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Re: [TowerTalk] Flexible coupler assembly

To: <>, <>
Subject: Re: [TowerTalk] Flexible coupler assembly
From: "Chuck Lewis" <>
Date: Thu, 25 Jan 2007 16:15:52 -0600
List-post: <>
> Does a shock absorber in the mast like this really take any stress off the
> rotor gears? The shock absorber will wind up allowing the antenna to twist
> further than it would without the shock absorber and have much more 
> "travel"
> when returning in the opposite direction thus increasing the force by
> allowing more travel and the antenna to whip around more than without any
> flexible joint.

Yes, but:

The donut helps because it spreads the impact over a longer time. Without 
the donut, the force is applied over a short time after the backlash in the 
gear train is taken up, and the gears absorb the total energy almost 
instantaneously. But the donut allows the same total energy to be applied 
over a much longer time, and the result is a much lower peak force on the 
system. Think of the donut as the physical equivalent of a capacitor. A 
capacitor smooths the sharp transients in a spikey waveform and lowers the 
peak voltage...the donut smooths the hard bangs in the rotor system and 
lowers the peak forces on the gears, etc.

The issue of how another spring (donut) in the system affects the dynamics 
is really complex, and the donut could either help or hinder oscillations, 
depending on the mechanical resonances of the elements, mast flexion, etc. 
But in any case the above paragraph still applies.

If you're so inclined,  check:

Here's an applicable excerpt:
"Impulse = Change in momentum
One focus of this unit is to understand the physics of collisions. The 
physics of collisions are governed by the laws of momentum; and the first 
law which we discuss in this unit is expressed in the above equation. The 
equation is known as the impulse-momentum change equation. The law can be 
expressed this way:

In a collision, an object experiences a force for a specific amount of time 
which results in a change in momentum (the object's mass either speeds up or 
slows down). The impulse experienced by the object equals the change in 
momentum of the object. In equation form, F * t = m * Delta v. "


With apologies to any REAL physicists (Rigor Gained is Clarity Lost)...


Chuck, N4NM


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