Same as the right side. The motor plate takes all the loads and incorporates
the rubber bushing motor mounts. It also directly takes
the thrust load as well as roughly an 800 ft pound peak torque pulse
applied to the prop from the gear box. I am not exactly sure the exact peak
value as it is mitigated somewhat by the rubber bushings in Tracy's torque
isolator plate. Peak torque is roughly twice average engine torque and average
torque at the prop is up to 400 ft pounds. Two times engine average torque
because of the 2.17:1 gear box. Since the rubber bushing are about three feet
apart they see only a 266 pound vertical pulse. If they were only
one foot apart they would see the full 800 pound vertical pulse and would
need to have roughly three times the travel for the same pulse absorption.

This is the main reason the Questair Venture is one of the smoothest
airplanes flying. I copied that design. It was designed by Jim Griswold
of Piper Malibu fame and Ed McDonald.

IMHO a major breakthrough in aircraft engine motor mounts.


Paul Lamar

Paul,
I'm curious why the bushings are vertical rather than horizontal thru the plate?
...Chrissi
Cozy Mk-IV 13B-turbo
www.CozyGirrrl.com
Chrissi@BlueMountainAvionics.com

Because of the 800 foot pound torque pulse prop reaction is in that direction.

Multiply these torque pulse values by two for a 2:1 gear box.
Note the ten times stiffer rate in the radial direction for the 
Barry rubber bushings.

Paul Lamar
 
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