Very hot motor

[Van Shteffy]

I was flying my Zoom inside a gymnasium and when I was putting it away I touched one of the engines and it was so hot that I couldn't touch it. Does any drone pilot know why this was and will it wreck the drone? Thanks

 

[old man mavic]

probably because you were inside and not flying very fast, so not much cooling air going over the motors ,if it was only one motor it could be something in the motor that is causing drag,it would be worth checking how it spins compared to the others but all that aside,the motors do get hot anyway even if everything is ok

 

[THE CYBORG]

I would give it a test flight to check that it doesn't get hotter than the rest before flying it at grate distance or hight.

 

[Van Shteffy]

Thank you for your information.

 

[AVInteractive]

As part of our risk assessment we check motor temperature for any abnormality immediately after landing. This would indicate an imminent motor failure in which case you should get it investigated before you fly it again and thus avoid a catastrophic failure.
Sounds daunting but something we had to write into our ops manual for CAA approval.
A catastrophic failure may mean more than damage to your drone it could mean personal injury to a 3rd party if it fell out of the sky !

 

[The Editor]

I was flying my Zoom inside a gymnasium and when I was putting it away I touched one of the engines and it was so hot that I couldn't touch it. Does any drone pilot know why this was and will it wreck the drone? Thanks

One motor hotter than the others usually indicates bearing wear.
On larger aircraft, bearings are easily replaceable (they all have a lifespan) but on the smaller hobby UAV’s you will need to replace the particular motor.
It is extremely rare for a brushless motor to actually ‘fail’ since they have no moving parts in them.
Highly likely to be a bearing or possible an obstruction.

 

[SpitFire]

Not a motor expert, but motor will usually start making a strange metallic sound before failure. If you spin them gently by hand, you can feel extra résistance. I make
part of routine to check motor with a leaser
RYOBI laser temp gun. Let me know what you think?

 

[Van Shteffy]

As part of our risk assessment we check motor temperature for any abnormality immediately after landing. This would indicate an imminent motor failure in which case you should get it investigated before you fly it again and thus avoid a catastrophic failure.
Sounds daunting but something we had to write into our ops manual for CAA approval.
A catastrophic failure may mean more than damage to your drone it could mean personal injury to a 3rd party if it fell out of the sky !

I have a remote thermometer and will do that thanks

 

[WithTheBirds]

Did you touch the other three? A significant difference in temp for one motor after running is cause for further investigation. All being hot to touch may be normal.

 

[Van Shteffy]

Thank you. Someone suggested a remote thermometer and I have one and check each engine before and after each flight. Everything seems normal.

 

[WithTheBirds]

Thank you. Someone suggested a remote thermometer and I have one and check each engine before and after each flight. Everything seems normal.

What are the post flight temperatures?

 

[Van Shteffy]

What are the post flight temperatures?

100 f - or close on all engines. 74°f outside temperature.

 

[WithTheBirds]

100 f - or close on all engines. 74°f outside temperature.

Thats nothing to even think about worrying about.

 

[Thomas B]

You’ll also likely notice the rear motors get warmer than the front.
I have had no problems in AZ flying at up to 102 degrees F. I always let the drone cool after each flight in high ambient temps with the battery removed and in the shade until I do not perceive the battery compartment floor or the motors as being warm to the touch.

 

[Happyflyer]

A little off topic but Thomas B can you send some of your AZ heat my way. It is only 63 here today.

 

[zinadoll]

I would give it a test flight to check that Dafont Showbox Adam4adam it doesn't get hotter than the rest before flying it at grate distance or hight.

why this was and will it wreck the drone? Thanks

 

[Vangaurd]

I thought a brushless motor only makes contact with the shaft and bearing. Should be the only place to generate resistance and friction causing heat. Just throwing the common sense element into the discussion and by doing so, fully expect to be ridiculed and told otherwise.

 

[WithTheBirds]

I thought a brushless motor only makes contact with the shaft and bearing. Should be the only place to generate resistance and friction causing heat. Just throwing the common sense element into the discussion and by doing so, fully expect to be ridiculed and told otherwise.

You are correct re the only mechanical friction points are the bearings. Bearing friction is only a small almost insignificant contribution to the heat produced though- most is from stator pole winding and core electrical losses of various types.

 

[Rockycat]

Has anyone ever put a drop of bearing oil on the shaft of their motors?
Is this even a good idea?

 

[Thomas B]

Has anyone ever put a drop of bearing oil on the shaft of their motors?
Is this even a good idea?

No, they are self lubricated. I fear the oil will catch dust requiring a dismantle and solvents to clean the motors if lubrication is added.