Guys please take it with a grain of salt as I am not an expert and trying to figure out the values.
I am wondering if its a desync issue and motor2 going full power then why RCOU.C2 is also going up? Looks like RCOU.C2 and motor 2 RPM went high almost at the same time and it looks motor 2 was commanded to go full power by the FC. I couldn’t find where Motor RPM’s shoot up without the command from FC.Does it make sense? Thanks.
Yea, I’m wondering about that too. Here we see RCout2 commanded high with an increase in RPM but a drop in current. So it seems it was losing thrust (current from torque). Did a prop break?
Here is a question; if a motor de-syncs will ESC RPM from telemetry show a drop? I don’t know the answer, perhaps not.
I’m pretty sure the telemetry will show zero if the motor is not spinning, it makes all my testing a pain because I have to attach motors to everything for it to be a valid test
@dkemxr No prop never broke .Luckily I was close to the floor. No damage.
Yes it looks like motors behaved as per the commanded PWM from the ESC. But question is why RCout2 went high?
@dkemxr Everything makes sense only if the RPM value of Motor 2 is not right. So In reality, Motor 2 desynced, lost thrust, current dropped and that’s why FC is commanding full PWM. Can we check by ATT from the log that which corner dropped first?
So it clarifies that RPM value of Motor 2 is not correct.
And this graph shows that the Roll and pitch movement was not desired by the FC.
I did a test of this on the bench with expendable parts. I locked the motor shaft from rotating with the ever useful Vice Grips and throttled up while logging. Some aweful sounds were coming out of the motor but it wasn’t rotating. Check out the ESC RPM in the log.
3 31-Dec-69 07-00-00 PM.bin (581.1 KB)
Changed the log the previous didn’t show any throttle input.
Good catch of RPM and current discrepancy Dave!! I think your test clears up all the doubts.!
Here is a similar test but this time the motor was throttled up and running free and I slowed it to a stall with a strap wrench. If you plot RPM, Current and RCINC3 you can see where it stalls and then a “de-sync” section and then free rotation again.
4 31-Dec-69 07-00-00 PM.bin (553.5 KB)
Crash log: My radio is set to have more that three fight modes but i need to engage a switch to get all of them does this look tike the radio is sending a bad command before and after loiter see image.
Hi @ninja_zx11,
Ah shoot, this is a 4.0.7 log! 4.0.x logs should be reported in the Copter-4.0 category. This category is for Copter-4.1 beta testers only.
It’s no big deal and I should have noticed but we need to keep them separated
Thanks for this testing. So I guess this shows that BLHeli ESC RPM values work OK with the possible exception being that they show slightly unrealistically high numbers when the motor is externally stopped. So for example the ESC.RPM value jumps around between 100 and 1400 when really the motor is stopped.
Below is dave’s log with the throttle shown in red (scale on the left) and ESC.RPM in green (scale on the right).
Steffen told me that RPM values are not valid when a desync occurs
@rmackay9 I am sorry Randy for opening my thread in a wrong category. My Bad…
And thanks for everyone for the suggestions. So it was the bad rear left ESC. It finally gave up on my next flight. Luckily close to the ground. Now when i try to run , motor behaves exactly like motor missing a phase. So new ESC is on the way.
Well, we got to do some interesting experiments at your expense none the less Am 
Just kidding of course, carry on!
