Re: REFLECTOR: Bulkhead Installation

["William Wade" <billwade@concentric.net>]

Larry- They may be right. I'm not an engineer but here goes.
  The way I visualize it is that a perpendicular load is redirected 90
degrees by the glass tape. The microballoon fillet would carry relatively
little load. In tension the load would act to peel the tape off the fillet.
In compression the fillet would prevent the tape from crumpling until the
fillet material failed. In either case I would think a microglass fillet
would give maximum strength to the tape.
  In the canard and most other bulkheads the force would be vertical, along
the plane of the bulkhead. In this case the joint is in shear, not
compression; with the bulkhead bottom in tension. The tape glass acts to
spread the force over a large area of the glass lining the fuselage. My
understanding is that the foam core of the fuselage is what ultimately
limits the amount of force that can be absorbed. If it tears or crushes
you've lost your structural sandwich and a large part of the assembly
strength. It seems to me that having equivalent structural material all the
way across the joint section (including the tape extensions) is preferable
to having a center which is relatively weak and which would fail first. That
way the load would be uniformly distributed over the whole area under the
tape.
  That being said, the microballoon would be stronger than the foam and so
should be sufficient- my method would be overkill and heavier. Oh well...
  However, if you have glass to glass or wood- think about it.    -Bill

prototype 'Super' Chipmunk N18EF
Velocity Classic RG N6098S in the works

>When I suggested doing this, some of the engineering types said this is
>an example of more is not necessarily better.  The way it was explained
>to me was that, the intent of a tape-glass "T" joint is the load from
>the bulkhead (or whatever) is transferred via the tape over a large
>area.  The fillet is not structural by intent.  If you use a microglass
>(load carrying) fillet, then the load will be concentrated at the butt
>joint.
>
>Larry Epstein
>173 FGE
>
>
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