Crashed - now P3P flips on takeoff

What you might not be allowing for is that the throttle doesn’t command motor speed directly and certainly not in proportion to the applied stick defection. Movements of the throttle stick from the centre detent are interpreted by the flight controller as an intention to increase or decrease altitude. Sitting on the ground moving the stick fully up the flight controller will apply power to the motors but will quickly detect an issue when no thrust is detected (the phantom doesn’t move). Even the flight controller didn’t do this the maximum RPM of the motors is determined by the ESC.. I can’t run faster than the max drive frequency set in the parameters flashed to the ESC SOC even unloaded. The motor won’t be taken outside it’s safe max RPM or thermal limits- winding current is obviously low when not required to drive a propellor.

"will quickly detect an issue when no thrust is detected"
How is the trust detected?
Barometer and or Gps Movement?

Rod
 
I have heard it here that "They will shut off after a few seconds with no props" True ?
 
Oh, you are very wrong. But I must say, I was very surprised as well the first time I saw that. It turns out man can often make up lacks in brains with physical strength.

I actually posted a video long way back showing how easy it was to fit wrong prop due to the plastic thread :

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BUT if someone did fit wrong props ... the AC would NEVER leave the ground as OP has written.
 
OK ...

1. You can run without props ... but it is not a good practice to do it for more than just a test ... prolonged running at full bore is an unloaded situation that lets motor spin up near to to its theoretical KV. I bet you would not do it to your car ?

2. Throttle command is intercepted by Flight Controller and it then adjusts each of the four signals to ESC's to arrive at completion of desired command ... BUT first it allows all command to pass so it then in nano seconds can correct and adjust accordingly. Flight Controller has ZERO knowledge of what to do, until something happens - it is a corrector item - similar to 3 / 6 axis stabilisation on heli's / other aircraft.

Think of it like this : Throttle advances and AC starts to lift. Flight Controller THEN detects AC tilting or moving in a way that does not meet command, it then immediately adjusts the required motor(s). It is so fast - you as pilot do not see that initial action.

OK ... lets get back to OP's problem ..... I would check rpm of the motors personally.

For just a few $ - ebay is full of cheap but good Tacho's that use LED. I have one. A small reflective strip on each motor can ... and the tacho will give you the RPM. Running up without props for the few seconds to about half throttle should be enough to find out if one motor is awry ... but it will not tell you why. It could be ESC, Flight Controller ....

If the RPM is same ...or at least similar ... then it could be bad prop .... who knows.
 
OK ...

1. You can run without props ... but it is not a good practice to do it for more than just a test ... prolonged running at full bore is an unloaded situation that lets motor spin up near to to its theoretical KV. I bet you would not do it to your car ?

2. Throttle command is intercepted by Flight Controller and it then adjusts each of the four signals to ESC's to arrive at completion of desired command ... BUT first it allows all command to pass so it then in nano seconds can correct and adjust accordingly. Flight Controller has ZERO knowledge of what to do, until something happens - it is a corrector item - similar to 3 / 6 axis stabilisation on heli's / other aircraft.

Think of it like this : Throttle advances and AC starts to lift. Flight Controller THEN detects AC tilting or moving in a way that does not meet command, it then immediately adjusts the required motor(s). It is so fast - you as pilot do not see that initial action.

OK ... lets get back to OP's problem ..... I would check rpm of the motors personally.

For just a few $ - ebay is full of cheap but good Tacho's that use LED. I have one. A small reflective strip on each motor can ... and the tacho will give you the RPM. Running up without props for the few seconds to about half throttle should be enough to find out if one motor is awry ... but it will not tell you why. It could be ESC, Flight Controller ....

If the RPM is same ...or at least similar ... then it could be bad prop .... who knows.
The motors won’t reach the KV rating. We aren’t dealing with basic ESC here- field orientation control is using voltage dividers on each leg of the motor feeds to directly measure back EMF and rotor position. TI’s instaspin algorithms are a long way past a basic pulse chain drive we all know and love from the earlier RC models. Yes- there is real potential to over stress unloaded motors with basic ESC.
 
To be honest, the most damage done to his motors is probably when the drone flipped over on take off,, and the props were grinding into the dirt.
 

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