I was flying my I1 around a newly constructed dam this afternoon taking footage for the final clip of a 2 year construction project.  I was airborn for approx. 5 minutes getting video of the spillway and surrounding landscape and started to lose control of my machine.  I was able to get it back over solid ground, but had little or no contol of it.  I was able to lower the landing gear, and it crashed into a fence surrounding the dam.  The only damage that I can see is a broken prop.  All of my updates have been complete, calibrated compass, everything seems to check out just fine. Just afraid to fly it again.  

Were you in GPS mode or Atti.?
Could be interference with your compass due to the large amounts of steel and concrete in the dam wall?
I always fly in Atti. mode if I'm near large man-made structures like multi-level carparks as I've had the same thing happen to me due to interference.
It's scary!! Lucky you didn't get much damage.

bobo81@y7mail.c Posted at 2015-7-23 15:20
Were you in GPS mode or Atti.?
Could be interference with your compass due to the large amounts of  ...

Bob,

I have heard this before in relation to calibrating the compass or IMU whilst the aircraft is on reinforced concrete or close to it, but never heard any issues whilst it is in flight.

I am struggling to understand how the aircraft could be affected by concrete with steel reinforcement when the concrete cover to the steel bars will be at least 50mm thick.  In addition, the aircraft I presume would be at least 2m away from the concrete dam or structure, so I am struggling to understand how steel re-bar can affect the stability and flight controls.  

I suspect it is more likely some bug in the system unless someone else can categorically prove that steel re-bar will affect an aircraft whilst in flight mode.  If this was the case, then what you are saying is that UAVs are simply no good for inspection purposes.  

What about where UAVs have been used to inspect wind farm turbines and flare stacks on rigs.  Lots of steel, but you don't read about the UAV going beserk due to the presence of steelwork.

Also, was the I1 on level ground when it was going through it's start up?
I find if you are not, you will get what you are saying. It has happened to me a few times.  Last time was off the back of my truck. Not being completely level (not to bad,  but not level).  and acted it such a way as you said, but I brought it right down, never took the legs up. I've learned to always hover for a good minute seeing how it acting before lifting the legs and flying. When I moved it to the ground restarted it, it then flew like it should.

GB44 Posted at 2015-7-23 17:03
Bob,

I have heard this before in relation to calibrating the compass or IMU whilst the aircraft i ...

Put a compass near a magnetic object, or fly a drone with a compass near a magnetic object and it's going to affect its performance right? It doesn't have a bug.
All I'm saying is switch to Atti. when your drone isn't behaving how it should, GPS mode isn't always foolproof.

I was in GPS mode, thanks for the advice. Next time I will fly in ATT mode.  I took off from flat ground, it flew perfectly for the first 5 minutes of flight, then went semi out of control.  Im just glad that fence was there or it would have been gone forever.  

bobo81@y7mail.c Posted at 2015-7-23 19:20
Put a compass near a magnetic object, or fly a drone with a compass near a magnetic object and it' ...

Bob,

I understand what you are saying about magnetic objects close to a compass, but if you were to stand on a concrete road or even on a dam head with a compass in your hand, its not going to affect the reading.

I just dont think  this may be the only reason and still don't understand how a UAV that would be a greater distance from the concrete whilst in flight would be affected in such a way that it disturbs the flight characteristics.

However, I would not rule out any wind turbulence rolling over the damm head, which would certainly also give you something to worry about and may cause the aircraft to become somewhat unsettled in flight until it regained its GPS stabilisation.