This is for those airplanes like the BearHawk
and the Zenair 801 with five hard points one of
which is centered near the top of the firewall.

It could also be adapted to those airplanes with composite firewalls
that are usually 1/2 inch or 3/4 ply with fiberglass or carbon
on both sides. When adding hard points to these airplanes
keep them as close to the skin as possible and beef them
up with a couple of extra plies.

  Here is the bracket for the 13B center housing with an exhaust heat
  hole. The turbo 13B center housing does not have this hole
  so it will require a slightly different bracket. This can be made in two
  parts. The top part is 1/4 inch thick mild steel plate. The bottom
  part is 3/8 th thick mild steel plate. They can be brazed together
  as the lower plate should be a slip fit in the large hole. This
  transfers the shear load directly into the cast iron housing and
  not by the hold down 8 mm and 1/4 inch flat head screws.
  The trust load from the prop is countered by a 1/2 inch all steel
  ball joint with a half inch bolt. The reason for an all steel ball
  joint on this end is they can accommodate higher mis alignment angles
  and they are less affected by temperature than a rubber ball joint.
  There can be a rubber ball joint on the firewall end to isolate
  what little vibration there is from the rotary.

This is hand fitted to the center housing as it is made with
crude tools like a hack saw or plasma cutter. You need to transfer
the stock center housing bolt pattern to this part. No need for
a high cost precision NC mill made part.

----------------------------------------------

Here is what it looks like on the BearHawk.

Paul Lamar