Cliff Manzke wrote:

OK Paul, since no one else is stepping up......

Total spring rate is 1000 lb/in (400+400+200) so the deflection is 400/1000
or .40 inch..........which is much greater than a Barry mount will handle in
the radial direction :(   That problem aside, the load on the two front
mounts would be .40in X 400lb/in = 160 lbs and .40in X 200lb/in = 80lbs for
the rear.  What will probably happen is that the spring rates will go much
higher than those you gave (i.e., non-linear response) and the front mounts
will carry more of the load.  Perhaps something like 175lbs on the two
fronts and 50lbs on the rear.  I don't have a Barry catalogue handy (Jeff S.
stole it) so I can't tell you how non-linear these mounts are.

The real question is what frequency will your engine/mount configuration
resonate at........

Cliff Manzke

Right on the deflection. Right on the non-linear response.
I guess I could put a look up data table in the program for the non-linear 
characteristics of the rubber mounts.

I have no idea on resonance. I don't think we will have to worry about it
in that mode as the main forcing frequency is torsional. Of course
there could be some weird cyclical effects caused by the prop passing in
front of the cowling or behind the wing in a pusher. If the redrive mounting 
ears deflect somewhat more of the load could be transferred to the rear mount.

Paul Lamar
 
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