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Date: Wed, 26 Jan 2005 09:15:00 -0500
From: Ernest Christley <echristl@cisco.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Flex plate <> Flywheel [FlyRotary] Re: flexplate
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Jack Ford wrote:

>Ernest,
>
>Are you sure that the "peak torque" number you're looking at isn't at the
>propeller, instead of the flywheel?
>Would make more sense. She'll gain a bunch depending on the gear ratio.
>
>Jack Ford
>  
>

There's a good chance the number I was quoting doesn't mean anything 
8*)  I'm the one whose hardrive (and rather large cache of good 
information and links to good information) just died.  I was quoting 
from memory.

BTAIM, I am almost positive that the peak of the torque pulse will only 
be about twice the average in a rotary.  The clutch springs will lower 
that some, but for the most part the interface between the flex plate 
and the clutch plate (which delivers the torque to the PSRU input) will 
have to withstand whatever the engine can throw at it.  Using Lynn's 
excellent numbers, that would put the maximum torque at only 300ft/lbs 
(IFF I can produce anything on the order of 200hp).  The Ross unit has 
the 9 bolts almost 12" from the center, so they'll only ever see on the 
order of 35lbs of stress.  If I use the clutch plate as I've been 
planning, the bolts will only be about 6" out and I will only have 6 of 
them.  The force on the bolts will max out at around 100lbs.  I'm going 
to go out on a limb and say that AN5 bolts should be able to handle that 
amount of shear stress 8*)