P3P Falls from Sky for No Reason

Yes i could see how a voltage increase would mean a missing prop but honestly I don't know how much of an increase it would be...

3.625V 3.672V 3.668V 3.586V
to this
3.777V 3.826V 3.806V 3.743V

Is that enough to consider it a prop?
I don't know. I know that when I land and shut down all four props, my voltage will go up as much as 300 mv. But in this instance, your voltage jumped up a whopping 600 mv 4 secs before it started falling. What's the explanation? Did you lose a prop? Did you lose four props? Did you lose eight props?

Where's @msinger?
 
What's the explanation? Did you lose a prop? Did you lose four props? Did you lose eight props?
Unfortunately, we won't know for sure since the OP is not able to retrieve the DAT flight log. With the information in that flight log, we'd easily be able to see if a motor died, a prop flew off, etc.

The TXT flight log shows speed errors at the time the incident occurred. That message commonly appears in logs when a prop flies off mid-flight. I cannot comment on the battery voltage since I've never attempted to compare the voltage in great detail. Again though, we really won't know what the voltage is telling us without the missing data in the DAT flight log.

I really don't think DJI would cover such a crash since the data we can see points to issues that are commonly not covered under warranty. Perhaps they'll offer a percentage off a new bird though.
 
No...it does not. I really do not feel like explaining what an active braking ESC is and what it does again, so just google it or watch a few you tube videos. Active braking is for racing quads. DJI calls it Braking to simplify what is actually position hold, the motors never brake at all. Do yourself a favor and do dome research on what active braking is and you will understand why the P3 does not have it and why the props do not fly off because of it.

The P3 has active braking system.
 
Unfortunately, we won't know for sure since the OP is not able to retrieve the DAT flight log. With the information in that flight log, we'd easily be able to see if a motor died, a prop flew off, etc.

The TXT flight log shows speed errors at the time the incident occurred. That message commonly appears in logs when a prop flies off mid-flight. I cannot comment on the battery voltage since I've never attempted to compare the voltage in great detail. Again though, we really won't know what the voltage is telling us without the missing data in the DAT flight log.

I really don't think DJI would cover such a crash since the data we can see points to issues that are commonly not covered under warranty. Perhaps they'll offer a percentage off a new bird though.


Is the DAT flight log only saved on the P3 itself and not on the app/phone?
And as an approved vendor, what do you think is the most effective channel to reach out to DJI regarding this issue?

Thanks a lot for your advice.
 
The Phantom 3 does not have active braking.
That's not how it works. Props won't fly off.

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The Phantom 3 ships with composite hubs not metal to deal with the braking force. If Metal hubs are used they could unduly unlock due to the p3 braking system. Or am I wrong again?

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No...it does not. I really do not feel like explaining what an active braking ESC is and what it does again, so just google it or watch a few you tube videos. Active braking is for racing quads. DJI calls it Braking to simplify what is actually position hold, the motors never brake at all. Do yourself a favor and do dome research on what active braking is and you will understand why the P3 does not have it and why the props do not fly off because of it.

Hmmm... I seem to remember a while ago, maybe a year or more, a guy doing a bench test and being able to replicate a prop flying off.
 
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No...it does not. I really do not feel like explaining what an active braking ESC is and what it does again, so just google it or watch a few you tube videos. Active braking is for racing quads. DJI calls it Braking to simplify what is actually position hold, the motors never brake at all. Do yourself a favor and do dome research on what active braking is and you will understand why the P3 does not have it and why the props do not fly off because of it.

There are all sorts of threads with "active braking" and P3s.

http://www.phantompilots.com/search/15538082/?q=active+braking&o=relevance

What's the story?
 
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Is the DAT flight log only saved on the P3 itself and not on the app/phone?
It's only saved on the Phantom's internal memory card.

what do you think is the most effective channel to reach out to DJI regarding this issue?
You can contact DJI support here.

As HWCM noted above, the DJI warranty shows that no part of the Phantom is covered under warranty after one year. So, DJI is most likely just going to tell you your Phantom is beyond the warranty period. It wouldn't hurt to try to each out to them. Perhaps they'll give you a discount on a new Phantom.
 
I did a test about 5 months ago to try to determine if an abrupt speed change cause a prop to come off. Maybe the results can shed some light on the active braking question. TBH I don't know exactly what active braking means. Maybe the motor gurus can render an opinion.

The elevator was pushed all the way forward and held until the P3 reached 16 meter/sec. Then the elevator was released causing the P3 to come to an abrupt stop.
upload_2016-9-16_6-41-44.png

upload_2016-9-16_6-41-55.png

Before the abrupt stop the back motors were at a higher speed. During the slow down all the motors decreased speed but the back motors were still higher. When the velocity reached 0 the motors returned to the values before the test.
 
No...it does not. I really do not feel like explaining what an active braking ESC is and what it does again, so just google it or watch a few you tube videos. Active braking is for racing quads. DJI calls it Braking to simplify what is actually position hold, the motors never brake at all. Do yourself a favor and do dome research on what active braking is and you will understand why the P3 does not have it and why the props do not fly off because of it.
What ever dji call to term it. The original query "what props were you using" was posed due to the fact that metal hubs have been shown to come loose due to the aggressive position hold / active braking (whatever you prefer to call it) on the p3 whilst in GPS.

All input is valid, we are here trying to help the op. Cheer up Mr Happy. [emoji11]

Sent from my SM-G935F using PhantomPilots mobile app
 
I did a test about 5 months ago to try to determine if an abrupt speed change cause a prop to come off. Maybe the results can shed some light on the active braking question. TBH I don't know exactly what active braking means. Maybe the motor gurus can render an opinion.

The elevator was pushed all the way forward and held until the P3 reached 16 meter/sec. Then the elevator was released causing the P3 to come to an abrupt stop.
View attachment 64899
View attachment 64900
Before the abrupt stop the back motors were at a higher speed. During the slow down all the motors decreased speed but the back motors were still higher. When the velocity reached 0 the motors returned to the values before the test.
Active braking is in the ecs programing, not in the motors. Basically it is for racing quads so that when you lower the throttle to zero, the escs send a reverse voltage to immediately stop the motors with braking force. This is the allow the quad to drop instantly to go under flags or poles on a racing course, not to stop it going forward. Unlike the phantom, the phantom "braking" works by lowering the speed of the two motors driving the quad forward and speeds up the opposite motors. ie the two rear motors slow down causing the rear to drop and the front motors speed up to push the quad back slightly.


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"Throws it in reverse" but doesn't "force" any props to slow down.

IF the motors have more internal drag than the drag on the props the difference could be enough to cause a loose prop to unscrew itself. Only way o know to test this would be to run a Phantom with no props and find out how long it takes the motors to drop from high speed to idle speed with no props, then test again with props. If the speed drops more slowly with props then the props have a tendency to spin faster than the motor under a fast reduction of power which could lead to unintentional prop removal.

For an idea of what ESC braking is look at RC planes. The ESC can be programmed to slow or stop the prop. Helpful in controlling the speed of some planes using the prop for drag (an air brake). If the ESC has braking programmed the prop will not spin when gliding at 0 throttle. If braking is off the prop will continue to spin when gliding at 0 throttle.

It's something that's hard to see visually on a phantom because the only time you have zero throttle is when ESCs aren't armed, or when something goes terribly wrong. Either way, the ESCs are likely dead anyways and any programmed braking would be irrelevant.

You would see a power spike at the ESC from the energy needed to brake the prop, but I don't know if Phantoms show individual power draw on speed controllers.


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Active braking is in the ecs programing, not in the motors. Basically it is for racing quads so that when you lower the throttle to zero, the escs send a reverse voltage to immediately stop the motors with braking force. This is the allow the quad to drop instantly to go under flags or poles on a racing course, not to stop it going forward. Unlike the phantom, the phantom "braking" works by lowering the speed of the two motors driving the quad forward and speeds up the opposite motors. ie the two rear motors slow down causing the rear to drop and the front motors speed up to push the quad back slightly.


Sent from my HTC6535LVW using PhantomPilots mobile app
That's what I thought. This isn't active braking. It's even less braking than what you described as the way the P3 brakes. The front motors don't speed up since all the motors slow down. It's hard to tell from the plot but the back motors have to be slowing down more than the front motors for the P3 to stop.
 
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"Throws it in reverse" but doesn't "force" any props to slow down.

IF the motors have more internal drag than the drag on the props the difference could be enough to cause a loose prop to unscrew itself. Only way o know to test this would be to run a Phantom with no props and find out how long it takes the motors to drop from high speed to idle speed with no props, then test again with props. If the speed drops more slowly with props then the props have a tendency to spin faster than the motor under a fast reduction of power which could lead to unintentional prop removal.

For an idea of what ESC braking is look at RC planes. The ESC can be programmed to slow or stop the prop. Helpful in controlling the speed of some planes using the prop for drag (an air brake). If the ESC has braking programmed the prop will not spin when gliding at 0 throttle. If braking is off the prop will continue to spin when gliding at 0 throttle.

It's something that's hard to see visually on a phantom because the only time you have zero throttle is when ESCs aren't armed, or when something goes terribly wrong. Either way, the ESCs are likely dead anyways and any programmed braking would be irrelevant.

You would see a power spike at the ESC from the energy needed to brake the prop, but I don't know if Phantoms show individual power draw on speed controllers.


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I have done it. On the phantom if you raise the throttle then quickly lower it, the motors wind down to a stop, no braking. On my racing quad with active braking, if you throttle the motors up then kill the throttle, the motors brake hard and instantly stop dead.

Sent from my HTC6535LVW using PhantomPilots mobile app
 
Unmatched Propulsion


Each motor has the power and precision needed to give you the best flight experience possible. Brushless motors work with lightning-fast ESCs to make your Phantom 3 fast, agile, and responsive.

These powerful motors give you the ability to speed up, quickly increase or decrease altitude, and stop immediately. DJI’s powerful air braking mechanisms stop your Phantom 3 instantly , making it hover in place as soon as you release the control sticks. Aerodynamic self-tightening propellers boost thrust and stay firmly in place no matter how you fly.

Phantom 3 Advanced - Aircraft | DJI
 
So if the P4 has "active braking" what does the P3 have?
The P4 in all likelihood does not have a true active braking system. This is just DJI terminology. Why would anyone need the motors of any Phantom to stop immediately.
Remember, active braking makes the motor stop, not slow down. A stopped motor has no spinning propellers, no spinning propellers means no lift, no lift means gravity takes over and it falls. No one has a need for a camera platform to fall, you want it to hold its position when the sticks are released. That's why what DJI calls "active braking" is actually a position holding function. The quad maintains its altitude, but stops its forward momentum. The motors and therefore the propellers never ever stop spinning. Again, Active braking is where the motors stop immediately on a full ZERO THROTTLE, not when you release the sticks to have the quad stop in its current position.
Go on YouTube and search for active braking esc vs non active braking.
I would not **** you. [emoji12]
I have done it. On the phantom if you raise the throttle then quickly lower it, the motors wind down to a stop, no braking. On my racing quad with active braking, if you throttle the motors up then kill the throttle, the motors brake hard and instantly stop dead.

Sent from my HTC6535LVW using PhantomPilots mobile app


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Unmatched Propulsion


Each motor has the power and precision needed to give you the best flight experience possible. Brushless motors work with lightning-fast ESCs to make your Phantom 3 fast, agile, and responsive.

These powerful motors give you the ability to speed up, quickly increase or decrease altitude, and stop immediately. DJI’s powerful air braking mechanisms stop your Phantom 3 instantly , making it hover in place as soon as you release the control sticks. Aerodynamic self-tightening propellers boost thrust and stay firmly in place no matter how you fly.

Phantom 3 Advanced - Aircraft | DJI
There you go, air braking. That is self explanatory.

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What ever dji call to term it. The original query "what props were you using" was posed due to the fact that metal hubs have been shown to come loose due to the aggressive position hold / active braking (whatever you prefer to call it) on the p3 whilst in GPS.

All input is valid, we are here trying to help the op. Cheer up Mr Happy. [emoji11]

Sent from my SM-G935F using PhantomPilots mobile app
If you 100% want to prevent a prop from flying off, get some 9045 non spin on props from gemfan or another prop manufacturer and use nyloc nuts. I have never had a prop fly off using them. Even in a high speed crash and tumble. Heck, some of those props are almost impossible to break.

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