Tonight's Dumb Idea...

[Bob Pastorello]

Actually, Jim, the vibration frequency of a typical YS or large 2 stroke is
QUITE a bit lower.  Simply, the 049 piston/counterweight is slapping around
at 22000 or more...the pattern motor somewhere around 8K.  That's an order
of magnitude less.
    Where the concern may be is the IMPULSE strength...the "thump" of that
counterweight.  Kinda like an oil rig pump....HUGE counterweight, and the
earth shakes with every thump....smaller pumps, pumping same rate but with
different MASS counterweight - way less thump.

Then there's the actual impact....If the servo, attached to the motor mass,
is moving at exactly the same rate and intensity as the motor itself, I'd
challenge that the RELATIVE force transmitted to the servo is LESS than that
of a servo constrained someplace in the airframe.  My theory is that the
constraining force, distance, and rigiditiy of mounting actually modifies
the resonance or thump that hits the servo.  AND - it's connected full time
via the pushrod to the motor that is thumping along at it's natural rate.

So we'll try it, and see what happens!!

Bob Pastorello, Oklahoma
NSRCA 199, AMA 46373
rcaerobob at cox.net
www.rcaerobats.net


----- Original Message ----- 
From: "jim ivey" <jivey61 at msn.com>
To: <discussion at nsrca.org>
Sent: Tuesday, February 17, 2004 6:59 PM
Subject: Re: Tonight's Dumb Idea...


> Ok enough. Have you ever held a .049 in you hand,between your fingers
while
> it was running.Multiply this vibration by 280 times and that is what the
> servo feels that is mounted on the mount of a YS 140.
> I'm dodging now.
>
> Jim Ivey
>
>
>
> jivey61 at msn.com

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