I just purchased a twin Otter from VMAR. It is a very poorly constructed ARF - bad wood, parts don't fit, covering cheap, and cheap plastic parts. The cowl for this ARF is paper thin like you would find on dime store toys. The cowls arrived damaged and I cannot get replacements. Is there any way to repair these cheap plastic cowls other than reconstructing them out of fiberglass?
Thanks,
Vic

You dont half to completely reconstruct them out of fiberglass but you can line the inside with fiberglass cloth and resin. It would still be plastic on the outside but the fiberglass on the inside will give it better strength.

Since I have never fiberglassed anything before, could you give me some instructions on how to fiberglass these plastic cowls?
Thanks,
Vic

You can get a fiberglass kit at Lowes, Home Depot, Walmart or just about any hardware store. Follow the instructions & go for it. Do it in a well ventilated area as the fumes can get fairly nasty. Get a couple of throw away paint brushes. Line the inside of the cowel with the cloth & brush on the resin. It's easier to do half & then when it dries, do the other half. Try a scrap piece of plastic ( any plastic will do) to get the feel of it. It is a messy job, but with a little care you'll be a pro in no time. I always use fiberglass & resin when joining wing halves together. It's very strong & a lot easier to sand than epoxy. Don't mix a big batch of resin until you get a feel for it. If you find it drying too fast, no big deal. Just use less hardener next time. Good Luck !!

Thanks folks, I will drop by Home Depot and get a kit.
Sounds like the only way to fix this problem.

Remember not to make the reinforcement too thick (it could make the inside diameter too small). It's always a good idea to do this AFTER you have made the cut outs for cyl head, needle valve, etc. That way, if you're off a little bit on a cut, it will be easy to fix. Good Luck !!

You may want to bypass the fiberglass at home depot-pick up the resin products but buy the fiberglass from a hobby shop that carries the 1 or 2oz stuff-you don't need that 5,6 or 7 oz stuff lowes or depot sells-too heavy! just a thought.

I had the same issue once and lined the inside with ~ 1 oz fiberglass cloth. I carefully cut/trimmed a couple pieces of the cloth so it would lay flat and not overlap too much. I then sprayed a very light coat of 3M 77 adhesive inside the cowl and layed the fiberglass in place. Next, I coated with epoxy resin - two coats if I remember correctly. Finally, I sanded and sprayed with black Lustercote (for appearance only). Came out fairly good and strong. Just be careful, if the cowl is a tight fit over the mating fuse etc. you need to keep the fiberglass real thin at the opening of the cowl as it obviously decreases the inner diameter of the cowl. Hope this helps.

Steve

If you have an old broken cowl, try practising with it first ( you'll find you can fix it this way! ).

After you've tried fiberglassing a few items, you'll come to realize that it is MUCH easier than it seems to work with.

Once I discovered this, I found I could easily fix broken cowls, wheelpants, canopies, etc. and re-inforce wood and plastic structures...

Hint: WAX PAPER IS YOUR FRIEND!

Epoxy does not stick to wax paper even when dry.... because of the wax.

Use the wax paper to help hold a shape, or keep the mix and materials smooth, and/or to keep the mix out of areas it should not go in.

Also remember that you can sand the fiberglass areas once dry too.

Thanks a bunch folks. I found a small Fiberglass Repair Kit at Walmart for around $12.00. Home depot on had large quantities (large sheets of heavy fiberglass and 1/2 gallon resin). I'll get started on the repairs/reinforcemenst soon. I know this will cure the problem of the flimsy plastic cowls. this may turn this ARF into something enjoyable!

To do it cheap and easy get some fine mested cheese cloth and two part epoxy.

Cut your cheese cloth to match the surfaces and then mix upthe epoxy (equal parts) and brush it on the surfaces thinly and then lay in the cheese cloth and then brush over thinly, let sit for 2hrs and trim with a very new sharp razorblade or Xacto knife.

Best part of this process is that it's as thin as you coat it and it's plyable once cured, so that it will contour to the shape needed.

Cheap and easy and it's virtually industructible after it sits for 24hrs

Think about fiberglass and how thin surfaces of it crack and break and then think how epoxy never becomes quite brittle enought to shatter like
fiber glass.