Bad Turnigy Motor or Bad E-Max ESC???
I recently put a turnigy 35-42 motor and 40 amp E-Max esc in my Multiplex Gemini. AWESOME performance but on about the 9th or 10th flight I noticed a funny grinding sound when going from dead stick to any amount of throttle when pulling out of a dive. Then after I landed tonight, I gave some throttle to taxi her in and I got nothing but motor shaking back and forth and nasty sounds from the motor...
is this the motor or esc???
I have never used either before.
I haven't had any problems with my other turnigy motors but they are a little smaller (shouldn't matter) I have never used this brand of esc.
Thanks for any input.
I de-rate my ESC by 120%.
That means for a 40 amp ESC
I don't plan to put more than 33 amps on it.
40 amps divided by 1.2 (120%) = 33.3 amps
Lets say you are feeding your SK35-42 (1250kv) with 4S at 39 amps.
39 amps times 1.2 (120%) = 46.8 amps
I would choose an ESC rated above 46.8 amps.
IMHO, of course!
Ok, your motor is between the two I looked at.
All these calculations are a SWAG (scientific wild-axx guess)
until you get a wattmeter and discover what's really happening.
Unfortunately, we can't trust the figures provided by the vendors or manufacturers.
The tests done by Dr Kiwi and Everyday Flyer suggest the performance figures are inflated
It could also be a simple timing/syncing problem.
I've had some ESCs that will do that if the prop spins at a different speed than the esc expects. ESC screeches and you have to drop throttle until it resyncs with the motor. Try changing the timing on the speed control.
Here's the figures as posted:
Input Voltage : 7.4V~14.8V (2~4S Li-po)
Kv : 1100 rpm/V within 10%
Current capacity : 45A/30s
Dimensions : 35mm X 42mm / 1.38in X 1.65in
Shaft diameter : 4mm / 0.16in
Weight : 132g
Number of poles/magnets : 14
Recommended model weight : 1000~2300g / 35~81oz
Power equivalent : .30 to .35 IC glow engine
Suggested prop size: 11x8
I bolded the parts that are signifigent
You are using a 40 amp ESC and the motor factoid says 45 amp at 12 volts (assuming that 30s is a typo and writer meant "3S")
The part I haven't discussed yet is the prop.
We are clueless as to how much load your prop sucks from the battery through the ESC.
And we can't trust what the factoids say till we have some test equipment to verify or disprove them.
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