Mini 4 Pro Would Not Come Down

[Dmonwai]

I just bought a Mini 4 Pro Fly More Combo minus the drone. The seller said he lost the drone and just wanted to sell the rest of the kit. I asked him how he lost the drone and he said he flew it straight up and then it wouldn't come back down. He said the drone stopped responding to the controller and then ran out of battery and it fell from the sky and he couldn't find it.

When I got home I started up the controller and looked Profile and it shows the seller had only done two flights, the second one he lost the drone. Looking at the second flight where he lost the drone, he flew it up over 1500 feet in altitude!

It stays up there varying by a few hundred feet until the battery runs out. When the battery gets so low that it automatically starts landing it doesn't seem to come down in altitude. It looks like it fell from over 1200 feet when the battery completely died. Can any experts give some insight on what or why it it didn't come down when it started auto landing/forced landing when the battery got low enough? I've linked the flight log. Thanks!!

Flight Log

 

[Meta4]

Can any experts give some insight on what or why it it didn't come down when it started auto landing/forced landing when the battery got low enough?

The previous owner knew nothing about drone flying.
His drone never stopped responding.

It was descending, but slowly (at about 0.2 metres/sec) and came down 240 ft before the battery ran out..
The reason for this was that the VPS sensors were showing that the drone was only a few inches above the ground and landing protection was active to prevent a hard landing.

It looks like the VPS sensors were dirty or blocked by an accessory.

 

[slup]

Exactly as @Meta4 said... something covered the VPS sensor making the drone think it was between 0-2,2ft above ground during the whole flight, that made the descent speed really slow (called zspeed in the chart below).

Here some facts visualized in graphs from the moment where the "smart battery landing" set in, still up above 1300ft barometric height...

Pink background = Smart Battery landing
Green background = Serious low voltage landing
Then the meaning of the graphs is shown under the chart in the legend.

Have placed a chart marker where the cell voltage have reached the usual major voltage drop off point that all lithium batteries have... it's easy to see where the voltage had become so low that it no more could keep the drone airborne, just in the end of the log the light green graph which is vertical speed, suddenly increases.

(Click on the chart to make it larger)

 

[Phantomrain.org]

We have also found the Sensors on the mini 3 and Min 4 to very sensitive to some third party landing gear as well as Rain and Dirt / Frost / Snow causing the drone to get confused.

This is why we put so much focus on the Wet Suits protecting the Sensors when flying in the rain/snow

Phantomrain.org
Gear to fly in the Rain, Protect the Sensors and the battery .

 

[MS Coast]

Do we know the location and date/time? It would be interesting look for a weather data archive and see if there was fog or low clouds that might have triggered the downward sensors.

 

[dave canada]

I just bought a Mini 4 Pro Fly More Combo minus the drone. The seller said he lost the drone and just wanted to sell the rest of the kit. I asked him how he lost the drone and he said he flew it straight up and then it wouldn't come back down. He said the drone stopped responding to the controller and then ran out of battery and it fell from the sky and he couldn't find it.

When I got home I started up the controller and looked Profile and it shows the seller had only done two flights, the second one he lost the drone. Looking at the second flight where he lost the drone, he flew it up over 1500 feet in altitude!

It stays up there varying by a few hundred feet until the battery runs out. When the battery gets so low that it automatically starts landing it doesn't seem to come down in altitude. It looks like it fell from over 1200 feet when the battery completely died. Can any experts give some insight on what or why it it didn't come down when it started auto landing/forced landing when the battery got low enough? I've linked the flight log. Thanks!!

Flight Log

when drones lose gps and compass there lost but usually this happens on a waypoint mission

 

[slup]

Do we know the location and date/time? It would be interesting look for a weather data archive and see if there was fog or low clouds that might have triggered the downward sensors.

Ground forecast from Airdata at the time of the flight... which was conducted mid day approx 2PM.

 

[Meta4]

when drones lose gps and compass there lost but usually this happens on a waypoint mission

That's an odd thing to say in this thread.
There were no GPS or compass problems and you wouldn't expect any on a waypoint mission either.

 

[MS Coast]

Ground forecast from Airdata at the time of the flight... which was conducted mid day approx 2PM.

View attachment 173113

That seems to rule out fog. Being in or above a low cloud might create a problem. But I just re-read post #3 and noted that @slup said the VPs sensor was triggered for the entire flight. So, not cloud or fog related.

 

[Dmonwai]

Thanks everyone!! Thats all very informative.

 

[Frank071]

Related question: given that the drone signals quite a lot, why doesn't it signal something is wrong when the IMU altitude is changing (considerably) whilst the VPS altitude remains the same. Is that not a clear signal that something is wrong? Especially if the drone consequently changes its behaviour (slow downward speed) based on the VPS alt.

 

[Meta4]

Related question: given that the drone signals quite a lot,

The data stream is continuous

why doesn't it signal something is wrong when the IMU altitude is changing (considerably) whilst the VPS altitude remains the same.

Because it's not programmed to

 

[Frank071]

The data stream is continuous

Because it's not programmed to

Thanks. Informative... What I meant was: there are quite many conditions about which the drone informs the user ("signals quite a lot"), what could be the reason why there is no warning about discrepancies between the two. I understand that it is not programmed to...

 

[slup]

That the barometric height & VPS height differs & one also maybe change but not the other doesn't mean that something is wrong. One measure the height relative to the HP & the other measure the height to whatever is sensed directly below the drone that is within the reach of the VPS sensor.

If you fly up a mountain, close & with a constant height above ground... the barometric height will tell you that you have ascended quite a lot from the HP, but the VPS height will not show any increase in height at all besides the initial in the beginning of the flight.

 

[Feek]

The previous owner knew nothing about drone flying.

Got to feel a bit sorry for the original owner. Buys a drone, takes it out for its second flight and decides to see how high it'll go and then gets knackered by a fault that stops him bringing it back down again. Yes, I know it was irresponsible to go that high but even so.

 

[Touring497]

The previous owner knew nothing about drone flying.
His drone never stopped responding.

It was descending, but slowly (at about 0.2 metres/sec) and came down 240 ft before the battery ran out..
The reason for this was that the VPS sensors were showing that the drone was only a few inches above the ground and landing protection was active to prevent a hard landing.

It looks like the VPS sensors were dirty or blocked by an accessory.

I agree with the assumption above. Same symptom happened to my mini 4 pro poor albeit at only 150 feet. I put on a landing accessory which unfortunately and unknowingly partially covered the vps sensor. The drone went up astonishingly fast but when I tried to bring it home down, it was coming down but at an excruciatingly slow speed… really slow as if it is not going down at all. Not surprisingly, as soon as I removed the landing gear and tested the descent, everything is back to normal. Be careful really with this vps sensor.

 

[skycam509]

Are there protective stickers on the VPS sensors when new? Maybe he forgot to remove them.

 

[jeplane]

Got to feel a bit sorry for the original owner. Buys a drone, takes it out for its second flight and decides to see how high it'll go and then gets knackered by a fault that stops him bringing it back down again. Yes, I know it was irresponsible to go that high but even so.

As an airplane pilot, an irresponsible drone pilot bringing his aircraft so high in the air where the rest of us are flying, p…sses me off to no end. The last thing I want is hit a drone at 250 Kts while flying a jet.
However I would also blame the drone sellers for not requiring a basic knowledge of regulations before flying a drone for the first time.

 

[Meta4]

I agree with the assumption above.

There was no assumption i the advice I gave.
It was the result of detailed analysis of the recorded flight data.

 

[Touring497]

There was no assumption i the advice I gave.
It was the result of detailed analysis of the recorded flight data.

I stand corrected. Tnx.