Bummed. New P3A Crashed. Pls Advise
- Thread starter McVenturesRC
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they are in the box with new phantom 2's and visions etc.
P3 doe come one as well and some of us own more than 1.....
whoops, some where I read they did not , I still am flying my p2's... at least for a little while
the used p3 pricing is getting real nice at b&h some days..
I only used mine a time or 2 to get stuck props off!
doesnt it initiate rth with signal loss? switches to atti mode when gps is loss. that shud show on the flight that was recorded on the tablet.
Oso
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Meta4
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Streve is correct. DJI have never supplied a prop tightening wrench.
They do supply a wrench that can be used to remove a stuck prop - like after a crash etc.
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With all due respect I believe the vast majority of folks in this thread are confused about how self-tightening propellers work -- they will NEVER unscrew themselves. They ONLY tighten.
Thus I don't believe this is the cause of the crash we're discussing here.
Personally, when I'm setting up my drone I place the propeller on top of the screw/motor and give it a single "flick" with my fingernail to screw them on -- I do ZERO hand tightening beyond that. As soon as the drone is powered on, they're getting tightened. As as you take off they tighten even more.
There is literally NO case in which the motor turns in a way that unscrews the propeller.
I'd love to hear this explained more because it makes no sense, sorry folks. If the drone is staying in the air, there's a force downward on the air under it -- Even when you're descending, the propellers aren't actually switching direction of spin, they're simply spinning a bit slower so there's less force. But again there's ALWAYS a downward force so the propellers are ALWAYS TIGHTENING THEMSELVES, NEVER LOOSENING. If there WERE zero force pushing down, it'd be in free fall. To unscrew themselves there'd somehow have to be a negative downward force (i.e. Props reversing the direction of spin) so the aircraft in that case would literally be descending faster than a free fall. Or you'd have to be flying it upside down. Neither of these cases happen in normal flight.
Thus I don't believe this is the cause of the crash we're discussing here.
Personally, when I'm setting up my drone I place the propeller on top of the screw/motor and give it a single "flick" with my fingernail to screw them on -- I do ZERO hand tightening beyond that. As soon as the drone is powered on, they're getting tightened. As as you take off they tighten even more.
There is literally NO case in which the motor turns in a way that unscrews the propeller.
I'd love to hear this explained more because it makes no sense, sorry folks. If the drone is staying in the air, there's a force downward on the air under it -- Even when you're descending, the propellers aren't actually switching direction of spin, they're simply spinning a bit slower so there's less force. But again there's ALWAYS a downward force so the propellers are ALWAYS TIGHTENING THEMSELVES, NEVER LOOSENING. If there WERE zero force pushing down, it'd be in free fall. To unscrew themselves there'd somehow have to be a negative downward force (i.e. Props reversing the direction of spin) so the aircraft in that case would literally be descending faster than a free fall. Or you'd have to be flying it upside down. Neither of these cases happen in normal flight.
If your prop comes off in flight, it is because your motor stopped suddenly. The prop coming off did not make your bird crash. When a motor stops, the bird will crash, with or without the prop attached. If a prop strikes something in flight, a bird or a tree or whatever, it will just tighten it. Unless it shattered the hub, the prop will stay on when it strikes something.
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YES, this is the true use of the wrench, and the only time I've had to use it in 16 months of flying -- after a crash when the propeller got screwed on so tight I couldn't get it off with my bare hands.
Here is an example of a prop coming off in flight (left side of the image.) It was caused by a bullet connector which was loose on the right rear ESC. The motor stopped, inertia kept the prop spinning which unscrewed it. The prop actually gained altitude as the bird tumbled from the sky. The prop was undamaged. The quad flew fine after the bullet connector was fully inserted. The prop coming off was secondary. The quad was doomed to crash with or without it.
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Remember the P3 has Active Braking, which can and will cause a prop to come loose under certain circumstances. That is why DJI switched over to the sticky nylon hubs. Now don't put words in my mouth, not saying this has happened in this case, just stating that there is a possibility that the prop could come off in flight. It's happened before, been documented countless times on all sorts of different MRs. It could be a defective prop, or a slightly 'off' thread, and once you enter a braking maneuver, off comes the prop.
Interestingly enough, there's a video in a FB group for the Yuneec Q500 doing just that. As soon as the pilot lets off the throttle, the prop zooms off. It's just physics after all.
dang,Streve is correct. DJI have never supplied a prop tightening wrench.
They do supply a wrench that can be used to remove a stuck prop - like after a crash etc.
Words Have Meaning!
propeller wrench does not equal prop tightening wrench.
That is only 1 of its uses. I suppose tightening may be another for some.
semantics, a wonderful word.
but we all knew what it was we spoke of!
Me I spin then on , finger check for tightness and fly
Simple.....and it makes perfect sense if you are able to consider ALL the factors.
(and btw, all caps doesn't make a point valid)
No matter how much time you spend not seeing how this makes sense, it still doesn't change physics or aerodynamics. There's also always a downward force on a car...does that mean the tires never come off the ground?
Vortex Ring State is just one time when the downward force is virtually eliminated. So much for the theory that there is ALWAYS a downward force. At certain times that downward forces changes from positive (thrust) to less thrust than needed to sustain flight (descending) and is at a maximum when ascending.
Read this thread over at DJIForums...
DJI Forum|All 4 props come off mid flight
It takes approximately 4/100's of one second for a prop to completely unscrew.
You're thinking minutes instead of milliseconds.
If the prop is loose (for whatever reason)...and the motor suddenly slows down what will happen to the prop if there is insufficient resistance (ie wind / air) and sufficient inertia in the propeller?
Correct (it WILL spin off the hub). This has nothing to do with switching direction.
The props spins off in the direction OF ROTATION.
You are forgetting inertia. You are neglecting to consider momentum of the aircraft. You are forgetting the whole vortex ring state discussion. You are assuming errors are never thrown to the motors that could cause hesitations or anything other than smooth running....ever.
Think about that for a moment. Really? A glitch from one ESC motor for 4/100's of a second could completely unscrew a prop. How can you be certain that's not what happens sometimes when a Phantom crashes and a prop is found way over there?
If you are ascending rapidly then pull back on the throttle suddenly, the aircraft will continue to rise for just a few seconds on momentum. What's happening to the air around the props at that moment? Is the pressure the same as when it was climbing under full throttle?
Fortunately this is not a common occurrence since not only do the props have to be loose enough to freely unscrew, but there also has to be almost no resistance to the props at the same time and this has to coincide with a significant enough drop in motor rpm while this is happening for a prop to actually spin off.
But....CAN it happen.....sure. It happens..
To convince yourself otherwise is at your own risk. You may never have a problem.
All this is saying is why risk it with loose props?
And that isn't to say you should jack down on the props until they strip or break. I like mine to be just a bit beyond finger tight, And yes, I use the wrench and slight finger pressure.
So you're saying it is impossible to have a "failing" ESC board that glitches?
You're saying ESC boards either work 100% perfect....or not at all?
If you say so
A failed ESC will not suddenly become a NOT failed ESC. If it fails it exhibits, for a brief time, the same thing as active breaking. ANY sudden slowing of the motor will give opportunity for the prop to keep spinning at the higher rate, even if momentary, leading to it unscrewing.So you're saying it is impossible to have a "failing" ESC board that glitches?
You're saying ESC boards either work 100% perfect....or not at all?
If you say so
This isnt rocket science people!! And its just a theory for THIS crash. Although I have never been wrong in any other crash prediction. EVERY time a prop is missing and is found the threads are either in tact (it unscrewed) or stripped (prop strike). There are no other options!
You guys are nuts, I tighten my props with a socket wrench and 24" torque bar before each flight. 
I think the manual recommends 160 ft-lbs.
I think the manual recommends 160 ft-lbs.
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