Mailing List Message #1572
From: Marvin Kaye <>
Subject: Re: plastic plane question
Date: Sun, 11 May 2003 08:27:49 -0400
To: <flyrotary>
Posted for <>:


I will have to make some cowl bumps for clearance, and have a question for
the plastic plane types.  I'll need some foam that is easy to sand to shape,
and notice that Spruce has "polyurethane foam" that sounds like what I need.
Is there anything like this that's obtainable locally?  Some sort of
building material, or craft item?  Thanks,

Rusty (I hate fiberglass)
Turbo 13B powered RV-3 (experimental aircraft)...Be Afraid :-)
1993 RX-7 R1... Not stock, carry bail money :-)

[You can use just plain ol' styrofoam, available at the local building supply place in the insulation area.  It's a bit messier than the urethane foam, but a fraction of the price... and for a couple little cowl bumps it's just the ticket.  Get your basic shape in the foam, put a layer of bondo over the top to fine tune them, then layup a couple layers of bi-directional glass cloth for your structure.  Once everything is cured up, remove the foam, sand out the excess bondo, bondo the irregularities on the exterior, sand & finish. I'm attaching a couple pictures of a scoop that I made for that Eagle540 installation I've been working on using styrofoam... proof that it works just fine.  I skinned this scoop (it's for our 3rd intercooler) with carbon fiber, but that would be way overkill for a little bump.  This scoop was much more complex than a simple cowl bump, but emminently doable.  I hope this helps.        <Marv>            ]
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