On 5/25/2021 8:06 AM, Flesner wrote:
That might keep the fittings from buckling under extreme load but you
have the same total sheer area.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
In the KR wing the upper attach fittings are, for the most part, always
in compression and the lower fittings are always in tension. It is the
sheer web, the ply between the upper and lower spar caps, that keep the
spar caps from moving in relation to each other. Think of it as the
lower spar cap always moving outboard and the upper cap always moving
inboard. That is the case under positive load. Generally speaking if
the wing is loaded to failure the web will fail and not the caps or
fittings. Even the sheer web on one side on the outer wing panels have
proven to be adequate to this point as I'm not aware of any wing
failures in flight. Later advise said to go with double sheer, ply on
both sides. At the Gathering where the spar was loaded to failure the
sheer web split right down the middle. Photos somewhere but I can't
locate them or the photos of the crash that mangled the wing structure
and left the WAF's intact.
Wing structure, when built to plans, is quite strong enough.
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