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Strange drone behaviour resulting in a crash

maccboy

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Hi.

First post so be gentle!
I've had an Air for around 6 months and had an unexplained crash on Friday. I fired it up intending to go up a hundred feet or so to take a photo of the sunset. That's all. The screen said it was flying on Vision, but it was just a straight up and down flight so I carried on. I put Sport on and sent the drone up. There was a pause before it started to go up and then it shot off eastwards, disappearing from view. I hit the RTH button but the family saw it fly off towards the sea, crash, and then take off and fly away from the beach before crashing again. Having searched this forum, I've found and converted the flight log ( I think), which I've attached.
Any information or help to explain what happened would be amazing!
Thanks.
Andy.
 

msinger

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maccboy

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Ah. My file has a csv extension so it was blocked. I've renamed it to txt.
Thanks.
 

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  • Sep-13th-2019-07-36PM-Flight-Airdata.txt
    214.6 KB · Views: 51

msinger

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Can you upload your DJI GO TXT flight log here and link it back here?
 

Northwood Mediaworks

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Wow, that's a smorgasbord of errors...:eek: Can you indicate the wind conditions at the time?
 

dbyantis

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Er, thanks. I was planning to go straight up and straight down. Appreciate your view.
Still, the GPS is the safety net, without a good home point set, RTH will not be available. I understand that you intended a short flight. But if you go into sport mode to get somewhere, it didn't sound like a short flight. Sorry for the loss/expensive lesson.
 

Northwood Mediaworks

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Thanks for your reply, but I don't like the sound of it! There was virtually no wind. If there had been anything more than a strong breeze, I wouldn't have put the drone up.

Ya, sorry for your loss, but as the others are saying, you indicate not the wisest of choices for flying that day. I guess my next question would be where you took off, any possible causes of magnetic interference? Concrete with rebar in it? Do you check your sensors (compass/imu) before each take off? I was trying to avoid calling out all the preventables here as you asked us to be gentle :oops:
 
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maccboy

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Thanks for all the replies. I did find it with just a broken prop. I was on a beach so there was nothing obvious that could have caused a problem with interference. As I said, I was aiming to fly vertically upwards, take some shots, and fly back down. It wasn't really that big a deal, in my view.
I was hoping someone could discover what the cause of the strange flight path was from the data. I did nothing to create the problem. Flying without GPS wasn't the cause, inference wasn't the cause, flying GoVision wasn't the cause. The sensors were fine. That's it, really!
 

Bigbird48

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SOUNDS LIKE YOU DIDN'T HAVE GPS LOCK you went up and the wind took it. with out gps your in atti mode and a slight brezze will wisk it away.
 

BudWalker

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Hi.

First post so be gentle!
I've had an Air for around 6 months and had an unexplained crash on Friday. I fired it up intending to go up a hundred feet or so to take a photo of the sunset. That's all. The screen said it was flying on Vision, but it was just a straight up and down flight so I carried on. I put Sport on and sent the drone up. There was a pause before it started to go up and then it shot off eastwards, disappearing from view. I hit the RTH button but the family saw it fly off towards the sea, crash, and then take off and fly away from the beach before crashing again. Having searched this forum, I've found and converted the flight log ( I think), which I've attached.
Any information or help to explain what happened would be amazing!
Thanks.
Andy.
I looked at the .txt. It's likely that the problem was a compromised Yaw at launch. With a .txt I usually look at a comparison between GPS data weighted position and position computed mostly from accelerometer data and gyro data. That can't be done here because GPS data wasn't available at launch

The curved trajectory in combination with a constant Yaw (aka toilet bowling) is almost always the result of a compromised Yaw. The Yaw data indicates that the MA was facing east at launch. Was the MA actually facing west, into the sunset?

I saw your comments about a clean launch site. There are other ways Yaw can become compromised. Did you power up in the presence of ferrous metal (car hood, steel picnic table, etc..) and then move it to the launch site?

The .DAT would help figure out more if you want to retrieve it.
How to retrieve a V3.DAT from the tablet

There seems to be a lot Monday morning armchair quarter backing in this thread. None of it based on an analysis of the log. My advice is to ignore it.
 

sar104

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I looked at the .txt. It's likely that the problem was a compromised Yaw at launch. With a .txt I usually look at a comparison between GPS data weighted position and position computed mostly from accelerometer data and gyro data. That can't be done here because GPS data wasn't available at launch

The curved trajectory in combination with a constant Yaw (aka toilet bowling) is almost always the result of a compromised Yaw. The Yaw data indicates that the MA was facing east at launch. Was the MA actually facing west, into the sunset?

I saw your comments about a clean launch site. There are other ways Yaw can become compromised. Did you power up in the presence of ferrous metal (car hood, steel picnic table, etc..) and then move it to the launch site?

The .DAT would help figure out more if you want to retrieve it.
How to retrieve a V3.DAT from the tablet

There seems to be a lot Monday morning armchair quarter backing in this thread. None of it based on an analysis of the log. My advice is to ignore it.

Agreed - this has a number of the hallmarks of a yaw error after takeoff leading to TBE:

Delta_V.png

That kind of error generally seems to be associated with a 90° yaw error, so I'd expect that it was actually facing north(ish).
 

maccboy

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I looked at the .txt. It's likely that the problem was a compromised Yaw at launch. With a .txt I usually look at a comparison between GPS data weighted position and position computed mostly from accelerometer data and gyro data. That can't be done here because GPS data wasn't available at launch

The curved trajectory in combination with a constant Yaw (aka toilet bowling) is almost always the result of a compromised Yaw. The Yaw data indicates that the MA was facing east at launch. Was the MA actually facing west, into the sunset?

I saw your comments about a clean launch site. There are other ways Yaw can become compromised. Did you power up in the presence of ferrous metal (car hood, steel picnic table, etc..) and then move it to the launch site?

The .DAT would help figure out more if you want to retrieve it.
How to retrieve a V3.DAT from the tablet

There seems to be a lot Monday morning armchair quarter backing in this thread. None of it based on an analysis of the log. My advice is to ignore it.

Thanks for your reply. I'll get the DAT file later today when I get home. I don't think I started the drone until I got to the beach as I'm usually very careful about battery usage.
 

maccboy

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Agreed - this has a number of the hallmarks of a yaw error after takeoff leading to TBE:

View attachment 81849

That kind of error generally seems to be associated with a 90° yaw error, so I'd expect that it was actually facing north(ish).

Thanks. I can't remember which way it was facing. Hopefully the DAT file will help explain a bit more.
 
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