I was originally going with the (heavier) Subaru engine and was worried abo
ut sufficient strength with a heavier engine. So I used thin plywood glasse
d and bolted on both sides to make the firewall (angled at about 30 degrees
) and tied this to a piece of plywood that runs back to the rear of the coc
kpit module. I glued this to the side, and and glassed it to the firewall s
o it makes a tee with the firewall. Then I used thin angle aluminum to tie
this to thin plywood 9also glassed and reinforced with thin aluminum sheet
on the cockpit sides of the center tunnel. The bolts for the frame that hol
ds the bungies (I actually used springs) goes through the plywood, the thin
aluminum and the cockpit module.
I weighed all this before I put it in and it probably added 8 - 10 pounds o
r so. I haven't weighed the plane yet. I rationalize this added weight in p
art by noting that the center board also serves as a mount for everything
in the center console which is necessary as I have the finger brakes, auto
pilot, all the various brake hoses, gas hoses, throttle, etc. All those mou
nts would weigh something.
Don't know if this was worth the effort but it sure is strong. I did learn
that putting the foam between glass (or thin plywood and glass) increases t
he strength by several magnitudes - but you need to figure in the force vec
tors to get the proper strength.
The cockpit picture shows the plywood on the outside that is bolted to the
bungie and front wheel frame and also bolted and fiberglassed to the tee sh
aped piece inside the tunnel that runs back to the rear of the tunnel. On t
he cockpit picture you can see Bud Yerly in the background, probably silent
ly (or not so silently) cursing builders who add their little "improvements
" that cause interference problems later on -
Gary Leinberger
A237
Lancaster, Pa.
________________________________________
From: owner-europa-list-server@matronics.com [owner-europa-list-server@matr
onics.com] On Behalf Of Fred Klein [fklein@orcasonline.com]
Sent: Tuesday, June 08, 2010 11:16 AM
Subject: Re: Europa-List: Tunnel Bulkhead Substrate
On Jun 8, 2010, at 4:59 AM, Tony Renshaw wrote:
> I am after advice on stiffening bulkheads in my tunnel, now that I
> have opened it up at the top to gain access to finger brake shelf
> etc. Like all of us, I have blue foam coming out of my ears, but
> I've also used ply as a substrate here and there, and I know about
> light weight composite substrates like Divinycell. So, does anyone
> speak positively about using a specialised foam substrate instead of
> blue foam with BID either side, or should I just use ply, or is even
> good old blue foam good enough???
Tony,
Personally, I would never use blue foam where thin sheets are called
for, even if I could make a simple jig and sand it down to say 1/8" or
1/4". For what you describe, I would find some LastaFoam...however,
since the amount you're talkin bout is so small, I would think 1/8"
birch acft plywood would serve.
Fred
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