Hi All

I work for a Magnetite mine and it would be useful to be able to use a drone for aerial pics, wall close ups etc but understand that can cause issues with the compass and IMU.

I'm looking to take my P3A down in a couple of weeks but won't use it if the risks are too high.

Has anyone had experience doing this, should I not even consider doing it, are there things I can do to make sure I limit any issues that might occur?

Thanks in advance.

You will need to fly in Atti mode and never use RTH.

Get some Atti practice first!

You can try using GPS, but be ready to gain height to miss collisions if it goes out of control and then use Atti mode to bring it back.  Be very careful if it is windy since gaining height into strong winds and then having to use Atti will be difficult.

Altitude hold should be no problem, just positional hold.

You could always start all up on the ground, and before taking off check for compass interference reading in DJI Go ('Main Controller Settings'/'Advanced Settings'/'Sensors'/'Compass Tab'. If that's good then some short test flights building up to the big one .

I'm assuming that the compass has already been calibrated in an open area (away from any known ferrous objects), if that's OK then it should only need to be recalibrated if the system prompts you, or if you are aware of any strange behaviour in flight path.

You might get a clue as to how bad things are by running the compass app on your phone/tablet and comparing it with true north as shown on a map, if there is a significant discrepancy then it is Atti mode only.

Don't calibrate the compass anywhere near the iron ore!

I don't think atti mode is the way to go at all and I don't think it would help.
You should be fine up in the air, people fly from steel ships with no serious issues.

The potential issue is compass related.
Do not calibrate the compass anywhere near the ore body.
Don't bother calibrating the compass at all.   Just leave it the way it is.
Try to find a launch point that isn't on top of exposed ore, either somewhere with a lot of soil rather than rock or maybe have a helper to hand launch from above his head.
Launch and get up 50+ feet and see how it behaves.
If the magnetic effect of the ore is strong enough you would see the Phantom wanting to slowly spiral rather than hover in place.
Going higher should get away from that.

Thanks for all of the suggestions - there are plenty of spots I can try to see how the drone behaves so I think I'll try in GPS mode first and see what happens. I'll post back and let you know how it goes.....

Interesting question. Looking forward to see how it works out.

Ok - so have taken the P3A for a fly at the mine today and have taken the advice from earlier in the post. Did not calibrate the compass, left in GPS mode, and flew a little away from the ore body.

Drone flew like normal, hovered fine, and remained in control for the whole flight. Only had some screen minor screen flickering when over one of the pits but that could have been wifi interference from the network. Seems to work fine - will try closer to the ore tomorrow.

Flysuzu Posted at 2017-6-3 01:08
Ok - so have taken the P3A for a fly at the mine today and have taken the advice from earlier in the post. Did not calibrate the compass, left in GPS mode, and flew a little away from the ore body.

Drone flew like normal, hovered fine, and remained in control for the whole flight. Only had some screen minor screen flickering when over one of the pits but that could have been wifi interference from the network. Seems to work fine - will try closer to the ore tomorrow.

Did you check the orientation of a compass or the compass on your tablet against map north?

It's quite possible that the magnetic field of the ore is lined up with the earths magnetic field and thus there is no problem.

Stay ready to gain height and switch to atti mode if it does suddenly shoot off into a curve though.

Thanks Nigel

Yeah the ore body does run reasonably north/south so that might be helping. Studied up on Atti mode just in case I needed it. So far so good.

Cheers