I was trying my drone after some gimbal issues, (check previous post) and suddenly i got a motor error! I was on my way back home and at the first notification the drone was ok, after a while i got a second notification and then the drone camera started to point down, it was like the drone was hanging and started to fell! The fall was slow (thank God) was like -3m/s and landed on a thick pile of snow so not any damage from the crash! Any idea what could have been the problem? I'm sending it tomorrow for the gimbal issue so they'll check also this but was wondering if someone have a logical explanation for that!
Ps Battery over current is normal? It's quite there the 9/10 times!

What was the weather like?  I searched on Google and it looked like you were flying slightly below freezing with 100% humidity.  You hit the dew point during your flight.  Not good.  I wouldn’t have flown in that weather.  

Hi

Best to get help/advice is to share your flightlog.

Use this link > https://www.phantomhelp.com/LogViewer/Upload/
Post the uploaded link on here

cheers
JJB

With limited info and a check on the local weather station over there, high humidity and sub zero temps, I would say you had prop icing, especially at that height

DroneApe Posted at 2-23 13:35
What was the weather like?  I searched on Google and it looked like you were flying slightly below freezing with 100% humidity.  You hit the dew point during your flight.  Not good.  I wouldn’t have flown in that weather.

Ha, my bad, i didnt check for previous replies but it looks like we're on the same page....

Around zero! Isn't it -10 or so the limit?

cycloholic Posted at 2-23 13:59
Around zero! Isn't it -10 or so the limit?

Yes you can fly in -10C  but not with high humidity though, therein lies your problem, sub zero and high humidity, yours was 99% or 100% humidity.
Was it foggy, i would be surprised if it wasn't maybe the little bit of wind kept it at by but if the wind dropped then fog would be inevitable.

FYI, prop icing can occur between -10ºC to 4ºC and high humidity

I see, even uav forecast shows green though :/

cycloholic Posted at 2-23 14:14
I see, even uav forecast shows green though :/

It does not take into account humidity, only temp and wind, you wind was very low, humidity very high and sub zero temps, that is a recipe for prop icing, also bear in mind, as a rule, for every 100m you climb, the temp drops 1C...

You should also follow JJB*'s reply so he can make a more informed assessment from your flightlog
see post https://forum.dji.com/forum.php? ... 770&pid=2988360

Yes i can do that later. I made a Google search for prop icing, i see that when this happens you can actual see the ice on the props, while i haven't noticed something on my props, they were quite clean. Isn't it strange?

cycloholic Posted at 2-23 14:35
Yes i can do that later. I made a Google search for prop icing, i see that when this happens you can actual see the ice on the props, while i haven't noticed something on my props, they were quite clean. Isn't it strange?

Im not sure how long it took you to get to the drone after, it was about 1800m from the HP so it may have melted by the time you got to it.

I am a little confused though, how come the flight started at 500m high and over 3km away and above water?
Actually it started at 0m but jumped to over 3km away in seconds

cycloholic Posted at 2-23 14:35
Yes i can do that later. I made a Google search for prop icing, i see that when this happens you can actual see the ice on the props, while i haven't noticed something on my props, they were quite clean. Isn't it strange?

I would pay closer attention to the dew point before you fly in freezing or sub freezing temps.  According to the weather data that I looked at, you literally flew the drone during the dew point.  Not good.

https://www.thedroneu.com/blog/how-cold-is-too-cold-to-fly-a-drone/#:~:text=It's%20generally%20recommended%20to%20avoid,28%2C%20that's%20a%20no%20fly.
I wouldn't fly the drone in above freezing temps during (or close to) a dew point either.  It's just asking for trouble.

Hi there. We're deeply sorry for the incident that happened to your unit. Our repair facility will assess your unit on our facility and perform necessary diagnostics and inform you once done. Again, we do apologize for the trouble. Thank you for your understanding and support.

As the other members have mentioned, and given the weather data, you were most likely in icing conditions.

Ice forms on the leading edge of the propeller when water vapor comes into contact with the propeller which is at the correct temperature (dew point). It's like condensation on the windows in the winter.

With luck the ice breaks and goes away because the plastic propellers are very smooth and they don't stick much. Hence the importance of having propellers in good condition.

Accumulation of ice on the lower surface of the blade which seriously degrades the profile and forces the engine to provide more power to maintain lift:



On this image taken on the return flight you can see that a piece of ice has disappeared:

The mass of ice which is added to that of the propeller also causes a change in inertia, which acts on the PID (the reaction of the engine).

Part 1https://www.phantomhelp.com/LogViewer/13L73PD817YC1FXZN4LR/

Battery overcurrent was the first notification,(except the no gps etc, i was flying through my window) i got that in the last flights, can it be cause of the icing?!

part 2
https://www.phantomhelp.com/LogViewer/8MRITPZT3B4RFMM7BFUT/

part 3
https://www.phantomhelp.com/LogViewer/9U2EU7KOTP5STW4FEMT7/

Hi,

Had a look at your log, the last part of your flight.

Many warnings, see my chart of your data.
At the end with RC stick UP, your drone did not climb but still descended.
So resulting lift of the 8 blades not enough for keeping it level or even climbing.
Battery overcurrent warning, so max revs of the motors, so must be icing on blades.

BTW  how cold was it at 500 meters height??

cheers
JJB [ charts by FRAP ; the 'best' software for flightlog analysis ]

I dont think  all the motors were working at the end, the drone was like it was hanging!

cycloholic Posted at 2-24 02:16
I dont think  all the motors were working at the end, the drone was like it was hanging!

Hi,

Combined your 3 logs into 1, see my chart of your flight.

Your first Battery warning at 2m35s in flight, at 202 meter baro height.
Wich such rpeating warnings best to return to home....

Motor block warning does not say motor is actually blocked, if motor < threshold revs warinng is seen too.

Last records vertical speed about 4.3 m/s, drone pitch and roll angles does not show really weird values. Thus motors were spinning, drone descending....

cheers
JJB

I see thanks, but the camera was pointing somehow down with an angle and was wobbling, maybe the gimbal also failed.

About gimball, can this problem in this video be happened because of the cold also? It started at around 40sec

DroneApe Posted at 2-23 15:06
I would pay closer attention to the dew point before you fly in freezing or sub freezing temps.  According to the weather data that I looked at, you literally flew the drone during the dew point.  Not good.

https://www.thedroneu.com/blog/how-cold-is-too-cold-to-fly-a-drone/#:~:text=It's%20generally%20recommended%20to%20avoid,28%2C%20that's%20a%20no%20fly.

To understand how dew point works, in this case for example i should not go near -3 for this particular weather report? So its like -1, at 200m of height it should be around -3 and  screwd up?

cycloholic Posted at 2-24 07:24
To understand how dew point works, in this case for example i should not go near -3 for this particular weather report? So its like -1, at 200m of height it should be around -3 and  screwd up?
[view_image]

Just pay attention to humidity and temperature. Just because the weather station tells you these numbers doesn't mean they will necessarily equal where you're flying.


As a rule, avoid fog + negative temperatures. When we reach the frost point it's the winning combo.

Humidity in general is not great for electronics even if recent DJI drones support it rather well.

cycloholic Posted at 2-24 07:24
To understand how dew point works, in this case for example i should not go near -3 for this particular weather report? So its like -1, at 200m of height it should be around -3 and  screwd up?
[view_image]

I think its when the dewpoint and the air temp are about the same, you can see in your image that the humidity isn't as high as it was when you flew when the issue occurred, e.g. 99%. lower humidity the lower the better, In your image, i would fly, also higher the wind speed the better as that keep the low cloud (fog) away

cycloholic Posted at 2-24 03:05
I see thanks, but the camera was pointing somehow down with an angle and was wobbling, maybe the gimbal also failed.

About gimball, can this problem in this video be happened because of the cold also? It started at around 40sec

Is that you turning the drone or is that the gimbal wobble youre on about? if so, thats crazy bad, sommat not right there for sure!

JJB* Posted at 2-24 02:11
Hi,

Had a look at your log, the last part of your flight.

Prob minus about 4C from the actual 2m temp at least at that height...

cycloholic Posted at 2-24 07:24
To understand how dew point works, in this case for example i should not go near -3 for this particular weather report? So its like -1, at 200m of height it should be around -3 and  screwd up?
[view_image]

Hey,

I’m hesitant to give you specific advice because weather can be tricky.  Sometimes the air is colder at 200 meters when compared to surface.  Sometimes it’s warmer.  Sometimes the wind plays a factor.  Sometimes the water temperature plays a factor if you’re near a body of water.  Sometimes the ground temp can play a factor. Sometimes your proximity to the weather forecast station plays a factor.  Weather can change really quick in winter.

In general, I would probably go by the Drone U advice in that link I gave you, but it’s just general advice.  A general safety guideline.  

I typically look at  current conditions. Then I look at the hourly forecast.  I don’t risk it in marginal conditions. If dew point is risky or visibility is risky or precip is risky or wind is risky or temp is risky. …  I don’t fly.   I live at a much lower latitude than you so there’s not that many days that I even need to worry about it.

Here in the U.S. the fronts are frequent in the winter time and fast moving.  We get a new front every 3-5 days in winter.  With summer  weather patterns the fronts move more slowly so you can have many days of nice weather between fronts.

Someone else may be able to give you more specific weather advice.  Good luck!

cycloholic Posted at 2-24 01:26
Part 1https://www.phantomhelp.com/LogViewer/13L73PD817YC1FXZN4LR/

Battery overcurrent was the first notification,(except the no gps etc, i was flying through my window) i got that in the last flights, can it be cause of the icing?!

Post 17#
Why does Part 2 show App Version 1.9.4 and Parts 1&3 show App Version 1.9.5?

never seen that before.

Because I can!!

cycloholic Posted at 2-24 13:53
Because I can!!

In mid flight?

Tried it again today with same condition an even lower temperature to see if I can replicate it and nothing, not even a battery overcurrent, nothing, nada

cycloholic Posted at 2-24 13:57
[view_image]
Tried it again today with same condition an even lower temperature to see if I can replicate it and nothing, not even a battery overcurrent, nothing, nada

Still doesn't explain 2 different DJIFly App Versions.

Hahaha I’ll keep it secret!

cycloholic Posted at 2-24 14:05
Hahaha I’ll keep it secret!

Congratulations on a lucky escape.
HaHaHa

That was not the problem though!

cycloholic Posted at 2-24 13:57
[view_image]
Tried it again today with same condition an even lower temperature to see if I can replicate it and nothing, not even a battery overcurrent, nothing, nada

The humidity is not high enough, anything over 96% is what I work too but its normally >98%

Something to note; these apps, they are just forecasts and its normally the max highest for that time, some mean for the whole day and may not resemble actual conditions and not only that, they are often wrong, it may have only been 88%, after all, it is a forecast.

Some that actually use current conditions will be using conditions from the local METAR, normally an airport and it will be from the nearest commercial airport to you, not a mickey mouse grass field airport.

As i have said before (poss other thread), use weather underground's wundermap under the maps & radars menu for actual weather conditions, you may need to hit the check box under sensors, see the menu on the right in the image to give you an idea, and I'm not just spouting all this, i actually know a little about it as i run a professional weather station and website for my local community.

A good visual for the humidity that is too high, is fog but this is not always the case certainly not if the wind is above say 4mph (as a guide) as thats too high for fog at ground level.

Yes i understand, it wasnt any fog both days though. Thanks.