Is this a pilot error or Malfunction ?

[BadWolf1]

I'm curious to know when you think that happened? Maybe I'm somehow reading the data wrong.

First row of the data is 8m22.6sec height 26.9ft, last row is 8m23.6 sec, height -19ft.
Subtract the two and it's gone 45.9 feet down in 1 second

 

[maelstrom]

First row of the data is 8m22.6sec height 26.9ft, last row is 8m23.6 sec, height -19ft.
Subtract the two and it's gone 45.9 feet down in 1 second

Apologies, you are absolutely correct. I took the last digit as the seconds rather than the decimal seconds!

However, that still looks suspicious to me. Falling from a fixed height with zero initial vertical velocity (level flight), it would take 1.7 seconds to cover 46 ft with no air resistance - see: Free Fall Calculator. Add some air resistance and it would take even longer. That means that the drone would have had to already be in a steep descent before the data in the table in post #1 started. The drone would have had to be descending at an initial velocity of around 25 ft/sec to cover 46 ft in one second due to gravity alone. It would be interesting to see the change of height for the few seconds before the table started to establish if it really was already descending that quickly.

 

[Meta4]

Apologies, you are absolutely correct. I took the last digit as the seconds rather than the decimal seconds!

However, that still looks suspicious to me. Falling from a fixed height with zero initial vertical velocity (level flight), it would take 1.7 seconds to cover 46 ft with no air resistance - see: Free Fall Calculator. Add some air resistance and it would take even longer. That means that the drone would have had to already be in a steep descent before the data in the table in post #1 started. The drone would have had to be descending at an initial velocity of around 25 ft/sec to cover 46 ft in one second due to gravity alone. It would be interesting to see the change of height for the few seconds before the table started to establish if it really was already descending that quickly.

But it wasn't in level flight with zero initial vertical velocity.
Here's the relevant part of the flight data.

It shows that the flyer was in Sport Mode and holding the left stick down hard from 8:19.9 (yellow highlight), so the drone already had significant downward velocity.
The first purple line is the approximate time that the issue started as indicated by the roll data.
The second purple line is the impact with the ground.
Vertical acceleration was about 6.3 metres/sec/sec and (vertical) terminal velocity was about 15.7 metres/sec.

The full data is available from here: DJI Flight Log Viewer - PhantomHelp.com

 

[slup]

is it this one? Now that you mention it when the drone hit the floor only the front left arm came loose from the shell, all propellers were still intact prior to the crash but the front left one snapped in half possibly from the drone taking the fall face first

Yep ... that's the correct DAT log. Strangely DatCon translate the time axis differently between the TXT & the DAT ... have seen this before so it's not related to the incident, just how DatCon translate (perhaps @BudWalker can explain).

Looking into the DAT make me now think that due to how the OP commands the AC there in the end with a sudden release of the elevator from full forward sport, applies max descend & begins to rotate CCW with approx 75% applied rudder input ... tricked me into leaning to a lost left front thrust.

Plotting in the combined acceleration of the AC to determine where it hit the ground (Black) shows a big spike at 555.3sec which then ought to be the touch down (it's there the AC reaches the lowest height also) ... so all that happens after that, should be a result of the crash & not the cause.

Comparing all 4 sides rpm's, FC command & current draw reveals that the front right doesn't behave at all before the crash ...

Note how the motor rpm (Red) drops to the bottom already at 552,3sec & never recovers. The initial decrease of the rpm is due to the OP's maneuvering, but at 554,2sec the FC commands 100% (Green) & the current spike high (Blue) ... but nothing happens with the rpm, it remains on 500-ish & drops then to around 100 rpm's.

Something jammed that front right motor in the end ... & that was the cause to this incident.



The front left then ... well that one didn't behave either, but that happened after the crash, and there the prop broke. After the touch down (the spike in the black graph) both the rpm & the FC command goes sky high meanwhile the current draw goes nearly to nothing. Before the crash where the marker is placed in the chart everything lines up as it should ... so the cause wasn't there.

 

[Rockport]

Not di

Looks like another crash due to losing a prop. That roll is usually the sign of it and since these are not hexacopters, they are unable fly with only 3... I dont thing that Dji will cover a prop loss as it is pilot error but i would still try.

Not disagreeing with you, I’m just a newbie. Just want to know what human error could cause “losing a prop?”

 

[BudWalker]

Yep ... that's the correct DAT log. Strangely DatCon translate the time axis differently between the TXT & the DAT ... have seen this before so it's not related to the incident, just how DatCon translate (perhaps @BudWalker can explain).

Looking into the DAT make me now think that due to how the OP commands the AC there in the end with a sudden release of the elevator from full forward sport, applies max descend & begins to rotate CCW with approx 75% applied rudder input ... tricked me into leaning to a lost left front thrust.

Plotting in the combined acceleration of the AC to determine where it hit the ground (Black) shows a big spike at 555.3sec which then ought to be the touch down (it's there the AC reaches the lowest height also) ... so all that happens after that, should be a result of the crash & not the cause.

Comparing all 4 sides rpm's, FC command & current draw reveals that the front right doesn't behave at all before the crash ...

Note how the motor rpm (Red) drops to the bottom already at 552,3sec & never recovers. The initial decrease of the rpm is due to the OP's maneuvering, but at 554,2sec the FC commands 100% (Green) & the current spike high (Blue) ... but nothing happens with the rpm, it remains on 500-ish & drops then to around 100 rpm's.

Something jammed that front right motor in the end ... & that was the cause to this incident.

View attachment 113863

The front left then ... well that one didn't behave either, but that happened after the crash, and there the prop broke. After the touch down (the spike in the black graph) both the rpm & the FC command goes sky high meanwhile the current draw goes nearly to nothing. Before the crash where the marker is placed in the chart everything lines up as it should ... so the cause wasn't there.

View attachment 113865

When the AC is landed and then re-launched OSD.flyTime seen in the .txt is held constant. This causes OSD.flyTime to have a lower value than the .DAT for every re-launch. There were 2 re-launches in this .DAT.

Another way to determine which motor/prop lost propulsion is to look at the time integrated gyro data. At 553.7 secs the MA2 began to tumble rolling CW (red), pitching down (green) and yawing CCW (blue) - all consistent with the rightFront loosing propulsion.

 

[Makwaii]

Sorry im a noob when it comes to this. So is it my pilot error because i was throttling the descend too fast which caused it to fall out of the sky? or was it an issue with the ac itself.

 

[Meta4]

Sorry im a noob when it comes to this. So is it my pilot error because i was throttling the descend too fast which caused it to fall out of the sky? or was it an issue with the ac itself.

It's impossible to descend too fast.
This was a hardware fault and should be covered under warranty.

 

[Makwaii]

It's impossible to descend too fast.
This was a hardware fault and should be covered under warranty.

thats a relief im just worried they're going to try to find a reason to blame it on me, considering all the horror stories im reading about their customer service.

 

[Meta4]

thats a relief im just worried they're going to try to find a reason to blame it on me, considering all the horror stories im reading about their customer service.

Synch your flight data and start an online chat with their support people.
They will get things started for you.

 

[slup]

Sorry im a noob when it comes to this. So is it my pilot error because i was throttling the descend too fast which caused it to fall out of the sky? or was it an issue with the ac itself.

The maneuvering wasn't at all the reason for one motor to jam ... it only made it a bit harder to predict which side that lost thrust already from the TXT log, which mainly only contain the flight telemetrics.

That one motor jams, can be the pilots fault though ... it's not at all unusual that debris is thrown up & into the motor during taking off & landing where it's dusty or dirty, then the debris is rattling around but suddenly it get stuck & stop the motor rotation. But it can also be due to that one motor shaft get a hit & get slightly bent causing it to wear out the bearing due to extra vibrations over time. But it can of course also be a manufacturing fault ...

My advice now is to make contact with DJI & follow their procedure ... that's the only way to know how this ends, you at least now know what made your AC go down.