Sheeting foam wings, how much weight is enough??

[Bartman]

Hi folks,

I've got an old Lanier 81" Cap 232 kit that is going to be my next build project but I've never done foam wings before. It's just something I've always tried to avoid doing.

The builder of my Carden Cap walked me through what I think is a great procedure for sheeting the wings but I'm not sure just how much weight I've got to use when compressing the wings/sheeting in the scrap foam that they're packed in.

Each wing panel is about 38" and so the plan is to lay a piece of 3/4" plywood over the stack and then put the weight on top of that. An option may be to borrow some 25lb weight lifting plates from a friend of mine so I might have 100 pounds or so from them but can there really even be too much weight for this?

I've also got the materials and stuff (from another project that didn't get completed, custom wing tips for a Pitts S1 project) to vacuum bag the wings but I'm going to pass on that as I've never actually tried vacuum bagging something and I'd like to do it the basic way before trying a more advanced way.

Thanks!
Bart

 

[ExtraJohn]

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[Jetpainter]

I've always used weight in the past, and put as much on as I could find.

The next time I'm going to vacuum bag. Terry (Terryscustom) is going to be bagging a set soon, and is planing on making a video of the process. He's got it down, and I'm looking forward to the video.

 

[Terryscustom]

I'm going to do a video on vacuum bagging next week as long as work cooperates. For weights I went to the big box lumber yard and got some landscaping blocks. The smaller ones are about 10 lbs. each and the larger ones are about 18 lbs. each.

I would distribute the blocks evenly which gave me a few hundred pounds of weight. Even with a plywood caul you will want to distribute the weight evenly.

Other than that, I'm not much help. I really suck at doing poly sheeting and always get them too heavy.

 

[Bartman]

More is better

Using a "guesstimate" of 10" average cord is 380 sq inches of area with a 38" long panel, 250lbs is only .65 pounds per sq in. of clamping force

good point considering vacuum bagging applies atmospheric pressure which is 14.7 pounds per sq. in.

@Terryscustom ; you had mentioned that video to me but I'm not ready to try vacuum bagging just yet. will definitely look forward to learning something from a builder like yourself.

also just remembered I have a stack of pavers in the basement and some other stuff I can use as weight. I'll have to start getting my ducks in a row to do this.

Thanks!
Bart

 

[ExtraJohn]

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[Dan767]

I built this kit long ago, never got to fly it (unsecured in the back of a pick up). When sheeted the wings, I used plywood over the shucks, pavers and four 5 gallon buckets from home depot filled with water. Probably 200-250lbs. Worked great.

 

[CatalinaWOW]

I agree, don't shy away from vacuum bagging. Much, much better and easier than weights. Weights seem straightforward, and they are, but complexity comes from doing one thing over and over. Let's see. Do I put the buckets alternated with the pavers, with lift weights on top of the pavers or.........

The air is every where, pushes evenly and doesn't tend to twist or warp anything.

 

[Terryscustom]

Biggest problem I had was the hustle. Gotta get them in the shucks, taped and held in place, caul in place and stack weights before the foam kicks to much to get a secure bond. Then if you get too much glue it floats and maybe pushes the part out of alignment.........augh!! Vacuum you can relax, drink a beer, crank up some tunes and enjoy the day.

But I should ask, Bart are you going to sheet with resin or poly glue?? Just curious, not trying to scare you off. You seem to have your ducks in a row.

 

[Bartman]

the builder that framed up my big Cap has a technique that he explained to me...

fit the balsa sheets and tape them along the seams with masking tape
using gorilla glue make a crisscross pattern on the foam and squeegee it out but don't cover the entire wing, leave gaps between the lines
mist the glue with water and then get everything assembled and weighted
the gaps between the rows of glue and the reason for not gluing the sheeting is so that the foaming glue can have a place to go preventing the sheets from floating on the foam

the balsa on the big Cap wings is really tight(he bags everything) and there's some evidence of the glue coming through the seams of the sheeting (sort of like a pressure release mechanism while also gluing the seams) so the technique looks like it works pretty well. i might spot glue the seams of the sheets every six inches or so but other than that I'll probably just do it the way he said.

His name was Jim Eble and I was going to touch base with him again before I do the new Cap wings. He's about an hour south of me.

Any comments on the above would be welcome and appreciated.

Thanks,
Bart