Nasty Crash - Quad Copter Fell of 10' hight into ground


Can someone please let me know what has happened to my Quad just before it crashed? it was flying fine until all of the sudden “lost its control” and fell into the ground in wrong spot and crashed, completely destroyed.

Please see the log attached.

what does these lines of errors mean?
Test: IMU Mismatch = GOOD - (Mismatch: 0.14, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = FAIL - Motor channel averages = [1796, 1703, 1690, 1843]
Average motor output = 1758
Difference between min and max motor averages = 153
Test: NaNs = GOOD -
Test: OpticalFlow = FAIL - FAIL: no optical flow data
Test: Parameters = FAIL - ‘THR_MIN’ not found

2017-10-18 18-24-53.bin (556.5 KB)

You can see it’s trying as hard as it can!

Probably underpowered.

Hmmm, power looks good. What else could be?

BTW, this is new copter, I have done few succesful flights “short distance” and never had any issues with it. This time the copter was flighying just fine until it just fell to the ground.

As @peterbarker pointed out in the graph he posted your quad is way underpowered/over weight.

It is more surprising that it actually got off the ground.

So as soon as it was disturbed in flight, probably by descending through its prop wash (ring vortex) it had no reserve power to recover.
It also looks unbalanced, or something not quite right with motor 4 as it is pegged at max the whole flight.

The crash - expected, and this is just from looking at the RCout logs.

@jeremylamesa says this quad flew fine before. Was that in this exact configuration?

One thing that could cause this is putting props on upside-down.

Now this is odd:

Not sure how to explain that at the moment. But that’s a lot of current. Magnetic field strength spikes at the same time, so it was real current. Looks like the first compass was OK, so I guess that’s on a mast or something.

Yes. The same exact setup and no changes at all. About 10 successfull flights and one crash.

There is a prop missing, I need to search for it. I talked to someone and as soon as he looked at the logs he said “did you lose a prop?!”. He mentioned that when motor 4 maxed out it was due to a missing prop and he is suspecting that the prop was the reason behind the crash.

Now, I really need to scan the area and find this missing prop. I have no idea how it fell off during the flight. Its new DJI prop that comes with the kit.

Is it common to lose a prope in the middle of a flight?

@peterbarker One thing that could cause this is putting props on upside-down.

I did not change it since I got it setup but I always make sure they are tide and in place “I never force it” so It wont break. Also, my understanding is that the way props designed is that they dont fit in the wrong motor, “X” gray, black and gray black.


The missing prop located about10’ away.