Ken Powell wrote:

Paul,
   I have been working on a similar motor mount crossbracing arrangement
as you described in your earlier post today.  As you know I am working
on the firewall-forward for the RV-4 along with Mike Wills.

   This is what I am attempting (will it provide adequate crossbracing???):
I am going to use the front cover from a 85 SE (w/13b) so I can use the
front motor mount on this cover to  bolt 1/2" tubing that will extend ~ 5"
past the right side of the engine and another tube that runs from this
point to the center housing engine mount. Note that the intersection of
these tubes will have a motor mount 'rubber' installed.  This forms a
triangle that is bolted to the engine. Next insert a piece of 1/2" tubing
from the top left motor/airframe mount across the engine compartment to the
tip of the triangle formed in the previous step.  The last step is to
insert 1/2" tubing from this new engine mount position to the upper right
airframe  and the lower right airframe mounts.  This creates a 3 sided
triangle in the motor mount that is bolted to the airframe.  Note that we
now have a triangulated crossbrace running across the engine compartment
that mounts to the engine thru a 5th motor mount rubber.  This should
effectively crossbrace the engine against side loads - is the flex in the
rubber motor mount a problem?

Ken get a cardboard camera and take a bunch of pictures and mail them
to me. I cannot quite visulize this well enough to tell if it
will work. Also make a sketch in MS Paint if you have that.

   This is necessary in order to mount the muffler under the footbox.
This allows the radiator to be mounted under the engine; it will be
level with the top of the footbox and slope downward toward the front of
the engine (this radiator location is why such an elaborate crossbracing
scheme).  The cowling will be pressurized.  The stock oil cooler will be
mounted on the spark plug side of the engine in a fore and aft
configuration and the exhaust air will exit thru the right side of the
cowling thru louvers.  This will also allow 31" exhaust pipes.  You will
not believe how tight everything is in a fuselage only 24.5" across.  I
am attempting to emulate Steve Beckham's RV-4, but no one seems to know
the size of his radiator or how he mounted it.  BTW, my mockup uses a
radiator 15.75" x 17.5" x 2" at this time.  I have to have a muffler; I
already have poor hearing without the abuse of an unmuffled rotary.
   Will this work or am I wasting my time?  I will have pictures in a month or
so - I am spending most of my spare time on my miniMax and hope to be flying it
by Xmas.

Ken Powell

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