to show gap.
    Shawn
    Building IV Classic

  8. #68
    Senior Member GWright6970's Avatar
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    Default Re: Hoenshell's Build

    Eddie,
    I also placed my backing plate on backwards during this step, to get a better "cowling front plane" to get the proper cut angle with. I hope this makes sense!
    Grover Wright
    Flying a KF IV-1200
    ROTAX 912UL

  9. #69
    Senior Member efwd's Avatar
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    Default Re: Hoenshell's Build

    Very well. My cowl came together so slick with the spinner installed so I am not sure of anything (you might say). I have had inquiry about this step in the past, so, glad everyone is squared away. I am so glad I didn't have to cut up my cowl as has been needed in those pics that's for sure.
    Eddie Forward
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  10. #70
    Senior Member HighWing's Avatar
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    Default Re: Hoenshell's Build

    Quote Originally Posted by Hoenshell View Post
    ...I'm unsure what would be the best fiberglass cloth and resin to use on this project. Anyone have some recommendations.
    One man's opinion, based on a little experience.

    Glass:
    I prefer the medium weight glass and for what I perceive to be your project the Twill weave would be my choice. This because the twill weave makes tightly forming over compound curves a bit easier. By adding more layers sufficient strength can be obtained. With extreme curvature on a piece or compound curves, cutting the glass so the fibers runs at a diagonal angle to the curve helps the glass lay down as well. I also prefer a "hard" epoxy as flexibility is not an issue in the complex curves of the cowl and it is easier to sand. Then for surface prep and smoothing joint areas, I prefer "Microballoons" added to the epoxy. This because consistency can be determined during the mix - a rather stiff peanut butter like mix for a quick fill of areas where a thinner mix might run. A thinner mix might be easier on a broad surface where weave filling is the main goal.

    Separating Media:
    Where lay-ups will be made against mating but not attached surfaces common to multiple piece projects a separating medium is important. Where locations allow, I like to use the common clear packing tape. Example - when finessing the edge between top cowl and windshield is desired, carefully laid out strips of the packing tape on the windshield will allow the glass to be laid directly to the windshield for a very precise fit. Use lots of care there, of course. Occasionally I will lay masking tape first, then the packing tape. Other separating media can be wax - like a paste car wax - or the liquid separating medium like PVA Mold Release. This can be brushed on or sprayed depending on size and desired finish. My understanding is that when wax Is used alone it requires several applications of wax - up to 6 in some cases and it is typically suggested that at least a couple of applications of wax be applied first before applying a liquid separator. With the wax or liquid separators, they should be thoroughly removed before adding glass / resin to that surface if it is necessary to modify those surfaces or painting, otherwise the bond might be insufficient.

    An example of using micro to finesse a top and bottom cowl joint. Connect top and bottom together - preferably with the Camlocs (or Piano hinge pin installed) on the airplane after permanent positioning of the cowls is complete . Mix micro to the consistency of peanut butter - so it won't run or sag. Fill the gap between top and bottom cowl to very slightly overflowing with the micro. Then with a smooth thin piece of metal like a very thin table knife blade or a small metal mixing spatula, run the blade carefully one time only (ideally) down the joint using the lower edge of the upper cowl as a guide. Allow to cure then sand smooth and separate. Firm pressure with the knife or spatula against the joggle of the lower cowl during the run will prevent large areas of adhesion that might chip during separation. This is the method that is typically used to finesse the joint when using the piano hinge attachment.



    The following pictures shows a tab attached to the lower cowl half that then fits into a pocket on the upper cowl that holds the outermost edges in the correct alignment without the need of a screw or camlock.
    Attached Images Attached Images
    Lowell Fitt
    Goodyear, AZ


    My You Tube Channel

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