2 fried motors

[Eli23]

So I built the tutor using the complete kit and “B” power pack/motor.
Everything went great, motor worked, and all controls worked.
Took it out for first flight and it did great till I crashed into a tree after about a minute of flight. No damage that I could see, motor and controls still worked. Tried to take off again and crashed on take off (got into some tall grass and went down less than 2 feet off the ground).
No big deal, right? Nope, motor would no longer work. Everything else (ailerons, rudder, elevator) worked.
So I bought a new “C” motor. Pulled everything apart tonight, mounted new motor to the power pod, plugged in the motor leads, only esc connected to receiver, turned on transmitter (throttle off), plugged in battery. New motor immediately started smoking. I unplugged it quickly but now I assume the new motor is toast.
What is going on? I assume the ESC is bad but how did that happen after two flights and crashes? It’s not like I nose dived from 60’. Am I missing something? I would have thought these motors and electronics would be pretty durable.
This is my first RC plane so I just want to make sure I didn’t do something wrong before I buy more parts.

Thanks.

 

[short_nathan]

Welcome to the Forum! Well, I dunno. Sometimes they fail and refuse to work, but I'm not really expirienced. I think it was the ESC. Maybe something got in the connectors. I would blame it on the ESC, but then again, I ain't expirienced so...yeah

 

[Masterguns]

So I built the tutor using the complete kit and “B” power pack/motor.
Everything went great, motor worked, and all controls worked.
Took it out for first flight and it did great till I crashed into a tree after about a minute of flight. No damage that I could see, motor and controls still worked. Tried to take off again and crashed on take off (got into some tall grass and went down less than 2 feet off the ground).
No big deal, right? Nope, motor would no longer work. Everything else (ailerons, rudder, elevator) worked.
So I bought a new “C” motor. Pulled everything apart tonight, mounted new motor to the power pod, plugged in the motor leads, only esc connected to receiver, turned on transmitter (throttle off), plugged in battery. New motor immediately started smoking. I unplugged it quickly but now I assume the new motor is toast.
What is going on? I assume the ESC is bad but how did that happen after two flights and crashes? It’s not like I nose dived from 60’. Am I missing something? I would have thought these motors and electronics would be pretty durable.
This is my first RC plane so I just want to make sure I didn’t do something wrong before I buy more parts.

Thanks.

Contact FT tech/customer support while you wait for someone who can hopefully help you diagnose the issue.

 

[Eli23]

I was looking for the tech support number but never found it. Do you have a link to it?

 

[Merv]

I don't have a phone number. Here is a support web from

Flite Test

www.flitetest.com

 

[Mr Man]

I bet (just guessing) that you accidentally left the throttle on on one of your crashes, this will smoke the motor or esc/both.

 

[Foamforce]

Yup. In the first crash you probably smoked the ESC. This means at least two of the big transistors on the ESC overheated and fried in the closed state, which would then dump raw battery power to one or more of the motor windings. When that happens, the plastic coating on the winding melts, and then the winding wires short circuit against each other. So then unfortunately you replaced the motor, but the ESC was still bad and it did the same thing to the new motor. As Mr Man said, the ESC was probably originally fried by leaving the throttle on for more than a few seconds when the prop was stuck. Sorry, that stinks. 🙁

 

[Houndpup Rc]

Yup. In the first crash you probably smoked the ESC. This means at least two of the big transistors on the ESC overheated and fried in the closed state, which would then dump raw battery power to one or more of the motor windings. When that happens, the plastic coating on the winding melts, and then the winding wires short circuit against each other. So then unfortunately you replaced the motor, but the ESC was still bad and it did the same thing to the new motor. As Mr Man said, the ESC was probably originally fried by leaving the throttle on for more than a few seconds when the prop was stuck. Sorry, that stinks. 🙁

Funny, I have never had that be a problem...But I always shut it off right away too....

 

[Eli23]

I feel like I cut the throttle immediately after both crashes but I guess my reaction time was slower than I thought.
How common is it to need to replace the motor and esc after a crash? Besides not crashing is there something I need to do to minimize damage? If I get in trouble should I chop the throttle before impact? I’m just getting into this so I’m sure there will be more crashes and I don’t want to buy new motors and esc every time.

Thanks.

 

[Shurik-1960]

The motors are easily repaired by rewinding. The voltage regulator can be repaired, BUT the cost of repair parts is usually more expensive than a new regulator. Open the regulator's packaging and look at both sides of the regulator for black parts. The regulator usually lights up after water droplets hit. I use the burnt-out regulators as a 5 volt power source in non-motorized models by simply removing all the key elements on one side.

 

[Mr Man]

I feel like I cut the throttle immediately after both crashes but I guess my reaction time was slower than I thought.
How common is it to need to replace the motor and esc after a crash? Besides not crashing is there something I need to do to minimize damage? If I get in trouble should I chop the throttle before impact? I’m just getting into this so I’m sure there will be more crashes and I don’t want to buy new motors and esc every time.

Thanks.

Yup, always chop the throttle before impact..

 

[Piotrsko]

Mosfets tend to fail shorted in my experiences ( unless they explode) , so, some portion of battery power would be always on, and running through the windings. Esc are high power, low voltages so ERGO, they are low reactance (AC resistance equivalent related to frequency). If someone had the DVM and the patience to actually check, you would see many amps of current across one or more winding legs of the motor, but not being turned off and on as the rotor portion spins, it is just "ON" draining the battery and getting hot from constant current flow. Even 1 watt not being radiated is enough heat to eventually melt solder.
When I crash ( which is often) I go to "off" motor throttle and then let go of the transmitter sticks until I retrieve the plane to turn it off. Gassers included.

Wiggling the sticks on a crashed plane is kinda useless.

 

[Foamforce]

I feel like I cut the throttle immediately after both crashes but I guess my reaction time was slower than I thought.
How common is it to need to replace the motor and esc after a crash? Besides not crashing is there something I need to do to minimize damage? If I get in trouble should I chop the throttle before impact? I’m just getting into this so I’m sure there will be more crashes and I don’t want to buy new motors and esc every time.

Thanks.

It’s not super common. I suspect, based on my own experience, that you didn’t chop the throttle as soon as you though you did, or you bumped the throttle back on as you ran toward your plane. Frying the ESC doesn’t happen instantly, it would take several seconds.

A tip is to have your kill switch in a very easy spot to reach, and get into the habit It flipping it as soon as you land or crash. If you hit the kill switch as soon as you crash, you probably won’t have this happen again.

 

[Shurik-1960]

I've never seen a regulator burn out at full throttle and crash. The regulator can burn out when the motor windings are closed on impact (not high-quality Chinese wire winding) or moisture gets on the power switches, at high current consumption (the screw does not meet the specifications), at high battery voltage (3S recommended...they installed 4S). factory defect (not soldering or poor quality of mosfets).There are no miracles.A lot of words...It's time to take a photo of a naked regulator, rather than guessing on coffee grounds.)))

 

[Foamforce]

I've never seen a regulator burn out at full throttle and crash.

It has happened to me. Almost exact scenario in fact.

 

[quorneng]

A low level take off crash, so with full power, into the ground is quite a likely scenario for a stalled motor burnout scenario unless you are very prompt in cutting the power. A motor burnout is also quite likely to damage the ESC too but you are unfortunate that it ended with a short circuit. All my ESC failures have failed to open circuit.
The problem is you have no way of knowing if the ESC has been damaged to open circuit other than to remove the shrink wrap and heatsink to visually check individual MOSFETS. A "blown" one will likely show a mark when the circuit inside has disintegrated from the overload.

Unlike mechanical things with electrics it is always better (& cheaper!) to try to identify why something has failed before trying again.

 

[Houndpup Rc]

I feel like I cut the throttle immediately after both crashes but I guess my reaction time was slower than I thought.
How common is it to need to replace the motor and esc after a crash? Besides not crashing is there something I need to do to minimize damage? If I get in trouble should I chop the throttle before impact? I’m just getting into this so I’m sure there will be more crashes and I don’t want to buy new motors and esc every time.

Thanks.

Hmmm...I was training someone and they didn't cut it off right away in a crash...But they had like a 50a esc when they only needed like a 20-30a...

 

[Foamforce]

A low level take off crash, so with full power, into the ground is quite a likely scenario for a stalled motor burnout scenario unless you are very prompt in cutting the power. A motor burnout is also quite likely to damage the ESC too but you are unfortunate that it ended with a short circuit. All my ESC failures have failed to open circuit.
The problem is you have no way of knowing if the ESC has been damaged to open circuit other than to remove the shrink wrap and heatsink to visually check individual MOSFETS. A "blown" one will likely show a mark when the circuit inside has disintegrated from the overload.
View attachment 253683
Unlike mechanical things with electrics it is always better (& cheaper!) to try to identify why something has failed before trying again.

Oh, regarding that, I one time suspected that I had a bad ESC. I plugged it into a known good motor very briefly, blipped the throttle for one second, and unplugged it. The motor jittered just a bit and got warm very quickly, so I knew it was a bad ESC.

However, on most of my blown ESCs, it was pretty obvious because the heat shrink on the ESC was melted. I use a lot of the cheapest ESCs and it shows. 😂

 

[Houndpup Rc]

However, on most of my blown ESCs, it was pretty obvious because the heat shrink on the ESC was melted. I use a lot of the cheapest ESCs and it shows. 😂

I use the cheapest ones too and they seem to work well...Though i think those ones with the yellow heat shrink aren't worth the money so much...