mavic mini crashed without a reason

[Greg6032]

do you believe that? Is this company so seriously? Or they will try to accuse me from doing something wrong

Please see DJI policy below
If this is electronic failure It will be replaced with new one which no cost

You can request Replacement Service:
√ Within fifteen (15) calendar days of receiving the product if the product has sustained a substantial damage in transit, provided always that the damage proof issued by the carrier can be provided to DJI.
√ Within fifteen (15) calendar days of receiving the product if the product does not match the original description of the product in one or more significant respects.
√ Within fifteen (15) calendar days of receiving the product if the product suffers performance failure.

 

[WooZie]

Please see DJI policy below
If this is electronic failure It will be replaced with new one which no cost

i have read these conditions, but i want to say, if they will try to put the blame on me, not as a product failure, that is my doubt

 

[sar104]

i have read these conditions, but i want to say, if they will try to put the blame on me, not as a product failure, that is my doubt

How about postponing all the worrying until you have their response?

 

[Greg6032]

Sar104 you are absolutely right
Let’s wait for DJI response
My experience with DJI was good
The are not playing games and when my Osmo+ stoped working on 10th date after I get it from DJI I send it back and get replacement in one week
Good luck

 

[MAvic_South_Oz]

That's a lost/failed prop or motor failure – rear left based on the initial rotation. That's starting to look like the most common failure mode on the early MMs.

wow, identically like my mini

Hmmm, I have always wondered about this new screw on props thing, and if it was as secure / safe long term as a well placed typical 'push on and rotate' DJI prop setup.

If screws are done up too tight (peoples natural tendency) it can easily crack plastic, making a starting point for fatigue / failure.

I wonder of people recovering their MM's after such a crash, and recovered it, can tell us if they found the prop failed at point of attachment, or if it was broken further up the blade.

Or, if blade was missing altogether, maybe people forget to nip up the screws on a prop properly.
Some might use the procedure to put all props on first with screws in place, then go around and do them up properly.

 

[TDZHDTV]

Hmmm, I have always wondered about this new screw on props thing, and if it was as secure / safe long term as a well placed typical 'push on and rotate' DJI prop setup.

If screws are done up too tight (peoples natural tendency) it can easily crack plastic, making a starting point for fatigue / failure.

I wonder of people recovering their MM's after such a crash, and recovered it, can tell us if they found the prop failed at point of attachment, or if it was broken further up the blade.

Or, if blade was missing altogether, maybe people forget to nip up the screws on a prop properly.
Some might use the procedure to put all props on first with screws in place, then go around and do them up properly.

If you look at the screws provided after the treaded section they step up in diameter, this is to allow the screw to bottom out and not crimp the plastic down. I’m a engineer and I checked the screws when I received the MM, using an ‘engineers nip’ there was no additional tightening/ movement, new screws also had thread lock pre applied. Let’s just hope DJI have designed a robust solution.

 

[WooZie]

How about postponing all the worrying until you have their response?

yes you are right, i am sorry

 

[DanMan32]

I understand the Anafi is the same way.

 

[BudWalker]

I was able to look at the motor data. Those interested in also looking will need to use Version 3.6.9 of CsvView/DatCon which can be obtained here
CsvView Downloads

As suspected there was a problem with the rightFront propulsion. Looking at the rightFront motor data it can be seen that at 224 secs the speed (red trace) decreased. This was immediately followed with PPM (blue trace) going to the max. Normally, motor PWM data is used to determine commanded speed but PWM isn't available in the Mavic Mini .DAT.


But, there was something else that was unusual. Up until about 152 secs the leftBack speed is unusually higher than the rightBack speed.The speed difference became even greater when full elevator was applied. But, then after 152 secs the leftBack and rightBack speeds were similar as is usually the case.


Don't know what to make of this - almost like something changed in the prop/motor connection.... Just a theory

Here is the .csv
19-11-18-03-17-33_FLY028.1697880.csv

 

[WooZie]

@BudWalker

so, your opinion is...factory mistake or something else? It is hard for me to understand this graphics, but if you can tell me what do you think about this behavior, thanks
if you want to compare, i can give you another file from a previous flight when it worked very well

 

[sar104]

I was able to look at the motor data. Those interested in also looking will need to use Version 3.6.9 of CsvView/DatCon which can be obtained here
CsvView Downloads

As suspected there was a problem with the rightFront propulsion. Looking at the rightFront motor data it can be seen that at 224 secs the speed (red trace) decreased. This was immediately followed with PPM (blue trace) going to the max. Normally, motor PWM data is used to determine commanded speed but PWM isn't available in the Mavic Mini .DAT.
View attachment 86293

But, there was something else that was unusual. Up until about 152 secs the leftBack speed is unusually higher than the rightBack speed.The speed difference became even greater when full elevator was applied. But, then after 152 secs the leftBack and rightBack speeds were similar as is usually the case.
View attachment 86296

Don't know what to make of this - almost like something changed in the prop/motor connection.... Just a theory

Here is the .csv
19-11-18-03-17-33_FLY028.1697880.csv

Agreed on the right front motor failure causing the crash, although it's odd that it came back at 229.4 seconds.

In terms of the left back high motor speed earlier in the flight, it looks to me that it was requested to achieve the required pitch and roll:



Separate question - do we trust the motor current values in the DAT file?

 

[BudWalker]

Agreed on the right front motor failure causing the crash, although it's odd that it came back at 229.4 seconds.

In terms of the left back high motor speed earlier in the flight, it looks to me that it was requested to achieve the required pitch and roll:

View attachment 86315

Separate question - do we trust the motor current values in the DAT file?

Yes, that's exactly right. On the outbound leg there was a cross wind right to left causing the MM to hold a CW roll that then required more thrust from the left side. Seems more pronounced than the other platforms though - the leftBack commanded was at the max.

Don't know what to make of the current data. I'm pretty sure it's the correct field within the motor record. I was going to check later to see if the ESC is done with Field Oriented Control like the Mavic Air. The MA current data is known to be inconsistent with the total current.

 

[BudWalker]

@BudWalker

so, your opinion is...factory mistake or something else? It is hard for me to understand this graphics, but if you can tell me what do you think about this behavior, thanks
if you want to compare, i can give you another file from a previous flight when it worked very well

Sorry, I can't say much about what caused the rightFront propulsion issue.

 

[B52-D]

Looks like we don't have autorotation capabilities with these Quad configured machines. If you lose on motor, you are SOL.

 

[sar104]

Looks like we don't have autorotation capabilities with these Quad configured machines. If you lose on motor, you are SOL.

At least one academic paper has been published showing that, with active motor control, a quad can descend in approximately level, spinning flight, after losing a motor. It's not a stable solution for a quad, however.

 

[Keule]

At least one academic paper has been published showing that, with active motor control, a quad can descend in approximately level, spinning flight, after losing a motor. It's not a stable solution for a quad, however.

There had been a successful demonstration at a show a few years back:

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[B52-D]

Excellent video, thanks for sharing.

 

[Skywatcher2001]

WooZie it is said that it gets the darkest just before sunrise. Its seems gloomy now (but) buy buying a DJI product will assure you of a new bird soon. I base that on what sar104 and BudWalker have seen and shared. What you may NOT know is they are the best at what they do and a tremendous asset to this forum. Don't think for one second that DJI is not aware of these two and this post . . . they are.

 

[WooZie]

ok friend, i will wait for them thank you very much
did i see you on youtube?

 

[Steve L]

That’s suspicious for a bird strike. At 1:52 the aircraft rapidly rotates to the left and very quickly the camera is facing nearly straight downward. At several points the craft seems to try to stabilize but does not. In the last moment while the aircraft rests on the ground a birds is seen flying over head-may be coincidence? I have had birds fly VERY close the M2P- hawks and swifts in particular.