Re: Wind hard or not so hard? [1 Attachment]

From: William Gowen <wdgowen_at_gmail.com>
Date: Sun, 17 Nov 2013 23:28:35 -0500

Wait a minute. I think this idea is counter to everything we know about
winding rubber motors. The reason that I wind to higher torque and back
down is because when you reach the desired torque coming down from a
higher torque the motor will have more turns than if you only wound up
to the desired launch torque.

So basically I don't think what Piecost said is true but the only
possible proof one way or the other is to do the test.

Also I remember Don S. saying several years ago that he thought winding
motors to the maximum destroyed the rubber. I actually used that line of
thinking for a few years and did okay with it. Lately I've been trying
to squeeze max turns out of my motors even for situations that require a
lot of backoff. It would be nice to know for sure whether this is a good
practice.


On 11/17/2013 9:22 PM, ykleetx_at_gmail.com wrote:
> [Attachment(s) <#TopText> from ykleetx_at_gmail.com included below]
>
> Recently in HPA were the following posts:
>
>
> Piecost wrote:
>
> I have read this thread with interest. I do not fly LPP but am trying
> to understand rubber motors better. Therefore I would like to ask why
> poeple wind up to near breaking before backing off?
>
> From a small amount of testing I performed on Super-Sport rubber I
> found that no matter what number of turns I wound to; the unwinding
> torque versus turns curve was the same. If this is true then there is
> no benefit in winding so high. The hysteresis took about 50 turns, so
> I only had to wind 50 turns more than required before backing off to
> the desired torque.
>
> His graph is attached.
>
> I replied:
>
> I think you have cracked the code. I have also concluded the same,
> but with a caveat. In my tests, the unwinding curves are equal only
> after the motor is broken in. In your example, I found if I wind the
> motor to only 600 turns before the motor is broken in, its unwinding
> curve falls below that of the 800 turns wind. But once the motor is
> broken in, the unwinding curve soon become the same after some unwinding.
>
> I believe for many people, winding to 800 then backing off helps
> because the motor has not been broken in, and the act of winding hard
> breaks the motor in. On subsequent winds, it's not necessary to wind
> to max turns/torque.
>
> However, a caveat. my conclusion and yours are arrived at by
> "looking" at curves and likely from limited experiments. I'm not
> sure I can say for sure that the unwinding curves are identical, say,
> to 5% of each other. That is, limited testing probably cannot reveal
> any advantages under 5%. And in practice, a 5% advantage is huge. I
> am not ready yet to completely dismiss the observations made by many
> people over the years. If you have the time, I would encourage more
> extensive testing.
>
> Blasphemy? Thoughts?
>
> -Kang
>
Received on Sun Nov 17 2013 - 20:28:36 CET