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Have thin green foam under paint on a fiberglass fuselage???

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Have thin green foam under paint on a fiberglass fuselage???

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Old 11-03-2014, 03:55 PM
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howeclan
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Default Have thin green foam under paint on a fiberglass fuselage???

I have a question for the people that may have seen a fiberglass plane that has a thin layer of what looks like green foam on outside and the paint layer is on top of this.

I have a flyable Sickle (Pattern Plane) and have one that was crashed and I would like to put the crashed one back together as a backup plane. As I am gluing the parts together I have noticed that there is this thin layer of green foam like material on the outside of the fiberglass body and the paint layer is put on over this.

Can anyone tell me what this layer is????

There are pieces missing and I will need to patch over the areas, but Iam not sure what I am patching over and if it will bond strong enough.

Any help here is great appreciated.
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Old 11-03-2014, 06:51 PM
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What you have is a fuse that is layed up with a core material. That core is most likely some type of Rohacell. There is an outer fiberglass skin, the core and then an inner skin. The way I have repaired this in the past is to use thin CA to get the peices put back together as best I can and then apply a scab patch of thin fiberglass and epoxy resin both inside and outside. For the missing peices you can use blue insulation foam. Simply glue a peice in place and then shape the inside first, glass, shape the outside and glass. While re constructing I have run peices of masking tape on the exterior then temporarily glue longerons onto the masking tape. Once the peices are glued in place the scab fiberglass is done on the inside and then the outside is done after the temporary longerons are removed. Sounds more complicated then it really is.
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Old 11-03-2014, 07:02 PM
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Thanks for the insight, but I am seeing an inner fiberglass skin and the core on the outside of that and then a paint layer on that. I will use your idea of the blue foam for the missing pieces.
Thanks for all your ideas. I really do want to make this ship flyable once again.
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Old 11-04-2014, 02:53 AM
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Speedracerntrixie

I did notice last night that I do have an outside layer of fiberglass. I thought it was just paint I was peeling of, but at a closer look I could see it was a painted fliderglass material.So the green foam was sandwiched in between layers of Fiberglass.

Thanks again for your help.
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Old 11-04-2014, 09:01 AM
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The green foam is Airex C70.75, rohacell is white.

i keep stock of the Airex foam and can supply you with small quantities. I keep stock of 1.2mm and 2mm.
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Old 11-04-2014, 09:20 AM
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Good info, what is the difference between Airex and Rohacell?
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Old 11-04-2014, 11:10 AM
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Thanks

If I find I need the Airex I will give you a PM.
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Old 11-04-2014, 05:03 PM
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Originally Posted by speedracerntrixie View Post
Good info, what is the difference between Airex and Rohacell?
Manufacturer.. lol

Both are essentially a closed cell PVC foam.

Airex has grey, yellow and green, which corresponds to strength and densities.

Rohacell has all of theirs in white with a ink label to differentiate the different versions.


Composite Arf uses Airex C70.55 in their models (the yellow foam in the wings, etc). Most any European manufactured composite model uses Airex as it is easily sourced over there. Here, not so much. I have to import it from germany
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Old 11-05-2014, 05:10 AM
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LOL Yea I didn't think there was too much difference. I suppose the term one uses may depend on their location. I have a Comp ARF 330 that has brown core probably started out as yellow but at work we only use Rohacell.
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Old 11-07-2014, 09:19 AM
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Originally Posted by howeclan View Post
Thanks for the insight, but I am seeing an inner fiberglass skin and the core on the outside of that and then a paint layer on that. I will use your idea of the blue foam for the missing pieces.
Thanks for all your ideas. I really do want to make this ship flyable once again.
The nice thing about the PVC foam is that it is shapable with a heat gun and some ingenuity. I've done this many times in the past.

But for my money, the simplest thing to do smaller repairs with is good ol' sheet balsa. I use 1/32" sheet usually, wet it and shape it in place and dry it with a heat gun. Then I apply the glass to both sides, as Shawn suggested.

The foam often has half the density of the balsa and is quite useful for large patches. But for small stuff, say 30 square inches or less, balsa is easier and the weight penalty is so small, it is negligible
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Old 11-07-2014, 11:56 AM
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I will be using the thin Balsa for the repairs. Hope to get a good start on it tonight and this weekend. Thanks
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Old 11-07-2014, 05:46 PM
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Originally Posted by MTK View Post
The nice thing about the PVC foam is that it is shapable with a heat gun and some ingenuity. I've done this many times in the past.

But for my money, the simplest thing to do smaller repairs with is good ol' sheet balsa. I use 1/32" sheet usually, wet it and shape it in place and dry it with a heat gun. Then I apply the glass to both sides, as Shawn suggested.

The foam often has half the density of the balsa and is quite useful for large patches. But for small stuff, say 30 square inches or less, balsa is easier and the weight penalty is so small, it is negligible
The formability is exactly why i import it.. The fact its lighter and stronger than the same size piece of balsa makes it even nicer.

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Old 01-07-2017, 08:00 AM
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Hi , do you still have Airtex 1.2 mm in stock If so let me know.
Stan. at sales@s-whobby.com
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