How hot is too hot for a SP400 motor? - RC Groups
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Oct 21, 2001, 03:56 PM
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Steve Fehr's Avatar

How hot is too hot for a SP400 motor?

How hot is too hot for a SP400 motor? After flying my FMA Razor for 4 minutes, the motor is uncomfortably hot. It cools down quickly, but creating a venting hole in the front of the lid didn't seem to cool it down much. Am I OK, or do I need to take more drastic cooling measures, like create louvers to force more air across the motor?
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Oct 21, 2001, 04:55 PM
tic's Avatar
Tough to say.. does it smell burnt?.... If you burn it up.. you'll know it... otherwise, keep it oiled and don't fly WOT all the time
Oct 21, 2001, 05:33 PM
Motors beat engines!
The answer according to motocalc is over 200 degrees is too hot, but the cooler a sp400 is, the more efficient it is.

BTW, too hot to touch is anything over 120 degrees. Not a very good way to measure.
Oct 22, 2001, 03:25 PM
Registered User
Steve Fehr's Avatar
OK, by that measurement, my motor is probably only 115 or so, so I'm well in the safe zone and don't really have to worry about damaging it I might add the louvers anyhow, I'll wait and see how hot it gets with the 1650mah batteries when they arive. Thanks!
Oct 22, 2001, 04:56 PM
Registered User

Buy a second motor . . .

Is there any way to remove the motor from the mount easily? If so, you can always solder up a second motor and use it like you would a battery pack - i.e. one in the air, one cooling.

It isn't as if S400 motors are expensive!

Ben C