Fred Osborn wrote:

Paul,

A while back I inquired about making Schertz type motor mount beam from
a 1/4 in. aluminum angle. Attached are 2 JPG's showing what I propose.
The angle is a 3 X 4 X1/4 in., 6061-T6, 30 in. long. It is attached to
the rear housing with 8 long oil pan bolts. To reduce the weight I will
cut out the X'd sections in the 4 in. vertical side to form a truss
beam. The oil pan will be attached to this side. Similar cutouts will be
made in the 3 in. horizontal side. Because I will be using this on a
single rotor engine I have reduced the estimated engine weight to 250
lb. or a 6 G load per side of 750 lb.

The support isolator total spread is 28 in. with 7 3/4 in. on each side
from the isolator to the side of the rear housing. The remaining truss
cross sections are:
1. Top = 0.28 sq. in. (way oversize, I think, because I did not want to
cut into the inner radius)
2. Bottom = 0.14 sq. in.
3. Diag's and posts = 0.16 sq. in. with the diagonals at a 40 degree
angle WRT the horizontal, the posts
     are 2 3/4 in. high and 4 1/2 in. center to center

I took my last statics course over 50 years ago and my 30 years of EE
and program management did not improve my skills. My back of the
envelope calculations say the truss is way over designed with excessive
safety factors but before I start carving on this would someone do a
quick check for me? It could save me from a fatal embarrassment.

Fred O.

Looks like that will work great Fred. Trick looking too.
It does look a bit overkill.

Paul Lamar
 
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