I have sent this on to Holger from Mikrokopter, but I thought I would submit my tale of woe to the crowd here in the hopes that something I missed might come to mind. BTW, the copter and all its parts survived just fine. One of my ghetto landing skids took the brunt of the impact, so I’m out one 300mm or so CF boom (which was pretty ragged anyway). Whew. I recently updated to the KDE 4012 motors in my X8 coax copter, and today I added the Tiger 18” props. I have been flying it for a few weeks without incident with other props. After testing the motors with the new props and running it up, I went out to fly it. It flew OK with a 10 pound dead weight on the copter. The compass (built-in) is a little out of whack, so I should probably recalibrate it. I’m using the NC 2.1, FC 2.5 (both with 2.06a firmware) and the Double Quadro 2XL board with the updated firmware. I have set the BLs as per your instructions. Whilst I was testing it, I tried a few aggressive ascents, and when I slowed the ascent, I got an error in the mx20 (“Motor Error”) and the copter got very wobbly. I was able to bring it down quickly and land it. My guess was it might have had something to do with the dynamic braking, so I made a note to be very gentle on the sticks and try again. I changed batteries to a new pair, and tried to fly again. It flew for a while, but then had another motor error, and I wasn’t able to land it well. I just looked at the video, and I remember I had done a hard yaw to the left just before it lost control. Again, I wonder about a motor maybe shutting down. Is there anything I can learn from the GPX files? I wonder if the minimum throttle should maybe be upped, and if I should turn off dynamic braking in the BLs? “14042800.GPX” is the one shown here where I was able to land it OK. “14042803.GPX” is the one shown here where it came down out of control. Thank you for any information you can give me!
Oh, and one more thing. If any of you is feeling adventurous, you can download the WMV version of the second flight and stuff it into the MKGPXTool. Note that because this is 2.06a, the rate of the log is 2 entries per second, so you have to tweak the MKGPXTool a bit. https://app.box.com/s/7cfy1ufdjg0waaup5th8
Steve, Really sorry to see your trouble today. It is pretty crazy to see the top motor on the left side of the screen literally stop, pause, change directions a little and spin back up the other way. I have my fingers crossed you don't end up having to turn off the braking feature to solve the issue because it sure looks like it adds responsiveness and saves battery. Thanks for always sharing so much info with all of us. Michael
Steve: I saw the motor stop in the video, but am never sure if it an optical illusion. I did look at your 2nd GPX carefully and other than the 3 "motor stop" errors I couldn't see anything. Sorry about your troubles, and I hope you sort it out soon.
I don't think the motors stopped GaryM....just the stroboscopic ("wagon wheels") effect of the Go Pro. I'll look at the GPX file tomorrow and see if I can see any things that go bump in night flight. Andy.
Steve, I'm sorry to see this. Glad the rash was minimal. It's scary flying a new rig, and I'm glad you are being cautions. I will be even more cautious now until you figure out what this is.
The GPX showed three "Motor restart" errors, sorry I said "motor stop". So the "optical illusion" might actually have happened. Hang tough Steve!
Holger looked and said it looks like motor #4 has some issues because it was flagged with the “MotorNOK” flag. But I can’t see it! There is a field in GPX files called “MotorNOK” which I can’t see using the latest version of the MKGPXTool, although I can see it in the XML source of my GPX files using a text editor. I tried deleting the .INI file in the MKGPXTool folder, but it still doesn’t show up. Anybody know what I have to do to see it? I tried installing the Simple GPX Viewer, but I don’t think it works on Windows XP (or something like that...it starts up but crashes after throwing several exceptions). Edit: reinstalled MKGPXTool and now I see that field. Interesting. I wonder if I’ve had motor and/or BL issues in the past and haven’t seen them for this reason.
I personally think 18x6.1 props are too much for the 4012 motors at 25lbs. Have you contacted kde and got any suggestions?
My typical AUW will be 21-22 pounds, and Patrick from KDE told me that he thinks this is a good match.
Interesting...I just noticed that Holger released a new version of the NC firmware. I noticed this issue whilst trying to debug my problem. Bugfix: NC 2.06b: Logfile stopped for some seconds after an error occuredhttp://forum.mikrokopter.de/topic-post514144.html#post514144
EDIT: These comments are for the 03.GPX file. Steve: There was a "SPEAK_UNDERVOLTAGE" alarm at row 33. The voltage dips to 22.9v. What I don't understand is why it happened in that row as there are plenty of other rows where the voltage is down to 22.9 and 22.8. See e.g. rows 63 - 68 -- yet these did not produce any SPEAK_UNDERVOLTAGE errors. The motor currents obviously go wacky (technical term) at row 205 -- it looks like the flight controller is fighting something or has gone into oscillation -- the audio on the flight video confirms as much. What is not apparent is (a) what the trigger event is and (b) what actually goes wrong, and (c) what to do about it. No other curious things that I can see -- the motor restarts at the very end of the flight were probably caused by prop strikes as you "landed" (I use the word loosely. ) Puzzling, though...I certainly wouldn't dangle anything expensive from this copter until you learn more about the failure. Andy.
Can you determine whether the end of the log file 14042800.GPX really is the end of the flight or is it missing data? Andy
Steve, I looked into your GPX files but could't find any valueable data for further digging. Motor #4 has errors; but after motor restart, other motors give error also. Since this looks motor / BL CTrl issue so I would try different timings. What is your motor timing on BL Ctrl? We have similar setups (Double Quadro2XL and KDE 4014XF) and I'm using 28' timing and PWM start value at 1.
Steve: Regarding the 00.GPX file. It looks like motor #7 is in distress. As Ozkan suggests, it might be that the motor timing is causing decommutation (the motor's rotor getting out of step with the AC signals from the brushless controller). Andy.
MK released a new version of the NC firmware today that seems to address this issue: Bugfix: NC 2.06b: Logfile stopped for some seconds after an error occured http://forum.mikrokopter.de/topic-post514144.html#post514144
Agreed. About to disassemble the copter and check all my bullets and BL pads. I suspect I'll find something janky with the #4 BL. As per Holger, I'm using StartPWM of 4 and timing of 28°. Like this: http://forum.mikrokopter.de/topic-post505200.html#post505200 Dave King reports that KDE have suggested "We have found that our motors like 22 degrees of timing". So I may try that today, too.
I don't know if MK is granular enough to set it at 22. If I remember correctly 22 wasn't an option. The closest setting might be 24. I don't have MK tools here to see what timing options are available to set the BL's too. Does anyone have MK tools and their copter near by to check?