Scorpion 4020 getting hot..

[drfrankencopter]

Logo 5003d spinning 553 mm blades with a 14 tooth pinion (mod 0.7 main gear).

Primarily I'm just doing hover right now with a headspeed around 2000 RPM as I try to dial in the heli. I noticed that the motor is coming down quite warm. I used an IR thermometer and read it at 80 degC (176 deg F). By comparison the side frames of the heli were around 45 deg C (warm day here), and the battery was only a couple degrees hotter than that.

Is this too hot for the motor? Could this be a sign of too tight of a mesh?

Cheers

Kris

[maarset]

Is your pinion getting hot? At the high point on the main gear you should have a tiny bit of backlash.


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[drfrankencopter]

Yes the pinion is quite hot...main gear doesn't seem hot though. It's hard to say if the pinion is any hotter than the rest of the motor. I'll try re adjusting the backlash to see if that improves things.

Cheers

K

[Kalpazan]

What's the ESC that is driving the motor ? If it is CC your could play with the PWM rate and/or timing. Actually you could detach the motor from the gear and try to spin it free to get an impression what's the temperature of the motor when it is not loaded. Also, keep in mind that when you shut the motor down after some long run it tends to get warmer then it is when spinning. That's because there is not active cooling at that time.

[drfrankencopter]

Thanks for the ideas. The ESC is a CC 120 HV, and it's at least 20 deg C cooler than the motor. I'll give your suggestions a try.

Cheers

K

[dswitkin]

It's worth remembering that an 1800W motor even if it's 90% efficient has to dissipate 180W of heat, as much as three 60W lightbulbs! Also, that heat is in addition to ambient temperature - how hot was it outside?

But I agree with the other posters about checking the mesh, backing the PWM down to 8 kHz, and using a less aggressive timing if needed. I don't have a heat gun but my 4020-1100 on 14T/6S does not get insanely hot.

[drfrankencopter]

Thanks for the response.

I re-adjusted the mesh...but the motor still gets quite hot. I'm pretty sure I have the backlash set well. I didn't adjust the motor timing since it seemed to be set up appropriately according to scorpion's spec page. Did you change your timing?

As far as power goes, my CC logs suggest that I average about 450W draw, so I'm not really taxing the motor excessively.

The day I measured temp it was hot outside (approx 33 deg C). The black frames of the logo measured at 45 deg C, so that can be considered as the base temperature that I would expect the motor to get to if I let it sit outside (in the sun). Motor temp was 80 deg C, so 35 deg above the standard 'black body' temp, and about 47 deg above ambient.

Cheers

Kris

[maarset]

Wow that seems awfully hot. If you fly without the canopy does it not get very hot?
On a 90 to 95 degree Fahrenheit day if I want to fly continuously I need to fly without the canopy. I have a 4025-890 on 6S in my logo 500.

Is your canopy vented?

[dswitkin]

Originally Posted by drfrankencopter

I re-adjusted the mesh...but the motor still gets quite hot. I'm pretty sure I have the backlash set well. I didn't adjust the motor timing since it seemed to be set up appropriately according to scorpion's spec page. Did you change your timing?

I'm using a Jive 80LV straight out of the box, so it's the standard Kontronk timing and PWM.

Daniel