Take off from boat - word of warning

[boblui]

Did you have any incidents following the glitch? I was thinking the 'yawing behaviour' might have led to something more serious?

Nothing at all, In fact I have tried to reproduce the glitch on the same day but it did not reappear. If you can post the flight logs ( TXT and DAT files ), may be more insights can be obtained.

 

[Meta4]

Meta4, you're certainly entitled to your opinion. IMO when holding the UAF 3 feet above a ferrous material, the compass will properly calibrate. It's not as though getting near a metallic object after calibration will reinitialize the compass and IMU.

I think you're confusing a ferromagnetic material with induction . In the case iron or steel, it doesn't emit a magnetic field

No confusion at all on my part.
I used the term magnetic since the Compass Error warning in the app says Magnetic Interference.
And if you get that warning because you are too close to some steel, recalibrating the compass won't fix it, but moving away from the problem will.

Regardless, I'm sure we'll all agree to error on the side of caution, if not a bit of superstition (and yes, I still do the "compass dance" more often then necessary).

I don't ever recalibrate my compass, and it's never been calibrated since it left the factory almost four years ago.
It's just not necessary unless you repair or modify the drone.

 

[BudWalker]

I attempted to get the dat file but there is nothing in the sub folder, I’m guessing DJI deleted it when they uploaded to the server?

That's unfortunate. Thanks for looking.

 

[AMRE2ME2]

No confusion at all on my part.
I used the term magnetic since the Compass Error warning in the app says Magnetic Interference.
And if you get that warning because you are too close to some steel, recalibrating the compass won't fix it, but moving away from the problem will.


I don't ever recalibrate my compass, and it's never been calibrated since it left the factory almost four years ago.
It's just not necessary unless you repair or modify the drone.

Meta4, interesting. So if I get a message to recalibrate, should I first try moving to a different location? I’ve received that message after traveling 75 miles from my place and trying to takeoff from a dirt road.

 

[Mavicvagyok]

You said you were in a canal, which I'm guessing may magnify the sonar from the boat.

This thread was a different aircraft but might have the same sonar sensors as yours, and maybe the same as the boat you were on.

Water Crash... Is this the VPS issue im now reading about?

Btw: the Mavic manual clearly states under "Flight Environment Requirements": The manual also has plenty of statements about what to do when flying over bodies of water.

mavicpilots.com

 

[Meta4]

Meta4, interesting. So if I get a message to recalibrate, should I first try moving to a different location? I’ve received that message after traveling 75 miles from my place and trying to takeoff from a dirt road.

DJI's wording for and even the name for compass error are confusing.
What they call a compass error isn't a compass fault that needs correcting.
It's a good compass warning or a problem close by.
The screen warning says Magnetic field interference, move aircraft or calibrate compass.
At least 99% of the time, the correct action is to move away from the problem that the compass is warning about, because recalibrating a properly working compass won't fix the issue.

DJI does some strange things that confuse even further, like making some models demand a recalibration after 30 days or moving 30 miles from the last flight, although there is no physical reason to.

All of this is explained in detail in the beginning of this thread:

A short explanation of compass function, calibration and errors.

BACKGROUND The aircraft compass is often misunderstood, both in terms of function and purpose, but it is important to understand what the compass measures, why, and what happens to that information. At the most basic level the purpose of the compass is to measure the earth’s magnetic field in...

mavicpilots.com

 

[RayKelly]

Hi all!

Just had my first fly-away today which was scary. From reading other posts I assume I had magnetic interference when taking off.

I hand launched the MM from the aft/rear of a small boat with a 200hp outboard motor. I have launched the MM from the same boat the day before, but from the stem/front without any problems.

What happened was that the MM lanuched ok, but as soon as I gained altitude and made some distance from the outboard motor, it suddenly darted away forward att full speed. There was nothing I could do to stop it. I tried to turn e t c, but the MM just sailed away at full pace and I realized that I quickly had to do something drastic. So I pulled both sticks downwards until it crashed in a field of thorn bushes. We were boating in a canal at the moment, so luckily there was land to crash the MM in/on.

I think that the outboard motor generated a magnetic interference which affected the "magYaw" input. As soon as the MM was away from the outboard motor, it freaked out and became virtually uncontrollable.

It seems to be unharmed though. I think I only need to change the props. What bothers me a little bit is that the drone never recovered in flight. If, according to the GPS, the drone travels at speed without any input from the RC - why does it not stop flying away??? In my opinion there must be an overlooked bit of code there.

Lesson learned? Never launch the MM from near the outboard motor or other electronics (which many of you already know and so do I now by learning the hard way).

Sorry to hear this. Glad you did not lose your mini. Were you recording? If so, please post video.

 

[hydrolift]

Sorry to hear this. Glad you did not lose your mini. Were you recording? If so, please post video.

Thanks! All well in the end after all and lesson learnt. The video is on the 2nd page.

Take care!

 

[YsniperY]

Hi all!

Just had my first fly-away today which was scary. From reading other posts I assume I had magnetic interference when taking off.

I hand launched the MM from the aft/rear of a small boat with a 200hp outboard motor. I have launched the MM from the same boat the day before, but from the stem/front without any problems.

What happened was that the MM lanuched ok, but as soon as I gained altitude and made some distance from the outboard motor, it suddenly darted away forward att full speed. There was nothing I could do to stop it. I tried to turn e t c, but the MM just sailed away at full pace and I realized that I quickly had to do something drastic. So I pulled both sticks downwards until it crashed in a field of thorn bushes. We were boating in a canal at the moment, so luckily there was land to crash the MM in/on.

I think that the outboard motor generated a magnetic interference which affected the "magYaw" input. As soon as the MM was away from the outboard motor, it freaked out and became virtually uncontrollable.

It seems to be unharmed though. I think I only need to change the props. What bothers me a little bit is that the drone never recovered in flight. If, according to the GPS, the drone travels at speed without any input from the RC - why does it not stop flying away??? In my opinion there must be an overlooked bit of code there.

Lesson learned? Never launch the MM from near the outboard motor or other electronics (which many of you already know and so do I now by learning the hard way).

Do you know for certain that the GPS had a good lock and info was correct?

 

[YsniperY]

When you startup, you get that audio: “Homepoint is updated please CHECK IT ON THE MAP“
Isn’t this the point of that audio alert? Because if the drone is not pointing at the same heading as what is portrayed on the map, you are having interference!

Ive never had a flyaway with over 400 flights, but I do check that my heading and map are reading the same. I assumed this is why we get that reminder With every flight.

That’s a good point. Ive gotten used to hearing that and haven’t really paid much attention to actually looking at its heading etc.

 

[hydrolift]

Do you know for certain that the GPS had a good lock and info was correct?

Hi!

Yes I think I had more than 12 satellites connected before taking off.