It has come to my attention that there are people
out there on the internet selling motor mounts for rotary 
engines that are not safe. Nice paint and workmanship are
no substitute for good engineering.

I am not talking about Jerry Hey. I have looked at his work
and it is excellent. 

If you see a motor mount for sale please, by all means,  make 
a 1/4 scale model using 3/16" square balsa sticks and apply a 
load. A defective design will be immediately obvious when you 
apply even the smallest of loads.  Apply a torque load and 
a side load as well as  a download. Do not assume rubber
bushings take load. They don't enter in to it at all.

Check for loads applied on tubes not at the juncture
of tubes. In other words loads applied in the
middle of a tube. That is a no no! Look for 
un-triangulated rectangular sections of the motor mount.

You can also buy a book on the subject of "Statics" in 
any college books store. Also introductory Physics also
covers the subject. A good book I just ran across is
University Physics by Hugh D. Young Addison Wesley. 
Lots of color illustrations in this modern book to 
make the concepts clearer.

The bible for aircraft motor mount design is Analysis 
& Design of Flight Vehicle Structures by Bruhn.
Tri State Offset Company 1965.

Another book is Aircraft Structures by D. Perry 
McGraw Hill 1950.

If you are still in doubt don't take my word for it but 
contact a professional  mechanical engineer and get his 
opinion.

Vance Jaqua on here is an excellent aircraft engineer.
Ask his opinion. Vance Jaqua <vjaqua@dslextreme.com>

Your life depends on it.


Paul Lamar
 
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