800mm Hexacopter crashed on Test flight

[gtranquilla]

A couple of my slightly used older motors had some run-out and were hard to balance so I replaced them with brand new. But during the first few test flights I noticed that older motors, M1, M3 and M6 were running hotter than the others and noticed some roughness in motor rpm during MR hovering. So I replaced M6 and did another test flight. Hovering seemed to be much smoother but M1 was still a bit warmer than the others and there was still a slight bit of roughness while hovering..... so then I replaced M1. On the subsequent test flight the MR took off in the direction of M1 for about 50 feet then flipped into the ground....... which seems to suggest the replacement motors was worse than the previous.
I don't think this is an ESC issues as they are all new, configured the same way as always with LVC set low as possible and with battery type as Nixx and bench tested.

The only other thing I can think of that changed in my standard Hex design is that I moved the WKM firmware up from 5.20 to 5.26..........
Are others having issues with 5.26?

Motors are Turnigy Multistar 22 pole 420 KV 4830.
ESCs are Turnigy Multistar 45 amp OPT.

 

[tombrown1]

A couple of my slightly used older motors had some run-out and were hard to balance so I replaced them with brand new. But during the first few test flights I noticed that older motors, M1, M3 and M6 were running hotter than the others and noticed some roughness in motor rpm during MR hovering. So I replaced M6 and did another test flight. Hovering seemed to be much smoother but M1 was still a bit warmer than the others and there was still a slight bit of roughness while hovering..... so then I replaced M1. On the subsequent test flight the MR took off in the direction of M1 for about 50 feet then flipped into the ground....... which seems to suggest the replacement motors was worse than the previous.
I don't think this is an ESC issues as they are all new, configured the same way as always with LVC set low as possible and with battery type as Nixx and bench tested.

The only other thing I can think of that changed in my standard Hex design is that I moved the WKM firmware up from 5.20 to 5.26..........
Are others having issues with 5.26?

Motors are Turnigy Multistar 22 pole 420 KV 4830.
ESCs are Turnigy Multistar 45 amp OPT.

I won't fly anything other than 5.16.

If it took off straight towards M1, then it sounds like a WKM issue. If one motor is bad, and you're in GPS, then WKM is supposed to keep flying, but your craft will be spinning. At that point you're supposed to switch to carefree mode and guide it down.

Were you calibrated after the fw update? Full GPS lock?

 

[gtranquilla]

I wait until I get complete GPS satellite lock.... but then I always take-off and land in Attitude mode........
So if WKM can only keep it level with one motor failed in GPS mode.... then I missed my chance to regain control to land safely.

In such a case it could still be the M1 motor or ESC.......

I won't fly anything other than 5.16.

If it took off straight towards M1, then it sounds like a WKM issue. If one motor is bad, and you're in GPS, then WKM is supposed to keep flying, but your craft will be spinning. At that point you're supposed to switch to carefree mode and guide it down.

Were you calibrated after the fw update? Full GPS lock?

 

[sk8brd]

i have heard of a couple flips of death type incidents on 5.26 reported on various forums- one recently when a guy upgraded to the imuv2. the majority of people say that they have not had problems with 5.26 though. i have heard of less issues on earlier firmware like 5.20 or 5.16. 5.16 seems the most recomended in post's i have read and is what i would stick with. i'm not sure if you loose certain functions with early firmware compared to 5.26 maybe someone can chime in

 

[gtranquilla]

Thanks Tom and sk8board......

So now I will see if I can roll the firmware back to 5.16 or 5.20......if I can figure out how.....
will test the esc/motor c/w prop load on the bench with my handy servo tester to see if I can get a glitch of some kind although I think that is highly unlikely.

 

[gtranquilla]

On the previous test flight there was no toilet bowl effect but it flew left of the intended heading. So looked up my previous Hex build configuration that flew perfectly on fw 5.20 to determine the best GPS arrow direction, i.e., 14 east then then recalibrated the compass getting the confirming white leds before it settled down to the typical GPS LED flashes.... then switched to Attitude for the single yellow flashes then took off....... as described above for the crash.
[MENTION=736]Tahoe Ed[/MENTION]

 

[tombrown1]

I think you're right that atti mode might not compensate for a bad motor - thus it was probably an esc or motor that needs fixing.

You do lose some functionality with 5.16, but it's nothing of consequence imo. Rolling back is exactly the same as upgrading. DJI keeps all the old fws on their site I believe - should be easy.

As for the compass - you just turn it until the thing flies straight. Here in New England I need to point the compass left pretty hard - maybe 10-20 degrees. In California I needed to point it way right - probably the same amount.

Sorry for your loss. Crashes suck.

 

[gtranquilla]

Crashes suck...... especially when you have just been paid just under $1000 to do the build for a friend and it crashes just a couple of days before you intended to hand it over as the final deliverable!!!!

I think you're right that atti mode might not compensate for a bad motor - thus it was probably an esc or motor that needs fixing.

You do lose some functionality with 5.16, but it's nothing of consequence imo. Rolling back is exactly the same as upgrading. DJI keeps all the old fws on their site I believe - should be easy.

As for the compass - you just turn it until the thing flies straight. Here in New England I need to point the compass left pretty hard - maybe 10-20 degrees. In California I needed to point it way right - probably the same amount.

Sorry for your loss. Crashes suck.

 

[sk8brd]

wkm should compensate in atti mode its in the release notes from 5.16 so i imagine 5.26 should as well, having control of the rig while its yawing around bad motor you would need course lock or home lock. home lock only works in gps mode, course lock works in atti but depends on which way the craft was pointed when started to determine what back is..this works on my naza n atti and course lock.

 

[gtranquilla]

thx sk8brd...

I just read the same re: Attitude..... However I have limited WKM input channels such that X2 or X3 was dedicated to RC remote gains making the option to activate course lock unavailable and no bluetooth module to allow me to shift the RC remote gains over to the IPad......

In any case I moved the firmware back to 5.20 which enabled my previous Hex with WKM to get beyond 200 successful flights to date..... sold it so I have no idea how many flight now but still flying apparently. I was almost going to suggest to the new owner to upgrade to 5.26..... I think I will hold off on that now.

Seriously considering moving over to MikroKopter now.

 

[Quinton]

I am flying 5.26 on a Skyjib hex, and I had 3 motors a lot hotter than the other 3 for quite a while and I could not figure out what was causing it.
Motors 1,3 and 5

Then after discussing it with Kloner, I decided to measure the height of motors/props, and discovered that 1 of them was a good 8mm below the others.
I went to take it apart and noticed that the boom/motor mount was not locked under the anti vibration o ring, so I took it apart and placed it on correctly, and now everything runs really cool even on 16" props.

Not sure if it helps your situation as it was flying well in GPS and ATTI when the 3 motors were hot, but it seemed that it was always the CCW motors compensating for the single misaligned one.