There is also no sudden acceleration changes before the event, so I find any active braking or sudden change unlikely. My own opinion is the motor stopped suddenly and as a result the prop spun off...I wish we had motor RPM!
Bummed. New P3A Crashed. Pls Advise
- Thread starter McVenturesRC
- Start date
The only problem with the motor stopping theory is that all 4 motors work now. Granted, electronics fail. But they usually just fail. They dont come back to life after failing.
agree they don't usually come back, maybe a fail in the motor controller or something....I dunno, also hard to think that a prop would unspin during a hover, seems like all the props would have to have about equal drag to maintain a hover...
I tested the whole prop flying off on its own thing again today. But today I did it outside with some wind blowing. All 4 props flicked on and allowed to stop on their own. Motors turned on and remain on the ground. I grabbed 2 motors and both props flew off. On flew almost 30 feet away. The other only about 7 feet. Again.. impossible to validate with actual active breaking. But definately proof of two things. The props being defined as "self tightening" has nothing to do with them actually locking themselves in place. And that the motor spin up doe NOT tighten the props properly. In this, I think its abundantly clear that "self tightening" only means that the hub threads are as such that lift forces the prop on to the hub. But every prop nut is designed this way. The spin up process being a prop tightening process was always a bit of a reach. Never made any sense. Now its proven to hold no water.
Air speed was reduced just as the event started. So at least some breaking was applied.
Steve, what do you think of my idea of holding landing gear firmly while it is hovering and rocking it around to make the motors react? That seems like it would be a pretty solid real flight test. Don't do if it seems unsafe to you, but I think it would be hard for the Phantom to overpower someone grabbing it...
Not sure what you're saying exactly. But, just to be clear the recording stopped on impact. Take a look at the barometer. The slope of that curve is constant until the end. I.e., it doesn't level out like would be the case if it spent time on the ground after impact.
Based on the last 6 or 7 lines in the log from the tablet.. This is only a small sampling of the data that shows what Im saying..
Based on this data... at 37:26:6 we have impact
rate of fall, and altitude indicated at C16 supports this as well
we also have rapid changes in non-trending directions for the data in D17 E17 F17 G17 H17 I17
Also, withing a tent of a second there is a GPS anomaly at C18
I included the gimble data because it too shows an HUGE spike in movement at my proposed impact point
Recording continued for .5 seconds or so after all of those huge changes.. leading to my saying that the battery remain intact for at least that half a second because it was still transmitting data to the tablet to be recorded.
Based on this data... at 37:26:6 we have impact
rate of fall, and altitude indicated at C16 supports this as well
we also have rapid changes in non-trending directions for the data in D17 E17 F17 G17 H17 I17
Also, withing a tent of a second there is a GPS anomaly at C18
I included the gimble data because it too shows an HUGE spike in movement at my proposed impact point
Recording continued for .5 seconds or so after all of those huge changes.. leading to my saying that the battery remain intact for at least that half a second because it was still transmitting data to the tablet to be recorded.
I am curious if you also tried this a few times with your props tightened as your normally fly. I expect they would not come off but curious nonetheless....
Yes... I tried them at my normal tightness also. No chance of moving. I will dont some spring scale tests to show pressures required to break each option loose maybe tomorrow. It will take a lot of set-upp time. Not sure I will have it. Will see.
I would respectfully disagree. I read through nearly all of these pages and didn't see anyone suggested a temporarily shorted motor/esc. My original phantom was at about 300' when it suddenly shut off and tumbled like there was no battery. It landed in a lake, so it had virtually no physical damage. After drying it out it worked fine.
On disassembly (to dry it out) I found a very small c-ring rolling wedged under the output contacts of one of the ESCs. Turns out it was from the back end of the motor shaft of that arm. I tried to put it back on, but the groove cut in the shaft was not in the right place. When compared to the other motors, it was definitely an abnormality.
I contacted my reseller who sent me a new motor. What is interesting is that the motor still worked just fine. The only downside without the c-ring on the shaft is if I pulled hard enough on the prop, the top shell of the motor (the stator) and prop would come off the base of the motor (the rotor). It was only the magnetic force between the rotor and stator that was holding the motor together - which was plenty to fly the bird.
My point is, if you have ANY metal floating around inside your case, and it shorts and ESC it will shut down all motors momentarily (long enough to drop 300' and crash in my case). Once the short is resolved, everything powers back up like normal.
In your case, I would suspect something mechanically loose that created an electrical short - which may have resolved itself after impact.
alokbhargava
Premium Pilot
A foreign metal piece can short an ESC or a loose current carrying lug can over heat and open the ESC. In both the cases, at least one of the motor will suddenly stop resulting into unscrewing the prop.
N017RW
Premium Pilot
This is a very common question.
Have you read any of the owners/operators manual?
CSC= combination stick command
It's how you Start the motors and one way of stopping them.
Have you read any of the owners/operators manual?
CSC= combination stick command
It's how you Start the motors and one way of stopping them.
N017RW
Premium Pilot
Can you point to a demonstration of this?
It sounds more like an assumption rather than a fact.
alokbhargava
Premium Pilot
Of course these are the assumptions. You will notice such cases frequently if you build your own drone. P3 is a professionally built unit and chances of such things happening are remote. One can find the reality only if one opens up the shell and carefully examine for burn marks on PCB or lug ends. Also check for any metal part inside.
This is just a suspicion. But maybe your battery wasn't locked in securely and it vibrated loose thereby making your phantom powerless. That's why I suspect the propellers were not turning as it crashed. This is just an educated guess.
N017RW
Premium Pilot
I'm speaking of the prop self loosening comment.
The one that was underlined.
People have tried this sudden deceleration or grabbing the motor to stop it on YouTube and the prop does not unscrew.
The one that was underlined.
People have tried this sudden deceleration or grabbing the motor to stop it on YouTube and the prop does not unscrew.
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