Dear all,

As i am a newbie in the quadcopter world, i did my first flight ever yesterday, which resulted in two fried motors. After my research, i decided to buy the following parts for my first quadcopter. Those are:

DJI F450 frame with its extension legs
DJI E310 tuned propulsion kit ( 2312 motor, 420S ESC, 9450 props)
APM 2.6 flight controller with gps module
Multistar 10000mah 4S 10C battery
TURNIGY 9XR radio with FRsky DJT transmitter and V8FRii receiver

The quadcopter should be in the 1,5-2kg range of takeoff weight.

So, I tried to do my first ever flights by slowly hovering over the ground for 10-15 seconds in order to see how the quadcopter responds. I had a couple of turnover to the side of the quadcopter during landing but without damages as the speeds were slow. However, in my last effort, the quadcopter landed and felt to the side with the 2 props attaching to ground. All The props didnt stop spinning and after 3-4 seconds i saw smokes coming out of 2 motors. In my panic i turned off the radio but it kept spinning a little faster and then i unplugged straight the battery cable.
After going back home, i tested all the ESCs with the DJI assistant software using a good motor and the result message was "motor parameters are OK".

1) does that mean that my ESCs are indeed ok and i can use them again?

After my cross checks i will need 2 new motors.
So, i need to find what caused these 2 fried motors.

2) in order to avoid cutting the long cable of the ESCs, i wrapped it around the quadcopter arm. Can this cause a fried motor?
3) is there a chance that with the prop attaching to ground and the quadcopter keep working, the fried motor was caused by the fact that the ESC kept sending signal but the motor/prop couldnt follow???
4)is there a chance that the motors started overheating/frying while the quadcopter was on air? Is that possible according to my specs? DJI says that the E310 kit is suitable both for 3S and 4S batteries and for weights up to 2,5kg.

Could you please help me find my answers?

Thank you very much

I think during your crash, the props are partially stopped by the ground and resulted in a semi-stall of the motor. The motor is overloaded during the accident and the temperature became to high for the insulation. That is the reseaon of the smoke. It is actually melted and smoked insulation polymer. There is a chance that the insulation layer is still functional after the smoke, at least partially, that is why the test process shows that "the motor is normall". Personally I will not risk my whole craft for two motors. But if your craft is not expensive, i.e. no gimbal attached and you only fly it a few meters high, you could still try it out.

Best

Wrapping motor wire round an arm can cause magnetic interference and affect the data input of the escs

Actually, the " motor parameters are ok"  message is shown for two of the motors.. So i giess the other two are damaged. In any case, i will just replace the two 2312 damaged motors. Regarding the parts combination of my quadcopter, i tested them with ecalc.ch and it shows that the motor wattage is beyond the limits. But my combo consists of the whole e310 kit as dji sells it and a 4s battery that dji e310 supports. What do you say about this? Is the ecalc.ch tool reliable?  Should i start having suspicions about the combo of my parts?  Thank you all

Your parts combination look fine to me. I would prefer a better lipo though, one with a higher c rating.

When I did my first landing I used both sticks to stop motors. Which caused my phantom to tip over
Now I just use the throttle stick and wait for the motors to stop. I have not had a tip over once I started this style shut down
Just my experience
Happy flying

Remember that the RC influences the copter. Turning off the RC won't change what the copter does.
Shutting the motors off using the throttle at the bottom is the best way.
Or unplugging.