Brand new Mini 2 landed in lake

[PascalG]

I don't know just a thought my grandma lives by Santa Barbara airport which is a class c and when I took off it allowed me to then prompted me to put in some information and check that I was liable for anything that happens but the prompt didn't come up until after I was about 5 feet up according to the prompt if you ignore it you will be autolanded in 60 seconds.

Ok good to know. Btw I m not Australian so I didn’t meant to calm you “mate” . Spailsheik converted “are you saying” to “mate your saying”...

 

[PascalG]

Minis don’t like flying low over water and tend to descend uncommanded. Did it possibly touch water the first time it dropped? Would explain the final drop. Hope you get it dry and flying again. Good luck.

what makes you say that the MM2 downs fluke flying glow over water? I would think the sensors would be similar to other drones.

I ve had a few close calls over the years with various drones sweeping down a little too low for comfort over water. I really wish DJI would add a minimum altitude setting in the software to prevent going below a certain height... 6’ 10’ 15’ whatever. Especially when shooting action watersports

 

[Slami]

Was the drone getting wet at 13 seconds, climbing and then failing?
How far above the lake was your launch point?

Thanks for looking the data again!

That is exactly what happened.
Maybe I was not clear enough in the first post. So the drone was hovering on top of the lake, then started to descent/land on the water and it actually touched the water before I realised what was happening and then I pushed left stick forward to get back to about 1 meter height before it just died and fell into the lake.

My launch point was about 1 meter above the surface of the lake and then the drone took off to that normal 1,2 meter height. So total distance to lake surface was about 2 meters when I started to move it on top of the lake. It was keeping the same level when moving but when I stopped and let it hover it started to descent. Definitely there was not 13 meters space for it to descent so that false readings from bottom sensors could explain that.
But is the drone only relying in those visual bottom sensors to keep it's altitude or is there more sensors to give altitude information?

Today I tried to start the drone again and it actually powered on and connected to the controller. Motors were also working without props and I didn't receive any error messages. Only thing is that the camera is full of moisture and pictures obviously looks quite dreamy. Is there a way to open that camera to get the moisture out? I tried to open all covers I could find and heat it slightly with hair blower but the moisture is not getting out from inside the camera lens.

 

[Meta4]

My launch point was about 1 meter above the surface of the lake and then the drone took off to that normal 1,2 meter height. So total distance to lake surface was about 2 meters when I started to move it on top of the lake. It was keeping the same level when moving but when I stopped and let it hover it started to descent. Definitely there was not 13 meters space for it to descent so that false readings from bottom sensors could explain that.

The data is confusing because it shows you using auto-takeoff and not making any joystick input until 6.2 seconds (to rotate the drone) and 7.5 sec to start moving forward slowly.
Without any joystick input, the altitude should have stayed constant at about 1.5 metres.
But according to the data it started descending almost immediately and was showing -5 metres before you gave any joystick input and continued descending to -13 metres.

This is clearly impossible if the launch point was only just above the level of the lake.
The drone cannot possibly have descended 13 metres.
The altitude data recorded cannot be believed.

But is the drone only relying in those visual bottom sensors to keep it's altitude or is there more sensors to give altitude information?

With your hands off the controller, the drone should have hovered and maintained a stable altitude and the barometric sensor should have given fairly accurate measurement of the height above the level of the launch point.
But this did not happen.
The data showed the drone going down, down, much further than the actual distance.

At the same time, the height shown by the downward VPS sensors (which should be quite accurate) show a different pattern.
With no horizontal movement, it should have stayed stable
Instead it shows the distance between drone and the surface below increasing steadily from launch, and reaching a maximum of 5.6 metres at only 4.2 seconds, when the drone should have still been hovering at the launch point.

 

[Slami]

The altitude data recorded cannot be believed.

Thanks again for your reply!

So we have two different altitude measurements. I guess GPS is not accurate enough for measuring altitude?
And now both of these measurements seems to have given false and conflicting readings. I can understand that bottom sensors could give false readings since water may not be the best surface for visual sensors but that barometer data seems quite interesting since obviously reality wasn't like that at all.

Any way I have already been in contact with DJI Support and sent them all logs. Let's see what they think about this case.

 

[Meta4]

Thanks again for your reply!

So we have two different altitude measurements. I guess GPS is not accurate enough for measuring altitude?

VPS and barometric sensors are both more accurate than GPS for altitude.
It's very unusual for the barometric sensor to show crazy values as yours did.

 

[PascalG]

Regardless of the sensor issue and odd data, which is a very interesting discussion, those who read the thread and may fly over water need to understand that precautions need to be taken.

yes sensors may fail or send conflicting data but the problem is that you have no safety net when flying over water.

as mentioned 90% of my flight time is over water and from a boat. I take off manually from the front deck and immediately go 35/40’ up so that even with a control issue, GPS or sensor glitch, the drone will clear the top of the boat and antennas.

when hovering to shoot a subject at low level, like people on a beach, sandbar or dinghy, I never go below 12/15’. I have had a couple of cases where the sensors for a bit confused at lower altitude (6’ or so) over water and I had to manually prevent the drone from descending on its own.

Flying over water requires extra precaution. Especially salt water.

I hope you can get the camera dried out.

 

[Dronejenta]

Hi!
I am new here and i just crashed my Mini 2.Similar problem.But i found out that the reason of my crash was the flight before the crash.
Naive me,flying above the water under 3 meters,sea was refleting the sun and that decalibrate the IMU...bring it back,calibrate again and took off..suddenly my mini just fell from the sky!
Got a amazing shot,a epic crash in someone apartament (i was able to recover the drone,get it to the store to send to repair)
Lesson learned.I was lucky i did not fall into the sea (it was pretty close!)
I was flying close to home,just to pratice,but is a warning zone and I cannot fly over 30 meters high/47 meters distance.I did check it all before take off..even being careful,i did this mistake!
Just got a cheap FPV to practice while i wait to my Mini 2 back.Is like losing a dog ?
Learning to teach my son and i will pass the drones to him after he take the tests and get a fly license,I already have mine!
Cheers from Norway!

 

[HWCM]

Rice does nothing to help any electronics. It's a myth and waste of time.

This is my first message to the forum and unfortunately it's not so positive

I had original Mini almost a year and then decided to upgrade to Mini 2. Today I finally got my brand new Mini 2 and went to a close by lake to test it out. I had flown my previous Mini in these kind on circumstances many times so I didn't have any doubts. First prior to the maiden voyage I updated all firmwares and downloaded the latest DJI Fly app from DJI's website. Then I calibrated the compass and waited to get 10+ satellites before take off. I flew the drone few meters on top of the lake but then all of a sudden drone just lowered itself on water. I tried to lift it up again and it rose to about 1 meter high but then it just cut off and dropped to the lake. Those were fun few seconds with my brand new Mini 2 !

I saw from other threads that here are capable people to dig through these flight logs. I uploaded logs from that flight to the link below. Can someone notice any mistakes that I made or any errors from drone's side? I don't see any mistakes that I made. There was decent satellite signal, compass was calibrated, home point updated and I didn't notice any error messages or warnings during take off. Only warnings in those logs are from weak signal and those came when the drone was already submerged.


I also uploaded flight animation from Fly app to youtube if that helps at all.

Now the drone is in sealed bag with rice but I don't have high hopes on it surviving. It was covered and filled with mud and I had hard time rinsing it all away.
The lake was still partly frozen and I was almost frozen solid when it took almost 15mins to find the drone from the water and it was neck deep.

 

[HWCM]

This is false.

It's called water. You probably were flying too low and drones do not do well flying super low over most water.

 

[Capt KO]

I’ve found that my altitude reading occasionally can be way off when low over water. It’s especially bad on my MM1. My P4’s will also decend slowly over water if hovering but the mini does it even at speed. I know the sensor can’t distinguish water very well but doesn’t explain why the barometer doesn’t compensate for it. Pressure change? Anyway, I’m used to it now so I compensate manually. Fly high, enjoy.

 

[Meta4]

I’ve found that my altitude reading occasionally can be way off when low over water. ... I know the sensor can’t distinguish water very well but doesn’t explain why the barometer doesn’t compensate for it. Pressure change?

I fly over water all the time and have never noticed anything like that.
I've never heard of any incidents like that either.
Air pressure shouldn't vary that much closer to water, and if it did we'd see this all the time.
Would be interested in seeing the data from a flight where this happened.

 

[DJayI]

Is there a way to open that camera to get the moisture out?

I am glad your Mini 2 appears to have survived the event. When I have electronics or electrical devices that get wet, my default procedure is to remove the power source as quickly as possible. Second step, do not return power source until one is sure all the moisture is gone. Cleaning PCBs with alcohol after drying is a good idea, as water can leave behind elements that are conductive or corrosive if left in place.
There is a video(maybe from here) where a user crashed their Mini 2 in to the river, it kept filming for several minutes, even though it was fully submerged. So the Mini 2 seems pretty tough. Still, for the cost of the drone and the fact that it was probably purchased as a camera, if it were me, I would send it in to DJI to check. But, I am funny that way, when it comes to untethered flying bags of money.

While you may eventually get all the moisture out of the camera, the same cannot be said for the residue left by the water. As an imaging device, do you really want a film of murk covering the image sensor, lenses and glass of the camera's eye?

 

[Capt KO]

I fly over water all the time and have never noticed anything like that.
I've never heard of any incidents like that either.
Air pressure shouldn't vary that much closer to water, and if it did we'd see this all the time.
Would be interested in seeing the data from a flight where this happened.

Only happens on my MM1 low over water. Will try posting it next time for review if I still have it (see below). Be interested to see the WHY. Usually it just slowly lowers unaided and shows that correctly on the altimeter. Scary when far (VLOS) and says it’s already (-) under water but then can see it’s not. All is well at 20ft over water.

Probably giving the MM to my landlubber grandkids as they love it and I bought an MA2 today on this forum. Hope that solves my wind and water droopy problems. Most of my flying is over water.

 

[Fernfly]

Make sure not to turn the drone on or charge it.

 

[stuka75]

mate you saying that the software will let you take off in restricted airspace and then just land the drone anywhere? Would not make sense

Bingo! Exactly what my spark did taking off from shore and venturing out over canal. Started descending after brief(very brief) ascent, but was able to wrestle it down to shore. I was using Litchi. Opened up Go4 and saw I was on the very edge of no fly zone. Even Go4 would have let me takeoff. Why DJI decided to have units descend instead of rtc is beyond me. Even hovering would be preferable.

 

[MadPup]

Rice does nothing to help any electronics. It's a myth and waste of time.

Uncooked rice is a desiccant. It may not be very efficient but it works to a degree. For one thing, it is used to keep salt from clumping in salt cellars.

The effectiveness of commercial desiccants and uncooked rice in removing moisture from hearing aids - PubMed

White rice shows promise as an effective alternative to commercial desiccants in reducing moisture in hearing aids when silica gel products are unavailable. As this study was conducted in a relatively dry region, additional research may be needed.

pubmed.ncbi.nlm.nih.gov

 

[Meta4]

Uncooked rice is a desiccant. It may not be very efficient but it works to a degree. For one thing, it is used to keep salt from clumping in salt cellars.

The effectiveness of commercial desiccants and uncooked rice in removing moisture from hearing aids - PubMed

White rice shows promise as an effective alternative to commercial desiccants in reducing moisture in hearing aids when silica gel products are unavailable. As this study was conducted in a relatively dry region, additional research may be needed.

pubmed.ncbi.nlm.nih.gov

Instead of waiting days for rice to (maybe) help remove water from electronics, flushing with alcohol and forced ventilation does the job right away, and more effectively..

 

[Slami]

While you may eventually get all the moisture out of the camera, the same cannot be said for the residue left by the water. As an imaging device, do you really want a film of murk covering the image sensor, lenses and glass of the camera's eye?

I kept the drone in a box with silica gel bag for couple of days and most of the moisture escaped from the camera but that left a lot of spots on the inside of the camera cover. So indeed not a desired situation with a imaging device.

DJI asked to send the unit to service for closer inspection and I already bought a new Mini 2 with DJI Care.
Now I have been able to enjoy flying Mini 2, it has all that the original Mini was lacking off. And I'm still keeping a proper safety margin when flying over water ?

 

[Slami]

Today I got an email from DJI Support that they will provide me a free repair service under the warranty.
Now I have to figure out what to do with two Mini 2's