REFLECTOR: Filler for wingtips

[Alex Balic]

Yes, you can't use the can foam because it is not stable, and stays too
flexible- even the pour foam is somewhat more flexible than the blue foam-
best to make a plug with the blue as close as possible to shape and wedge in
with a big gob of micro. If you want to play Mr. Wizard, I made some pure
epoxy foam that cured very rigidly- did it by accident the first time but
was able to recreate one time for a fillet that I made- mix up some
structural, add about 10% acetone by volume, then get it really hot with a
heat gun while you are mixing- the epoxy will exotherm, and vaporize the
acetone (probably could use alcohol too I would guess) when it finally cools
off it will be a really stiff, light weight and stable foam- go ahead and
experiment with it a couple of times- it's fun.....

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
Behalf Of richard at riley.net
Sent: Tuesday, June 29, 2004 8:39 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Filler for wingtips


At 07:21 PM 6/29/04, you wrote:
>What is everyone using to fill canard tips, winglet tips, and lower
winglets
>these days?  I went by my local West Marine this morning to pick up a
little
>kit of polyurethane pour foam, and the only size they had cost 85 bucks!
>After re-inserting my eyes in their sockets, I noticed that this kit would
>produce 2 cubic feet of foam, which is a lot more than I will need.  At
that
>price, I could just whomp up a dry batch of Alphaepoxy/microballoon and use
>that!
>
>How about the pressurized cans of foam sealant at Home Depot?  The
resilient
>latex type probably isn't what we're looking for, but they may still have
>the "semi-rigid polyurethane" type.  Any other good ideas?

The one part foam will never completely cure.  If you get a good hot day on
the ramp, it will swell underneath your expensive paint job and end up
looking like a goiter.  Some of the 2 part foams will do the same thing.

I always used blue foam, gued to the tip with epoxy/micro slurry.  Rough
cut on a band saw first, wipe with slurry, put in place, hold it there with
drywall screws till it cures.  Remove screws, sand to shape, cover with 2
plies of glass.  Fill with micro, sand, prime, paint.

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