Help analyzing a Mini crash - link to Phantomhelp.com log provided

[shorttimer]

Am bringing this over from the DJI forum with the pilot's permission. Was wondering if someone could help to analyze what was the exact cause of the crash. Was a very short flight about 40 seconds. Pilot ascended rapidly to 120', home point was recorded and it stayed in P-GPS mode. Once at 120' both sticks were in the neutral position and the Mini started increasing horizontal speed starting at abut 1MPH and exceeding 40MPH before crashing. Also, looking at the logfile it appears the drone was not parallel to the horizon but a lot lower on the left and higher on the right which would possibly indicate it fighting the wind. There didn't appear to be any high wind warnings but then again the flight was extremely short. Any sage advice out there. They already shipped the Mini back to DJI but still was looking for an answer.

Here is the link: DJI Flight Log Viewer - PhantomHelp.com

 

[blakamin]

Looking at those logs, that's called "flying straight up until the wind gets you".

At 128ft you can see stick input stopped, and it got blown away.

 

[Meta4]

Looking at those logs, that's called "flying straight up until the wind gets you".

At 128ft you can see stick input stopped, and it got blown away.

If you look closer you see that forward motion started while the drone was just a foot above the launch point and with no right stick input.
Do you want to guess again?

 

[Meta4]

Am bringing this over from the DJI forum with the pilot's permission. Was wondering if someone could help to analyze what was the exact cause of the crash. Was a very short flight about 40 seconds. Pilot ascended rapidly to 120', home point was recorded and it stayed in P-GPS mode. Once at 120' both sticks were in the neutral position and the Mini started increasing horizontal speed starting at abut 1MPH and exceeding 40MPH before crashing. Also, looking at the logfile it appears the drone was not parallel to the horizon but a lot lower on the left and higher on the right which would possibly indicate it fighting the wind. There didn't appear to be any high wind warnings but then again the flight was extremely short. Any sage advice out there. They already shipped the Mini back to DJI but still was looking for an answer.

Here is the link: DJI Flight Log Viewer - PhantomHelp.com

No right stick input and the drone accelerates to faster than normal speed on a smoothly curved path ....
It looks like another case of launching from a magnetically compromised spot, (possibly reinforced concrete) causing a yaw error situation.

 

[blakamin]

Do you want to guess again?

Nice Attitude... Was that before or after the "home point updated" message??

You want to look at the home distance all the way up to 123ft???
Allowing for some wind drift, it did sweet FA, but thanks for being the "expert".

 

[Meta4]

Nice Attitude... Was that before or after the "home point updated" message??

I'm not sure what relevance that has but his drone recorded a home point at 0:00.8
It started to leave the ground at 0:07.8, the same time as the Home Point Updated message.

You want to look at the home distance all the way up to 123ft???
Allowing for some wind drift, it did sweet FA, but thanks for being the "expert".

There is no hint of a wind problem in the data.
He only gave it left stick up - no other stick input at all and it's being blown away from the moment it left the ground?
No.
Being blown away at >40 mph would require a wind of approx 60 mph.
No-one is launching anything in that.
If you can't see it in the data, just look at the flight path.
A curved wind?

 

[blakamin]

There is no hint of a wind problem in the data.
He only gave it left stick up - no other stick input at all and it's being blown away from the moment it left the ground?

It was within 3ft of the home point until it was 125ft high.

The fact it went straight up until 130ft and then went in a direction, with a full attitude tilt sideways against the hover, as shown on the log, sort of blows your idea away.

Being blown away at >40 mph would require a wind of approx 60 mph.

No it wouldn't. It wasn't flying "into" a wind, it was sideways, hovering, and being blown away. That pretty much requires the wind to be blowing, from the directions it was, above the takeoff point.

If you can't see it in the data, just look at the flight path.
A curved wind?

A wind that goes around a house and trees? Sure, never heard of a wind that goes around things...

 

[Meta4]

It was within 3ft of the home point until it was 125ft high.

You are correct, I was looking at the wrong column.

The fact it went straight up until 130ft and then went in a direction, with a full side tilt sideways against the hover, as shown on the log, sort of blows your idea away.

No it wouldn't. It wasn't flying "into" a wind, it was sideways, hovering, and being blown away. That pretty much requires the wind to be blowing, from the directions it was, above the takeoff point.

A wind that goes around a house and trees? Sure, never heard of a wind that goes around things...

The rest of my explanation is unchanged.
It's not wind, there's no hint of a wind issue and lots of indications of a yaw error issue caused by launching from an unsuitable location.

 

[Keule]

Wind was blowing from East:

 

[blakamin]

Considering the MM can't break 31mph, in sport mode, I dunno how it would ever do 42mph hovering without the wind being involved.

 

[Meta4]

Considering the MM can't break 31mph, in sport mode, I dunno how it would ever do 42mph hovering without the wind being involved.

That's because you've not dealt with a yaw error issue.
Look at the wind direction and the direction of flight and tell me you still think it's wind.

 

[grahamjohnson10]

Am bringing this over from the DJI forum with the pilot's permission. Was wondering if someone could help to analyze what was the exact cause of the crash. Was a very short flight about 40 seconds. Pilot ascended rapidly to 120', home point was recorded and it stayed in P-GPS mode. Once at 120' both sticks were in the neutral position and the Mini started increasing horizontal speed starting at abut 1MPH and exceeding 40MPH before crashing. Also, looking at the logfile it appears the drone was not parallel to the horizon but a lot lower on the left and higher on the right which would possibly indicate it fighting the wind. There didn't appear to be any high wind warnings but then again the flight was extremely short. Any sage advice out there. They already shipped the Mini back to DJI but still was looking for an answer.

Here is the link: DJI Flight Log Viewer - PhantomHelp.com

I have already analyzed this crash in the other forum.

I used both CsvView and also FRAP to analyze the flight log.

IMHO it is no fault of the pilot or wind.

1) Everything is fine except the GPS health being 4 instead of 5 during the whole flight.

2) The IMU had velocity and direction failure about 27 seconds into the flight.

 

[pmshop]

I do not think it was wind.
It would have blown it back to him.

 

[grahamjohnson10]

I do not think it was wind.
It would have blown it back to him.

It was a her not a him.

 

[shorttimer]

Thanks for all the suggestions so far - I initially thought it was wind as well. But being it was in P-GPS like stated earlier the wind would have had to have been blowing 60MPH to get the mini moving at 40MPH. But with all the houses and trees around it would have been sheltered from the wind down low. I live in an open area, at 8k' with no trees on acreage so I can easily detect the wind but when the houses are so close and trees all around I know it is different. I just wanted to post it here to get some opinions.

Like I said it has been sent off to DJI for repair so that might glean some information but the pilot would really like to know exactly what happened.

Thanks again...

 

[shorttimer]

Wind was blowing from East:
View attachment 88754

The Airdata log shows just the opposite the wind at 238 degrees NE. Here is the airdate log.

 

[pmshop]

The Airdata log shows just the opposite the wind at 238 degrees NE. Here is the airdate log.

Yes, that is the ground wind.
Look at the wind from 125ft in post #9 that you qouted, that is the in-flight winds.
To view Inflight winds requires a paid subscription.

It is quite possible to have different directional winds at different altitudes.
Even as narrow as 125 ft.

One time I flew at the edge of a hurricane to video flooding.
On the ground it was 10mph winds from the east but just 150ft up it was 40 mph from the north.
I was flying a home made hexacopter at the time.

 

[Keule]

The Airdata log shows just the opposite the wind at 238 degrees NE

This is windspeed on the ground.
Use 'InFlight Windspeed' to see the windspeed/direction while the drone is actually flying at a specific height.

 

[grahamjohnson10]

This is windspeed on the ground.
Use 'InFlight Windspeed' to see the windspeed/direction while the drone is actually flying at a specific height.

It was only 11 mph at 328 feet, she was only about 120 feet.

Ventusky - Weather Forecast Maps

Live wind, rain, radar or temperature maps, more than 50 weather layers, detailed forecast for your place, data from the best weather forecast models with high resolution

www.ventusky.com

 

[Danr-62]

According to my math and I could be wrong, it was doing 30 mph where the log viewer lists it as traveling at or in access of 40mph?

Based on time and distance traveled using the 35s to 36s marks = 44 feet traveled so for that one second in flight time = 30mph?

Nose of the aircraft actually pointing south rather than north as illustrated in the viewer?