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Foamie question

PostPosted: Fri Mar 13, 2020 7:42 pm
by TerryB89
ok, this may be a stupid question
when I build my Foamie, instead of using PMF, what if I cover all the seams with this Flex Seal Paste they advertise and then just paint the whole thing with several coats of paint?

Re: Foamie question

PostPosted: Fri Mar 13, 2020 8:12 pm
by John61CT
Seems to be more a caulk.

You'd need to try the glue version, or ask them if they know about adherence to the specific foam board you want to test.

But that's just the edge-joining,

whole point with PMF is the added **tensile strength** of the sheeting glued to the panel surfaces.

Plus the added 3-dimensional strength of wrapping around the corners and edges.

If you do sway with all that I'd suspect reinforced framing would be needed to compensate holding it together subject to highway-speed wind forces.

But hey, every new idea can always be tested, let us know how it goes!

Re: Foamie question

PostPosted: Sat Mar 14, 2020 5:33 am
by GPW
Good question !!! The Skin is the STRENGTH of the cabin . the foam merely supports the skin … Think of how a sock works … :thinking:

Now then , we’ve been flying bare foam RC planes for many years now at higher speeds that our cars usually go , and rarely have we exceeded the “ Speed of Foam “ ... The higher the speed the greater the “ aeroelastic divergence” … :o

Re: Foamie question

PostPosted: Sat Mar 14, 2020 8:20 am
by RJ Howell
To me and my build it came down to strength. Adding reinforcement to the seams (as in glued cloth strips) made sense to aid in keeping that joint tight and secure. I used bedsheet to stay thin, yet still add strength as the reinforcement at the seams. The canvas/cloth over also laps the seam adding yet another layer of strength.

I wasn't sure how much of an effect layering the entire side with canvas/cloth would do, so it surprised me as to how much it did indeed add. :thumbsup:

Your question leads to wondering if the foam itself is strong enough to perform under real conditions. My guess is probably, yet I do see how it could crack or split at the seams from just running down the road. Going the route of skinning and reinforcing the seams just adds durability to your project! I'm certain you want it to last years of service. :D