Thanks for the information, Tapio. I had no idea what the differences were before your analysis.
Bruce
--- In Indoor_Construction_at_yahoogroups.com, Tapio Linkosalo <tapio.linkosalo@...> wrote:
>
> Leo P. commented that not everybody receives attachments, and requested
> the pic about rubber test, so I uploaded it to the Yahoo files area
> (there should be a separate message about that.
>
> The tests are made with a stretch method for 30 gram F1B motors, with
> pull force recorded at intervals during the release phase, after the
> motor is first stretched to maximum stretch (90% of estimated breaking
> force). I first tried to measure these by hand, writing down forces from
> a scale at 10cm intervals, but that turned to depend heavily on the
> intervals. Thus I built a computerized system, where the force is
> automatically logged at 1cm intervals (with about 300 measurements per
> motor, as full stretch of a F1B motor is 320 to 340 cm). I'm quite
> confident with the results, as they show very little variance within a
> batch, less than 1% standard deviation, yet show clearly different
> energy return values for different batches. Also I found out that
> temperature effect the results, and while having repeats of same batches
> (made motors to contests at different times), fitted some statistics to
> the data, with temperature and batch as independent variables, to find
> out that the energy return changes about 0.8% per degree centigrade.
> This variation is corrected for in the figure that I posted.
>
> http://f1.grp.yahoofs.com/v1/4F6zSeKetyv0SnWxOME8HE2F1BCnP_4F11Vo1iyHVtFVn9DkBjwUjyXFF9mIQzWb6rHu0cU05v9TMKPg8Tz0PNYBxoQGKlU/rubber.GIF
>
> (I hope the link above works? Anyway, file called rubber.GIF in the
> files area...)
>
>
>
> -Tapio-
>
Received on Tue Mar 10 2009 - 19:56:04 CET
