Gringo Flyer

My Feedback: (18)

I have been working on a TF 60 sized P47 for about a year now. I have been taking my time on the build and it is looking great. I am in the glassing phase right now and am glassing with WB poly. After the initial coats of poly on the bottom of the wing I started working on the top of the wing. A few hours after applying the first coat of poly I went out to check the wing and noticed the sheeting had warped. Apparently I had not applied enough sanding sealer to the top. Anyway I was so frustrated that after so much careful work one little mistake made such a mess of the wing. My problem now is deciding what to do with it. I had planned on painting it and adding panel lines and rivets as a first fairly detailed scale project. With the warp I am not sure how much time I want to spend on details and have just about lost motivation to finish but I have spent a lot of time and money on the plane to get to this point. the warps are not enough to make a difference in the way it flies but it is noticeable.

My question is, is there any way to fix it? The wing itself is not warped just the sheeting in a few spots. The warps are confined to the top of wing starting about 1 inch back from the LE to about 3-4 inches back. I am tempted to try and cut out a piece of sheeting from the top of the wing and replace it with new sheeting. I am not sure if this is going to cause more problems than it solves. Is it possible to switch out sheeting without damaging the wing?

aerowoof

is it a warp or just bowed from the wood absorbing moisture and swelling?steam iron may be able to steam them out

CGAV8R

My Feedback: (2)

Yes, if the sheeting is low, add light weight filler, sand, re fiberglass.
If the sheeting is high, sand it down with a long sanding bar, re glass.
If the sheeting is only bad in small areas between the wing ribs, you can cut out the bad sheeting, add balsa to the sides of the ribs and re sheet, reglass.
If the sheeting is bad for a long distance, cut out the bad area, carefully sand the ribs to 1/16" below the balsa skin sheeting, resheet, re glass.
Don't worry man, we all make mistakes. The good thing about working with wood is it always can be fixed with a little effort.

Aaron D.

Live Wire

Gringo FLYER
What sealer did you use. If it was not water proof you alread have no chioce than finish it or strip off the sheeting and start all over. If all it is, is showing where the ribs are on both side I would leave it and finish the best you can. I used Laquer wood sealer and still had a small amount of what I call waves on the surface.
I would not start cutting hole and trying to repair spots or you will have a bigger mess to contend with[:@]
Larry K

The wave show where there are ribs which are high spots. Do not try to sand these down or you will be sanding all the skin away.

Gringo Flyer

My Feedback: (18)

The bows run parallel to the LE and at 90 degrees to the ribs. They are more like little waves with some low spots and some high spots. Probably too high to sand out and too low to fill. I used a lacquer based spray can sanding sealer. It worked fine on the bottom of the wing and the control surfaces with no warping. The only thing I can figure is that I was doing everything in stages and when I sealed the bottom of the wing either I didn't coat it well enough or maybe I only applied 1 coat instead of 2.

I don't think the steam iron would work now because it has a coat of dried poly on it that seals the wood.

So I guess my decision is whether to spot replace the sheeting or not.

Live Wire

By any chance , did you put the wing in the sun or in a place where it could get warm or hot to dry it. The moisture will get into the wing core and cause it to get moist then dry[:@] and cause the warp.
Larry K

One thing more if you used cloth in your glassing do not, do not use steam. It will cause the poly to blister.

Gringo Flyer

My Feedback: (18)

It wasnt in the sun or anything, it was just in my shop and it was cool out. The waves are not at the ribs, they run at 90 degrees to the ribs. Its just where the sheeting buckled with the moisture.

Live Wire

When replacing sheeting do it in a solid panel not in a section, It will come out better when you are ready to refinish it. If you could post a Pic of the wing close up it would help I bet it really is not that hard of a fix. May just need a small sliver of wood removed and reglued and refinished . How thick was you rsheeting.

bigtim

My Feedback: (13)

here is some insite into your issue from a guy who had to deal with it on my build, same thing, same area, I only noticed it after glassing the wing, using the WB poly just like you did.

in my opinion, the waves were probably there before you glassesd the wing, they were just not as noticable, at least mine were nearly invisable,the balsa is really the thin, the sheeting used in the P-47 kit, the 1/16 wood is really thin, if I build another one I will use 3/32 wood instead so its less likely to have these issues, do not over sand the sheeting, you will just sand through it the wood is so thin there is little room for this.

now to the cure, not the definative one of course but the one I used for my build, since you have already got the glass on, finish the process,first make sure the sheeting is glued down to the ribs, if there is some areas where the sheeting has pulled off the ribs, then make a small slice in the sheeting and drip some thin CA into the slot to tack the wood together, make sure the area is tightly glued, and no loose areas that are moving around.

then get your 5-6 coats of poly on the wing, and sand between the coats with a bar sander, to get the high spots on the same level, while you get the glassing done.

after that, prime the wing with a easaly sandable auto primer(from a spray can),just the wing top, and mostly in the suspect area, sand the primer off with a sand bar so the low spots show up clearly, if you use loose sand paper it will sand the depressions and they don't show up as well so use a bar sander, or a piece of sandpaper around a flat piece of wood, paint sturrers work well.

then get some filler of your choice, I used Bondo auto spot putty , the kind that comes in a tube, it sands easy and will sand to the thinnest edge, again when sanding use a bar sander so the surface is level, the weight is minimal and the spot putty takes primer well, fortunitly the area is forward of the CG .

you can use this method for the whole model if there is imperfections in the sheeting on the fuse or tail as well, after your satisfied with the contour then shoot a little primer on the area and sand it lightly with fine paper any depressions will show up and you can fill them to your satisfaction.

photos you have seen before but more to point out the problem area, notice the unfinished wing you can't even see the depressions unless there was a strait edge on the area, something I didn't do before glassing the wing.

how do you think I got my surfaces so smooth

Gringo Flyer

My Feedback: (18)

I do think part of the problem is the sheeting being so thin. Before the build I had read several recommendations to use thicker sheeting.

After reading through the suggestions I took a second look at the wing. If I press on the ridges they will flex some. I also noticed that if I apply pressure to the ridges over the ribs a lot of the waves get a lot smaller. I am going to go back and re-glue those spots that pulled loose from the ribs and I think that will take out a lot of the waves. After that I think high build primer and spot putty should take care of the rest.

As with most building mistakes sometimes they are not as bad if you just step back a day or two and get a second opinion. I won't be able to work on in for a couple of weeks but I'll be sure to post an update when I do. I'm open to any other input as well.

Live Wire

Your friend the good old # 11 blade and CA Pick up off the floar and use ir

Gringo Flyer

My Feedback: (18)

Update-

I was able to get out the worse offenders using an exacto knife and making an incision on the wave. After making the incision, I would make a pinhole directly over the rib and use CA to tack the sheeting back down to the rib. I didn't really have to cut out any of the wood. The incision made with the exacto knife gave enough space for the sheeting to lay back down. The wing looks much better and with spot filler and high build primer I think I can get the rest of the waves out.

If I was going to build the kit again I would definitely go with a little heavier sheeting for the wing like many folks here on RCU recommend.

Thanks for your help, I think you guys saved me from making a bad decision and ripping off some of the sheeting.