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Bob Axsom

Well Known Member
I plan to use some blue foam (from ACS) to fill some external recesses. The plane is painted. I had thought of applying a single layer of fiberglass over the external exposed surface of the foam and painting it to match the plane. It occurred to me that other foam surface closure methods might work better. Any suggestions, like resin and micro balloon seal?

Bob Axsom
 
Bob Axsom said:
I plan to use some blue foam (from ACS) to fill some external recesses. The plane is painted. I had thought of applying a single layer of fiberglass over the external exposed surface of the foam and painting it to match the plane. It occurred to me that other foam surface closure methods might work better. Any suggestions, like resin and micro balloon seal?

Bob Axsom
Click to expand...

Micro is a little on the soft side, and won't resist crushing as well. A layer of fibreglass would be better in this regard. I often use a mixture of micro and cabosil for a stronger filler. It's not as strong as flox but lighter and easier to shape.
 
Paul is right; micro alone over foam is not very damage resistant. I'd do a wipe with wet micro to fill the foam cells, then lay two plies of 9oz glass, then peel ply. After cure you can pull the peel ply and go directly to a surface fill; straight epoxy wipe, polyester filler, or epoxy/micro.
 
You would be surprised at the strength of relatively light cloth with epoxy.

We finished our One Design aileron recesses on the wing in sanded blue foam - we then covered with one piece of .75oz deck cloth (fiberglass) laid on with West Epoxy. It was resistant to all kinds of knocks and was very light.

The other advantage is a very quick prep for paint.

We will be closing our 'ends' with blue foam and deck cloth - can't see any point in going heavier.
 
Bob,

Go to a hobby store and check out the cloth they sell. You can get some REALLY light weight bi-directional cloth there that would be prefect for what you are going to do. Us some pealply (sp?) to help with the finish.
 
That's exactly what I did. I think it's .75oz from a local hobby shop. Can barely tell it's there, quick to smooth afterwards with surface fill...at least I think so, we'll see.:eek:

Learning as I go--

Joe
 
Thanks for the input

Let me add a few thoughts on this. As I said the plane is painted and I don't want to mess that up. I have blue foam left over from my cowling work and it is kind of theraputic to cut and fit the material in place so that is probably a given. Typically there will be no handling of the ends of the control surfaces so I'm not concerned with people poking the surface with fingers, etc. I don't want the blue foam exposed to the outside world because of it's nature to crumble, etc. My original thought was to load the upper and lower outside surfaces of the items being filled with mold release wax then cover the outboard surface of the foam with one layer of fiberglass using EZ-10 epoxy resin and EZ-83 24 hr hardner which I have from all my other work. Once hardened (well semi-hardened actually) I would use a sharp No.11 X-acto bladed knife to carefully cut off the extension above and below the surface. I know I can brush on my Blue Imron and all would be fine if there are no fat finger mistakes in the process. As I thought more about it while putting on the third layer of glass on my MLG subfairings today I had a little concern about the adhesion of the fiberglass to the very small edge at the end of the control surface and I wondered about just skinning the foam with the epoxy resin or epoxy resin and micro balloon (I have the flocking material as well). It seems to me from the inputs that a fiberglass skin is the general choice.

Bob Axsom
 
Bob Axsom said:
I plan to use some blue foam (from ACS) to fill some external recesses. The plane is painted. I had thought of applying a single layer of fiberglass over the external exposed surface of the foam and painting it to match the plane. It occurred to me that other foam surface closure methods might work better. Any suggestions, like resin and micro balloon seal?

Bob Axsom
Click to expand...

Bob, I've really enjoyed reading about your quest for speed, but you know I have the beginning of a Rocket kit for sale cheap. You can stop playing around and go big time. :D

I sure hope you find time to document all of this. Now that I'm selling my Rocket kit, I guess I'll have to speed up the RV-9.

Cam
 
Thanks but we are in this for the duration

That is a great offer but this thing the three of us are in is unique I believe and I feed off of it. Those Rockets really are pretty and fast though - good luck with the sale.

Bob Axsom
 
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