Lost all control and crashed

[supra59uk]

Hi Budwalker
To be honest I cant remember which way it was facing
I think the compass is at the top of the shell
I'm going to power the phantom over the weekend I'm sure it will be dry by then and see what the damage is its just so annoying I treat like a baby really gutted, got a reply from the dealer yesterday, I sent them the log and they replied back there was 183 errors of which the first one was 8 second and you would of seen them on my screen insinuating I should of stopped the flight there and then and its not a warranty claim , this as really annoyed me its ********, I had a total of 4 warnings the rest of them was purely in the log file first 1 was home point 2nd and third was about 23 seconds in I already new by this time there was something wrong, and I wasn't watching the screen I was to busy trying to get the craft down.

I replied to there comments has you can imagine and asked to see the log and picture of all these warnings I am supposed to have seen on the IPad, told them I was going to get legal advise, they mailed me back today and said they have had there engineer have a another look
and he has spotted there was a compass error so they would like me to send the quad to them. are these people for real !!!

I don't know what to do now what do you guys think?

 

[Meta4]

I think the compass is at the top of the shell

The GPS antenna is under the top shell.
The compass is in the landing gear.

You've mentioned that the pond was salt water.
Even after flushing with fresh water, there is only a low probability the Phantom will work again.
Electronics + salt water never works out well.

 

[supra59uk]

The GPS antenna is under the top shell.
The compass is in the landing gear.

You've mentioned that the pond was salt water.
Even after flushing with fresh water, there is only a low probability the Phantom will work again.
Electronics + salt water never works out well.

Thanks Meta 4 learn something new there about the compass

yeah salt water is not good time will tell there is no sign of residue showing on any of the boards now its dry and I've used electrical cleaning spray so fingers crossed I can salvage some of it, we will soon find out hopefully.

 

[supra59uk]

Hi Guys

ok update the craft is now back together and I'm pleasantly surprised the damage that I can see so far is number 2 esc, the battery which I already new and a slight crack in the top cover which I new about must be a weak spot next to the motor.
Both the imu and compass are green its finding sats and the gimbal seem to work fine.

possible issue with the memory card slot wouldn't recognise my cards tried 2 different ones, once I reformatted the cards and it seems to be reading them who knows!!
so maybe all is not lost, had a real good look at the boards and I don't see any residue any where so that's a good sign.

I have managed to recover the dat files as well so I will post it up for you guys to look at if you get some spare time.

 

[supra59uk]

I think that there is a good chance this is a warranty issue, but we really need to see the DAT file to know for sure. If you haven't sent the aircraft for repair yet can you extract and post it?

hi I have downloaded the files but don't know how to get it on here
can you help thanks paul

 

[BudWalker]

hi I have downloaded the files but don't know how to get it on here
can you help thanks paul

You'll need to use something like Dropbox or GoogleDrive. Upload the .DAT to one of those and then provide a link to the uploaded copy.

 

[sar104]

hi I have downloaded the files but don't know how to get it on here
can you help thanks paul

Too big to post directly in most cases. Most people use Dropbox and then share the link.

 

[supra59uk]

You'll need to use something like Dropbox or GoogleDrive. Upload the .DAT to one of those and then provide a link to the uploaded copy.

thanks I will have a go

 

[Soulcoffr]

I’m new here and I’m new to drones, but since he was photographing a model aircraft club, couldn’t the loss of control be due to some kind of radio interference? It’s the most common cause for flyaways, according to the FAA. And in dealing with RF equipment frequently in my career, this wouldn’t surprise me one bit.

 

[sar104]

I’m new here and I’m new to drones, but since he was photographing a model aircraft club, couldn’t the loss of control be due to some kind of radio interference? It’s the most common cause for flyaways, according to the FAA. And in dealing with RF equipment frequently in my career, this wouldn’t surprise me one bit.

There was no loss of control - the aircraft simply switched out of the mode where it controls position, attitude and altitude to one where it just controls attitude and altitude, and will drift on the wind and obey Newton's 1st law of motion.

And to say that radio interference causes most flyaways is simply incorrect - it may interrupt the uplink and/or downlink, but if the FC loses the uplink then it will automatically return to the launch point, unless programmed to do otherwise.

 

[Just Mark]

Sorry for the interruption, but I hope you all can elaborate on a few points made in this thread already about the compass and magnetically "bad" areas to fly.

1) Should you not power on the AC if you are launching from concrete and you SUSPECT there might be rebar in it?

2) Can you power on the AV from a NON-FLAT surface and wait for it to warm up, and then move it to a flat surface (where there might be rebar underneath the surface) and launch from there? Meaning, is it ok to power on the quad when it is not level? And is it ok to launch from an area that might have magnetic interference below the craft if it has already gotten past the warm up / home acquisition stage?

Thanks in advance and sorry for the interruption.

 

[sar104]

Sorry for the interruption, but I hope you all can elaborate on a few points made in this thread already about the compass and magnetically "bad" areas to fly.

1) Should you not power on the AC if you are launching from concrete and you SUSPECT there might be rebar in it?

2) Can you power on the AV from a NON-FLAT surface and wait for it to warm up, and then move it to a flat surface (where there might be rebar underneath the surface) and launch from there? Meaning, is it ok to power on the quad when it is not level? And is it ok to launch from an area that might have magnetic interference below the craft if it has already gotten past the warm up / home acquisition stage?

Thanks in advance and sorry for the interruption.

It's not that you should not power up the aircraft in a distorted magnetic field - it's that you should not fly at all in a distorted field because it will cause compass errors and may lead to loss of attitude control, if it is bad enough. So powering up elsewhere and launching in such a location does not help.

A better approach is to use the magnetometers in your phone to check for magnetic field distortion, using one of the available apps. That method works very well to determine if it is a poor choice of location.

On the other question, flat and level is best, but slightly off level doesn't seem to cause problems.

 

[Soulcoffr]

There was no loss of control - the aircraft simply switched out of the mode where it controls position, attitude and altitude to one where it just controls attitude and altitude, and will drift on the wind and obey Newton's 1st law of motion.

And to say that radio interference causes most flyaways is simply incorrect - it may interrupt the uplink and/or downlink, but if the FC loses the uplink then it will automatically return to the launch point, unless programmed to do otherwise.

Ah! Well, like I said. I’m new here.

 

[GrampaF]

I feel your pain.

1. From my experience of dropping a P3S into Long Island Sound, nothing will bring it back to normal... even if it works for a few flights. And from my experience where a SW 1000 took off, immediately wobbled the wrong direction and crashed into a building ($5,000 worth of damage), I rarely trust GPS-mode on any flight.
2. It looks like DJI will conclude that you failed to notice the switch to ATTI mode, and then dropped it in the salt-water pond.
3. I now almost never take off in GPS-mode. I practice all flights in ATTI mode, and ensure I know which way to fly it if the winds kick up (that is, where it is pointing, what I would have to do rotate, left, right, etc.) to get it back to its home.
4. If I have to take off in GPS mode, I now always use a tether: paracord from the ground up to a little pulley under the drone, and back down to me. I step on it. If the take-off is good and control is good, I remove my foot, take the P3S up, and the end of the rope goes up, slips through the pulley and drops. At this point the P3S is un-thered, and I can fly with confidence.

But, sorry for your loss.

 

[sar104]

I feel your pain.

1. From my experience of dropping a P3S into Long Island Sound, nothing will bring it back to normal... even if it works for a few flights. And from my experience where a SW 1000 took off, immediately wobbled the wrong direction and crashed into a building ($5,000 worth of damage), I rarely trust GPS-mode on any flight.
2. It looks like DJI will conclude that you failed to notice the switch to ATTI mode, and then dropped it in the salt-water pond.
3. I now almost never take off in GPS-mode. I practice all flights in ATTI mode, and ensure I know which way to fly it if the winds kick up (that is, where it is pointing, what I would have to do rotate, left, right, etc.) to get it back to its home.
4. If I have to take off in GPS mode, I now always use a tether: paracord from the ground up to a little pulley under the drone, and back down to me. I step on it. If the take-off is good and control is good, I remove my foot, take the P3S up, and the end of the rope goes up, slips through the pulley and drops. At this point the P3S is un-thered, and I can fly with confidence.

But, sorry for your loss.

I think that you are worrying too much. GPS issues almost never cause a loss of control - that is almost always due to compass errors which trigger ATTI mode anyway. Manually selecting ATTI mode is not going to help. I very much doubt that your original crash was caused by GPS.

Question: on the occasions when you have taken off in P-GPS mode (tethered), have you seen many problems?

 

[Just Mark]

It's not that you should not power up the aircraft in a distorted magnetic field - it's that you should not fly at all in a distorted field because it will cause compass errors and may lead to loss of attitude control, if it is bad enough. So powering up elsewhere and launching in such a location does not help.

A better approach is to use the magnetometers in your phone to check for magnetic field distortion, using one of the available apps. That method works very well to determine if it is a poor choice of location.

On the other question, flat and level is best, but slightly off level doesn't seem to cause problems.

Thank you.

As I have further questions on this, I will start a separate thread.

Thanks again.

 

[GrampaF]

I think that you are worrying too much. GPS issues almost never cause a loss of control - that is almost always due to compass errors which trigger ATTI mode anyway. Manually selecting ATTI mode is not going to help. I very much doubt that your original crash was caused by GPS.

Question: on the occasions when you have taken off in P-GPS mode (tethered), have you seen many problems?

You are right. I should have said, I think the GPS mode relies on an accurate compass, and the mis-calibrated compass causes the problem. Isn't that correct?

In answer to your question, no problems yet. It's like carrying an umbrella on a cloudy day ensures it won't rain...

 

[Just Mark]

In answer to your question, no problems yet. It's like carrying an umbrella on a cloudy day ensures it won't rain...

Although it might increase your chance of getting struck by lightning...

 

[sar104]

You are right. I should have said, I think the GPS mode relies on an accurate compass, and the mis-calibrated compass causes the problem. Isn't that correct?

In answer to your question, no problems yet. It's like carrying an umbrella on a cloudy day ensures it won't rain...

Yes - it's quite counter-intuitive that compass errors lead the FC to go to ATTI and stop positional stabilization, even when the GPS data are good.

 

[BudWalker]

....
2) Can you power on the AV from a NON-FLAT surface and wait for it to warm up, and then move it to a flat surface (where there might be rebar underneath the surface) and launch from there? Meaning, is it ok to power on the quad when it is not level? And is it ok to launch from an area that might have magnetic interference below the craft if it has already gotten past the warm up / home acquisition stage?

Thanks in advance and sorry for the interruption.

Yes... but it can be tricky. At batteryOn the Yaw value is initialized to a value determine by the compass. After that the Yaw value is determined mostly by the IMU (gyros, and accelerometers) with the compass providing corrective inputs at low gain. If Yaw is correct but the AC is then moved to a geomagnetically distorted location the Yaw value will start a gradual change to the incorrect value dictated by the distortion. So it's possible that if launch occurs without delay after moving then Yaw will still be OK.

Your post could be summarized as asking how can it be determined if Yaw is correct before launch. The single most effective method of determining this is to look at the red triangle heading indicator on the Go App map. If that is inconsistent with the actual heading then Yaw is incorrect. It's almost guaranteed that erratic flight, possibly a fly away, will occur after launch.

This method will always work. If you just gotta launch from concrete just make sure this heading indicator is correct before launch.This method will work in those cases where your P4 is sitting in the middle of a grassy field but unbeknownst to you there is a hidden 1/4 " washer sitting directly below the compass.