What happens to a Mavic in a steady 30 mph wind?

[marklyn]

Recently I was flying my Mavic in a very rural area. The ground speed wind was 10-12 mph. When I got straight up around 150-200' my Mavic would not follow the Litchi mission it was set for, or at least it seemed to be, trying, at around 1-2 mph, occasionally speeding up to 4 mph instead of the programmed 21.5 mph.
I had pre-checked all settings (max speed was set to 33.6 mph, wp's 1-5 were set to 21.5 mph, etc.).

So yesterday I signed up for the paid subscription of AirData UAV and checked the weather tab on that flight for that day and found out that winds aloft (around 150' and higher) were actually around 29-30 mph! It's odd that I never got a high wind warning as the drone appeared to be "drifting" as if it were in ATTI mode or something (but it wasn't). I should add that I cancelled the Litchi mission while it was barely moving, switched it to sport mode, and then I could fly manually much faster in the direction it was supposed to be going.

So does this sound like expected behavior if the winds are steady and high? And if so, why was I able to manually fly faster in sport mode but, even on a second (different) mission, the same thing happened, until I again cancelled the mission and flipped on sport mode and flew manually at my desired speed.

Would appreciate any insight into this.

 

[Just_nick]

Flying in 30mph winds aloft is a good way to lose a drone, so I would highly advise you don't do it unless you don't mind your drone disappearing. Gusts can far exceed the steady 30mph speeds, I've seen days where steady speeds were 30-33mph and gust were in the 60-70mph range, which could gust hard enough to flip your drone.

That being said, these drones do not like windy conditions in non-sport mode. They try to prioritize the angle for OA and keeping the props out of the shot, which means that it does not pitch enough to fight against the wind until you flip it into sport mode.

 

[sar104]

It's very simple - the aircraft performance is entirely defined by airspeed, not ground speed. In the regular flight modes (P-GPS or Litchi mission) the maximum airspeed is determined by the maximum available pitch (or roll), which is 25°. That corresponds to an airspeed of around 20 - 25 mph. If you are trying to head directly upwind, then subtracting the windspeed will give you the achievable groundspeed, which may be negative.

In sport mode the maximum pitch is increased to around 35°, and so the maximum airspeed is higher too. It doesn't permit the aircraft to achieve any ground speed that you want, but it does allow it to make headway against stronger winds.

 

[marklyn]

Really. I wasn't trying to fly the drone in 30 mph winds. At the time I had *no* idea that the winds were 30 mph, no high wind warning, etc. I continued to fly it (mindful) to help determine if there was a problem with the Litchi mission or maybe the drone. If I would have gotten a high wind notice I would have ended the mission for good and flown another day but as it were I was trying to evaluate or understand what was going on as best I could.
I know wind speeds can be different at different altitudes, but putting all of that aside, my main curiosity is questioning the behavior of the Mavic in the wind conditions I mentioned using a pr-programmed flight mode vs sport mode.

 

[marklyn]

sar104, thank you for answering the question in a way that I can understand. Now if I can just figure out why I didn't get a wind speed warning.

 

[MavicCF]

It's very simple - the aircraft performance is entirely defined by airspeed, not ground speed. In the regular flight modes (P-GPS or Litchi mission) the maximum airspeed is determined by the maximum available pitch (or roll), which is 25°. That corresponds to an airspeed of around 20 - 25 mph. If you are trying to head directly upwind, then subtracting the windspeed will give you the achievable groundspeed, which may be negative.

In sport mode the maximum pitch is increased to around 35°, and so the maximum airspeed is higher too. It doesn't permit the aircraft to achieve any ground speed that you want, but it does allow it to make headway against stronger winds.

Dang it, I had my answer all typed out and perfect but than you had to go beat me too it. I guess my thumbs can't keep up with your keyboard...

 

[sar104]

sar104, thank you for answering the question in a way that I can understand. Now if I can just figure out why I didn't get a wind speed warning.

That's a good question. I'm not sure if I've ever seen a wind warning in Litchi - perhaps that app simply doesn't provide wind warnings. If you want to post the Litchi csv log it should be easy to check.

 

[sar104]

Dang it, I had my answer all typed out and perfect but than you had to go beat me too it. I guess my thumbs can't keep up with your keyboard...

Sorry. Post it anyway - the more information the better...

 

[marklyn]

Attached. (had to zip file to upload here)
And, I'm pretty sure I've seen wind warnings in Litchi since I use it 99% of the time.

 

[MavicCF]

Sorry. Post it anyway - the more information the better...

Yours covered all I tried to say in a much more understandable format. Plus I learned the exact degrees of pitch in the two modes! Now to download a file...-CF

 

[MavicCF]

I'm not seeing any warnings in that log are you Sar?

 

[sar104]

I'm not seeing any warnings in that log are you Sar?

No, but those are not the full Litchi log - just the AirData csv. Not sure if it even includes messages. Also, sport mode was not engaged during this flight. If you look at the tilt angle (combined pitch and roll), the maximum during the waypoint mission appears to be only 16°. Once it switched to RTH at 430 s the tilt increased to the regular 25°.

 

[marklyn]

SAR, I just realized by looking at the log myself that it was the second mission that day where I aborted the mission and then switched to Sport mode to fly freely. The first mission I just RTH basically because I now remember thinking maybe I screwed up setting up the mission in the Litchi Mission Hub. I've attached the Litchi flight file for the second mission. Sorry for the confusion.

 

[sar104]

SAR, I just realized by looking at the log myself that it was the second mission that day where I aborted the mission and then switched to Sport mode to fly freely. The first mission I just RTH basically because I now remember thinking maybe I screwed up setting up the mission in the Litchi Mission Hub. I've attached the Litchi flight file for the second mission. Sorry for the confusion.

Similar story, but now you see the higher tilt angles in sport mode.

 

[Tinmania]

I thought you didn't get wind warnings in Litchi. That is what I have always understood to be the case (and I have never received one).

I bet if the OP was trying that same flight, manually, in Go4, they would have most definitely gotten wind warnings.

Also, in between Sport Mode and regular P Mode, is P Mode with obstacle avoidance turned off. With OA off the MP will not contain pitch to 25 degrees (the maximum for OA sensors to function properly) and top speed is about 30MPH. The Mavic Air will turn off OA automatically if it can't make enough headway due to wind--you have to do it manually on the MP.

I suspect the OP's mission might have completed, albeit not quickly, if OA was off (though still of course risky).


Mike

 

[marklyn]

Now, I'm scratching my head... I've done well over 100 flights and 99% of them are Litchi freeform flights or pre-planned missions. I have seen various errors/warnings (compass, etc) before in Litchi and I could swear I've seen wind warnings too but now I'm wondering. I guess I could search my litchi csv files, assuming that would be in there.

 

[marklyn]

It came to me now. When I first got the Mavic and started using Litchi, I recall seeing a warning on an occasional flight (usually compass or some other warning) and it always just appeared on the tablet screen. It was enough that I put the drone down, re-checked everything, and flew again. I do now recall that I could never find the warnings in the log so when I asked Litchi about it, they ultimately responded something to the effect that the errors/warnings aren't in the log file and it had to do with the DJI Go app (or API?) not recording them. I didn't really understand, I was very new to droning, so I just took the answer as "no" it's not recorded. Does anyone know if using DJI Go records errors/warnings?

 

[sar104]

It came to me now. When I first got the Mavic and started using Litchi, I recall seeing a warning on an occasional flight (usually compass or some other warning) and it always just appeared on the tablet screen. It was enough that I put the drone down, re-checked everything, and flew again. I do now recall that I could never find the warnings in the log so when I asked Litchi about it, they ultimately responded something to the effect that the errors/warnings aren't in the log file and it had to do with the DJI Go app (or API?) not recording them. I didn't really understand, I was very new to droning, so I just took the answer as "no" it's not recorded. Does anyone know if using DJI Go records errors/warnings?

DJI Go records all messages.

 

[Tinmania]

Now, I'm scratching my head... I've done well over 100 flights and 99% of them are Litchi freeform flights or pre-planned missions. I have seen various errors/warnings (compass, etc) before in Litchi and I could swear I've seen wind warnings too but now I'm wondering. I guess I could search my litchi csv files, assuming that would be in there.

I usually start with Go4 for a quick shakedown flight before landing, updating the home point, killing Go4 then switching to Litchi for a mission. There have been several times where I got wind warnings in Go4 but never in Litchi even though it was right after.

I assumed the wind warnings in Go4 were calculated from telemetry data. Perhaps those calculations are proprietary to DJI. Litchi has access to the same telemetry so presumably could do likewise.

Other warnings are shown in Litchi, such as compass. I suspect these come straight from the aircraft and need no to little calculations in the app.



Mike

 

[sar104]

I usually start with Go4 for a quick shakedown flight before landing, updating the home point, killing Go4 then switching to Litchi for a mission. There have been several times where I got wind warnings in Go4 but never in Litchi even though it was right after.

I assumed the wind warnings in Go4 were calculated from telemetry data. Perhaps those calculations are proprietary to DJI. Litchi has access to the same telemetry so presumably could do likewise.

Other warnings are shown in Litchi, such as compass. I suspect these come straight from the aircraft and need no to little calculations in the app.



Mike

The wind speeds are computed on the aircraft I think because they are in both the DAT files when Go is running. I suspect that they are available telemetry fields, but that Litchi doesn't request/record them.