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Prop flew off

Discussion in 'Phantom 2 Vision Discussion' started by MikeON, Mar 21, 2014.

  1. MikeON

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    I prepared for the flight like the several dozen previous ones. Put the props on the correct motors and gave them a quick spin. Watched them make a few revolutions before bottoming out and making the motor turn a little. Also checked visually that they were bottomed out.
    Went out and launched, hovered about 10' up for a few seconds - all looked normal.
    I then gave it full throttle up to about 80' to get above some trees, and let the left stick return to center. At that time, a prop came off to the side. The PV turned upside down and plummeted. It rubbed against a bushy evergreen tree, and landed on its feet in the grass with the battery popped out. The prop came fluttering down and landed about 20' from the PV. I looked everything over and saw no damage. I reinstalled the battery and prop, and flew it up to 600' for some pictures, and it flew as normal. Got my second battery, and flew at 1000' with no problems.
    My theory is that with the sudden motor deceleration when I backed off the throttle, the angular momentum in the prop plus the rotational thrust placed on the prop from the upward momentum (acting like a turbine) was enough to loosen it.
    These are the original self-tightening props, and it was one of the black ones.
    From now on, I plan to snug them up with the little wrench they provide for removal.
     
  2. gbshovel

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  3. ZonComGMZ

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    :shock: :shock:
     
  4. skyhighdiver

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    :eek: :shock: :shock: :shock:
     
  5. amrflyingdude

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    That is weird.

    When you installed the props before the crash, did you screw them all the way in?

    It is possible that the momentum during a very aggressive deceleration causes this but very unlikely, I mean the lift needed for a 1200gm unit to stay aloft would requires a lot of prop spin so for the prop to make the needed turns in the oposite direction for it to fly off is not imposible but man really unlikely. so very surprised this happened.
     
  6. DesertFlyer53

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    Really? If that had happened to me... I'd be done for the day!
     
  7. flyNfrank

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    I never thought I would read where someone flew without tightening the props at installation.

    You should definitely consider the experience as your one mulligan based on the no damage part. Btw, do you have lottery tickets in your area?
     
  8. pault

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    I have never tightened mine - I got the impression from the original Colin videos that it was a 'feature'.
    Any chance of some feedback from others - does everyone tighten before flight (I mean the props ;)) ?
     
  9. amrflyingdude

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    I never do
     
  10. Mal_PV2_Ireland

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    I spin mine on then hand tighten them by holding the motors with my fingers and screw on the props that little bit extra by hand
     
  11. xgeek

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    Same here.
     
  12. amkorp

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    It's not physically possible for the props to come off. At no point do the motors spin counter to their original orientation. Since the props are self tightening, they would only try to seat themselves in further during flight.


    There is no scenario where anything would occur to the unit to allow the props to back themselves out.

    Did you check the nut inside the plastic hub? It may have come loose inside the hub, or the plastic prop might be spinning on its own hub instead of on the motor rod.

    This is a very weird situation.
     
  13. gunslinger

    gunslinger Moderator
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    I never tighten the props. I figure... They're self tightening, so... I THINK I've just changed my mind, though... :shock: :shock: :shock:

    -slinger
     
  14. MikeON

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    The motors don't have to spin opposite normal. They just have to suddenly slow down while the prop is spinning full speed. The angular momentum in the prop plus the air trying to spin the prop (from the still rapidly-rising PV) is what I think did it.
    I know the props were fully seated on the motor shafts, because I had always spun them on by finger until the motor turns, then visually check. This time was no different.
    I'm just saying that might not be enough, and from now on will snug it up with the wrench.

    I won't let something like this ruin the rest of my day. And wanted to fly and make sure the PV was still healthy.
     
  15. Duke131

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    I've had props fly off on 2 occasions: once with DJI self-tightening props and another with carbon fiber w/locking cap. Luckily, the P2V survived both 60-80ft crashes unscathed. That's a tough little bugger! I remember one of the self-tightening props going on a little tight, possibly stripping the thread on the prop, but I was flying a little aggressively when the prop flew off too, so it may have also been the same thing you described. The other incident with the locking cap was probably just a loose cap on my part. Now I always do the pre-flight checks! I think I've used up my quota for dumbass mistakes with my P2V! :?
     
  16. gunslinger

    gunslinger Moderator
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    Hmmm... You guys who've had props fly off. Were these actual DJI props? I've been looking into the difference between the DJI props and the crappy knock offs that are available everywhere out there. I wound up with three or four sets before I woke up. The threads on these props are nowhere near the quality of the original DJI props. These props are easily recognizable by the "XOXOXO" logo on them as opposed to the "dji" logo. I'm wondering if this problem might just be relegated to these crappola props... :(

    -slinger
     
  17. Great Pumpkin

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    MikeON -
    You didn't say if you are flying a Phantom 1 or 2. I've read on the forums that you must always check that P1 props are tight before every flight, but P2 props are supposed to self tighten.
     
  18. MikeON

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    It's a Phantom 2 Vision with DJI self-tightening props.
     
  19. gunslinger

    gunslinger Moderator
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    Okay... then... that's pretty weird. Keep in mind though, that I thought I was running strictly DJI self-tightening props. I wasn't. There's a very big difference between the DJI and XOXOXO props, but they aren't at all clearly evident unless you pay close attention...

    1: They're not even close to being balanced
    2: The threads are really poorly done
    3: The leading edge of the prop is square, as the DJI prop is rounded.
    4: The logo is XOXOX or some such, and not DJI...

    -slinger
     
  20. gunslinger

    gunslinger Moderator
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    Don't mean to get off on a rant here, but I'm going to keep hammering this point home on this forum to be sure that both newbies and experienced pilots are aware... (If I'm boring you, tune me out. If you have trouble doing that, contact my wife) ;)


    These guys have multiple listings on eBay for the rip off props...

    http://www.ebay.com/itm/4-Pairs-9-Self- ... 43c472b073


    So do these guys...

    http://www.ebay.com/itm/DJI-Phantom-2-V ... 3f325c134b



    Here's my favorite "Authentic DJI Phanton 2 Vision Replacement" They should be drummed off ebay, and I AM going to complain to eBay about this...

    http://www.ebay.com/itm/DJI-Phantom-2-V ... 1e8742d122



    Here's a top rated plus seller with 99% positive feedback. Who do you trust?

    http://www.ebay.com/itm/4pcs-Self-tight ... 3cdd38d888


    The real deal...

    http://www.ebay.com/itm/DJI-Phantom-2-V ... 1266244277?
    pt=Radio_Control_Parts_Accessories&hash=item4accf5dab5

    Again... sorry for hijacking this thread with a rant that' may or may not even be on topic... :oops:

    And now back to our regularly scheduled program...

    -slinger