Perry Mick wrote:

OK, I think I got it. Let me know if you see any problems. I will
replace the upper 1/8 x 1 x 1 aluminum extrusions with square
steel
tubing with an endplate welded on and a hole drilled in the
center for a
bolt.

Perry

Yep. That looks like it. Have your son make a 1/4 scale  balsa
model to verify.

Paul Lamar

Ops just saw a problem. Can of worms. The model would show this
quick.

Here is a simpler fix. Rubber rod ends. Still the one! :)

Paul Lamar

OK, I fixed it. Certainly looks bulletproof.
Perry

Ops again.

By fix it I hope you don't mean this.
This is still not fixed. If you build a model and twist it
you will see what flexes. This becomes a larger and larger
can of worm. A real bird cage Mass of Rattles (Masarati) limiting
access to parts.

BTW 3/16" square balsa wood has ideal characteristic for modeling
motor
mounts as it has low modules of elasticity in bending while still
maintaining
high compressive and tensile strength.

The strut with rubber rod ends solves a myriad of problems.
Also allows you to adjust the down thrust angle for max efficiency.

I hope you mean strut with rubber rod ends and not this one.

Paul Lamar

If you still want to use the third Barry rubber bushing as a front
mount
this might work.

Decouple the front mount beam from the rest of the structure using rod
ends
or rubber bushings. As Vance is fond of quoting some English engineer:
"an
ounce of rubber is worth a pound of engineering." :) Sometimes you can
add
too many tubes to a space frame and wind up with undesirable side
effects
such as local bending moments in joints that lead to cracks.

Again 1/4 scale balsa stick models made from 3/16th square do wonders
when
it comes to understanding a particular space frame design and I highly
recommend
doing one.

Paul Lamar

Perry,  is there a problem with running a strut to the firewall?   I
know you have a different situation but I am trying to learn from what
you are doing.   Could the LEZ forward mount use a bracket on  the  oil
pan  for the lower end of the strut.  Since this idea has been around
for a while,   I assume there is a good reason  you are not doing it
this way.    Jerry

I suppose you could mount something to the center of the upper surface
of the main spar. I will not drill any holes in the spar, only fiberglas
things to it's outer surface. I have a lot of stuff on the firewall,
mainly the two stock coils and the coolant overflow bottle up in that
area. There is no reason other than I just haven't studied it yet. I
guess I'll take a look since I haven't started construction of the new
mount yet.

Perry

Won't take up much space.

Paul Lamar
 
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