Glass Fiber Wing Top Layer

The Smithsonian National Air and Space Museum credits the Laser 200 for bringing about a new generation of aerobatic aircraft
youngman1
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Glass Fiber Wing Top Layer

Post by youngman1 » 11 Nov 2016 15:45

Hi Guys

I've got some repairs to do on my wing and have noticed that it has a glass layer on top of the ply... this isn't in the original plans but i'm guessing it does a pretty good job of stiffening the wing up!

I think this is also done on the one designs? Does anybody else have this on their wing and if so what sort of difference does it make?

Cheers
N23LZ
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Re: Glass Fiber Wing Top Layer

Post by N23LZ » 12 Nov 2016 21:36

On most all of these types , the fiberglass is just to protect the plywood from the environment.
It is a very lightweight 'deck cloth''.
There is little to no strength consideration.
davevon
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Re: Glass Fiber Wing Top Layer

Post by davevon » 18 Nov 2016 02:04

A lot of them also have fabric on the wing skins. I think the reasoning at the time was light weight, easy to do and easy to remove for repairs.

I've heard of carbon under the skins to add strength.

The fiberglass may be easier to get a glass finish too.

Dave
Dexws
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Re: Glass Fiber Wing Top Layer

Post by Dexws » 27 Nov 2016 06:58

Hi
I started the restoration of a Stephen Akro and I plan to cover the wing with a bidirectional cloth of fiberglass in order to increase the stiffness particularly in torsion (you know the flutter problem of the Akro)
I didn't perform any assessment yet but according to a friend of mine who did it on a cap 21 (similar wing area) the extra weight is around 7-8 kg but it is worthwhile doing it
Ciao

Alberto
Italy
youngman1
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Re: Glass Fiber Wing Top Layer

Post by youngman1 » 05 Sep 2019 03:30

So I went ahead and got this job done after getting confirmation that a proper glass reinforcement does in fact increase wing stiffness enough to have a marked increase in roll rate.

Took over 12kg of paint and fabric off before I took out much of the filler which was unnecessary.

Went for a 100gsm bi glass cloth. A tad over 6kg added. Will go for a high build primer next and cut back, want to avoid filler.
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Dexws
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Re: Glass Fiber Wing Top Layer

Post by Dexws » 08 Sep 2019 20:37

after a long waiting the shop did the repairs and mods i requested to the Stephens Akro wing

> general check;
> repair of some cracks;
> increase in main spar height by 19 mm / 0,75 inch (max possible without modifying the fuselage), so now the max thickness is about 13% in the center section, decreasing up to zero at the aileron start;
> application of 4 mm plywood on both spar sides up to the aileron;

the result is attached
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i plan to cover the wing with a layer of 200 g/m2 bidirectional fiberglass cloth, i hope to stay around 6-7 kg of extra weight and to have a good increase of torsional stiffness.

ciao

Alberto
youngman1
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Re: Glass Fiber Wing Top Layer

Post by youngman1 » 09 Sep 2019 04:01

I'd be careful with 200gsm. That's twice the fabric weight I used and added 6-7kg. 50/50 resin to fabric ratio is as good as you get hope for with wet lamination.
Dexws
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Re: Glass Fiber Wing Top Layer

Post by Dexws » 12 Sep 2019 21:00

Thanks
If I remember correctly 200 gsm was the minimum weight I found for structural fiberglass cloth. Which one are you using?
youngman1
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Re: Glass Fiber Wing Top Layer

Post by youngman1 » 12 Sep 2019 22:43

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