Note to self...

[careysb]

1) Don't go flying when it's above 90 degrees (F) (a personal comfort issue, not a flight issue).
2) Always recalibrate compass after you swap batteries.
3) Make sure GPS has locked in to satellites.

Actually, I don't know if #2 and/or #3 was really my problem. I didn't experience a "fly away" as such but the controls got very squirrely. Fortunately it wasn't too far away from me, maybe 150', so I could see how it was behaving and guess at the joy stick position it wanted to bring it back to me, if not for a rather hard landing. Breeze was about 3mph.

I was flying with a new ARRIS gimbal, a ImmersonRC 600mw transmitter, in GPS mode, and home lock.

The other possibility was the ARRIS interfering with the GPS (?).

 

[Gizmo3000]

Well, there should be no need to recalibrate your compass too often.
but always wait for GPS home location to be recorded.

interference does occur tho sometimes.

 

[tanasit]

RE #2, the compass calibration.
I did it once and never since after several months.
You should look for the culprit which in my case the very first time the compass messed up because I placed my Phantom in the back of my hybrid car near the traction battery.
Also the flying field may have some type of metal either around or underneath. A few members reported compass error only to find out later that there're metal pipe under ground where they fly!

 

[GearLoose]

RE #2, the compass calibration.
...Also the flying field may have some type of metal either around or underneath. A few members reported compass error only to find out later that there're metal pipe under ground where they fly!

I'm a bit sceptical about the supposed influence on the Phantom of underground metal such as pipes. A large percentage of the flight videos we see are taken in heavily populated and industrial areas. The amount of wire, pipe, rebar and other metal in a typical urban street and neighborhood is huge, so wouldn't you expect problems such as described by the OP to be quite common?

Just a thought....

 

[Buk]

I never considered my hybrid's batteries to be highly magnetic source.

I wonder if you can take an old fashioned "boy scout" compass and wave it around and see a deflection of the needle if there are potential problems?

 

[Racklefratz]

I'm a bit sceptical about the supposed influence on the Phantom of underground metal such as pipes. A large percentage of the flight videos we see are taken in heavily populated and industrial areas. The amount of wire, pipe, rebar and other metal in a typical urban street and neighborhood is huge, so wouldn't you expect problems such as described by the OP to be quite common?

You're correct in your skepticism. For starters, what would magnetize said pipes in the first place? Metal pipe isn't magnetized when it leaves the factory that produced it, nor in the process of laying it in the ground.

Magnetic compasses are one of the primary and/or backup navigation instruments used by real aircraft. If there was any substance to this claim, this issue would be common knowledge.

"People" report a lot of things. That makes them valid? It's a non-player, brought to you by the uninformed. It's a myth.

 

[tanasit]

Well, I have a car with the see through acrylic roof in the front. When I placed my Phantom on the back above the metal roof, I always get RED/YELLOW flashing but when I moved it over the acrylic roof, it was ready to fly.
Even in the Phantom manual, there a section warning about ferromagnetic substance nearby!(see below) Also several members reported compass error when trying to take off from the sidewalk but once they move away from the metal bars underneath, it was then okay, so I think it's better to check out the surrounding if you get the compass error. If that is NOT the case, then we can go on to something else.

RE: From Manual section 6 Power On the Aircraft.

1. There are ferromagnetic substance around; first make sure that the compass has been calibrated correctly, you
can lift the aircraft up (about 1m from the ground), and stay away from the surrounding possible ferromagnetic
material object, if there is no red and yellow flashing after lifting it up about 1m from the ground, then it will not
affect the flight.

In addition from: http://www.armystudyguide.com/content/P ... pass.shtml

Effects of Metal and Electricity. Metal objects and electrical sources can affect the performance of a compass. However, nonmagnetic metals and alloys do not affect compass readings. The following separation distances are suggested to ensure proper functioning of a compass:

High-tension power lines ................................................. 55 meters.

Field gun, truck, or tank .................................................. 18 meters.

Telegraph or telephone wires and barbed wire ................ 10 meters.

Machine gun ................................................................... 2 meters.

Steel helmet or rifle .......................................................... 1/2 meter.

My Prius traction battery is 273.6 volts.

Compass calibration should take place outdoors, away from any metal objects etc ( that includes cell phones, keys, coins, cars etc.)
Be aware that some concrete bases, foundation slabs etc contain reinforced steel ! so because you cant see it does not mean its not there. Always think ," is there any metal near me? " when doing the compass dance.