Strong Wind Warning -- scary situation

[Deleted member 103366]

Nospampls, is it possible that " Aircraft unable to return to home automatically" means that in high winds the drone may be unable, in solely automatic flight, to fly fast enough, with respect to the air, to, with respect to the ground, move towards home ? i.e. if in automated RTH flight its maximum AIR SPEED is 20m/s and it is flying DIRECTLY into a head wind of 25m/s will it, as seen from the ground, be able to make headway towards the home point or will it be blown away from the home point at 5m/s.
Taken literally the above quote does not say that the RTH is disabled, it says the drone is not capable of returning home though, by implication, it will try.

With regards to the conversation with Vergel, the phrasing of their responses makes me think that English is not their first language, no offense intended to Vergel. If that is the situation then I think it is highly likely that subtle errors could arise in their understanding of what you were saying or asking and their understanding of the nuances of their answers.

Of course you could always test wether RTH is disabled etc. and take your drone out to a wide open space on a windy day or to some windy place, launch the drone, attached to a long and strong tether, and fly away from the homepoint to a suitable distance and then switch the controller off. If RTH is disabled at loss of connection in high winds then your drone will presumably not attempt to RTH and possibly be blown to the limit of the tether. I have held a Mavic Mini on a strong, nylon, sewing thread tether so would imagine it would be fairly easy to find something capable of holding an Mavic air 2. Personally I suspect you would find it tilts to try to RTH.

When failsafe RTH is 'discussed' in the manual I can find no explicit mention of RTH being disabled in high winds. It does however say " The aircraft may not be able to return to a Home Point when the wind speed is too high.", to me that implies that the drone will try to RTH but it may not succeed in making headway against high winds.

 

[GadgetGuy]

Vergel vs. @Meta4
@Meta4 by knockout in the first round!
Poor Vergel!
He is so out of his element and in the wrong weight class!
Vergel is likely a computer bot!

 

[GadgetGuy]

Your mistake was to believe that DJI help people have any idea what they are talking about.
Most have never flown a drone.
Most are way out of their depth if you ask them anything they don't have a prepared script for.
Many are not proficient with English language
They will often say anything just to get you off the line
The forum is full of cases of incorrect information coming from DJI help people.

I've given you correct information already.
I don't seem to be able to convince you of it's accuracy.
But that doesn't mean I was wrong.

Regardless of your attempt to interpret the poorly worded warning message and the incompetent DJI help people you chatted with ...
Your drone will always enter RTH on loss of signal* or initiating RTH regardless of strong wind warnings.
* Assuming you have not changed the Loss of Signal action from the default setting of RTH

Amen! ?

 

[SW_Drone_Guy]

...the drone will try to RTH but it may not succeed in making headway against high winds.

SOLVED IMHO

 

[Ian in London]

I can't wait for another really windy day to test this message! Video will follow

Ian

 

[Deleted member 103366]

Ian if you are talking about testing with a tether attached, I would suggest using something like a fishing rod, reel and maybe line, hand winding 100m or so of thread around a brush shaft is .........tedious. Also, some distributed paper clips attached to perhaps the first 10m or so of the tether nearest the drone seems a good idea as I became concerned about my thread (which is very light) not sinking as fast as the drone, a few distributed paper clips seem to be enough to weigh the tether down but not load the drone.


PS a taut tether will tend to pull the drone down and don't do this where anything can snag or interfer with the tether. During my earliest flights and because I was flying for the first time in an open space I tethered a Hubsan X4 H107C , I must have sent it out 50m or so and there wasn't a problem.
With the mini I did a Homer, metaphorically and literally, the wind took it and the tether went over the telephone line which caused the tether to go taut and pulled the drone down into a hedge line tree.

 

[InvisibleName]

Ian if you are talking about testing with a tether attached, I would suggest using something like a fishing rod, reel and maybe line, hand winding 100m or so of thread around a brush shaft is .........tedious. Also, some distributed paper clips attached to perhaps the first 10m or so of the tether nearest the drone seems a good idea as I became concerned about my thread (which is very light) not sinking as fast as the drone, a few distributed paper clips seem to be enough to weigh the tether down but not load the drone.

Just curious, why the need for a tether?

 

[GadgetGuy]

Just curious, why the need for a tether?

So it won't get blown away! ?

 

[Searat290]

It's really simple (If this was already stated in some way, my apologies) If Wind speed is higher than drone top speed in current mode, it can't get home no matter how much battery strength is left. If you fly longer distances away from you with the wind, you risk losing the aircraft.

 

[Seagull01]

I have no idea why I thought of this:

Maybe because you're going slightly mad?

 

[Seagull01]

By coincidence the battery on my tablet died....

As an aside, I'm interested to see that your tablet battery died. Do you find your tablet uses more power than the RC provides? My phone always ends up with more power after flying

 

[Deleted member 125666]

Prepare to be surprised.
I'm surprised that you haven't encountered this issue before.
It's been a factor in the loss of many drones and the subject of many complaints to DJI.
Especially with the Mini that has an RTH speed of only 8 m/s.

Do a still air test first to establish what speed DJI have set for RTH Mode.
I'm not certain it is 12 m/s, just that it won't be more than 12 m/s.

How accurate are the wind speeds you use for those calculations?

I don't know if you already have come to a conclusion, but I was also intrigued by Wellsi question.

As it is possible for the drone to fly in different speeds, it is possible for the drone(s) to counter gusts to stay in place and as the drone draws more power when travelling against the wind it is obvious that the drone have different programming to speed modes (not all hardware limitations) and adjust the power distributed and positioning to maintain the speed.

Will it not try to maintain the speed when travelling against the wind in RTH?

Which might mean that it may/if it could/ travel in 12m/s flying towards a 12 m/s wind it would in theory have meant travelling by 24m/s on a windless day which is faster than the sport modes 19m/s of course. (Just like a car going uphill where you distribute more power to maintain speed but not to go faster.)

The sport mode 19m/s is it a hardware limit? (The normal modes 12m/s and tripod modes 5m/s is a software/programmed limit?)

 

[Meta4]

Will it not try to maintain the speed when travelling against the wind in RTH?

Flying your drone against a headwind is like rowing a boat upstream against a current.
In still water you can propel the boat at 5 metres/sec,
If you row against a 2 m/s current you can only achieve 3 m/s (velocity over the ground) but you would be rowing as hard as when doing 5 m/s.

The drone's speed is governed by the angle the drone tilts forward.
To fly faster, it tilts more and increases motor speed to counteract the vertical thrust lost because of the increased tilt angle.
For DJI drones before the Air 2 DJI had set tilt angles for flight modes.
For example the tilt angles for the Phantom 4 pro are: S-mode: 42° P-mode: 25°
Its still air max speeds are: S-mode 20 m/s and P-mode 16 m/s (with OA disabled)
In P mode it won't tilt more than 25° and won't fly faster than 16 m/s.
If you fly it against a 5 m/s headwind, the max speed (over the ground) will be 11 m/s (but the airflow over the drone will be 16 m/s).

The Air 2 specs show that DJI has a new trick for this model.
I've only just noticed this and haven't seen anyone discuss it yet to know exactly how it works.

According to the specs the Max Tilt Angles for the Air 2 are:

35° (S Mode)​

20° (N Mode)​

35° (N Mode under strong wind)​

That suggests that the Air 2 can achieve Sport Mode speed in N Mode under strong wind.
I'm not sure how that is implemented.
But if flying against a 10 m/s headwind, it still won't be able to make more than 9 m/s (over the ground)

The manual doesn't explain what the situation is for RTH.
I wouldn't guess whether DJI allow the extra speed in RTH.
Perhaps someone can do some testing and provide the data.

 

[Ian in London]

Flying your drone against a headwind is like rowing a boat upstream against a current.
In still water you can propel the boat at 5 metres/sec,
If you row against a 2 m/s current you can only achieve 3 m/s (velocity over the ground) but you would be rowing as hard as when doing 5 m/s.

The drone's speed is governed by the angle the drone tilts forward.
To fly faster, it tilts more and increases motor speed to counteract the vertical thrust lost because of the increased tilt angle.
For DJI drones before the Air 2 DJI had set tilt angles for flight modes.
For example the tilt angles for the Phantom 4 pro are: S-mode: 42° P-mode: 25°
Its still air max speeds are: S-mode 20 m/s and P-mode 16 m/s (with OA disabled)
In P mode it won't tilt more than 25° and won't fly faster than 16 m/s.
If you fly it against a 5 m/s headwind, the max speed (over the ground) will be 11 m/s (but the airflow over the drone will be 16 m/s).

The Air 2 specs show that DJI has a new trick for this model.
I've only just noticed this and haven't seen anyone discuss it yet to know exactly how it works.

According to the specs the Max Tilt Angles for the Air 2 are:

35° (S Mode)​

20° (N Mode)​

35° (N Mode under strong wind)​

That suggests that the Air 2 can achieve Sport Mode speed in N Mode under strong wind.
I'm not sure how that is implemented.
But if flying against a 10 m/s headwind, it still won't be able to make more than 9 m/s (over the ground)

The manual doesn't explain what the situation is for RTH.
I wouldn't guess whether DJI allow the extra speed in RTH.
Perhaps someone can do some testing and provide the data.

Windy day today; I'm going to test this.....
Ian

 

[Deleted member 125666]

Windy day today; I'm going to test this.....
Ian

Can you also test to see if the speed differs in flying against and towards the wind for each P - N - S modes, outside of the RTH test?
I know that my question might be a bit moot

I am contemplating, if the tilt angles are the max allowed and not the regular tilt angles, or the same for power distribution to keep the altitude when the drone flies in different angles. Let for instance say that for the drone to travel in 19m/s in sport mode it would need an angle of 27dgr (out of possible 35dgr) when it is not any wind, the extra 8dgr are a marginal to be able to keep speed up to a maximum amount wind against the drone. I also assume that the drone in that case would not be tilting the same going down wind as against the wind.

If the drone are able to keep 5m/s, 12m/s, 19m/s, against the wind could at least give a hint for that?

 

[itsneedtokno]

Last night I got a max motor speed warning when pressing both sticks up in Sport mode. Totally random, but thought I'd throw that in the mix.

 

[Meta4]

Let for instance say that for the drone to travel in 19m/s in sport mode it would need an angle of 27dgr (out of possible 35dgr) when it is not any wind, the extra 8dgr are a marginal to be able to keep speed up to a maximum amount wind against the drone.

You will find that the drone achieves its max Sport Mode speed of 19 m/s in still air by tilting to 35°.
There is no reserve to deal with headwinds.
Flying against a headwind will be like rowing against the current and speed over the ground will be reduced.
If the wind is faster than the drone's max speed, the drone will go backwards, just as your row boat would.

If the drone are able to keep 5m/s, 12m/s, 19m/s, against the wind could at least give a hint for that?

I've already given more hints than you should need.

 

[OneQuickSix]

...Actually I'm not at all concerned that I got a message from the drone. I think warning messages are essential. My concern is that the message might be correct -- "Strong wind warning. Aircraft unable to return to home automatically." I would hope strong wind does not disable automatic RTH. Sure, it's a backup. But I don't like losing my backups ...

I wondered about this as well. This was actually with my Mini and not my Air 2, but hope this helps ...

I just took mine out an hour or so ago, and after being told by two different sources that winds were fine (more than fine according to one) minutes before launch, I got that message (Strong wind warning, no auto RHT) after being in the air less than 5 minutes and at 97% battery ... AND the Mavic was only a few feet away horizontally @ ~275ft. alt.! Additionally the max gust was ~16mph.

So, it has nothing to do with it calculating that it can't do RTH because of remaining battery vs. distance/winds. (In my case, it literally could just come down.) So you are correct, but I am still not sure if it is just poorly worded, or it actually will not RTH if it detects strong winds. Which I agree with you, is pretty moronic ... why wouldn't it try, especially if your RTH altitude is lower (and therefore likely lower winds) ?

 

[OneQuickSix]

PS> The manual states: "The aircraft may not be able to return to a Home Point when the wind speed is too high."

Key word being "may". So I'm really leaning towards it just being poorly worded in the interface. But, next really windy day, I'll send both drones out a bit further (to avoid it autolanding instead) and break the connection and/or press the RTH and see what it does.

Sounds like others are planning on doing some tests as well, so take heart ... I imagine we will get to the bottom of it sooner than later.

 

[Meta4]

I am still not sure if it is just poorly worded, or it actually will not RTH if it detects strong winds.

If this really was an issue, it would have been noticed long ago.
As someone already said earlier in the thread:
Your drone will always enter RTH on loss of signal* or initiating RTH regardless of strong wind warnings.
* Assuming you have not changed the Loss of Signal action from the default setting of RTH