Polyfiber closeups

[JoeRuscito]

Anyone have closeups of leading edge seam after bottom fabric and after attaching top fabric with polytak. I want to make sure I’m wetting/getting enough through the weave. I really coat it quite heavy but I don’t get wetness through the fabric. Only at the edge where it squeezes out. https://uploads.tapatalk-cdn.com/20190319/14ec185b224fcb4c30f53f523bbf05aa.jpghttps://uploads.tapatalk-cdn.com/20190319/5c1fe0bced15b159d11cfc637bb625b2.jpghttps://uploads.tapatalk-cdn.com/20190319/27df56bc65e36bc2aa6bc35fc7544210.jpg

[aviator79]

It's really hard to tell from photos, but It looks to me like you're doing fine. I used a body filler spreader squeegee it down which gets good adhesion and squishes out the excess. Just make sure you only do 18 inches or so at a time, and add MEK to your PolyTak periodically to maintain the correct consistency.

[avidflyer]

Are you thinning the poly tac with MEK? You should. That will help it to wet through to the top of the fabric. JImChuk

[JoeRuscito]

I’m not thinning it unless it gets thick! I work pretty quick really only doing 9-10 inches at a time but I finish a cup before it gets thick. I usually only pour out 3oz at a time. It squeezes out the edge of the fabric when I get close to the cut edge but the first inch of the two inch overlap I don’t feel it coming through the weave and I rub it good after laying it on he wet poly tak. Just making sure that is consistent with everyone’s experiences. Want to make sure this thing doesn’t come apart later!

[avidflyer]

Try thinning it a bit and see it if doesn't work better for you. I've found that with older cans of poly tac the glue was thicker, it's almost like it dries out in the can somewhat. YMMV, JImChuk

[jiott]

I will second what Brian and Jim said. I also worried quite a bit about wetting thru the fabric; the most you will ever get is a slight wet feel on your bare hand after squeegeeing it down good. Its not like you will get a lot coming thru. No need to put on so much that a lot comes squirting out the edge either. I think keeping it thin enough, like a new can, with MEK is the best answer. I never had a single seam pull apart when I started shrinking with heat; if it doesn't pull apart then, it never will. So don't worry about your fabric coming apart when flying.

[JoeRuscito]

Ok cool. I have shrunk to 325 on one wing with no seam movement just second guessing my work/self. Thanks for the reassurance!

[temecula50]

I am getting ready to cover the wings of my K5 project,I have noticed some wings are scalloped aft of the false ribs and some are flat.I have been told this is all in the heat shrinking technique used.Is there any performance advantages to either result or is thin primarily cosmetic choice? Thanks...Gerry

[jrevens]

I think you may be referring to wings that have the Laker leading edge option. Some of us who do have that have scalloped the top surface of that fiberglass part between the ribs.

[aviator79]

I have been told this is all in the heat shrinking technique used.

Important: There is only one correct technique for shrinking Poly Fiber. Do exactly what the manual says, including the bit about ignoring the "Leroys" who think they know better than the manuals.

I think there could be two things you're thinking of:
1) What John says: Some people add scallops to the aft edge of the fiberglass leading edge fairing (Laker Leading Edge). This is mostly cosmetic, but might also reduce stress on the fabric at the edge.

2) No fiberglass leading edge. The Laker Leading Edge is optional. If you don't use it, the top surface of the wing will have normal bow of the fabric in between the false ribs. From what I understand there is a small performance gain in using the LLE, but nothing dramatic.

[efwd]

And if your short like me, looking up at the leading edge, you won't notice that you don't have the LLE. ;)