REFLECTOR:RE: Top door strake dents

Andy Millin reflector@tvbf.org
Fri, 31 Oct 2003 11:28:25 -0500


I don't have the top door, but I agree with Alex, I think the micro
would do the trick.

To remove the top skin and then the foam and rebuild seems like a lot of
work.  I have an idea that "might" work.

I have a guy in my chapter building the Glasstar.  Their fuselage is
foam sandwich over a steel tube frame.  To make the hardpoints for
attaching the skin to the frame, they drill a small hole through the
outer skin.  Then take a piece of wire bent at a 90 with about 5/8"
after the bend (could be an allen wrench, or a bent nail???) and chuck
it up in the drill.  Then carefully slide the wrench inside the hole and
crank up the drill.  Work it around.  The wire will crush the foam on
the inside leaving a hollow disk.  Use a vacuum to suck out as much of
the debris as you can.  Then using a piping bag you could pump the voids
full of micro. (On the Glasstar they fill the voids with microglass)
Sand it off an it should be much stronger.  Yes.  It will weigh more.
But what do you want.  The dent's don't weigh much...

FWIW,

Andy


-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org] On
Behalf Of Richard@riley.net
Sent: Friday, October 31, 2003 2:14 AM
To: reflector@tvbf.org
Subject: REFLECTOR:RE: Top door strake dents


The strakes on Berkut were carbon bid over 5 lb PVC or SAN foam, we
never 
had a problem with them denting.  Micro would work, but it's LOTS
heavier 
than the foam you have now .  Stripping out the inside skin, getting rid
of 
the foam, replacing it with micro, reskinning the inside and keeping it 
from changing shape while you're doing all of this would be a BIG job.

Easier just to add some carbon bid to the outside of the upper skin.
The 
higher the load, the more plies.  If you're going to be walking on it in

spike heels, 6 plies should be enough.  Taper them an inch per ply and
it 
will be easy to blend in when surfacing.

Be sure to remove any kevlar in the selvage, or it will come back to
haunt 
you in the finishing.


At 11:54 PM 10/30/03 -0600, Alex Balic wrote:
>I would say that even packing the area behind the skin with dry micro 
>would solve this problem, the micro probably weighs just a little bit 
>more than the foam, but it is very firm, I can't see it allowing any 
>dents. Honeycomb will dent at least as easily as the foam core does. 
>for really rigid lay-ups we would fill nomex honey comb with micro, 
>this way it would not dent, but for the velocity, you could just 
>replace the foam with micro, and it would be as resilient.

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