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<< Lancair Builders' Mail List >>
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James--
I looked at several aircraft, and most noticably Orin Riddel's (sp?, from
the >factory) has a very odd shape. The doc's recommend a uniform 3 inch
width, and yet most I have seen taper towards the longerons. Has anyone
seen, or >could recommend reasons for the irregular shape?
Those of us who are tall had to recline the seat-back several inches
behind the rollover. This left the bottom of the structure hanging down in
mid air, ready to gouge into our shoulders. In my case, I tapered the
bottom of the rollover somewhat so it would clear my shoulder, and blended
it into the side of the fuselage.
A second question: the manual indicates that the longeron's, once
installed, should have the innermost spruce laminate running the complete
length of the wood, i.e. no trimming. However, the manual says nothing
with respect to finishing the piece, should it me layered with a 2 bid
layup? bonded to the honeycomb? suggestions also welcome...
The longerons are STRUCTURAL! Do not trim them in whatsoever - they need
all the cross-sectional area possible since they are what is supporting
your engine hanging out there in front. I know enough about statics to be
dangerous, and when I ran the numbers I got real scared. Based on my
simplified calculations, I figgured the longerons should snap in tension
directly above the main spars at about 10Gs, assuming that they had no
holes in them.
Therefore I did not install the NACA ducts in the side of the fuselage in
this area, neither did I drill any holes for the canopy mounts in my
longerons. I also beefed up my longerons with unidirectional carbon fiber
in the critical area. Yeah, I know that mixing carbon and glass is not
recommended, but I figure the worst that can happen is the carbon debonds
from the regular glass and I will be no worse off than I was before... At
least I won't be worring about the front half of my plane breaking off on a
hard landing <G>.
But I digress...yes, you attach the longerons to the fuselage with 2 bid.
--John, L-235
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