Why I do believe there's a HUGE problem with the Mavic Mini - Flew AWAY the 2nd day

[BudWalker]

Okay, so it was a technical fault after all? I hope DJI folks monitor these threads (they better do), and take it into considerations for further improvments of their products...

Not enough is known to determine if this was a technical fault. At least to me not enough is known. I'm working on the theory that the leftBack and rightFront motors are not as powerful as the other two motors (or some variation thereof). We've seen some indications that this may be true, but more evidence is required to make the case. If you could perform the experiment that was described here

Mavic mini, unresponsive on forward command, logs for the pros.

that theory can be tested.

 

[amriceman]

Hi BudWalker,
It's an interesting theory, but I would think that technically all 4 motors are the same DJI brushless motors, and if there are some differences, it could be a flight controller's fault not calculating properly the RPM's for each individual motor in a difficult situations like going into a strong head wind. Or erroneous input from IMU sensors, which could also confuse the FC. I have calibrated the compass on my now-gone Mavic Mini on a few occasions, but never did the IMU calibartion, as it never asked for it.

 

[BudWalker]

Hi BudWalker,
It's an interesting theory, but I would think that technically all 4 motors are the same DJI brushless motors, and if there are some differences, it could be a flight controller's fault not calculating properly the RPM's for each individual motor in a difficult situations like going into a strong head wind. Or erroneous input from IMU sensors, which could also confuse the FC. I have calibrated the compass on my now-gone Mavic Mini on a few occasions, but never did the IMU calibartion, as it never asked for it.

You no longer have the MM?

 

[amriceman]

Sadly , not... All the later discussions on this thread was my Mavic Mini fly-away case, I was not able to retrieve it...

 

[BudWalker]

Hi BudWalker,
It's an interesting theory, but I would think that technically all 4 motors are the same DJI brushless motors, and if there are some differences, it could be a flight controller's fault not calculating properly the RPM's for each individual motor in a difficult situations like going into a strong head wind. Or erroneous input from IMU sensors, which could also confuse the FC. I have calibrated the compass on my now-gone Mavic Mini on a few occasions, but never did the IMU calibartion, as it never asked for it.

It's clear from the .DAT that the FC wasn't confused. The left back motor was maxed out and couldn't produce more thrust than it was. The FC adjusted the power to the other motors so that stable flight was possible. If there was a sensor problem like an incorrect gyro or accelerometer stable flight would not have been possible.

 

[amriceman]

In this case, shouldn't be the right-back motor to match the left-back output in order to achieve the required 20° tilt? As per charts, the RB thrust was higher than the front motors, but far from the the LB thrust. That's why I think the FC was struggling to coordinate the effort between all four motors...

 

[Thomas B]

L

In this case, shouldn't be the right-back motor to match the left-back output in order to achieve the required 20° tilt? As per charts, the RB thrust was higher than the front motors, but far from the the LB thrust. That's why I think the FC was struggling to coordinate the effort between all four motors...

likely a prop problem or motor malfunction.

 

[sar104]

Likely a prop problem or motor malfunction.

I'm not sure about that. There have now been several incidents with this signature, and it's hard to say what kind of motor or prop malfunction might lead to this kind of intermittent problem. It's a bit of a mystery at this point.

 

[amriceman]

likely a prop problem or motor malfunction.

It might be a good idea to analyze the .DAT files from the very first flights to see if the problem already persisted in the fresh out of factory drone.

 

[m80116]

Honestly despite my case being A. for complete loss of communication and B. for failed RTH the main problems of the MM are the following atm (in order of frequency of occurence):

- Being carried away by the Wind
- Unexpectedly descending from height

and both can be easily discerned from pilot error. Until now despite the incautious challenge mounted by new drone users it's being pretty clear that Mavic Mini in certain occasions fails to respond properly and is carried away by the wind when it probably could counter it very well, tilt as much as it could and get back anwway, and has unexpected sloping path for no apparent reason, the pilot must be alert enough to counter it before the drone crashes.

While I can exclude my drone was carried away by the wind I can't exclude my drone has brought itself down because of the unexpected height loss during automatically initiated RTH.

 

[AntDX316]

Hello, I am m80(116) new drone and forum user from Italy.

I am writing here because I've lost my Mavic Mini after the 2nd day of ownership. This is by far one of the most embarrassing accident I've ever had in 2019 and one that I feel can't really be blamed for...

I went through a month of preparation, tutorials, safety guides, drills before actually flying my Mini on a b-roll shootout... it all went away in A MINUTE ! And so here I am... to verify am not a complete idiot, although maybe on the way to become, with an open fly-away case from DJI... and plenty of company as I can see.

To be brutally honest considering the sheer amount of cases here, and not being too unfamiliar with faultiness statistics, I do believe I am one of the many victims of a glitchy firmware or bad hardware, and that DJI will never acknowledge the fault, hence compensate us for the trouble and inconvenience caused to us.

If you want to read my experience in full extent here it is How the DJI Mavic Mini TOTALLY RUINED my Christmas Holidays
or at full URL How the DJI Mavic Mini TOTALLY RUINED my Christmas Holidays

I didn't read all the post here but if you like to fly get an M2P or an M2Z.

 

[BudWalker]

There are some additional analytical tools available since the last post. Specifically, more messages can be extracted from the .txt log file. In this incident those messages indicate that the MM had reached it's maximum power output.

240.1 +STRONG WIND. FLY WITH CAUTION (CODE: 30149)AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
:
273.1 +STRONG WIND. FLY WITH CAUTION (CODE: 30149)AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
292.4 +STRONG WIND. FLY WITH CAUTION (CODE: 30149)AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
295.4 )AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
:
:
432.4 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)

434.2 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)

443.7 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
447.2 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
448.4 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)

458.1 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)

476.2 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)

481.5 +STRONG WIND. FLY WITH CAUTION (CODE: 30149)*WEAK SIGNAL. ADJUST ANTENNAS (CODE: 80016)AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)

484.1 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
487.2 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)

513.4 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
515.1 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)

593.8 +STRONG WIND. FLY WITH CAUTION (CODE: 30149)AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
594.8 FAILSAFE MODE IN PROGRESS

598.8 603.4AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
606.5 AIRCRAFT MAX POWER LOAD REACHED. DECREASE ALTITUDE AND FLY WITH CAUTION. IF THIS ISSUE PERSISTS, LAND IMMEDIATELY (CODE: 30168)
OK

 

[ob1quixote]

Re different power from rear motors...if the AC were flying directly into the wind, I would expect the power levels to be equal.

If flying into the wind at some angle, wouldn't that account for unequal power to the rear motors?

 

[slup]

Re different power from rear motors...if the AC were flying directly into the wind, I would expect the power levels to be equal.

If flying into the wind at some angle, wouldn't that account for unequal power to the rear motors?

No, the rear props need to power up in order to set & maintain the tilt angle required for the commanded speed in forward direction ... see my 2 different examples below from a Mavic Air.

Straight forward flight in Sport mode, only elevator commanded nearly full, AC close to maximum tilt angle of 35 degrees. Both rear props have considerable higher rpm's then the front.



Here it's full forward right diagonal with max aileron & elevator commanded. AC again pretty close to maximum tilt angle of 35 degrees. Both rear props have again considerable higher rpm's then the front but you also have a differentiation between left & right props as the AC travels forward right.

 

[FoxhallGH]

No, the rear props need to power up in order to set & maintain the tilt angle required for the commanded speed in forward direction ... see my 2 different examples below from a Mavic Air.

I'm with @ob1quixote on this one ... It seems to me that if your drone was battling a cross-wind e.g. from the front-right, then the back left prop-set would have to be working a lot harder to push the aircraft to keep it on course & speed. If (in this example), the back-left motor was max. rpm and the drone was still unable to maintain course, then the back-right motor would be cutting back to try and allow the drone to bank/roll right - but then it would present too much 'surface area' to the airstream, which would push it further left.
[I don't think this has anything to do with the case you are analysing, but comments about the two back motors providing equal rpm intrigued me ...]

 

[m80116]

When you folks reply to a post in the middle I'd really appreciate if you could mention that you're not referring to my flight, my data log or anything else related to my incident, better still would be to talk about that on a completely different thread.

Because you know... people tend to read from page 45 and ignore all the other pages that came before, yet they still sentence...

 

[Thomas B]

When you folks reply to a post in the middle I'd really appreciate if you could mention that you're not referring to my flight, my data log or anything else related to my incident, better still would be to talk about that on a completely different thread.

Because you know... people tend to read from page 45 and ignore all the other pages that came before, yet they still sentence...

Agree. OP problem is solved. Let’s have new threads for crash analysis for each individual to avoid confusion. That said....