Fallen Phantom

[Fly Dawg]

With the data we have, the last thing I can think of is either you possibly clipped the tree, or something was sucked in to the motor. But without the motor data there is no way to know......I didn't go in to terrain detail.

 

[oconnb]

I'd love to be able to see what you see here in this flight graph....please where at the 110 seconds how can you see that the prop came off.......I want to some day be like you and read these and help others here.....Thank you...and besides the prop issue what else can you see in the multi colored lines.

I agree I would love to be able to interpret these things much better

 

[ArgenBrewer]

I did not touch the tree and if something got into the engine, it came off only with the blow without affecting the engine ... it may be an explanation, but it does not convince me much ...

 

[cgvett]

The aircraft pitches up and rolls left, which implies loss of lift rear left. The rear left is a CCW motor, leaving two CW props balancing one CCW prop, which causes the aircraft to enter a CCW spin. The final clue, which requires having seen these events before, is the 2 Hz oscillation that is typical of a lost prop.

However - the OP states that none of the props came off, which doesn't leave much room for any likely hypothesis.

What about a pc bug causing a temporary shutdown of the left rear motor ?

 

[sar104]

What about a pc bug causing a temporary shutdown of the left rear motor ?

That would have a similar effect, but I've never come across such an event. The DAT file would show that in the motor command data.

 

[cgvett]

That would have a similar effect, but I've never come across such an event. The DAT file would show that in the motor command data.

Perhaps an impact with a large insect (like a locust) or maybe a small bird ?

 

[BudWalker]

It appears that the left rear propeller came off at 110.6 seconds into the flight. It's likely that you had not attached it properly. Did you tighten it or just spin it on?

View attachment 98307

Given that the P3S flew again without incident the only possibility I can think of would be an intermittent motor/esc issue. If so, the .DAT from the P3S might help. Specifically, the motorCommanded data might show an increase on the leftBack (too bad the P3S doesn't record motor data). Also, the contents of the eventLog stream might be helpful.

@ArgenBrewer can you could provide the .DAT from the P3S? Look here to see how to do that. It'll be large so you'll need to DropBox or GoogleDrive it and provide a link.

 

[ArgenBrewer]

at night I'll upload it

 

[sar104]

The flight Data!!
FLY181.DAT

That's the wrong DAT file. That was not a flight - it was just a 14 s power up at timestamped 2018-04-29 17:38:22Z.

 

[ArgenBrewer]

The DAT file!!

FLY180.DAT

 

[sar104]

The DAT file!!

FLY180.DAT

That's the one. Nice data, but they don't really help. Unwrapping the higher sample-rate attitude data reveals the same as before:

Looking at the motor command data at the end of the flight shows what I expected:

At 110.6 seconds the FC suddenly requests 100% from the rear left due to loss of lift, and at the same time drops the front right motor to counteract the backward pitch and CCW yaw. Without the motor speed data there are two possibilities. One is prop loss, which would have resulted in the rear left motor speeding up, while the other is some kind of motor or ESC failure that led to the motor slowing down or stopping. The former is apparently ruled out, while the latter makes little sense if the aircraft flew fine immediately afterwards.

I can think of no credible explanation for the event.

 

[BudWalker]

@ArgenBrewer you might find this incident interesting, maybe even relevant.
Standard - My first drone failure today.. Help!?!
and here
Standard - My first drone failure today.. Help!?!

It's a P3S incident where there was a propulsion issue with the leftBack motor/esc. There is also the video showing the motor start behavior after the incident. You might want to check and see if you have something similar.
IMG_0810[1_.mp4

 

[ArgenBrewer]

The video!

 

[Fly Dawg]

Looking at this frame by frame, you can see the right front of the aircraft pitch up and left, the left front follows suit. Consistent with all the data presented. I saw nothing else in the frames. If this was not a rear left prop, then it has to be a motor or esc failure of some sort, which makes no sense whatsoever if it flew afterwards just fine. Perplexing.....................

 

[ArgenBrewer]

flew for the next three days without incident

 

[RodPad]

Well I have been watching this thread.

Watching the video I see string on the prop guards. I have used string at times in the past, but what was supplied seem to stretch in time also if it got wet, etc.

It has been a while since I have used prop guards and even longer than that I have used string. The stretching seems to be even more noticeable if your were using quick release prop guards.

I had tried clear fishing line it was less noticeable it would stay tighter, and if somebody was looking at your Phantom it looked more dangerous.

I'm sure you guys know what I'm thinking.

Rod

 

[Fly Dawg]

Watching the video I see string on the prop guards.

Please provide a screen shot and description. Never saw anything close to that. Just for my own sanity after watching this frame by frame 5 times.....................

 

[sar104]

Please provide a screen shot and description. Never saw anything close to that. Just for my own sanity after watching this frame by frame 5 times.....................

It's quite visible for much of the movie:

Prop guards are bad enough, but adding string seems like a very bad idea. If the string got caught in a prop then that would certainly bring it down.

 

[Fly Dawg]

It's quite visible for much of the movie:

I only looked at the few frames at the time of the incident. Frame by frame appeared to be the top of the cloud formations in the foreground. Looking back that is correct, but why string? Never used guards before on any quad I have had.

 

[sar104]

I only looked at the few frames at the time of the incident. Frame by frame appeared to be the top of the cloud formations in the foreground. Looking back that is correct, but why string? Never used guards before on any quad I have had.

I have no idea. I've never used prop guards either.