Divorce is inevitable, MM and me

chriscuk · Jan 28, 2020

Well airdata seems to think you was flying in wind. 24mph over water with questionable downward sensors is a bit iffy to me. Seems its just a limitation of the mini.

You had the first batch of warnings when the battery was down to 60% and then they just got worse as the battery got lower.
Looking at your inital link you can see you're full throttle in sport but only acheiving 11-12mph. This tells you that you're fighting a stronger wind than "calm".

Also 10mins54-> 10mins58 you're pretty much full stick down = the sudden descent.

Dave Maine · Jan 28, 2020

Wind weather forecasts are just that. They are based on measurements and forecasts for a general area. There are 2 problems. Forecasts are just that. They may not be right at all, or they may not be right at your particular location. Only a wind strength meter at the location tells you what the conditions are at that moment. Nothing is known about before and after.

The second problem is that the wind speed forecast is only for the surface. The speeds and direction change at different altitudes.

The wind speeds reported by the drone are actual instantaneous measured speeds calculated by the internal flight control system. This is the only actual measurement that exists for that time and place.

Measurement beats forecast every time. DJI should be thanked for providing it.

Peio64270 · Jan 28, 2020

Dave Maine said:
Wind weather forecasts are just that. They are based on measurements and forecasts for a general area. There are 2 problems. Forecasts are just that. They may not be right at all, or they may not be right at your particular location. Only a wind strength meter at the location tells you what the conditions are at that moment. Nothing is known about before and after.

The second problem is that the wind speed forecast is only for the surface. The speeds and direction change at different altitudes.

The wind speeds reported by the drone are actual instantaneous measured speeds calculated by the internal flight control system. This is the only actual measurement that exists for that time and place.

Measurement beats forecast every time. DJI should be thanked for providing it.

Usually, wind forecasts are given for 10m (~30 feet) altitude above ground.
Second, many specialists here said that windspeed calculated by Airdata (and not "reported by the drone") are biaised since Airdata doesn't uses the Spark profile instead of any MM profile.
Having read multiple reports of this issue, I think the op is right : there is something wrong either with the Mini flight control or with the motors/propellers.

chriscuk · Jan 28, 2020

Seriously am I the only one to see the stick inputs at 10mins54sec where he is left stick down. Funnily enough the drone drops in height.

Also check my other thread of mini vs mavic2 as I checked them in the wind and there was a max of 10% difference in the wind readings from m2p to mini. The guts were <3% diff.

Gkinghrn · Jan 28, 2020

chriscuk said:
Seriously am I the only one to see the stick inputs at 10mins54sec where he is left stick down. Funnily enough the drone drops in height.

Also check my other thread of mini vs mavic2 as I checked them in the wind and there was a max of 10% difference in the wind readings from m2p to mini. The guts were <3% diff.

Nope - I see it too ...stick goes orange then red ....

m80116 · Jan 28, 2020

I think the FC on the Mini is messed up by some weird logics, probably the GPS altitude or barometer altitude is having precedence. I've experienced this problem myself and managed to find a way to reliably reproduce it. Until DJI fixes the problem one should be very careful flying at high altitudes (mountains) or descending while going forward at max speed to a halt.

RodPad · Jan 28, 2020

chriscuk said:
Seriously am I the only one to see the stick inputs at 10mins54sec where he is left stick down. Funnily enough the drone drops in height.

Also check my other thread of mini vs mavic2 as I checked them in the wind and there was a max of 10% difference in the wind readings from m2p to mini. The guts were <3% diff.

I don't understand why you think that is an issue, yes it is working correctly at the point.

Here there are no stick movement shown, between these to points.
10m 59.6s 16ft
11m 0.4s 12.1ft
Then from here stick moments are all up, but the AC is still going down.
This part would be correct if was flying inverted.

Rod

RodPad · Jan 28, 2020

m80116 said:
I think the FC on the Mini is messed up by some weird logics, probably the GPS altitude or barometer altitude is having precedence. I've experienced this problem myself and managed to find a way to reliably reproduce it. Until DJI fixes the problem one should be very careful flying at high altitudes (mountains) or descending while going forward at max speed to a halt.

I agree with you, but "one should be very careful flying at high altitudes (mountains) or descending while going forward at max speed to a halt."
A really don't think any location is going make anything safe or safer.
Yeah something is wrong with it.

@sar104,
There is a new link for the flight log.

Rod

chriscuk · Jan 28, 2020

So

RodPad said:
I don't understand why you think that is an issue, yes it is working correctly at the point.

Here there are no stick movement shown, between these to points.
10m 59.6s 16ft
11m 0.4s 12.1ft
Then from here stick moments are all up, but the AC is still going down.

So during that time it's just been descending and still has downward momentum. stick up wont just instantly gain height it'll have to stop the deceleration AND provide lift. All the time there is no horizontal stick movement but the craft IS being pushed backwards at 3-4mph by the wind so clearly struggling.

It's been noted before that the craft will gradually drop in height when fighting wind.

Chrislopez · Jan 28, 2020

I'm sorry friend. unfortunately the mavic mini is a toy with a camera and that's it. It has no resistance or strength like spark or air

David2111 · Jan 28, 2020

Gentlemen thank you for your wise input into what happened (DJI don't provide such detail).

Here are a couple of short videos showing the conditions that day, please note the ripples on the water and the general area. IMHO it was a mild day.

And here is the Flight log again.

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

I can honestly say if the Mavic Mini cannot fly in these sort of conditions without some potential catastrophic failure, then its back to the Mavic Air for me.

This thing dropped 27 feet in front of me and failed to respond to my inputs.

RodPad · Jan 28, 2020

@chriscuk,

This is what bugs me.....

Section A:
10m 53.4s 39 ft.
10m 59.6s 16.1 ft
He brings it down.
22.9 ft in 6.2 seconds.

Section B:
10m 59.6s 16.1 ft
11m 0.4s 12.1 ft.
Stick at center.
Lost 4 ft in 8 seconds.

Section C:
11m 0.5s 11.8 ft.
11m 4.9s -11.2 ft.
Stick up with a left
Lost 23 ft in 4.5 seconds

Section D:
11m 4.9s -11.2 ft.
11m 8.8s 11.5 ft
Stick up with a left.
Gained 22.7 ft in 3.9 seconds.

Between Section B:, and Section C:
It drops faster with the stick up.

Between Section C: and Section D:
It looks it acting normal, did it get more lift from the water, it didn't want to get wet.

At its lowest point you see a the cell2 may be struggling is that also more lift from the water?

Rod

Mossiback · Jan 28, 2020

It is possible that DJI has sacrificed lift over positioning for the Mini with the idea that losing height might find lower wind speeds (of course, it may also find a tree). At hover in a strong wind with no stick input, my MP will try to maintain height and position by increasing rpm and tilt. Once rpm and tilt are at their maximum it will be blown downwind while maintaining height. Up stick and windward stick input will have no effect due to already being at the max. That may be why up stick input had no effect in this case; the Mini was already at max rpm.

Having said all that, I have to agree with the OP regarding winds in his flight. The videos show ideal flying conditions. I know the wind speed and direction can vary greatly between ground and flight altitude but if he was having control problems at the altitudes shown in the videos there is something wrong.

chriscuk · Jan 28, 2020

well his flight data shows gusts of 24mph so far from ideal.

Mossiback · Jan 28, 2020

chriscuk said:
well his flight data shows gusts of 24mph so far from ideal.

Like I said, speeds are different at higher altitude. The videos at low altitude did show ideal conditions. Perhaps if he had stayed at the lower altitude there would have been no problems.

David2111 · Jan 28, 2020

chriscuk said:
well his flight data shows gusts of 24mph so far from ideal.

Hi Chris, I don't want to argue with facts, but it honestly did not feel like a windy day. Do you have the stats around 11 minutes when the drone did its dive?

RodPad · Jan 28, 2020

chriscuk said:
well his flight data shows gusts of 24mph so far from ideal.

15 feet above take off point he has 20 mph wind?

Air Data
2m 05s
Elevation 4.5 meters 14.7 Feet
Home Distance 23 meters 75.5 feet
Wind 20 Mph

But it seems to holding very well, no stick movements and no drift

Flight Log
2m .05s
Elevation 14.8 Feet
Home Distance 72.9
Speed 0 Mph

Air Data
9m 5s
Elevation 18 meters 59 Feet
Home Distance 68 meters 223 Feet
Wind 23.5 Mph

But it seems to holding very well, no stick movements and no drift

Flight Log
9m 5s
Elevation 59.1 Feet.
Home Distance 222.7 Feet
Speed 0 Mph

Yeah my P3A would have troubles in ether of these cases, it would be drifting, it would not have a speed of zero.

If I did believe Air Data's Wind Data. Then the OP is not showing video he took that same day.
I would also be using my free account that came with Litchi, but I wasn't impressed before when there were Healthy Drones.

BTW, why are the showing results in meters, but the wind speeds in Mph?

20 Meters per hour, 0.01 Miles per hour
23.5 Meters per hour, 0.01 Miles per hour.

20 Kilometers per hour, 12.4 Miles per hour.
23.5 Kilometers per hour, 14.6 Miles per hour.

So what are we actually looking at for wind speeds?

Rod

chriscuk · Jan 29, 2020

At the 11min mark it's showing you're drifting in the wind but airdata doesn't have any calcs for that time.
it's got one at 10min 10secs @ 7.63mph then at 11min 50 its showing 23.96mph.

David2111 · Jan 29, 2020

Thanks Guys for all your help on this. However, they mystery deepens. This is the local weather forecast for Armagh on the day that I flew, Sunday 12th January at around 12.18

Winds are light.

This is the full video that I took that day, it covers about 6 minutes of the flight. This was my maiden flight over an open space with the Mini, I got it before Christmas and did a few flights in my garden. All firmware including batteries was up to date. I was checking the feel of the controls, quickshots etc. and getting familiar with the new app. There is a strange tilt on the drone at 4.10, it might be what DJI mentioned in there reply to me. To me, it was a perfect day for flying, but according to Airdata and DJI I was flying in 24mph winds.

I don't understand, I have flown my Mavic Air at the top of the Stelvio Pass in Italy and in other windy conditions, does this look like 24mph winds to you?

chriscuk · Jan 29, 2020

At ground level it is calm as the wind altitude map shows. You can argue that it was calm as much as you like but we can only go on data. It's calm on my driveway right now but the big tall trees nearby are swinging around making it look 20+mph

also you're flying in a very flat area so ground level may be fine but higher could be anything.