Why does a motor burn out?

Started by learner, June 10, 2015, 10:36:33 PM

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learner

Hi All,
I am beginner in this field...
I just burnt a brush-less motor in my attempt to fly my second model.

The total weight of my model is 180 grams(including everything).

I am using a Avionic-1818-4500kv motor with 2s LIPO and 12amp ESC.
The prop is a direct drive 5X3 blade.

my model just took off and came back down in few seconds with fumes coming out of the motor.

Can someone help me understand where the issue would be.

thanks
learner.

girishsarwal

Might want to eliminate possibilities in that order
- used a much higher prop than the one recommended
- something was jamming the motor and it was forced to run
- bad bearing
- loose fitting leading to coil twisted, leading to short circuit
gs

aditya

Mechanical Engineer

Darshan for multirotors

Clearly it's a prop issue ... I use 5x3 props with my 2400kv motor and they get warm so there is no doubt that you have used too big props ...
put your heart in flying and flying will never leave your heart

tantragna


learner

Not that I am giving the solution my self...

but to me it looks like it was bad way to mount...
I had embedded the back side of motor in foam, leaving too little a space to dissipate the heat.

I am saying so because I got a new motor of same specs, everything same accept that i made a mount out of aluminium spacers.
this time no issues everything is fine.

except that model still doesnt fly :banghead: (looking into the issues one by one).

learner

by the way  I wanted to understand if I am using correct power setup:
My AUW=180gms.

wingspan = 609mm

chord = 150mm

motor : 1818 -4500kv
prop : 6X3

battery: 500mA 2S LIPO 7.4V

i measured the thrust in a crude way and at full throttle (before the esc start raising an alarm) it gives 100gms of thrust.

is there someting I am missing here big time?
what should be the angle of thrust here?

thanks to all of you in advance.