Gordon Robertson wrote:

Hi fellows,

I am looking for a source of engineering data on the Lord or Barry

mounts

for the engine.   I need technical information, plus the dimensions.   I
have checked the Barry website, but to my surprise they dont seem to

give

technical specs.

Does anyone know where I can find this stuff?

Gordon Robertson
RV8 - 13b engine installation.

And some more. Can also be used in a composite firewall design.
Not to worry the 1/2 inch bolt can take the momentary bending loads
but the welding cup must be supported by parallel tubes
with the firewall as shown in this Perry Mick implementation.

Paul Lamar

Dean Head wrote:

Group,
I am very interested in the mount discussion as I want to fabricate my

Cozy

MK4 mount. I see a couple of way that it has been done and would like to
take advantage of what folks have learned as I construct mine.
Dean Head
Cozy MK 4 #1040

Here is another very good  implementation that uses a steel cross beam under
the back of the engine to hold the Barry rubber mounts by Bill Schertz.
The steel cross bar fits just behind the oil pan aft vertical
panel. At the top in this jpg.

Paul Lamar

Gordon Robertson wrote:

Wow!  I opened a floodgate.   Very good information, thank you.   I will
send away for the catalog.

One more question, what are your thoughts on the thrust and weight loads
required?   Weight is obvious, about 350 lbs static all day every day, and
up to 2000 lbs in a 6G situation.   I presume that we need not size the
isolators for the occasional 6G or 10G loads, but we must of course size the
support framework for those loads.

What about the thrust?   Very rough calculations suggest that a good thrust
figure is about 850 lbs.  This is from presumed 3000 fpm climb capability in
a 1500 lb aircraft at 80 mph.

It is shared by both mounts and that of course is a worst case scenario.
Thrust drops off with speed of course. The 1/2 inch bolt going through
the steel spacer in the middle of the rubber mount is more than
up to the job.

So my question is which way should the isolator be arranged?  I know that
you favor the vertical support mounting , and Tracy prefers the horizontal.
But I have not seen that this is the result of the axial or radial loading
of the isolator.

Any insight would be appreciated.

Gordon Robertson

I and Jim Griswold, designer of the Piper Malibu and the IO-550 powered 
Questair Venture, favor using the Barry Mounts in the bolt vertical orientation
as in the picture of the Questair motor mount on the ACRE NL web site.
The mounts are softer in this direction to better attenuated torque
pulses. If you really have 3000 FPM climb capability you might
consider the next size up. 

BTW talking to people that have flown the Questair claim it is one of
the smoothest piston engine airplanes ever.

Paul Lamar
 
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