"<start sarcasm> Ok, so Tan II will reach a point where the torque is zero
at -106C, while SuperSport will give zero torque already at -91C."
It may well do that, when the rubber (or the lube?) freezes. But that is
extrapolating a lot farther down than just 0 C. If you have data from 30 C to
15 C, 0 C is not too far to go. If you know how to do linear regression, you
can calculate the 95% confidence interval at 0 C.
"And, on the other hand, the hotter you can warm your rubber, the higher
torque you will get out of it?"
Exactly. Until you break it. With 95% of maximum torque, you can't add 16%
more torque without breaking the motor.
"Too bad I did not know this at the times we used warmers on F1B motors to
get more energy out of them. The thermostat to restrict the warming to
+40C was an expensive unit to buy, as it was obviously useless. And also
shame for the poor guy, whose thermostat broke and his motor warmed too
much. He broke the motor, while he should have known that actually he had
a super-rubber in his model, and he should ha outclimbed all the others
with his hottest motor!
<end sarcasm>"
The motor did not break because the heat softened it. It broke because the
temperature induced linear increase in tension exceeded the strength of the
material. You can put only so much energy into a pound of rubber before it
breaks, one way or another. Rubber is vulcanized (hardened) at about 285 F,
140 C. Estimating the maximum turns for heated rubber would be difficult
because of the nonlinear changes in cross section and density.
"So sorry again, but the torque vs. temperature dependency is linear only on
a limited part of the temperature scale."
Yes, at least as far as -60 C to +60 C, -76 F to 140 F, covering most of
the range of interest to modelers. ;-)
Gary
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Received on Mon Feb 26 2007 - 06:14:56 CET