Yes. I'd looked at (and have made some prototypes) covers in the seat pan
that span the aileron torque tube tunnel and sit on small ledges glassed
around the sides of the seat pan.
By calculation, 5mm of PVC foam laid up with 1 ply of carbon on the top face
and 1 ply of carbon/kevlar hybrid on the bottom face gives way at about 4g
(with JAR-weight pilot). An intermediate suppport will increase this to
about 16g, but by then the torque tube tunnel will likely have failed (which
is a good thing as it and the enclosed alloy tube will absorb energy and
remove the hardspot beneath the spine).
The balance of the composite construction is good in that the PVC foam
should fail in shear just before the carbon lets go; so there's no point in
adding further plies in an attempt to increase strength.
Of course the real challenge is to provide for energy absorbtion rather than
strength. Any ideas on that? A pile of brass tubes?
Duncan McF.
----- Original Message -----
From: <irampil@notes.cc.sunysb.edu>
Subject: Europa-List: Re: Harnesses again
>
> Also, he thought 3 inches of tempurfoam is not adequate for safely passing
> the 19g
> vertical acceleration test. He thought it would provide insufficient
> damping and
> secondary impacts. I had the idea that low compression strength
honeycomb
> material, if laminated up to a couple of inches in the seat pan might be
> useful.
>
> Anyone want to collaborate on such a design?
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