Mavic Mini Flyaway in Adelaide

[sar104]

I think @sar104 has a paid subscription to Airdata??
That has a 'fairly good' indicator of wind speed and direction??
Plus, simple graphs of the pitch and roll versus control input could confirm the wind speed too?

I think that AirData's Spark aerodynamic model that they are currently using for wind speed estimates with the Mini is giving numbers around 30% to high. On this flight in RTH mode the aircraft averaged a ground speed of 3 m/s backwards, suggesting a wind speed of 11 m/s (25 mph).

 

[sar104]

I was aware of that, hence the 66's & 99's!
That is the first time I have ever heard AirData's weather estimator questioned though.
And has been used in the past even by Sar104.

I frequently use it as a sanity check, although it's not part of my calculation for drift. It's good for most DJI aircraft.

 

[sar104]

Gives rth only 1 specific motor speed? I think it would be logic for dji to apply a groundspeed at rth so in windy conditions that's full power.

Airspeed is entirely controlled by tilt angle, with the motor speeds adjusted to maintain altitude. Higher motor speeds are required at higher tilt angles since the vertical component of thrust that has to be equal to the weight of the aircraft, M, (Mg = F cos ?, ignoring aerodynamic lift), decreases with tilt.

 

[sar104]

I just found it suspicious that the line away from the home point was so straight and at such a constant speed, so close to the speed it would normally return at. The behaviour looked to me like it just had the direction of home backwards. I would have imagined gusts would knock it about more but as I generally try to avoid flying when it's windy I guess I don't have enough experience to know.

Thanks for all your help and I'll have another go searching for the drone further from where I thought it landed. If I ever recover it I'll also start using that UAV forecast app.

It's not suspicious at all - the wind was out of the SE, and so the aircraft was blown to the NW - away from the home point.

 

[RickinWaST]

Always sad to see a fly away post. The number of these reported by mini users (Both new & experienced pilots.) based on wind issues.

 

[Ian in London]

Airspeed is entirely controlled by tilt angle, with the motor speeds adjusted to maintain altitude. Higher motor speeds are required at higher tilt angles since the vertical component of thrust that has to be equal to the weight of the aircraft, M, (Mg = F cos ?, ignoring aerodynamic lift), decreases with tilt.

Excellent point; this probably sums up why we are seeing so many flyaways with the Mini, with both new pilots (who don't appreciate the increased wind speed with altitude) and also experienced pilots (who are used to ignoring the wind warnings on the Air and 2 Pro etc).
My New Year's Eve flyaway occurred just one 1week after I had carried out a proper wind test on the Mini and had seen first hand how poorly it handles very strong wind and STILL I got caught out. Using AirData for my flight, it seems to me the issue is probably compounded by the decrease in power as the battery depletes. Look at the voltage drop across my flight, coinciding with the ESC errors that occur once the battery drops below 60%, with the blowaway really starting when the battery goes below 40%. The AirData analysis also shows clearly the calculated wind speeds being so much higher at 100 m / 300 feet.

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It's a real shame that so many people are losing their aircraft.

@ridion I'm really sorry you had to join this forum to report your loss and get it explained. There is so much that can go wrong and it's a shame that you had this happen. I lost a $1500 Mavic Pro three years ago and I really know how gutted you'll feel; all I can say is get another Mini or check out eBay for a used Mavic Air and get flying again; they're great fun and give you amazing pictures and video.
Cheers
Ian

 

[Meta4]

it seems to me the issue is probably compounded by the decrease in power as the battery depletes. Look at the voltage drop across my flight, coinciding with the ESC errors that occur once the battery drops below 60%, with the blowaway really starting when the battery goes below 40%.

The voltage drops with time like it does with any battery but the speed of the drone doesn't.
The Mini's P-GPS speed is half that of its bigger brothers.
That's why it doesn't handle wind very well.
It can be blown away just as easily with the battery at 100%.

 

[Caleb R.]

He’s Mavic mini blow away’s are happening at an alarming rate. I really feel terrible for everybody this has happened to, but at what point does commonsense kick in? I spent the better part of six months reading up on my Mavic pro platinum before I actually bought it, to spend a minimum of $400 on a new drone only to lose it in the wind is really sad.

 

[Ian in London]

The voltage drops with time like it does with any battery but the speed of the drone doesn't.
The Mini's P-GPS speed is half that of its bigger brothers.
That's why it doesn't handle wind very well.
It can be blown away just as easily with the battery at 100%.

I think the voltage drop is less for the bigger drones (as per 2 Pro below).
But very true; the Mini can't tilt as much and has a lower max speed meaning it's way more susceptible to wind....

 

[sar104]

I think the voltage drop is less for the bigger drones (as per 2 Pro below).
But very true; the Mini can't tilt as much and has a lower max speed meaning it's way more susceptible to wind....
View attachment 89658

Battery voltage drop doesn't affect motor speed until it gets much lower because the full battery voltage is not being applied to the motors - it's not like a light bulb that gets dimmer as the supply voltage drops.

 

[RayOZ]

He’s Mavic mini blow away’s are happening at an alarming rate. I really feel terrible for everybody this has happened to, but at what point does commonsense kick in? I spent the better part of six months reading up on my Mavic pro platinum before I actually bought it, to spend a minimum of $400 on a new drone only to lose it in the wind is really sad.

Yes. I wonder at what point does someone starts to think, “it looks pretty windy, would my lightweight drone get blown away?”

 

[MAvic_South_Oz]

Basically I took off and flew around an area I know well in Adelaide. It's in the hills so there are occasional gully winds but they are generally just short gusts or it's really obvious that it's a windy day. I took some Christmas snaps then went for at look at the city from a few hundred meters away and the drone and weather seemed fine. I started to try and come back with 70% battery remaining to no avail, the drone just couldn't fight the wind it seemed.

Oh heck, Christmas Day and all . . . sorry to see your drone blow away, it has happened to many with the MM, and no doubt it will happen some more.
One thing is the loss of WIFI can be so quick, and doesn't give much time to get your head together and take good control / make good decisions.
It's just panic stations sometimes !!

Did you have your info on the drone (contact info in the battery compartment, or maybe info file on the microSD) ??
If so, someone with half a brain that finds it may discover it, do the right thing and contact you.

If going back to take a look, I would make up some leaflets too, and drop them in letterboxes while walking the streets, it's more than likely either come down in a street / footpath by the looks, where it could be picked up by anyone, but possible it landed in someones yard or on a roof, and maybe you could get lucky with a leaflet asking for assistance finding it.

Let's hope it didn't auto land on a vehicle, or person, but if it did it probably would have made the news by now.

Good luck with the searching, otherwise DJI didn't offer a small discount on a replacement aircraft only (and battery) ?

 

[m80116]

I think the chances of auto-landing on a moving object are small, not only because they are rare compared to other immovable objects but also because of the downward looking sensors. It should sense if the zone directly below is suitable for landing, in case it isn't it should hover there waiting for input before finally auto-landing for battery depletion. Furthermore as it can't take off from the roof of a car (because it's metal) I believe it shouldn't land on it as well.

 

[Gryphon962]

Can you turn off the sensors on the Mini so that it flies faster in P-GPS, especially when its trying to do a RTH?

If so, turning all that off as default might be good advice to get out there.

 

[Meta4]

Can you turn off the sensors on the Mini so that it flies faster in P-GPS, especially when its trying to do a RTH?

If so, turning all that off as default might be good advice to get out there.

The Mavic Mini doesn't have any obstacle Avoidance sensors to switch off so that isn't an option.

 

[ridion]

Just thought I'd spread a bit of a good news story. Some kind soul found my drone, looked at the last video and returned it to the house I took off from. It's time to write my number on it and try and be more cautious. I thought I had a pretty good idea of the drone's limits when I took it out to the middle of nowhere to test it but I guess I just need to be even more careful.

 

[Thomas B]

Just thought I'd spread a bit of a good news story. Some kind soul found my drone, looked at the last video and returned it to the house I took off from. It's time to write my number on it and try and be more cautious. I thought I had a pretty good idea of the drone's limits when I took it out to the middle of nowhere to test it but I guess I just need to be even more careful.

Glad to hear you got your drone back!
If you haven’t yet... recommend reading the full 60 page, online only manual from DJI. Scroll down a bit on the page linked below.., and welcome to the forum from the deserts of Arizona!

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www.dji.com

 

[sar104]

Just thought I'd spread a bit of a good news story. Some kind soul found my drone, looked at the last video and returned it to the house I took off from. It's time to write my number on it and try and be more cautious. I thought I had a pretty good idea of the drone's limits when I took it out to the middle of nowhere to test it but I guess I just need to be even more careful.

Do you happen to know where it was found?

 

[ridion]

Yeah, it landed about 1/3 of the way between the last known GPS coordinates and sar104's landing point, almost exactly on the red line.

 

[MAvic_South_Oz]

Just thought I'd spread a bit of a good news story. Some kind soul found my drone, looked at the last video and returned it to the house I took off from. It's time to write my number on it and try and be more cautious. I thought I had a pretty good idea of the drone's limits when I took it out to the middle of nowhere to test it but I guess I just need to be even more careful.

Great news, so no damage and it likely auto landed safely where it was found ??
Great that the person finding it was so smart to check the micro sd card, and follow up like they did.
Very soon this year, hobbyists will have to take the CASA online test, and label drones with pilot registration number, so that will also be a way perhaps to eventually get a drone returned.
That said, better to also have your info in it so things like this incident can lead to a similar ending.
Safe flights to you from now on.