Peter Cowan wrote:

Have I missed something in this latest discussion of building a system

to allow bolting a 13B to

an existing dynafocal mount because when it came up some months back it

was quickly shot down for

a couple of reasons. One was that most of us have the engine within a

very short distance from the

firewall compared to a Lycoming to accomodate cg issues and the overall

36 inch length of

engine+psru. Won't most dynafocal mounts position the engine 5 or six

inches further forward

affecting cg and cowl fit?
How were these issues addressed in this current discussion?
Peter

That is the reason I rejected this plan for engine mounting.  It moved the
engine far enough forward to eliminate the posibility of using the stock
cowl and the CG would be at the extream forward end of the envelope even
with the battery moved back.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

Since it is not practical to bolt the device on to the front cover
for structural reasons two things are different. 

First: The front end housing is replaced with an aluminum part 
that accepts the stock front cover (with minor modifications) 
and the stock water pump. This reduces the engine weight by 
about 30 pounds. 

Two: The engine is moved back somewhat
as the front cover and the water pump are inside the dynafocal
mount. These points are apparently being missed when considering
the CG location. The weight of the motor mount brackets, whatever
are not being used, also must be considered. If it is an alloy  plate
under the engine and it is 14.5 by 15 by 1/2 that is 10 pounds
right there. Less what ever holes you can put in it. If you
NC mill it down the cost will be several hundred dollars.
If you use the un-milled motor plate/motor mount idea you 
will add about three pounds further forward. I digress.

This sketch is roughly how it should be done but I cannot guaranty it
will be done this way or even at all. What is shown in this
sketch is the use of low cost barry rubber bushing instead
of a dynafocal type mount or a conical mount. The conical
mount would vary only in detail from what is shown here.

Paul Lamar
 
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