Mavic mini fly away

[Bthag]

After a wonderful year with my mavic mini it decided to fly away. I was using litchi. Can anyone tell me what happened by viewing the csv log?

2021-04-15_18-29-48_v2.csv

 

[sar104]

The wind at the final flight altitude of 140 m was over 11 m/s from the north west (~ 300° but variable). That's more than the Mini can combat in RTH, and it was being blown away to the south east at a couple of m/s. It had around 680 seconds of battery left before autolanding (assuming 15% - Litchi doesn't report the exact smart battery autoland level), and so it is likely to have continued for around 1.5 km. The intersection of the red line and circle below indicates an estimated landing location, but given the variable wind and the unknown autoland battery level the margin of error is going to be significant.

 

[CactusJackSlade]

Wind was going to be my first guess. Wind at altitude, even only several meters above the ground can be very different.

 

[Meta4]

After a wonderful year with my mavic mini it decided to fly away

Your recorded flight data tells a completely different story.
It shows you gave your drone away to the wind.
Your first mistake was having no concern for the direction the wind was blowing and flying off downwind.
The second was to fly higher, not realising that higher up, the wind is usually stronger.
The third one was with the drone up 450 feet and 2900 feet away, you left it to RTH to bring it home against a strong headwind.
The drone was being blown backwards at 6 mph while trying to get home.
The fourth mistake was to just leave it up there to be blown away.

So why say that the drone decided to fly away?
Someone else made all the important (and wrong) decisions.
The drone had no say in the matter.

 

[DBT_Drone]

Ouch........hard lesson learned for him I guess.

 

[Duds]

Hahaha Meta, harsh words but true. Pilot error. Never be complacent. In preflight check its not only the craft but weather and terrain conditions too. If possible always make downwind the rth direction.

 

[Me262]

Can someone please tell me why on earth does the program not display the wind speed? When the drone hovers high in the air, all it shows is 0.0m/s, but that can also mean the drone is actually traveling close to it's maximum speed to try to maintain that hold position, meaning it's like flying it full forward.

This simple aspect I find absolutely moronic from DJI, and I really think DJI is omiting this info just to have people lose their drones so they can sell more (how come there is no option to buy JUST the drone, without the remote? oh yea, I think I know...) or at least motivate their insurance sales.

I still don't know if the actual horizontal speed that it does display is ground speed or air speed. Because if it's air speed, it's absolutely worthless.

 

[Meta4]

Can someone please tell me why on earth does the program not display the wind speed?

It does, if you are smart enough to use the info it provides.
Know how fast your drone flies in still air.
Try flying straight into the wind and note how much the wind takes off your still air speed.
That's all the wind speed info you need.

This simple aspect I find absolutely moronic from DJI, and I really think DJI is omiting this info

How would DJI display the data?
Wind can come from any direction, which makes everything much more complex to display and to understand.
For most flyers, it would only confuse things more.

I still don't know if the actual horizontal speed that it does display is ground speed or air speed. Because if it's air speed, it's absolutely worthless.

It doesn't take much thinking to work it out. (and it's not worthless).

 

[Me262]

It does, if you are smart enough to use the info it provides.
Know how fast your drone flies in still air.
Try flying straight into the wind and note how much the wind takes off your still air speed.
That's all the wind speed info you need.

How would DJI display the data?
Wind can come from any direction, which makes everything much more complex to display and to understand.
For most flyers, it would only confuse things more.


It doesn't take much thinking to work it out. (and it's not worthless).

If it's air speed, the speed will always be the same no matter if the wind blows 5m/s or 50m/s. The only way to figure it out is if the speed is actually ground speed. Then if you fly it into wind, you can see the slower speed.

As for how they could easily tell you the wind speed and direction, is by the GPS, since the drone must move into the wind to maintain ground speed. That gives it air speed. They could display the air speed, which is what the wind speed is, if it's hovering.

 

[sar104]

If it's air speed, the speed will always be the same no matter if the wind blows 5m/s or 50m/s. The only way to figure it out is if the speed is actually ground speed. Then if you fly it into wind, you can see the slower speed.

As for how they could easily tell you the wind speed and direction, is by the GPS, since the drone must move into the wind to maintain ground speed. That gives it air speed. They could display the air speed, which is what the wind speed is, if it's hovering.

The FC calculates wind speed and direction based on the relationship between tilt, heading and ground speed. Those data are recorded in the DAT files, but are not displayed in the app. The aircraft speed displayed in the app is ground speed, before you go to much further into that debate.

 

[MAvic_South_Oz]

If it's air speed, the speed will always be the same no matter if the wind blows 5m/s or 50m/s. The only way to figure it out is if the speed is actually ground speed. Then if you fly it into wind, you can see the slower speed.

As for how they could easily tell you the wind speed and direction, is by the GPS, since the drone must move into the wind to maintain ground speed. That gives it air speed. They could display the air speed, which is what the wind speed is, if it's hovering.

I guess they could introduce some sort of algorithms based on rotor revs needed to fly in a direction as it moves, gauge approx wind speed from any direction, but it would require a lot bigger (another) processing capability.
Extra cost is most likely going to be prohibitive, possibly weight in larger hardware needs (could be miniscule though), and in general most info can be gleaned from the way the aircraft is behaving.

Heck if a mini still moving / flying away on RTH isn't dead easy to see, then the pilot really isn't aware of that sort of flight info being right there on screen.
If they are aware, they can either land immediately in a safe place, if not too far away, drop to an altitude where the wind is less strong, though signal then can be affected and an auto RTH starts again.

Probably the best thing to do (in hindsight) is flight planning to include wind direction, plan to start flying into the wind, gain altitude and monitor resistance to speed as you go up.
Once you are confident your scope of airspace is safe for the drones capability, you can relax and do your flight in relative ease, not much is going to change in 15 - 20 mins.

Pity the attitude bowl is still not shown on the Fly app ?
Unbelievably easy to use this on Go4.

 

[Me262]

I guess they could introduce some sort of algorithms based on rotor revs needed to fly in a direction as it moves, gauge approx wind speed from any direction, but it would require a lot bigger (another) processing capability.
Extra cost is most likely going to be prohibitive, possibly weight in larger hardware needs (could be miniscule though), and in general most info can be gleaned from the way the aircraft is behaving.

Heck if a mini still moving / flying away on RTH isn't dead easy to see, then the pilot really isn't aware of that sort of flight info being right there on screen.
If they are aware, they can either land immediately in a safe place, if not too far away, drop to an altitude where the wind is less strong, though signal then can be affected and an auto RTH starts again.

Probably the best thing to do (in hindsight) is flight planning to include wind direction, plan to start flying into the wind, gain altitude and monitor resistance to speed as you go up.
Once you are confident your scope of airspace is safe for the drones capability, you can relax and do your flight in relative ease, not much is going to change in 15 - 20 mins.

Pity the attitude bowl is still not shown on the Fly app ?
Unbelievably easy to use this on Go4.

How do you monitor the resistance to speed if there are no indications?

 

[MAvic_South_Oz]

How do you monitor the resistance to speed if there are no indications?

True, not easy, motor revs will change with direction flown / wind direction, not sure if Fly shows this (like Go4).

 

[sar104]

I guess they could introduce some sort of algorithms based on rotor revs needed to fly in a direction as it moves, gauge approx wind speed from any direction, but it would require a lot bigger (another) processing capability.
Extra cost is most likely going to be prohibitive, possibly weight in larger hardware needs (could be miniscule though), and in general most info can be gleaned from the way the aircraft is behaving.

Heck if a mini still moving / flying away on RTH isn't dead easy to see, then the pilot really isn't aware of that sort of flight info being right there on screen.
If they are aware, they can either land immediately in a safe place, if not too far away, drop to an altitude where the wind is less strong, though signal then can be affected and an auto RTH starts again.

Probably the best thing to do (in hindsight) is flight planning to include wind direction, plan to start flying into the wind, gain altitude and monitor resistance to speed as you go up.
Once you are confident your scope of airspace is safe for the drones capability, you can relax and do your flight in relative ease, not much is going to change in 15 - 20 mins.

Pity the attitude bowl is still not shown on the Fly app ?
Unbelievably easy to use this on Go4.

As I said above (post #10) - wind speed is already calculated by the aircraft FC. It's not a function of motor speed - just tilt angle, direction and ground speed.

 

[Meta4]

How do you monitor the resistance to speed if there are no indications?

But there are indications if you look at your screen.
You do it by monitoring the drone's speed and being conscious of the wind direction and how that relates to the direction you are flying.
You have to do a little thinking to be in command of a flying machine and be able to bring it back home.
You have to think about the wind and how it will affect your planned flight before you launch.
Pay particular attention to what wind the drone is going to deal with on the return to you.

It's no simple matter to display the wind data in a form that's helpful.
Wind is a two dimensional thing, it can come from any direction.
Pushing into a wind at 30° to the drone's heading has a completely different effect to having the wind at 45°, 90° 120° or some other angle.
How would you display that simply and then the operator could be facing a different direction compared to the drone's heading.
Do you factor that as well?
It all becomes too cumbersome and would provide even more opportunity to confuse flyers.
Particularly when many don't even think about wind direction (or know that their indicated speed is groundspeed).
More data isn't the answer, more thinking is.

 

[ATW]

If I decide to fly my mini on a windy day, and I have. Then I fly into the wind heading outbound, so the wind will help bring it back to me. I may see 10 mph outbound, and 40 coming back.

 

[Me262]

If I decide to fly my mini on a windy day, and I have. Then I fly into the wind heading outbound, so the wind will help bring it back to me. I may see 10 mph outbound, and 40 coming back.

What do you fly? I fly mini 2 so I use the go fly app, but I don't know if I can trust the speed it shows, even if it is ground speed as some claim. It always shows 10m/s for me in normal mode even in high wind, which makes me think it's air speed (and thus, useless)

 

[Meta4]

I don't know if I can trust the speed it shows, ... It always shows 10m/s for me in normal mode even in high wind, which makes me think it's air speed (and thus, useless)

Why would you imagine that DJI would show a useless speed indication?
Where is the sensor that could measure airspeed?

even if it is ground speed as some claim.

As some claim ??
As in some who have flown DJI drones for >6 years and know them inside out?
I very much doubt that your speed indication shows a constant 10 m/s.
If it does, you've never flown into a significant headwind.

 

[ATW]

I fly a Mini, and mine shows all sorts of different ground speeds. I can fly 6 different directions away from where i stand, in a 10 minute time period, and get 6 different speed readings.

 

[Flycaster]

I believe you should have received a "high wind warning", derived from the angle of attack the drone needs to hold position. If it exceeds a preset (by DJI) angle needed to keep a hover position, then that is how they "calculate" the high wind warning"....