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Epoxy or Polyester Resin

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I have a Valenta Models Parabola which has some damage to the fuselage. I’m not sure the best way to repair and strengthen it.

In places the resin inside of the fuselage is opaque as in the photo, which looks like it is delaminating. A club member has suggested running superglue into these areas to rebond it.  Then I was going to apply a layer of resin and glass fibre to provide extra strength.  I don’t think the extra weight will be a problem as it’s already a heavy model.

Does this seem a viable option.

Finally does anyone know if the fuselage would have been made from polyester or epoxy resin.  I’ve tried bonding epoxy to the inside of the fuselage but it does not hold so I am assuming it was polyester. Is there any way to confirm that I need to use polyester for the repair

Thanks. Brian



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There is no smell but the model is pretty old.

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Most likely to be epoxy - very few manufacturers use polyester

sand the inside a bit - then smell it - like John suggested - polyester has a very characteristic smell - epoxy no smell

Yes, run/wick thin superglue into the delam areas & cracks. Rough up the inside surfaces with fairly rough sandpaper (or it wont stick) & add glass/epoxy across the breaks. Use laminating epoxy, not epoxy glue. Search & you will find several threads dealing with fuselage repairs.


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Thanks Phil. I’ve given a section a good sand and there is no smell so must be epoxy.  Maybe I didn’t clean/sand the inside sufficiently when I did my adhesion test with epoxy.  Will the surface need cleaning with anything as well as sanding?

I will search for fuselage repair for more tips


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7 minutes ago, BrianL said:

Will the surface need cleaning with anything as well as sanding?


Not really - I usually try & get the vacuum cleaner narrow nozzle in there to clear out all the bits/sandings !

Sand/rough up lots for the new epoxy to grip to - last one I did needed much sanding back to remove a previous badly done repair


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Also put any repair under pressure while it dries, and keep it warm.

In a big fuselage a bag of hot water, or sand etc may be an option. 

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Sometimes the dust from the sanding can cause a problem. Get rid of as much dust as you can.

While less glue is better, I find it's better to brush some epoxy over the area the cloth is going to go before applying the cloth.

Pressure is really the key to getting a good stick though. Heat helps but it makes it go off quicker it doesn't help if the mechanical adhesion isn't good.

I use peel ply which allows you to uses layer of tissue or similar to absorb epoxy between the cloth and whatever is giving you the pressure (tape, clasps etc).

Doing the inside is harder. Outside you can wind round tape with good pressure. 


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Bladders can be useful as well. I’ve used bicycle tyres in the past.

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