Field of Death

[AeroJ]

I live a short drive away from a lovely little Hampshire village called Buriton. It has a large sports field just off the high street where we can safely and legally get some rewarding views of the picturesque village and the surrounding countryside. The trouble is, every time I fly here, I crash, through no discernable fault of my own !!

6 years ago I found the site, and with my home-assembled and previously reliable DJI flamewheel quad, running their Naza FC, and conducted 4 perfect flights with no problems. On the fifth one, we started well, but then what I have come to refer to as a non-pilot-error flyaway, in which the craft just took off at maximum speed and throttle until I killed the motors and it crashed in someone's back garden. Nice people, I recovered it, rebuilt, and flew again with no issues for about another year or 2.

2 years later, and I was back in Buriton again, this time to give a talk to the local RC model club about drones ! This would include 6 spectated flights on the same sports field. 5 went well, and then in flight No 6, the Naza M did another flyaway, this time in a Flamewheel 550 hex, and this time it just swerved up then ploughed itself into the ground. I did the talk with the mangled pieces in front of me

Again, I rebuilt, this time with a Naza M2 in a TBS Disco Pro, and kept flying, incident-free for another year before it did the last flyaway somewhere else and I decided I couldn't trust their flight controllers and abandoned the hobby. At no time could DJI or anyone else tell me what had gone wrong and this was before the days when we could look at telemetry. I blamed the IMU.

And now I'm back, with my trusty Typhoon H (150 flights, no crashes), wondering if it might be a good idea to fly at the Buriton Sports field. What do you think ? Is there something there that makes flights go wrong ? Or is the location of 2 previous crashes just coincidence ? Can Yuneec prevail where DJI failed ?

Here it is on Google maps.

Google Maps

 

[gwhuntoon]

With such a small sample size it may just be coincidence, however you can't rule out the environment. You've had 2 incidents years apart but how many successful flights between incidents? How far apart geographically were your incidents? I've found a lot of my incidents were probably related to my own mistakes, either during pre-startup impatience or neglected calibrations.

Just food for thought -
Have you noticed any magnetic compass anomalies when traveling about the area near to where your incidents occurred? I'm referring to a traditional handheld magnetic compass.

Not knowing anything historically about the area, I'm curious as to how much metal from any battles, both modern and ancient which may be in the ground. Are there any significant magnetite deposits in the area?

There don't appear to be any rail lines in the area. What about the power grid, i.e. lines running under the channel, cell towers, radar installations, broadcast towers?

 

[AeroJ]

Have you noticed any magnetic compass anomalies when traveling about the area near to where your incidents occurred? I'm referring to a traditional handheld magnetic compass.

I haven't checked but will do next time I'm there...

You've had 2 incidents years apart but how many successful flights between incidents?

Oh loads - apart from a few user-error crashes very early on as I was learning, these are the only crashes I have ever had.

How far apart geographically were your incidents?

Different sides of the park, but generally speaking in the same place.

There don't appear to be any rail lines in the area.

You mean apart from the massive railway lining the entire back of the field ?!! I did wonder if that had anything to do with it, but I had other flights much closer to railway lines than I ever got in the flights here with no problems, so I had kind of discounted that...

The battle metals theory is interesting, and I also wondered whether someone had a GPS jammer or something similar. I also fly fairly regularly at Halls Hill, just up the road from this field, and have never had any problem there.

 

[PatR]

When you had the previous fly aways you were using a system noted for considerable problems experiencing fly aways and IMU instabilities. There flagship FC during that period (Wookong)was also considered unstable and acted similarly so those using it learned to use a firmware version that was generally stable but avoided using GPS coordinated flight modes. In essence, we rolled back to a certain firmware version and only flew in Attitude mode. So what you experienced has a very high probability of being caused by defective FC design.

I would fly the H, without fear of the location being “ jinxed”, but always ready to exit GPS if necessary. Just flying in Angle mode would reduce to possibility of GPS induced problems.

 

[gwhuntoon]

I missed that rail line on the map. I zoomed out and was looking for something shooting straight across but didn't see anything. From what I've heard from others, the most impact they've seen from rail lines has been drifting or the inability to hold a bearing but no fly aways (that I know of).

As far as the other possibilities I suggested, most are way out there. I usually take the Occam's Razor approach to issues and assume I may have made a mistake before looking at other possibilities.

One other item which I should have mentioned is the Kp reading for the days of your fly aways. I'm not sure if you check the Kp index referring to disturbances of the Earth's magnetic field which is mostly influenced by the sun. But then again, while I'm sure Kp is a factor, I personally haven't experienced issues on a higher Kp day but then again, I do try to avoid flying on those days when it's high.

Unfortunately there isn't any single causal factor with a fly away other than it's usually related to conflicting compass and GPS data which can't be over come by the flight controller. Back in the day, I remember my Cheerson CX-20 would occasionally loose home which would default to the manufacturing plant in China when RTH was initiated. Depending on my orientation the flyaway would seemingly be random but on closer inspection the bearing would take it to China or attempt to.

 

[AeroJ]

Well - I just did it and it was totally fine. Good little TH

 

[PatR]

Somehow I knew it would[emoji106]