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Mavic Mini turned submersible

MavicMiniSubmarine

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Hi all,

So I've had my Mavic Mini for over a year now, I had DJI care for the first year to get comfortable with it and I have gotten pretty comfortable with it, I have no worries of it losing connection to RC in flight, I have no worries going high up.

Today I was flying my Mini across the lake, I wanted to see if I could get it all the way across and back (2km one way), I was 100% certain the Mini would give me no problems at all. And I don't think the Mini gave me any problems, my problem today comes from the other wildlife we share the skies with. I am not certain, but I think a bird tried to snatch the mini and that led to it tumbling into the water 400m from the shoreline.

Now I have no hopes of recovering a functional drone, but I would like to recover my SD card and scrap the drone for parts if it doesn't work, if I ever find it. I have uploaded the flight log to airdata which I will link below.


I looked online, I am unable to find any water current data for the lake, so if it does wash up on the shore I wouldn't know where to look except in the general vicinity of where it splashed down.
Would anyone know of any way to retrieve the drone or know where the drone may wash up on shore?
 

MAvic_South_Oz

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..
Welcome to the forum, as bad as the intro thread is.

From the warnings, you are probably right about a bird strike, although a prop fail / prop throw might also result in the tumbling / those warnings . . . someone viewing the CSV data might be able to tell.

Lakes are probably not going to see anything washed up, unless it was floating and wind blown.

You are stuck with that forum name now forever, you know that !? 😬 ;)
 

eEridani

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10 seconds sounds like an awfully long time for a bird to be hammering the drone. Unless both were tumbling down to the lake at that point and the bird was really pissed at the outcome.

What was the camera telling you at that point?

As for washing up on shore? I don't think much on the Mini is considered flotation.






















Detected side shock / possible collision
Detected forward shock / possible collision

Aircraft not connected to RC
 
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MAvic_South_Oz

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10 seconds sounds like an awfully long time for a bird to be hammering the drone.

After the initial strike (or prop problem), the drone was tumbling down from approx 510' for the remaining warnings.
(Altitude going into the negative territory from home point by somewhere around -184'.)
Rolling / pitching in all directions for the remaining 14 seconds.
 

slup

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...don't think the Mini gave me any problems, my problem today comes from the other wildlife we share the skies with. I am not certain, but I think a bird tried to snatch the mini and that led to it tumbling into the water 400m from the shoreline...
...From the warnings, you are probably right about a bird strike, although a prop fail / prop throw might also result in the tumbling...
All those "Detected Forward/Backward/Side shock" messages is purely Airdata's own interpretation & speculation coming from the major Pitch & Roll deflections ... it has nothing to do with what really happened. The only valid message from the log is yellow marked in the TXT message stream here below.

message.jpg
Looking at the pitch, roll & yaw data they strongly suggest that this most probably was a prop failure in the right front side ... 205,5sec into the flight the Mini heavily pitches down, roll right & start to yaw CCW. If the thrust becomes limited or completely disappears from the front right ... the AC would initially dip nose down & lower the right side ... as the front right is a CW torquing prop, losing that would mean that the torque balance would be 2xCCW torquing against only 1 CW torquing = AC starts to rotate CCW.

In this case I suspect that only one of the 2 blades break lose first ... this as the AC somewhat stabilizes after the initial incident ... then somewhere around 210sec the other blade snaps & the Mini rotates even faster & losing height rapidly.

1635067040868.png

...Would anyone know of any way to retrieve the drone or know where the drone may wash up on shore?
Totally impossible to say ... as said, the Mini will not float, it sinks like a rock, were it may end up can not be calculated.
 

MAvic_South_Oz

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All those "Detected Forward/Backward/Side shock" messages is purely Airdata's own interpretation & speculation coming from the major Pitch & Roll deflections ... it has nothing to do with what really happened. The only valid message from the log is yellow marked in the TXT message stream here below.

message.jpg

Thanks for the feedback.

I was just viewing the motor error appearing on the airdata report above 5 seconds after the first side shock / possible collision warning.

G03m 25s324.5 ft4,513 ftMedium Risk Medium severity, more serious safety impact Detected side shock / possible collision, aircraft is rolling sharply to the right
H03m 26s319.5 ft4,526 ftMedium Risk Medium severity, more serious safety impact Detected backward shock / possible collision, aircraft is pitching sharply backwards
I03m 30s307.4 ft4,566 ftWarningMotor error. Check propellers and fly with caution (Code: 30163)

Does the TXT itself show the motor / propeller problem first, before any other warnings ?
 

slup

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Thanks for the feedback.

I was just viewing the motor error appearing on the airdata report above 5 seconds after the first side shock / possible collision warning.

G03m 25s324.5 ft4,513 ftMedium Risk Medium severity, more serious safety impact Detected side shock / possible collision, aircraft is rolling sharply to the right
H03m 26s319.5 ft4,526 ftMedium Risk Medium severity, more serious safety impact Detected backward shock / possible collision, aircraft is pitching sharply backwards
I03m 30s307.4 ft4,566 ftWarningMotor error. Check propellers and fly with caution (Code: 30163)

Does the TXT itself show the motor / propeller problem first, before any other warnings ?
No other warnings exists in the log besides "Motor error. Check propellers and fly with caution" coming in at 210,1sec ... Airdata's view of thing's isn't reliable, they interpret wrongly a severe roll or pitch movement as "Detected XX shock".
 

bcfd29

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Make friends with your local dive shop: perhaps someone will be able to help you recover it depending on depth and water temp, visibility and conditions. Alternatively find out who the local dive rescue team is and see if for a donation they might do some training there and help you out. Checking some online nautical charts the area looks fairly shallow but given it is part of the st lawrence river system i have no idea of tides or currents to see if a dive is safe or feasible.
 
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MavicMiniSubmarine

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Thanks for the feedback.

I was just viewing the motor error appearing on the airdata report above 5 seconds after the first side shock / possible collision warning.

G03m 25s324.5 ft4,513 ftMedium Risk Medium severity, more serious safety impact Detected side shock / possible collision, aircraft is rolling sharply to the right
H03m 26s319.5 ft4,526 ftMedium Risk Medium severity, more serious safety impact Detected backward shock / possible collision, aircraft is pitching sharply backwards
I03m 30s307.4 ft4,566 ftWarningMotor error. Check propellers and fly with caution (Code: 30163)

Does the TXT itself show the motor / propeller problem first, before any other warnings ?
The first warning I got on my display was a motor error. I assumed that meant that the motors had turned off in flight so I tried to force the motors back on in the tumble. Looking at the power consumption it didn't seem that any motors were out, they was a pretty high power draw from what I can tell from the graph and from the limited knowledge I have of electricity. So I'm thinking now, like someone had suggested that a propellor came off and the mini throttled all the motors to try and stabilize.

I am not sure how a prop would have come off. I don't perform a super extensive pre-flight, but the motors and props were intact before take off and the were no problems on previous flights or during takeoff.
10 seconds sounds like an awfully long time for a bird to be hammering the drone. Unless both were tumbling down to the lake at that point and the bird was really pissed at the outcome.

What was the camera telling you at that point?

As for washing up on shore? I don't think much on the Mini is considered flotation.






















Detected side shock / possible collision
Detected forward shock / possible collision

Aircraft not connected to RC
When the ac started tumbling the camera went spinning with the aircraft, there is hardly any useful footage from the cache. There is a good 3 or 4 seconds of stable footage during the fall, the camera was pointed down at the water during this time and it wasn't obviously falling, then it started falling and spinning faster.
I will upload the 15 seconds of footage of it falling later today.


I think I'm going to try and build my own drone next, maybe quad or fixed wing, or both.
 

eEridani

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The drone changed heading rather fast after the first side strike event, then even faster a second later. Then started falling. I'm inclined to believe the drone was hit by something, probably broke an arm or prop blade, which later became detached, caused the motor failure error, and then flailed on the way down, causing the other impact events. The IMU probably won't record an impact if there was no shock that moves the aircraft sideways or some other direction.
 

MAvic_South_Oz

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No other warnings exists in the log besides "Motor error. Check propellers and fly with caution" coming in at 210,1sec ... Airdata's view of thing's isn't reliable, they interpret wrongly a severe roll or pitch movement as "Detected XX shock".
Ah.
I tried opening the txt in phantomhelp, I’m not sure why, I just prefer the report layout.
All I got was error messages, no report.

Could have been a problem with phantomhelp at that particular times I tried (twice).

Is phantomhelp more reliable in that regard, or should I get the csv viewer downloaded and start learning the graphs ?
Do you use the csv viewer data / graphs in conjunction with airdata or phantomhelp reports to marry up flight outline with data ? ?
 

eEridani

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Airdata does a better job consolidating useful information. In PhantomHelp and FlightReader you need to know what you are looking for and then search for it. Similar to knowing what can be plotted in CSVview ... lots of options, but again, unless you know, hard to use them.
 
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slup

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...Is phantomhelp more reliable in that regard...
Do you use the csv viewer data / graphs in conjunction with airdata or phantomhelp reports...
Airdata sometimes put in way too many own interpretations to be fully reliable, especially if you aren't used to reading logs & can spot when ... nowadays I only use Airdata for the wind estimations (have a paid subscription), and for my own logs to get the possibility to monitor the trends for my batteries.

From Fly app v1.2.2 DJI changed the encryption key making it impossible to decrypt/read the TXT log ... then Airdata suddenly could & their csv file could be downloaded & processed in excel to easier show & understand what happened in a flight ... shortly after our forum member Budwalker equipped CsvView with the ability to read the downloaded csv also, saving time instead of being forced to plot everything up in excel.

The available data signals from Airdata's csv file:

No message stream included in their file ...

1635103683792.png


After a while also PhantomHelp could read logs from Fly app v1.2.2 & onwards ... & it also here became possible to take their csv up in CsvView. The major difference is that PhantomHelp include so much more data ... compare Airdata's available data signals above with what's available from a PhantomHelp csv below.

The actual message stream is also included in PhantomHelp's file ... making it possible to directly see which messages came up in the app during flight.
messagestream.jpg

signals.jpg

In both Airdata's & PhantomHelp's web views only a limited amount of data is shown ... so it's usually not enough to rely only on that ... to get out all available data either excel or CsvView is needed.
 

MAvic_South_Oz

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Airdata sometimes put in way too many own interpretations to be fully reliable, especially if you aren't used to reading logs & can spot when ... nowadays I only use Airdata for the wind estimations (have a paid subscription), and for my own logs to get the possibility to monitor the trends for my batteries.

From Fly app v1.2.2 DJI changed the encryption key making it impossible to decrypt/read the TXT log ... then Airdata suddenly could & their csv file could be downloaded & processed in excel to easier show & understand what happened in a flight ... shortly after our forum member Budwalker equipped CsvView with the ability to read the downloaded csv also, saving time instead of being forced to plot everything up in excel.

The available data signals from Airdata's csv file:

No message stream included in their file ...

View attachment 137124


After a while also PhantomHelp could read logs from Fly app v1.2.2 & onwards ... & it also here became possible to take their csv up in CsvView. The major difference is that PhantomHelp include so much more data ... compare Airdata's available data signals above with what's available from a PhantomHelp csv below.

The actual message stream is also included in PhantomHelp's file ... making it possible to directly see which messages came up in the app during flight.
View attachment 137127

View attachment 137126

In both Airdata's & PhantomHelp's web views only a limited amount of data is shown ... so it's usually not enough to rely only on that ... to get out all available data either excel or CsvView is needed.

Thanks very much for the in depth info, it'd be great to take time to learn this.
 

slup

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@eEridani "-The what is TimeSeries:General:message?"

TimeSeries will generate graphs ... so having plain text there will not work, imagine that this in equal amounts have to do with how CsvView is built up & how Airdata put in the messages in the csv file.

Taking a Airdata csv & column divide it in excel will show all messages that is shown in Airdata's web view "Notifications" ... meaning even the fabricated messages like "Detected XX shock" are included.

If you want access to as much data as possible from a DJI Fly app version above v1.2.1 ... you go with the PhantomHelp csv.
 

NG Wildman

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Besides the local dive shop check Craigslist type ads for underwater inspection.
I, myself, dive a chasing with 100M depth, and a mechanical claw to retrieve things.
Sorry I can't help you myself.
 
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