radiisteve

My Feedback: (24)

Hi Guys -

I'm working on a giant scale project with sheeted wings over an open framed wing structure. As most of this design and build have been from scratch there's no accurate how to in this case. I've been building off and on for 40+ years, and have sheeted many a foam wing without problems, but recently had some problems when just sheeting the stab on my project and wanted to have a more full proof method planned out for the wing with glues and techniques that best suit the job at hand.

My problems sheeting the stab centered on the sheeting coming up around the 30% area of the ribs as I glued up the leading edge (having started from the T.E rolling forward). I tried switching from all CA, to CA on the Leading and Trailing edges with Aliphatic Resin over the ribs and horizontal stringers in the middle, but again the sheeting came up unless first pinned down.

Am I just doing this wrong, using the wrong combination of glues, or what? Thanks for the input.

sensei

The problem is that you have no shucks like you have when sheeting a foam wing, the shuck allows you to to apply equal pressure everyplace throughout the cure. So maybe using a slow cure glue or epoxy and creating yourself a weighted blanket of sorts that you can lay on top could help you, it has to be something with some weight that falls and conforms easily to the airfoil appyling weight everyplace at once.

Bob

radiisteve

My Feedback: (24)

Yeah, perhaps I was just being impatient, trying to get the sheeting to go from trailing edge to leading edge and also aheare to the tip block all in one fairly quick CA process. The end result was having to undo the problem I had created, which took quite a bit of time. I do believe in being patient, but here I just didn't have the right technique.

foodstick

On a deal like that I would use Aliphatic. Make sure the wing is supported in the correct shape, and won't be distorted, I would use pins, tape, and sandbags to hold things down. Once you are sure everything is good just leave it until the next day.Thats what I would do...

speedracerntrixie

My Feedback: (29)

When I was building the old Ohio R/C giant kits I would glue the sheeting at the LE with thin CA by pushing the sheeting against the sub LE and then hitting the joint with the thin CA. Once that was done I would go over the tops of the ribs about halfway to the spar and press the sheeting into place with an aluminum bar. Once that was tacked into place I would ease the sheeting up enough to get slow CA on the remaining length on rib and the spar then again hold in place with the aluminum bar. It sounds more difficult then it actually is. Nowadays when I scratch build I always do sheeted foam. If I have all the materials in house I can have a built and ready to hinge 30% to 40% wing in 10 labor hours.

radiisteve

My Feedback: (24)

I'm building this with the intent to compete in he US Scale Masters with my brother who's a hell of a pilot with some very good showings here out west. So, I've researched every assembly a best I can, laid out the design using AutoCad and an angular bench top set up just for drawing.

radiisteve

My Feedback: (24)

Sheeting a small area like the tail was no problem at all with just CA.

Charlie P.

I use Titebond II for such things - but I am a dinosaur.



And some lead to keep the sheeting in place while it dries (though this is the spar and CA is great for that).

radiisteve

My Feedback: (24)

Using CA on a step by step basis from TE to LE sounds doable for the wing, as it will be done in three sections (again just like the full scale PT-19 is done). Using Aliphatic Resin in the middle with pins and weights and plenty of patience would seem to be the safest. I certainly appreciate the replies guys.

Now all I have to do is lay out the wing design quickly with the scale landing flaps (one piece extending beyond the center section), scale hinging for the ailerons and flaps, and all that goofy stuff on the bottom side mid wing.

j.duncker

My Feedback: (2)

I have done a few of these and found that if I used regular PVA wood glue on the ribs and TE then fitted the sheeting up to the LE with more PVA but used CA to tack it in place this would work. Then lots of small sand bags to hold the sheeting down with steel strip at the TE on top of the sheet with more sandbags. It helps if you LIGHTLY mark the approx position of the ribs and position the bags on the ribs.

Leave overnight at least - 24 hrs better.

The reason for using regular PVA is the longer working time.

raptureboy

Pretty much the same. CA the trailing edge and wood glue the ribs and then add sandbags or get some lead shot from a gun shop, I also wet my sand after putting it in the heavy freezer bags, as it makes it heavier and helps it to form around a shape. When I get to the leading edge I use CA again.

MTK

For smaller wings, CA gives adequate time to work the sheeting on.

But for larger wings, either Carpenter's Glue or Gorilla works for me. Plenty of working time to glue down even larger, one piece sheets. I prefer pins, tape and some lead shot bags (not too many.... concern with warps) to hold things. I've also pre-formed the sheeting prior to glue in the past. Simple spritzing with water spray and laying over the structure to take the shape first. Then allowed to dry. More work, but more accurate assy in the end, particularly for thicker sheeting

Gray Beard

My Feedback: (-1)

On this years build I took a trip down memory lane and gave the Sigment a try to see how it works these days. I was impressed, not only did it stick well it sets up quickly and sands easily. As Bob pointed out, making up something to act as a shuck is a good idea so you can get even pressure.

kenh3497

Someplace I read a thread about a wing for a pattern plane being built. The wing was laid in a cradle of the "left over" ribs. (A negitive of the rib in the wing) Each negative rib was directly under a positive rib. In essence he built a wooden shuck. This was all calculated before hand of course. The builder used polyurethane glue which gave him plenty of time to get everything just right. It looked like a slick system to get a strait, well bonded wing.

Ken

MTK

First I read about this technique was some 36 years ago, from Hal DeBolt. Turned out Hal and other racers developed the method for their racers.

I built one of Hal's designs back then using this exact technique. It worked well enough. Everything was hand cut back then.... tedious work and precision wasn't great.... just good enough. BUT The plane flew okay.

The same technique would be a cinch today if the wood cradle (and ribs) was laser cut. Great thing about this technique, sheeting was laid first into the cradle. Then ribs and spars were installed and glued. And finally top sheeting was glued to the ribs. In other words, the whole assy was put together in one pass

fred985

i wet my sheets and bend them over the wing and let them dry. this lets it conform with less spring. i always start at the leadiong edge. i use instant glue along the leading edge . when this sets i sneek under and put a seam of carpenters glue where needed and finish at the trails edge. using pins and weights and let it sit overnight.. this has never failed me. i would never start at the trailing edge.

radiisteve

My Feedback: (24)

Hey Fred, thank you so much for the input. The idea of starting at the Leading Edge first with preformed sheeting sounds great, get it all adhered to the toughest area first then finish with the more flattened out area of the back of the rib.

The cradle idea is very sound also, a bit more work, but very sound.

As for glue combinations, I have both Gorilla (which was used on the stab effort), and Titebond II for non Ca's plus I even found and old (really old, say 30 years) tube of Ambroid that still had useable glue in it (I overnight tested some).

I want to say my most sincere thanks to everyones input, it's all been very helpful and I'll post pictures of the Wing assembly in the next week or so. The "scale" PT-19 started out as a "will ya build me a Dynaflite kit for fun" for my brother, but though the kit is very popular as a fun scale plane, I wanted to create something quite a bit more true to scale for my brother to fly, so I began by a .......well that's another entry to do as a build string.