*D Great TIP, Thanks, Tapio!*
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***Ding*
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On Tue, Mar 1, 2011 at 2:15 AM, Tapio Linkosalo <tapio.linkosalo_at_iki.fi>wrote:
>
> [Attachment(s) <#12e70ea804520613_TopText> from Tapio Linkosalo included
> below]
>
> On 28.2.2011 21:11, Carl Bakay wrote:
> > I have done a lot of rubber testing thanks to Goldstein's prodding
> > during my INAV days, testing mostLy 7 inch loops of 1/8 strip, and
> > without exception, those that broke did so at the knot. These knots were
> > un lubricated, due to the difficulty of tying a lubed knot. The stye of
> > the knot did not matter ... It seemed that that was where all of the
> > stress was located.
>
> I test all my F1B motors by stretching, and have also found the knot to
> be the weak link, very hard to tie so that it would take similar load as
> the rubber strand when stretched. It seems, that a lubed knot tends to
> slip open, while knots tied to unlubed strip cut into the rubber itself
> and then fail from the cuts. With many, many failed motors I have ended
> up with my current practice of using the "norsk strikk-knute" tied to a
> lubed motor to make the knot, but the knot needs to be lubed with a
> thinner silicone (500 to 1000 CTS) than I use to lube bu motors (for
> this I use silicone of 14,000 CTS). The "norsk strikk-knute" (which I
> learned from Bror Eimar) is a double overhead, with extra loops to hold
> the ends.
>
> -Tapio-
>
>
--
*Long live Free Flight!*
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*Ding Zarate*
Received on Tue Mar 01 2011 - 04:19:51 CET