Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml@lancaironline.net
Date: Thu, 19 Feb 2004 16:16:36 -0500
Message-ID: <redirect-2999077@logan.com>
From: "'Scott Richardson'" <scott_m_richardson@sbcglobal.net>
Subject: Strengthening the longerons?
MIME-Version: 1.0
Content-Type: text/plain;
	charset="us-ascii"
Content-Transfer-Encoding: 7bit
Importance: Normal

Hi all,

I'm looking for some advice from the collective wisdom of the group.

I'm building a 235 with a forward hinge canopy - hinge brackets mounted
to the header tank and gas strut brackets mounted on the longerons -
what I was told was the "standard" method for the 320's at the time.
This method required drilling two 3/16" holes through the longeron for
the AN3 sized screws holding the gas strut bracket on.  I've done this,
but this means that I've now removed roughly 1/4-1/3 of the longeron's
vertical extent and reduced it's strength by some proportional amount.
I'm concerned that I've introduced a failure mode whereby a hard landing
could in effect snap the nose off the aircraft.  I've seen at least one
picture (which I can't find now) where this sort of thing happened -
hard landing split the fuselage from the gas strut bracket, to the
cutout for the NACA vent, to the load transfer pad.

I'm sure others have built their aircraft w/o drilling the longerons
like the plans indicated, but since I can't "undrill" them, have any of
you done any additional strengthening of the longerons?  The thought
that I had was to layup some unidirectional graphite from the engine
mount gussets back to about the middle of the cockpit.  Maybe 1-2" wide
in the overhang area right under the longeron, overlapped on both the
bottom of the longeron and the inner side of the fuselage.

Thoughts?  (...and no, I haven't asked anyone at the factory about this
- yet).  Thanks.

Scott
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
Scott M Richardson                   scott_m_richardson@sbcglobal.net