How cold is too cold?

[clolsonus]

+5F is officially too cold for a DJI phantom 4.

My previous best was flying at +19-20F. We did a 3 battery mission and it all worked out ok (prior to our DD / ipad issues.)

Yesterday the forecast was for +17F, but according to our vehicle the temps never got above +5F in our specific area. We must have found a cold pocket of air or something.

I could be completely wrong about everything, but here's what I think happened.

We were attempting a multi-battery survey mission, flying with pix4d capture on our ipad. I had tested this all out on Monday in +30F temps, and everything worked perfectly.

Our first flight was perfect. I set the mission up to work from far to near, so the first flight was the most challenging in terms of distance, but it sailed through that fine. Partway through the 2nd flight the drone just stopped and hovered in place. The hand controller/app was receiving data back, but it appears that the drone couldn't hear [all of] the messages the hand controller was sending. We still had a positive link apparently and the come home button worked immediately. We reset the mission and sent it out again, but after one leg of the route it stopped and hovered in place again. We repeated this about 10 times, with the range/results getting less and less. Finally we couldn't even get 100' outbound to resume the route before the drone stopped and hovered in place.

Also, on the landing attempts, as the drone got colder it had more trouble finding it's landing spot. It would hover above and move around, reset it's orientation, and do that about 5 times before it finally would descend and land. On the final flight it didn't seem to want to come down at all, so I just pulled the stick down and forced it to decend ... however, it stopped at about 6' AGL and wouldn't descend any further. Also, it was pretty far from it's landing spot, so I attempted to steer it over closer to me. I discovered that my control inputs only worked one direction and that was full speed. I couldn't fly side to side or the opposite direction, and I couldn't nudge it slowly. Now I'm 6' above the ground and can't land and my attempts to nudge it have just pushed further away, now dangerously close to being under a tree overhang. When I let the stick up it wanted to climb back up to altitude. I still had clear sky above me so I gave up trying to force the landing and let the drone resume whatever it was going to do. My mission altitude was 150' AGL, but now the drone climbed to 320' and resumed it's attempts to land. Thankfully I had plenty of battery at this point and the system eventually found itself and landed safely.

My theory is that the cold actually affected our hand controller first and more severely than the drone itself. Somehow this degraded our transmission power, so at some level, the drone was not hearing our ground control messages and just stopped. But I could never reestablish the mission/route in flight. The only thing I could do was return, land, reset the mission there, and it would take off and resume again.

But then after being out for an hour, I think the cold was beginning to adversely affect the phantom 4 itself and somehow caused issues with finding it's landing spot. We kept our batteries warm so flight times were fine, but the cold seemed to get us in other area.

Hopefully we don't have any more of this crazy cold weather until next winter now ... but lessons learned?

1. The coldest I've flown a successful multi-battery mission is around +20F.
2. Keep your hand controller warm if you can, it seems like the cold might affect that first and more severely than the drone itself.
3. If we have to go out in this sort of weather again, we might try bringing the drone and hand controller into the car between flights and just blast the heat for 10-15 minutes before sending it off with the next battery.
4. The cold does take some time to soak in, so you might be able to sneak off one successful flight, even if the temps are way below recommended.
5. Store your fresh batteries in your arm pits to keep them warm.

Anyone else have any arctic tips for when it's way too cold, but you still have to be out there doing work?

Thanks,

Curt.

 

[BigAl07]

Too cold for Allen or too cold for the aircraft ? LOL

I flew this morning for a client at 21F with a stiff 10mph breeze and I got so cold in 5 minutes that I finished flying from INSIDE my car. The windchill really got to me quickly and thank goodness it was only a 20min flight total.

I've flown a Phantom 3P to around 0F but not for long and not for multi-battery flights. The parts get very brittle in those temps and things break way too easily IMHO.

I suspect it wasn't actually the Tx (hand controller) but sensors on the aircraft trying to adjust to the changes going from a warm climate (inside) to a brutally cold area.

 

[clolsonus]

We were lucky we at least had light winds and sun! There is an Eskimo saying that goes something like: "there is no bad weather, only bad clothes."

I speculated the hand controller was being affected because I started having problems with the app trickling the mission waypoints up to the drone. When I tried to reset the mission in flight, the checklist kept failing at the upload mission step. But all the while I was getting good signal back. As the afternoon progressed the workable range kept diminishing ... eventually couldn't get past about 100' away. My understanding from chatting with someone in the app making industry is that the DJI drone can't store the entire route with all the waypoints, so at various times during the flight, more waypoints need to be trickled up. If there is a problem with that process, the drone can just stop and hover in place ... it has run out of waypoints, but isn't receiving more; the ground station stops (or can't) send them up because of a communication fault, and it gets in a sort of dead-lock state. Different apps handle this differently I think. Probably some of this is embedded in the DJI api, but it seemed like once it failed, I could never get a route uploaded again until I came back, landed and reset everything. I was working my way from far to near, so when all this was happening, I had already finished an entire battery further away ... my first flight was perfect ... everyone who saw it said they thought it looked perfect (sorry, hah!)

My best guess is that the cold affected the ability of the hand controller to transmit, or the ability of the drone to receive the messages.

Then as the afternoon progressed further, the drone itself started acting weird. This included a weird momentary bobble on lift off that I wasn't used to seeing and apparent issues finding the landing spot and getting oriented. Then further issues manually flying the drone (again, I'm wondering if that was on the hand controller, because the drone itself could still navigate and fly just fine ... it seemed more like a weird issue with the commands.)

I don't know ... it's all speculation because everything is secured inside a proprietary black box and we can only guess based on the observed external behavior.

Curt.

 

[PatR]

When it’s so cold your fingers, nose, and toes start to burn after a couple minutes of exposure it’s too cold.

 

[clolsonus]

When it’s so cold your fingers, nose, and toes start to burn after a couple minutes of exposure it’s too cold.

 

[mfabo]

Cold is one thing. Wind is a very deciding factor. Even flying a Drone Deploy mission, I only had to monitor the controls. 35 degrees, but 15 mph wind meant twenty minute route took about 27 minutes. Drone struggled a bit, but mostly the toll is on the body and not the drone. Looking forward to Spring...