First let me say thank you, I've been a Pixhawk user for several years and think the work of the FC. This is my first HEX build so obviously I put a Pixhawk 2.1 inside.

This is the first flight of a new build, one which I had trouble configuring the 30amp ESC's and originally loaded CHIBIOS build on the PC trying to use pass through connection for ESC's...which did not work.

So, I loaded APM back on the board... I HOPE there are no negative values left over from this????

So the first flight was VERY twitchy and Unstable.. lasting just over 3 minutes..

First(First issue), I've had issues with the Safety switch seemingly doing nothing .. It will not arm the copter..

I have no messages within mission planner as no pre-flight checks look to have failed....

So I change BRD_SAFTYENABLE = 0 and All motors spin, ARM and looks good.

Second (Second issue) ON takoff the EKF2 IMU immediately re-calibrates as the Copter veers left....

Once that in-flight calibration complete, the HEX settles down...Trim seems good but slightly off... Pulls to the left at a constant rate..(I dont think this is CG but correct me if I'm wrong)

Third (Third issue) IMU keeps re-calibrating and adjusting YAW mid flight at a constant rate.. How do I stop this and why is it happening?
Forth (Forth issue) LittleBee 30Amp ESC with APM set at 2 = Oneshot125... These ESC's auto detect but the CHIBIOS build says option 3 = DSHOT however, I dont see that value in Mission Planner.. Could this instability be caused by incorrect ESC signaling ?

The main focus is Stability, the flight was VERY unstable , so much you see at the end I just about lost it on landing, flight seemed to be getting worse

I'm attached the Tlog hopping someone could offer some insights, at 84% of the log is where the actual flight begins..


Many thanks in advance

2018-05-13 17-25-57.tlog

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • Greg,

    Thanks so much for the response. I'll be posting a photo showing the level of the props, I'm 95 percent sure we are good there however.. I did go over the ESC MIN->MAX values and they were inconstant, each differ by as much a 5 which could be from a previous calibration (With CHIBIOS build)

    Makes me think the Radio was sending inconsistent values causing the drift.. I have reworked this and moved to the FORTH issue..

    I failed to mention the 30 Amp LittleBee ESC's are BLHELI_32

    1) Could this be why (While running APM 3.5.5) the safety switch will not ARM (It does nothing) (MOT_P = 2 = OneShot125)

    2) I also must mention these are OPTO  ESC's... Could the lack of common ground on the Backside rail be cause ...

    I'll get the MAUCH power module completed to address #2 above and report back

  • The clockwise motors,1,3,6 are less power than the counterclockwise,2,4,5 motors. It is compensating for an inherent yaw in the airframe. I am assuming you have clamp type motor mounts and tube arms. Check that all the motors are on the same plane, level with the frame. Just eyeball the propeller tips with the arms. Sight down the center and have the prop as perpendicular to the arm. if its not a misaligned motor, then I don't know what it is. Something is trying to yaw it CCW and it is fighting back by trying to go CW.


This reply was deleted.