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Overheating ... I think!? Advice is needed.

#1
I built the sparrow with a Emax MT1806-2280kv using the BL Heli 12amp ESC. I'm flying at about 2/3 throttle for 2 or 3 minutes, then it starts lagging and losing power. I bench tested with the wing off and felt the ESC and motor... both really hot. I just replaced the ESC because the prior setup was doing the same thing (losing power). I used to get 9 minutes of flight time with NO problems... wondering if I just need to replace the motor. Any suggestions?

Note: I have the ESC mounted inside the plane, but that is same location as when it ran fine (9 min. flights).
 

Craftydan

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#2
Hey BMarvin, Welcome to the forum!

First, double-check that the prop can swing freely -- I expect you have already so I doubt your bearings are going bad.

If swapping out the ESC didn't change anything, then the ESC was probably fine. So . . .

What sized prop is your poor tortured motor swinging?

There is a good chance your motor has been slowly wearing out. If you've been running it under a "hard-but-not-too-hard" load, the motor will run warmer than it should and the magnets will slowly weaken (excessive heat kills magnets). Eventually, the motor no longer has the oomph to swing the prop you've given it, so it runs even less efficiently, heating up more . . . making the problem worse.

This process can take quite a while -- I burned out a motor in April that I'd mildly overpropped for the last two years and flown it hundreds of times, all the way to it's death :( but no worries! I replaced it with a larger motor . . . and then overpropped that one too . . . in for a penny . . .
 
#3
RMRC Bullnose 6x4.5.

Sounds like you are onto something. It was a problem that has developed slowly. 1st time it happened was on a super hot day 90 to 100 and 90% humidity. Probably pushed the little engine into heat stroke and doomed the magnets.

So I don't repeat my error, what prop would you recommend for that size motor. I'm thinking of replacing it with the EMAX RS 2205 2300KV MOTOR here at FT. My sparrow is a little over-weight as I made it with Elmers Poster Board, so I fly a little faster to give it enough lift.

There are no recommendations for props in the description for that motor (mentioned above).

Thanks for you comment and experience.
 

Craftydan

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#4
Sorry, there's a missing element in that (shoulda asked earlier) -- what voltage (cell) battery pack are you using?