George Lendich wrote:

Paul,
Drew in some stiffeners, but not sure if their best placed.
George (down under)

Much better pictures. I am beginning to get the big picture. Since you are
using one large flat area on the front face you will need a lot
more and longer internal ribs. Tracy's psru is only about 6.5 inches (165
mm) in
diameter so that puts high bending loads into the front plate of your bell
housing.
On the other hand if it is a full 13 mm thick all over it's face
that would be stiffer than what Tracy has now. The big elephant ears
are not useful for mounting as the rubber bushing would be oriented
in the wrong (vertical) plane. They should be accommodated in the
horizontal plane with bolt on brackets to the flat sides.
No real problem as they can be cut off. Ups shipping and
casting cost however. Don't forget to check the exact position of
all the bell housing mounting bolts and make sure you have
material in there to take the bolt compressive loads.

Paul Lamar

FWIW, for an RV-4 (mine), using bolt on brackets would be better.  For my
airframe I need this to be kept to a minimum width.  My engine mount at the
fire wall is only 23 inches wide.

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode

That is another advantage of the bolt on brackets. Can be made
in a variety of lengths. Milled out of billet, welded out of plate
or cast.

Paul Lamar
 
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