Sudden Crash New Mavic 2 Pro

[sar104]

Well....... look at the video. Please. Look at the speed and frame clips. I assure you it was in a hover when it spun. I cannot see what I could have done to cause that event. Can go take a pic of the site. Cannot see grass flying until ground impact. I slowed the last posted tube video to frame by frame.

No - you were not in a hover - you were descending. That is perfectly clear from the graph I posted previously. Throttle was down and the aircraft was descending:

 

[Yhodah]

I don't think anyone believes that you are misrepresenting anything, but are you quite sure that it was well above those tall plants that are visible in the video as it crashes?

I was walking under the drone as it fell before me. Nothing hit the drone I assure you. It fell out of the air like a shot bird.

 

[Yhodah]

You can read the data. My memory is not perfect. I could have been bringing it down. but only enough to walk under it for the lapse shot.

 

[Yhodah]

Can you see the relative movements of me with the controller and the drone like the flight replays show?

 

[Yhodah]

Can these motors suddenly obstruct in flight? Yet be un obstructed after the event?

 

[Yhodah]

I don't think anyone believes that you are misrepresenting anything, but are you quite sure that it was well above those tall plants that are visible in the video as it crashes?

Again I can go back and take a pic of the site. I was clear of the trees in view. Again the same thing happened the first day I had the drone.

 

[sar104]

Would you care to interview me by phone? I have another witness. Can these motors suddenly obstruct?

If the props contact vegetation they will behave like that. An alternative would be for the motor to seize mechanically, but note that the motor speed subsequently recovers - characteristic of an external factor. Perhaps there are ESC failures that could do that, but I've not seen any - hence my observation that since the aircraft was descending the most likely explanation was vegetation. I cannot guarantee that's correct - it's just what the data suggest.

You have explained in detail what you saw, but some of your recollection is demonstrably wrong - in particular that it was hovering and not descending. It was descending at 0.9 m/s under down throttle when the problem occurred:

 

[BudWalker]

Certainly can't rule out hardware, but it looks just like every case of motor obstruction that I've seen. How do you get a motor current spike with motor speed reduction without physical obstruction?

I agree. It's like a motor obstruction. I think the 2 (so far) possible explanations are each not quite satisfactory. I'm gonna go for the motor temporarily obstructed scenario. 12 foot high grass is a little more than I can accept.

 

[sar104]

Again I can go back and take a pic of the site. I was clear of the trees in view. Again the same thing happened the first day I had the drone.

If you are certain that it didn't hit anything then it has to be a hardware issue as @BudWalker suggested. Perhaps DJI will be able to figure it out.

 

[sar104]

I agree. It's like a motor obstruction. I think the 2 (so far) possible explanations are each not quite satisfactory. I'm gonna go for the motor temporarily obstructed scenario. 12 foot high grass is a little more than I can accept.

I agree - my initial view was that it was too high to have hit the vegetation. Perhaps someone with a better understanding of these kinds of motors can weigh in on those data.

 

[Yhodah]

Here is the data from my first three flights. I think the 8 one was the sudden crash. My son in law was 2 feet from it watching it when it flipped and crashed.

 

[Yhodah]

This is the 8 one. I probably have surveillance cam video of this.

 

[Yhodah]

I appreciate your time today. Thanks!

 

[Yhodah]

Just looked at my video again. I think the height of grass issue and foliage issue is clearly observed in the video. Will wait to see what dpi does. And sar104 curious as to what program you use to get that graph. I could not do it with csview.

 

[BudWalker]

........And sar104 curious as to what program you use to get that graph. I could not do it with csview.

I think he must've gotten the RC_throttle data from the .txt and overlaid it onto the .DAT data. @sar104 ?

 

[Yhodah]

View attachment 61735

I think he must've gotten the RC_throttle data from the .txt and overlaid it onto the .DAT data. @sar104 ?

Thanks..... I clearly was dropping on the video also. Shows how memory can be influenced by perception. The data, video, does not lie. In my memory I thought I made a brief push down and was hovering. Nonetheless thank you for your time and analysis. I look forward to learning more about your data tools. Thank you for making them public.

 

[sar104]

View attachment 61735

I think he must've gotten the RC_throttle data from the .txt and overlaid it onto the .DAT data. @sar104 ?

Yes - that's what I did.

 

[sar104]

Just looked at my video again. I think the height of grass issue and foliage issue is clearly observed in the video. Will wait to see what dpi does. And sar104 curious as to what program you use to get that graph. I could not do it with csview.

I export the data as csv from DatCon or TXTlogToCSVtool and analyze it in Igor Pro.

 

[sar104]

Just looked at my video again. I think the height of grass issue and foliage issue is clearly observed in the video. Will wait to see what dpi does. And sar104 curious as to what program you use to get that graph. I could not do it with csview.

But you also mentioned that the aircraft had exhibited exactly the same behavior previously. I haven't had a chance to look at those files yet.

 

[Lon Denard]

I have had this exact type of crash. The barometer is not a perfect judge of height. The drone calculates height relative to take off. I don't think 12 feet is that big of a difference in my experience. I fly in the negative all the time. The video shows the vegetation immediately after the failure. I don't get the sense that the drone fell 10+ feet before we saw grass. A Phantom 2 had several inches of clearance to the props, a Mavic has almost none. You may as well have sent it back but if it was damaged, DJI probably won't refund it. The data shows an obstruction. I could literally recreate this scenario/ those dat files in my shop. If you got it from a retailer, you may have better luck with them.

Wal-Mart took back a GoPro Karma from me that I crashed into a tree after it lost GPS. Best Buy took back a TV we dropped bringing it home.