I finally broke down and called Brian Alley about the prop/spinner
bulkhead mounting, and he said that it is meant to be sandwiched between
the prop and the hub. He says that a coat of epoxy paint on the mating
surfaces and it should be just fine. The hub has lugs that fit into the
aluminum facing on the prop, which is about 3/16 ~1/4 inch thick(the
facing that is, not the prop). So, I'm comforable with that, since he
says that this type of application has worked in the past with other
aircraft. I assume that these other applications are flat four lycoming
and conti engines, with strong positive and negative torque pulses on
each rev. The rotary has 2.85 pulses (mostly positive) per rev, which
should be less in amplitude and would also be somewhat mitigated by the
rubber dampers in Tracy's redrive. So, I proceed onward towards completion.


Brian Trubee


5.7 pulses per prop rev. The two rotor fires twice per engine rev.
I can't say for sure what the peaks are but the average prop
torque is about 456 foot pounds. Peaks are mitigated by the
torque isolator but could be as high as 800 foot pounds.
The big difference is the frequency of the pulses applied
to the prop are 2.85 times the frequency applied
by a 4 cylinder. The direct drive four cylinder applies two per rev
while the geared rotary engine applies 5.7 pulses per prop rev.

However, if the prop maker says it will work on a 200 HP
Lycoming I'll take his word for it.

Paul Lamar

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