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Assembly Order on Covering Wing

GDS

MEMBER
Front Range CO
Greetings All,

I'm new to this forum and couldn't find an answer to this question by searching:

I'm re-covering a 1962 PA-18 tow plane and am on the wings using the blanket method. I have the top and bottom covered, but not shrunk. As I understand it, I need to rib stitch the bottom ribs under the fuel tank before I install the fuel tank. I don't want to rib stitch prior to shrinking the fabric. I'm concerned that if I shrink the fabric without the tank installed, it will pull the wing out of square a little and make the cross bar that goes through the fuel tank impossible to install. What is the proper build order?

I'm thinking of installing the cross bar without the tank, doing a 250 degree shrink, do the rib stitching under the fuel tank, then install the fuel tank before the final shrink.

Comments or suggestions?

Thank you for any assistance you can offer.

Gary
 
You can rib stitch with the tank in.
use a needle shaped like a half circle, preferably make your own needle out of (gas) welding rod so you can bend it to suite your hole spacing.
Pound the end of rod flat and drill a hole for lacing cord.
Stitching technique is hard describe, Maybe polyfiber manual has a photo?
 
Gary, and especially if it's a 180hp Supercub, think extra-tight ribstitching in the fuel tank area (e.g., high horsepower acro planes): This fabric really gets beat up in the towing operation.

All best on your project, let us know how it's coming along. As you know, some of the best expert resources on this site.

Thanks. cubscout
 
Shrink it. Then stitch it. Then install tank, and find drain location. Cut that. Install grommet. Fabric over that. Then do the painting steps


Sent from my iPhone using SuperCub.Org
 
To cubscout’s point,
2” spacing in prop wash area, not difficult to get these bay areas snug because you don’t have to worry about distorting ribs from over tightening. Don’t overdo it though.
 
What Mike says. Stitching before shrinking is a prescription for disaster - or at least wavy ribs.

Also,if using Stits or Ceconite, at least dope a 2" area around ribs before stitching, and run some dope over the dead-straight reinforcing tapes to keep them straight.

One more tip - watch the videos that show how to hide the seine knot. Do it that way - results are simply spectacular!
 
Shrink it. Then stitch it. Then install tank, and find drain location. Cut that. Install grommet. Fabric over that. Then do the painting steps
no problems with distorting the square shape of the fuel tank bay and not being able to get the fuel tank brace into place? (I've been over-thinking it and now I'm chicken)



Thanks for the great suggestions, guys, spacing on rib stitching suggestion is a good one, I'll do 2" in prop wash area and 3" outboard from there. The aircraft is a 180HP towplane. I'm covering and painting with Stewart Systems.
 
Of course put the brace in. No requirement for the tank to be there. When you do put the tank in, fit the cover to make sure you have the tank laterally positioned. I didn't do that and had to re-do the grommet.

Stewarts is a good system, but not for the inexperienced. My very talented buddy even made a spray booth and visited experts for lessons. Used the exact setup Stewart recommended. Spotty results. It will look good at ten feet.

I have seen pictures of glossy Stewarts, but so far no actual aircraft. I admit - I no longer go to air shows.
 
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Have the brace in place, it’s easy without the tank. You’ll have to install the tank to get the drain location. If you put a cap plug in the drain it will mark the fabric from the back side. Burn the hole through after paint with a soldering tip for a nice clean hole. Or install an inspection cover.
 
I install the brace prior to cover. Leave the outboard bolt loose enough to raise the rod up to install the fuel tank. That rod does keep the first bay square.
 
Thanks again guys, got all the fabric shrunk and the rib stitching completed under the fuel tank bay, no racking problem. I had to use a short curved needle and the technique described above for some of the blind stitches aft of the fuel tank bays. Having a rib stitch party for the rest of the wing tomorrow.
 
How did your wing project come out? Also, noticed I was not very precise in my earlier post: Meant to say tight DISTANCE between stitches in fuel tank bays, not tension. Others corrected, and looks like you picked it up.

Thanks. cubscout
 
Thanks for asking, wings came out great. No problem with the fuel tank bays, I did the covering and shrink with the cross member in place across the fuel tank bay and it worked fine.

I knew what you mean't on stitch distance, I spaced them at 2" in the prop wash area, 3" for the rest. The Stewart System top coat came out OK, but it's pretty hard to avoid orange peel over fabric. Much better results over the metal parts.

Just finished painting and striping the fuselage, will start mounting the factory reman O-360 next week.

This beast got a new Univair airframe, new main landing gear, new covering and paint and a factory reman. It had 16000 hours on the airframe and 2300 hours on the engine. Nice freshen up job and it'll be good for another 16000 hours or the next ground loop, whichever comes first.

Interior parts are pretty rough looking, but they'll be fine for a tow plane. If it was mine I'd spend more time on the interior and do some minor upgrades on the panel, but I just want to get it finished and flying before the big soaring season starts in June.

Thanks to all who have given advice,

Gary
 
What Mike says. Stitching before shrinking is a prescription for disaster - or at least wavy ribs.

Also,if using Stits or Ceconite, at least dope a 2" area around ribs before stitching, and run some dope over the dead-straight reinforcing tapes to keep them straight.

One more tip - watch the videos that show how to hide the seine knot. Do it that way - results are simply spectacular!





Sent from my iPad using SuperCub.Org mobile app
 
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