Cinestar 6 WKM sudden wobbles

[Kari]

Hello,

I was shooting some footage early yesterday morning and after few flights my CS started suddenly shake and wobble quite badly and turned about 270 degrees left. I managed to land it safely after few seconds failure (thanks to it was high enough to recovery).
It has done this once last week but not this badly, and i thought it possibly was because of solar storm disturbed compass but that's not the case.

Any ideas what can be behind this failure? I already ordered new set of ESC:s if one is faulty and drops one motor for few secs.

Kari

 

[Michael64]

What flight mode were you in when this occurred by chance.

Michael64

 

[Kari]

Gps mode both times. Last week i also power cycled after wobbles and tried again and it was still unstabile. Yesterday it was flying great and smooth first 4 batteries and then this again. Wrote today also to dji support and they suggested bad soldering but i have double checked all and connections looks fine.

Kari

 

[Michael64]

So does this only happen in GPS mode not in Atti mode.

Michael64

 

[Droider]

Aye Up Karl.. sounds like bad motor or ESC.. Problem is which one? Guess you are sure all props are tight...

Dave

 

[Michael64]

If its in GPS mode when it happens like in the video you can hear the motors rev way up like is lost GPS. There has been some people had this happen. Not saying its not a motor or esc but looks like he would have seen the prop slow or cut off monetarily.

Michael64

 

[Kari]

Hi Dave,

Props are 100% tight and motors aligned with laser spirit. My first guess is bad esc and i ordered yesterday a set o 30A rapid esc:s and few new power distribution boards from abusemark. Don't know how reliable rapids are with current fw but still think it might be a best working option at the moment. All well working options with wkm seems to be chinese cheapo esc:s coming from same factory with just different labels and slightly different firmwares.

Michael: I haven't been using enough atti mode to make fault appear. Might be bad gps/compass issue too.

 

[Kari]

Michael i totally agree. Some of the motors are running full power to recover and some motor sounds running very slowly. Didn't see any prop to stop, actually i can say quite sure none of the motors stopped completely for the moment. But of course all this happened very quickly and i almost sh&+ to my pants so it's hard to say.

 

[Michael64]

Kari
I can understand dirty pants for sure, but if you did lose GPS lock it will make the controller go nuts which sounds like what happened. You should try atti mode for sure if you replace ESC's or not. Its the only way you will truly know if that is what happened.
Hope you get it sorted out.

Michael64

 

[robvree]

Kari
I can understand dirty pants for sure, but if you did lose GPS lock it will make the controller go nuts which sounds like what happened. You should try atti mode for sure if you replace ESC's or not. Its the only way you will truly know if that is what happened.
Hope you get it sorted out.

Michael64

Why would the controller go nuts if you lose GPS lock? I was under the impression that the WKM will switch to ATTI mode if GPS lock is lost.

I have lost some satellites while flying (went to 1 blinking red) with no noticeable change in flight but never full lock. It sure would be great if the WKM would act as a black box and store data about the last several minutes of your flight.

 

[Michael64]

For some reason in some faulty GPS's it seems to send misinformation to the controller. Its just not losing satelllite its sending what it thinks its reading but not real time data if that make sense. I have heard of just a few do this and sometimes hard to sort out to find out its the GPS unit. Your right if it just loses satellites thats what it does but these situations seem there is more going on than that.

Michael64

 

[Gunter]

I stupidly used 30A esc's with 30A motors with my first build. They got hot and after a few minutes flying I almost lost control, just like yours. After fitting 40A esc's, the problem is gone...it could be the cause.

Gunter.

 

[Kari]

Faulty gps-unit giving false information is totally one possible reason. I'll try to fly more in atti mode or try to switch to atti if wobbles next time appears.

Gunter, that's also something i've thought a lot lately. Is 30A ESC enough for this setup. It just feels weird if my hovering amps are around 40-45A and fast climbing amps 70-80A there should still be a lot in reserve total 180A constant. Also every time i've checked esc:s after flights they are barely warm, and that's with fast timing advance setting. Maybe 30 amps in these cheap esc:s are much less in real life. Crap, i just ordered another set 30A esc:s, now i have to buy smaller hexa frame and motors for them

Maybe i need to be sure of big enough ESC:s and order also a set of 40A flyfuns. They seem to be fine basic option too, although they all HobbyWing/Maytech/Turnigy seems to come from same factory so don't know are there really any difference in functionality or reliability: http://ztwoem.en.ec21.com/

Otherwise i would buy herkules II:s but i don't want to spend that much without knowing it will work well with wookong. Haven't seen anyone yet using herks with hexa.

Kari

 

[Kari]

I've tested with other esc:s and no problemos so far. But, last were maytech v2:s, and v2:s really are not as good as V1:s. There is difference for sure regarding in stability in mr use. Don't know what did they change in fw makes that big difference. I'm going to try funfly 40A next and then rapid esc:s and i'll let you know what works best.

 

[BorisS]

Maytech V2 ruined my axi six of them. I dont recommend using them. As an answer i got from Maytech support sorry to tell you the V2 are not compatible with you motors great. I understand if it dosent work, but resulting in this and smoke from the motors is a different story.

it think its had to be a FW thats not tested enough cant explain it otherwise that they dont start up on every second try and some of them smoked up !

Boris

 

[Kari]

Boris sorry for your motors, i remember that case. I've also had some not so good startups with qc motors and V2:s. Not smoke yet but if i'd let that last little longer it certainly would have ended up smoking motors. Sticky startups, and yes i also tried all different "start up strenghts" available in V2 settings. Hope rapid esc:s works well so i'll order some 40A versions for cinestar.

 

[wbrown]

Sorry to post my problems in your thread but it seems relevant, and I didn't want to start a new one just for similar issues.

I have a Cinesatr 6, wkm running Hobbywing Pentium 40a ESC's.

It flies great in manual but develops constant small wobble throughout the whole craft whenever I change to atti or gps mode. It affects the video so much that I' am forced to use manual mode as my only option.

 

[Kari]

I had similar constant wobble with maytech v2. Didn't find any gain combo to make it smooth but maytech v1 it flied great. What props do you use?

Kari

 

[wbrown]

Hi Kari

I have heard pretty good things about the maytech v1's, thinking of trying a different distro board with some of them.
Do you use 30A, and can you still get the v1's?

I'am using apc thin electric 12x6 lifting canon 7d - pretty heavy set up.

Cheers

 

[RTRyder]

Sorry to post my problems in your thread but it seems relevant, and I didn't want to start a new one just for similar issues.

I have a Cinesatr 6, wkm running Hobbywing Pentium 40a ESC's.

It flies great in manual but develops constant small wobble throughout the whole craft whenever I change to atti or gps mode. It affects the video so much that I' am forced to use manual mode as my only option.

Could be one or all of the following, gain settings, prop size, ESC firmware. My CS6 flies nicely in both ATTI and GPS mode, I'm using AXI 2814-22 motors, Graupner 11 x5 props, DYS 30A ESCs with FastPWM firmware, and gain settings of 220 on basic pitch and roll with ATTI pitch and roll TX adjustable from 40% to 110%. With this setup I can get video smooth enough to not need any post process stabilization while flying in ATTI mode.

I've seen the wobble you're referring to and it took a lot of trial end error to eliminate it, the end result being the setup I'm currently using. I just thought of one other thing that can contribute to the wobble, the Z axis measurement used in the Assistant software has to be within a CM +/- of the actual CoG for the axis. The method I've found most effective to measure the CoG on Z axis, take a piece of wire or heavy twine and loop it through one of the outer openings on the lower frame plate. With the CS setup as though you were about to fly it, battery(s) and camera in place, lift it by the wire and note if the center plates are vertical or angled to the right or left. If they're perfectly vertical the CoG for the Z axis is where the wire is, if it's angled so that the lowest part of the centerplate is to the left of vertical it means the CoG is also towards the left. Move the wire to the left and see if the centerplates are vertical there, if it now has the bottom of the centerplate right of vertical then the CoG would be somewhere in between the two points the wire was attached at. If you have the patience and can find appropriate places to hang the frame from you can find the exact Z axis CoG by moving the wire the frame is hanging from until you find the point where the centerplates are perfectly vertical, measure from that point to the center of the side of the IMU and enter the number in the Assistant software.

In your case it would help to know what gain settings you currently have as well as the takeoff weight and what the rest of your setup is. The WKM like to have heavy disk loading on the props, it seems to fly best with the smallest props that will get the job done, a lot of stability problems people have had were solved by swapping to a smaller prop and doing some gain adjustments.

Ken