From: Sky2high@aol.com
Message-ID: <0.869a560f.2596476a@aol.com>
Date: Sat, 25 Dec 1999 11:14:34 EST
Subject: LNC2 Subfloor
To: lancair.list@olsusa.com
Mime-Version: 1.0

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Rob writes:
<<<
I don't think I've damaged the core, but I sure don't want to be stepping
on those areas, particularly if they're covered by carpeting and therefore
not visible.  So I planned on having my subfloor extend over those areas.
>>>

You have damaged the core by crushing the nomex.  We all have.  Stop it.

The core, acting as the web, keeps two semi-rigid skins separated at many 
points.  this contributes greatly to the stiffness and strength of the 
fuselage.  If the core is crushed locally, that area is not as rigid.  It is 
locally weaker than before but not as weak as a hole or removal of one of the 
skins, even if you put back as much glass as in the removed skin.  Having 
said that, the fuselage  is very strong and the occasional "weak" spot is 
probably not going to matter.

Nomex cores make the skin very susceptible to puncture damage (your honey's 
spiked heels or a dropped wrench), but provide the lightest weight for the 
strength (all moveable control surfaces).

For these reasons, the wing skins use foam cores (heavier, more points of 
support, some give without crushing, stronger structure) and especially the 
stiffer foam used in the upper stub wing skins so that you can walk on them 
to get in the plane, spiked heels aside.    

Build the sub-floor as described in the manual.  Why?

Because:

The 1/4 inch nomex is plenty strong since it is supported and glassed all 
around.  The ramp at the front not only provides extra strength, but is 
necessary as a foot rest and as a push off point to get out of the plane.  
The fuselage floor that is exposed is a very small area upon which you will 
never be able to put any weight because of the instrument panel.  In 
addition, the sub-floor ramp and the main spar provide plenty of strength for 
that area.

The foot rest is important because there are only four (4) positions during 
cruise flight:
a) Both feet forward
b) Both feet back (knees up, feet on footrest)
c) Left foot forward, right back
d) Right foot forward, left back

The footrest is needed for three of the four positions.

BTW,  Use 1/4 inch phenolic hard points and nut plates for the adjustable 
(fancy) pedals.  If you want to remove the pedals or make the cable length 
adjustable, use turnbuckles on the aft side of the pedals to connect to the 
rudder cable. 

Go sit in somebody's LNC2.

Scott Krueger
N92EX

PS:  220 lbs of blubber and I haven't broken my sub-floor or floor yet.
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