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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Dennis Toth on May 06, 2022, 07:58:51 AM
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Just finished a test flight of the S1 with the BadAss 2380 820k running on a 5S 1600mah 120C pack with a 10 x 7 at 9650 rpm fixed, about 16 amps. I toughed the motor housing after the flight, it was hot enough to notice it was hot but you could grab it without getting burned. It was still a lot less then an IC engine after a flight. The motor ran fine no sag or sign of anything wrong, just wondering how hot do other find their motor at the end of the flight? I know we don't push them hard like RC racing but how hot is too much?
Best, DennisT
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If you can touch the motor with ought getting burnt it's OK.
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If you can touch the motor with ought getting burnt it's OK.
Too uncomfortable to hold but not hot enough to burn is about 50 degrees C. That's low for almost any motor.
I'm really pleased with the BadAss motor that I put into my current plane. It's a converted slimer, and I had to really struggle to get airflow in there. It killed the first motor I put in it (a Cobra); the BadAss of the same size runs around 20 degrees cooler.
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Thanks for the input. I decided to open up the cooling holes in the front firewall mount, they were just a bit off to give direct airflow into the motor cooling slots, should be even better.
Best, DennisT
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Just finished a test flight of the S1 with the BadAss 2380 820k running on a 5S 1600mah 120C pack with a 10 x 7 at 9650 rpm fixed, about 16 amps. I toughed the motor housing after the flight, it was hot enough to notice it was hot but you could grab it without getting burned. It was still a lot less then an IC engine after a flight. The motor ran fine no sag or sign of anything wrong, just wondering how hot do other find their motor at the end of the flight? I know we don't push them hard like RC racing but how hot is too much?
Best, DennisT
I have gotten Cobra's hot enough that I could barely hold them after a flight but my BadAss(s) have never gotten too hot to hold. I run the 3515 710k on 2800 5s 25C 10-6 three blade at 9600. 30% headroom. Why the 120C? We only need about 20 and those extra "C"'s just add weight and $$$.
Ken
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Single-point IR thermometers are inexpensive and reliable. If you have a clear "view" of the motor from the outside of the plane you can check its temperature right when you land.
Since burning up a motor (it got my attention by stopping when the plane was inverted, but thankfully at 45 degrees) I've been diligent about checking motor temperature.
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Ken,
The 120C is because that is the only rating that has the capacity and dimensions that fit in the nose of the S1 (on 78mm long).
Tim,
I have a IR temp meter and will bring it next time out.
Best, DennisT
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We just measured a motor temperature today while flying in 85 degree air. After landing, it was 105 degrees F.
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We just measured a motor temperature today while flying in 85 degree air. After landing, it was 105 degrees F.
In a couple of weeks the circle will be hotter than 105!
Ken
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In a couple of weeks the circle will be hotter than 105!
Ken
Yeah, it will be!
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To answer your actual question -- it depends. Cheaper motors will be more susceptible to high temperatures, better motors will withstand them better.
The two top contenders are probably the windings getting hot enough that the insulation fails, and the outer bell getting hot and the glue holding the magnets on fails. Both of these depend on the manufacturer, basically on what materials they used and, hence, what price vs. quality compromise they decided to make.
AFAIK, if you land and the outer bell is lower than about 80C you're fine for even cheap motors, and ditto 120C for the windings. But -- I dunno, and I'm always getting surprised by just how cheap of cheap crap gets unloaded on unsuspecting modelers. If it's a name brand motor and they're making promises about temperatures, I'd believe them more -- but only more, not absolutely.
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if you land and the outer bell is lower than about 80C you're fine
It will still be cooler that our circles in August! LL~
Ken
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I once asked Lucien at Innov8tive. 160°F for the Cobra was about top safe on the stator. I found the Stator about 40ish°F cooler that the Rotor using an IR thermometer. I have a profile where I could get a shot at each. As Tim noted, 50°C or about 120° is touchable. 160 on the Stator was very uncomfortable to a swipe of the finger.
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Found problem - the back of the prop collet was just close enough to the head of the motor mount bolt to were once airborne and when I did a couple maneuvers it rubbed the head and both heated up and expanded enough to cause additional heating and a little weird noise. When cool just a bit it made no sound or rough feel so it was hard to find. I filed down the back of the collet a few thou and did ground test. All good, flew it today for longer then prior flight (over 2 min) and no sounds and motor was only warm to the touch.
Best, DennisT
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Found problem - the back of the prop collet was just close enough to the head of the motor mount bolt to were once airborne and when I did a couple maneuvers it rubbed the head and both heated up and expanded enough to cause additional heating and a little weird noise. When cool just a bit it made no sound or rough feel so it was hard to find. I filed down the back of the collet a few thou and did ground test. All good, flew it today for longer then prior flight (over 2 min) and no sounds and motor was only warm to the touch.
Best, DennisT
Wow! Who would of thought. As always it is what it is. Thanks for sharing. Points out another thing for us to keep and eye out for. y1 #^