Really strange flight glitch

[cgreer00]

So my Phantom 2 with gopro and zenmuse has developed a very strange flight characteristic. It hovers in place just fine, locks onto the GPS in no time, and the compass calibration always works well. BUT, when I am flying in GPS mode and fly forward (or backwards) for a while, when I release the stick it begins to veer off and does a very large toilet bowl, sometimes 20+ feet in diameter. If I correct the toilet bowl with the sticks and stabilize it, it will hover again just fine. It doesn't do this in ATTI mode. So it makes it very difficult to fly in tight spaces because when I fly forward and then release, I have to immediately correct it because it wants to veer and do a toilet bowl forever (it never actually corrects the toilet bowl on its own). Things I have done:

- compass calibration many many times
- advanced calibration with IMU

Thoughts? What is causing this? What can I do to correct it?

Again, it is just fine in Atti mode, so there is something going on with the GPS/compass, but only after I have been flying forward or backwards.

 

[ianwood]

You should check magnetization, compass orientation, calibration location/method and consider replacing the compass if those measures don't work. What is your mod value? How and where do you calibrate the compass?

 

[cgreer00]

Mod value alternates between 1400-1600. I calibrated out on the beach, no metal or anything anywhere close to me.

 

[ianwood]

Mod value alternates between 1400-1600. I calibrated out on the beach, no metal or anything anywhere close to me.

Mod looks OK but the beach may be a problem. There can be iron in the sand which will have a magnetic property that will throw off the calibration. Try calibrating in a grassy area away from all know drainage pipes, wiring, etc. Make sure you have no metal including keys, etc. or unrelated electronics running within 5 feet.

 

[Shrimpfarmer]

I would also check out the thread with the title 'Fixing the DJI compass' or something very similar. Sounds like you have the same problems others report there.

 

[Madwak]

We have just cured the exact same problem with same phantom setup. When we checked the mod value it was showing just over 1600 so we did the advanced calibration yet again (after many previous unsuccessful attempts) but this time while the phantom was sitting on the desk noticed that something put down on the desk started to roll away. We decided the desk wasn't perfectly level and calibrated the phantom on the floor instead, the mod value now shows 1161 and the phantom is back flying straight and true.