Hi all,

Well today I went for a test flight, trying to get my octocopter under control because I have an important demo to do on Saturday for a potential client. It did not go as expected. Here is my config :

- RCTimer F1000 Cinestar Clone

- RCtimer HP4108 380KV motors

- RCTimer 40A ESC (SimonK)

- 14x4.7 carbon props

- APM 2.5

- 2 x 5800 Zippy 6S

- Brushless gimbal + 1 5000 3S for power + 1 gopro

The first 2 crashes happened like this : I'm flying at about 10 m high and lower my throttle, the copter goes down slowly and at 3 meters or so I'm going full throttle with absolutely NO effect. The copter just crashed on the ground. 2 times. 1 crab leg broken. 

I'm going up in the air for a third time, then this time it starts spinning like crazy then crashes. 1 prop broken. 

So please, take a look at my logs as I cannot understand what is going on. As one would expect, I'm really frustrated because it's not the first time the APM gets out of control and I break stuff. 

Thanks in advance for your time guys !


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It has nothing to do with the FC.

Your problem lies in the choice of ESC/motor/LiPo. It is wildly known and acknowledged that 24-coil pancake motors don't do well on SimonK ESCs unless one starts studying motor advance angle and timing offset for his particular motor and load. To make matters worse, RCTimer chose to add some 10nF caps on the output ESC rails on the 40A model and they cause havoc with phase measurement.

The clear path out of this problem is the use of high-speed SiLabs-based ESCs. The model that's popular with people I know is the Turnigy K-Force 40A, re-flashed with BLHeli. I've flashed 25 of them so far, for a pair of okto and a hexa plus spares, and I can confirm they run well. You'll need either a SiLabs Toolstick programmer, or an Arduino board running Toolstick emulator.

You may be able to use Plush or Hobbywing FlyFun ESCs as well, but I haven't personally tested them yet.

Thanks Para for your answer, you opened a new field of investigation for me (just as if I needed to have one more !). I'm going to give a try at the Turnigy Plus 40A as they are available from HK USA warehouse. The flashing stuff seems to be well documented but quite scary as I can brick the ESC. What is the major difference between SimonK and BLHeli firmware ? 

What do you think about this tool to flash the Turnigy Plush 40A with the BLHeli firmware ? Can I just plug the lead cable or do I still need to do some soldering on the ESC ? Thanks !

Can you please update on this?

I am using HK Turnigy Plus on my quad, never had problem, never flash this ESC, why do you want to flash it?

To make it better? But if the original software in the plush 40a can handle 22pole and 6s at 380kv with good throttle resolution there is no need. I ordered the multi star 4108  a few days ago NAD start reading about those sync issues. With simonk.

40A for the 4108?

I fly them with 4S since one year with 20A Multistar Opto in a 7kg OctaQaud wthout any problems. The ESC never come over 50°C.

Im trying to find answer for what esc will work with 6s and 380kv 22pole motors.

Hi Cirilo ,

the problem is classic resync problem . It was present also on T-Motors 3506 - 08 . 

It is solved in last revision of SimonK firmware that try to manage resync problem.

You cound found this problem in this way : 

Fix your drone to Ground in better way ... arm it , and start to doing gas up and down fast ... if you solve resync problem the motor follow throttle command. If not you can also burn an esc keep atention ...

There are some video online also one from Marco Robustini where you can see this problem.

this is the link :  https://www.youtube.com/watch?v=0lRTN5o4UCM



Thank you all for your answers. My problem was due to a faulty motor, I changed it and now everything is working perfectly. I don't seem to have any issues with resync though, but will keep an eye on that. Any hints on how to detect this kind of issue ? 

What kind of fault it had?


Had issues on u8 motors and simonk rctimer esc. "Pop" noise changed back to my favorite tmotor 40A and all ok!

A bientot.

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