air2s dissapeared at 300ft during sunset

[scott492010]

The flight data is on your control device. You have been told how to retrieve it.

by god i forgot all about that... i will look into that when i get a chance... currently i have a messed up back and have been laying around while it rained... in the next few days i will be getting some chores done....extremely slowly.

 

[scott492010]

I'm not going to plough through the thread again but I thnk you said the drone was working. If so and if you want to get some, based on fact, idea of what happened, download the DAT from the drone and send it to DJI for analysis.
They may charge for this.

The DAT on the drone is recorded internally within the drone and not subject to controller disconnections.
If the crash whatever was not a simple battery disconnection then the drone's DAT should cover the period from drone switch on, through disconnection and landing, to drone switch-off/battery_exhaustion.

That said the crud on the battery reminds me of the residue I find when cleaning mulched grass from the lawn mower, I think the mower hit the battery at least.

As for damage to the right rear prop, to me that looks like damage to the blade's trailing edge.
If correct my guess of the cause is that the tip of that blade was stopped dead by something and that the other blade on that motor came round and smacked into the damaged blade's trailing edge.

I've seen similar damage on an m2p blade where the blade caught a piece of solid wood and would have stopped dead or been 'dragged' backwards relative to the motor.
The impact with the wood would have been to the leading edge but the damage to the blade was to the trailing edge. I think the above was the mechanism of that damage.

I would guess that if you turn the damaged blade to its limit of REVERSE travel and then turn the other blade fully forward, the leading edge other blade will meet the damaged blade at the point of damage.

You don't show enough of the front left prop to judge anything, if 'judgement' is even possible.

If you think the drone 'took off' and yet say you were/are, at night, able to see the drone at great distance thanks to the existing LEDs, how then do you explain it becoming invisible in what I assume were the few seconds that you were looking at the screen and not the drone?
Surley it couldn't have flown out of the range of your eyesight in those few seconds ?

My first thought would be it became invisible because the LEDs switched off due to some sort of power failure. Of course it is possible that zooming did something that screwed up the control system but we will never know a fact based reason unless DJI decrypt the DAT from the drone and tell you.

If you send the DAT in I suggest you ask them if they can send you csv's etc of the decrypted DAT.
Whether or not they will do that is anybody's guess.
Aside from anything else I am sure some people here would love to get a look at such csv's.

I agree with everything you said. You are in agreement with me full heartedly. I do have the other prop but i have not taken a photo of it....mostly because it is in my truck and i have a sore back and keep forgetting to grab the prop when i am out there. that other prop most definitely chopped at the ground or gravel.

the reason i believe it became invisible is.... this will also give an explanation why i keep harping on this... In the dark at night .... ( do not quote me on exact wording of warnings. i dont have them in front of me now. ) when i am flying multiple alarms show. Two of which i notice each time this all happens. sensors not working due to low light and compass needs calibration. Upon receiving those specific alarm warnings at the same time i have repeatedly witnessed my drone start flying in crazy uncontrolled ways. flying uncontrolled whacky maneuvers. Sometimes i have even lost connection to the controller but not every time. I believe this is what happened. Once the drone went behind a building i would not be able to see it. If it was invisible to me behind a building then it would be very low to the ground.

once it was on the ground behind a building i believe it and the battery were dragged and or carried around by either the fox or my neighbors dog. My neighbors dog has definitely stole my dogs toys in the past and that fox i swear wants to come in and have me feed it from this point forward due to the jealousy of my dog.

and yes... after all that i definately think the battery was ran over by the mower. not the drone though.

yet someone here....not pointing fingers... keeps stating i am ignorant to the facts and do not know what i am talking about because i supposedly did not analyze this or that.... now i did forget that i could go back on the tablet used on the controller to find the logs and therefore i did not provide logged facts but come on.... so ****. As stated above this forum is supposedly to help or inform other pilots. Well i would think it would be informative to let others know this has happened before without someone saying no that is impossible simply because you did not provide the logs etc.... what is next? in order to participate in this forum i need to fill out a 5Y report? Or is it just simply put that in order to participate in this forum i have to spend the extra time....an hour or two preparing this and that with corresponding photos and or videos.... interview possible witnesses. tie the dog to the chair and focus a bright light close to her face and drill her for answers? what possible purpose would i have for lying about such a thing?

Ostensibly, I only intended to see if there was a way to find the drone without it being powered.

 

[Yorkshire_Pud]

You are in agreement with me full heartedly.

Sorry but I am not in agreement with you.
I suspect it is more likely that the drone became invisible because there was, for whatever reason, a power failure, be that a battery disconnection or something else........
At a height of 300ft+ I think the drone might have taken some time to be masked by the buildings closest to the home point ..........BUT given that there is currently no conclusive proof either way I am keeping an open mind about things.

This is why I am suggesting sending the drone's DAT to DJI.
If the drone went crazy then there will be, or should be, DAT data that would show the drone at least being powered beyond the disconnection and, if the DAT wasn't corrupted by any craziness, then it may show what actually happened.

If the drone's DAT ends at the same time as the disconnection then it is, I think, fairly conclusive proof that the disconnection was caused by a power failure.

Currently a Fly App screen device DAT for the mavic mini runs to 290 columns of data.
A Fly App screen device DAT from a Mini 3 Pro runs to 485 columns.
By comparison a drone DAT from a Phantom 3 runs to 710 columns of data.

Not ideal comparisons I agree but the DATs from my later-model-drone drones are all encrypted but given my recollection of the size of Fly App drone DATs I think there is likely to be an awful lot of data in the drone's DAT that DJI can analyse.

 

[Yorkshire_Pud]

This is why I am suggesting sending the drone's DAT to DJI.
If the drone went crazy then there will be, or should be, DAT data that would show the drone at least being powered beyond the disconnection and, if the DAT wasn't corrupted by any craziness, then it may show what actually happened.

If the drone's DAT ends at the same time as the disconnection then it is, I think, fairly conclusive proof that the disconnection was caused by a power failure.

It has just occurred to me that you can perhaps perform a crude experiment concerning the above.

Assuming the size of the drone DAT is proportional to the length of time the drone was switched on and assuming you can split the DAT available from the drone into individual flights ( I do not know if the relevant Assistant 2 facilitates this, you will need to check that for yourself ) and that you can identify the drone DAT for the troubled flight, then you could see the log's size for the troubled flight.

If you then create a new DAT for a low level flight lasting 424 seconds or so, including motor start, take off, landing and motor stop.
Start the actual flight after a drone-switch-on-to-motor-start-delay that matched the corresponding delay preceding the troubled flight and switch the drone off ASAP after landing it.
Compare the size of the new DAT with that of the DAT of the troubled flight.

If I am correct in assuming that the DAT size is proportinal to its duration then if the two DAT's are of similar size then it would mean that the duration of the switch on was similar.
Whereas if the DAT of the troubled flight is significantly larger than the DAT of your test then it perhaps supports your "crazy" hypothesis.

@BudWalker @msinger @sar104 @slup .......... is the size of the drone DAT proportional to its duration ?

 

[Meta4]

If the drone went crazy then there will be, or should be, DAT data that would show the drone at least being powered beyond the disconnection and, if the DAT wasn't corrupted by any craziness, then it may show what actually happened.

A simpler test would be to check the battery level.
If the drone "went crazy" (it didn't), the battery level would be substantially less than the 69% indicated when the power went off.

 

[Yorkshire_Pud]

A simpler test would be to check the battery level.
If the drone "went crazy" (it didn't), the battery level would be substantially less than the 69% indicated when the power went off.

True but the battery is dead, isn't it ?

I suppose one could measure the voltages with a volt meter but would that serves as a percentage checker?

 

[MS Coast]

when that warning comes up at the same time as "compass needs calibrated" it does. please do not quote me on exact wording of the warning.

How many instances have you observed where those two messages occurred simultaneously and you lost control of the drone? What did the drone actually do that you describe as flying in "crazy uncontrollable ways?" Was there a crash on each occasion?

 

[BudWalker]

.......... is the size of the drone DAT proportional to its duration ?

I expect so.

 

[BroomRider]

Just my observation here, & I don't have nor have I ever flown anything other than the Mini 3 Pro, & admittedly, it's a different bird, but although if I do fly in low(er) light conditions, I will always get the “low light” warning.

I've never had any regular “compass calibration error” warning, at night, dawn/dusk, nor day, regardless of the light level.

The only time I ever got a “compass calibration error” was when I tried to launch from the top of a power transformer case, & when I saw that warning, picked the drone up, & launched it from a nearby (wooden) picnic table with no problems.

No idea how old that battery was, nor how many cycles it had accrued; thankfully, I've not had a battery failure to date with which to compare experiences.

I think that a potential issue might have been, if there was some kind of “Elevated Kp event” interfering with the signal.

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Last summer, I did launch at dusk to do a video recording of 2 Independence Day celebrations, & specifically, to record the fireworks displays over the water.

Both times, for the entire duration of the battery, I had no difficulties whatsoever, & landed without any issues.

While I think it is an interesting exercise in speculation, I think, IMO, it is prudent to retrieve the flight data & base any analysis from that.

As for autorotation of the props on the way down, & whether they might provide some mitigation of the free-fall descent velocity & resulting impact with the ground.

They are lots lighter & hence would not have the inertia to keep rotating after the power was removed.

In the case of helicopters, in an autorotation due to loss of engine power, the pilot is still able to control the pitch of the rotor blades. He pitches them downward to use the downward velocity & the wind generated from that to keep them rotating, & able to soften the landing by pitching the rotor blades up, using their inertia from rotation, just before impact/landing.

Drone pilots have no such control, & some — like mine & the 1 in the picture — have folding rotor blades. I think it worth pointing out that, the prop blades fold, & thus in doing so, would fold to provide the least resistance due to wind pressure. The drone would tilt similar to an arrow, with the heaviest part (the body of the drone) aimed down & the folded prop blades acting as the feathers or fins.

Also, the drones, afaik, will auto-shut-off their prop blades, if the drone exceeds a certain degree off horizontal.

Anything lacking the retrieved flight data, is, IMO, mere speculation, not fact, & claiming otherwise is… ill-founded at best.

 

[Meta4]

I think that a potential issue might have been, if there was some kind of “Elevated Kp event” interfering with the signal.

High Kp events don't cause a drone to fall to earth.
In fact they don't cause any flight incidents.

While I think it is an interesting exercise in speculation, I think, IMO, it is prudent to retrieve the flight data & base any analysis from that.

That's been done, but when the power fails, so does the data and there is no data to show what happened after that.
But sensible flyers have no trouble imagining what happens when there is a sudden loss of power and gravity takes over.

Also, the drones, afaik, will auto-shut-off their prop blades, if the drone exceeds a certain degree off horizontal.

At the time the power and data was lost, the drone was hovering on perfectly calm conditions.

Anything lacking the retrieved flight data, is, IMO, mere speculation, not fact, & claiming otherwise is… ill-founded at best.

That's 100% correct.
And speculating things that are outside the realm of drone performance possibility will never be close to what actually happened.

 

[Yorkshire_Pud]

As for autorotation of the props on the way down,

I think it is questionable as to whether or not these foldable props will rotate at all during a free fall, if they do then I suspect they will be driven backwards. I have seen a DAT from a free falling P3 and from memory the rpm's were negative and experiments suggested that drone props are driven backwards if not powered and there is sufficient 'updraught'.

 

[Yorkshire_Pud]

think it worth pointing out that, the prop blades fold, & thus in doing so, would fold to provide the least resistance due to wind pressure. The drone would tilt similar to an arrow, with the heaviest part (the body of the drone) aimed down & the folded prop blades acting as the feathers or fins.

If air 2s props are as stiff to fold as m2p props I am not certain they will fold especially in the event of a power failure, look at what happens when you stop the motors of a drone that has landed and there I think the motors are actively braked. In a power failure I do not know if they would be actively braked. From memory mini props are thrown forward during a landed motor stop but their pivots are almost frictionless.

I think it is also questionable whether or not the props of a mavic style drone will produce enough drag to act as arrow feathers, it would be nice if they did.
With a phantom 3 they do act as arrow feathers but in the p3 they sit a lot higher relative to the CoG than do the props of mavic style drones.
It would be nice to see the DAT from a CSC'ed mavic just to see what the angles of tilt were during the freefall but who is going to risk not being able to do a restart and save/lose the drone.
I have seen a video of such a test but the free fall was rather short and the drone initially tilted an awful lot during the start of the free fall, however the drone did restart and was ' saved' .... but it looked awfully dicey at the start lol.

Admittedly in a power failure motor stop a drone would probably not have the initial angles of tilt that are associated with the CSC joystick positions. I have CSC'ed a mini when it was low but I performed the CSC with the drone in the slowest flight mode.

 

[Murph66]

Only just reading this, I'm dreading something like that happening to me (touch wood fingers crossed) so pleased you found it

 

[slup]

Only just reading this, I'm dreading something like that happening to me (touch wood fingers crossed) so pleased you found it

Use anything man made long enough... & it will fail.

Get prepared...

With enough knowledge about how the gadget works, what thing's that are most critical for the main function & how to maintain it... will give you a possibility to predict the failure. If the prediction can't be accurate enough... use the gadget in a way that minimize the overall damage from a failure.

 

[scott492010]

i have not check in on this forum in a week approx. and was totally surprised to find so much activity here. Sadly, i am experiencing a possible herniated disk in my lower back and it is effecting me sitting as much as standing or walking.... So, as a result i have not taken the time to mess with my drone at all. Hopefully when i have a chance i will still able to find that dat file. Have not flown that drone since so i think i should have no problem. Luckily i have two air 2s drones.

As far as the battery being dead or not..... the battery is not and was not dead. I believe i could use the battery now if i wanted. kinda concerned by the fact that the outer shell has a huge hole in it though. I did not however check the exact battery level and now that it has been sitting on the shelf for two weeks approx. i am pretty sure it is to late to get a accurate reading for our purposes.

Somebody asked how often i get the compass calibration warning and the low light warning at the same time..... Make note of the fact that during fireworks for example i have attempted flying both drones at the same time or one right after the other rather..... Considering the use of both Air2s drones.... I would estimate i have seen both warnings at the same time well over a dozen times.

Somebody mentioned that the only time they have seen the compass calibration issue or warning is when in the area of certain objects like electrical wires or transformers etc..... In my experience this has only been the case once.

 

[scott492010]

How many instances have you observed where those two messages occurred simultaneously and you lost control of the drone? What did the drone actually do that you describe as flying in "crazy uncontrollable ways?" Was there a crash on each occasion?

Considering the use of both Air2s drones.... I would estimate i have seen both warnings at the same time well over a dozen times.

There was not a crash every time exactly....

one example in the video below the drone starts moving in one direction without me touching the controls. I can however fight it and gain minimal control as i did in this video. but as soon as i let go of the controls it continues in that same direction.

I have also witness the drone go multiple directions as if somebody else is controlling it but has no clue they are controlling anything. Once the drone flipped as if one prop was spinning one direction while another prop was spinning the opposite direction. Another time the entire drone powered on and off super fast while also flickering the lights individually and spinning up the individual props.... it reminded me of trying to start a old automobile after it had been sitting for a decade and the timing was off and the gas was old..... it sputtered and misfired and everything else.....all while in the air.....

another time it flew itself in a huge circle before taking off and changing direction of flight several times all the while traveling approx. 1/4 mile before i was able to regain control and get it to return to its take off point.

amazingly, i always change batteries and restart the drone and it seems to work fine. Usually i may have to go thru the procedure of calibrating it. most definitely in a cold sweat.