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

From: <ykleetx_at_gmail.com>
Date: 17 Nov 2013 20:34:34 -0800

What Piecost and I are suggesting is to wind above launch torque then unwind, but not wind all the way to near breaking torque.
 

 For example, for a F1L flight at Urbana where the desired launch torque is 0.15 in-oz, wind to .35 in-oz, then back wind to 0.15 in-oz to launch. Do this instead of winding to the max torque of 0.45 or 0.5 in-oz, then back winding down to 0.15 in-oz.
 

 We both found that the turns versus torque are identical (wind hard versus not so hard) as the motor unwinds down from 0.15 in-oz.
 

---In Indoor_Construction_at_yahoogroups.com, <wdgowen@...> wrote:

 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_... mailto:ykleetx_at_... wrote:
 
   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 - 20:34:35 CET