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HELP!

Discussion in 'Phantom 2 Vision + Discussion' started by Brent, Jul 4, 2014.

  1. Brent

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    My pv2+ came in the mail yesterday. I have prior experience with my dji hexacopter with naza-m but still consider myself fairly new to quads/hex. The video posted is my 5th flight with the pv2+. Flawless operation until this flight. I had already performed a fail safe test on flight #2 from near by and it worked fine. This time I wanted to see how high (straight above me) it would go until I lost signal. It happened at 1250 feet which was around 2:29 in the video. It then started to return home normally and descend. Around 3:13 you can see minor rocking and then smooth out. At 3:50 all hell breaks loose. It began to wobble/shake/rock uncontrollably. I quickly toggled down then back up on the right switch hoping to regain control and give it some gas to pull out. It did not respond at all, however there was not much time as it was dropping at a considerable rate. I am running it stock WITH dji prop guards. There were 5-10 mph winds at the time. Somehow it survived with no damage as far as I can tell. I fired it back up and did about a 20 foot hover to see if all was okay. It would not hold as good position as before so I brought it back down and recalibrated then it flew perfect for another short 20 foot hover flight. What happened? What put me into that uncontrollable rocking? Prop guards? Wind? Please help.

    https://www.youtube.com/watch?v=1M6Y5S8QoD4
     
  2. dkeshish

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    Its well documented here that this is alllllll prop gaurd issue. I have 2 sets on gaurds that I will never use. I rather buy 30 propellers than crash ans total a 1500 drone
     
  3. HunterSK

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    Hi Brent,

    From looking at your video, it looks like you got the quadcopter into the Vortex ring state (VRS). This can result in catastrophic loss of attitude and control.

    Whatever you do, do not descend quickly down vertically. Always descent at an angle, or descent slowly to prevent the Vortices from forming.

    http://en.wikipedia.org/wiki/Vortex_ring_state

    Hope that helps. I'm surprised it isn't mentioned in the manual.
     
  4. DownunderPhantom

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    This is not the case, how do I know, my P2VP after only 5 flights from brand new when hovering at 119m I activated the RTH feature and it started descending then at the 60m mark it started an uncontrollable decent and mine DID NOT have prop guards.

    I have only just received my P2VP back from repair to the gimbal but looks like it needs to go back to have the GPS module replaced.

    If you look through the forums there are more instances of this happening without prop guards.
     
  5. Dirty Bird

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    Definite VRS crash. The way out is leave the left stick alone and shove the right stick in ANY direction to get out of the wash. Your Phantom was totally out of control at the end so right stick input may have been ineffective. Hope your Vision+ is OK? You just missed that house! I only read this forum, and 99% of the VRS crashes involve birds with prop guards. Better to replace a prop than risk the gimbal.
     
  6. Werz

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    Once again, two directly contradictory statements on this issue. And I must admit, I've read a lot of recent posts about crashes which sound a lot like VRS/SWP but with nary a word about prop guards.

    I'm beginning to wonder if it's a lot less about prop guards and a lot more about pilot error in folks who don't think to avoid direct vertical descent.

    Just sayin' ...
     
  7. DownunderPhantom

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    in my case Return to home (RTH) had been activated and when the oscillations started I immediately tried to regain control with little or no affect until just before impact.

    As DJI have been in the business for a few years now and have no doubt heard of VRS wouldn't you think that when implementing RTH they would have designed the feature to avoid VRS and avoid "direct vertical descent". When designing features like this every known problem that may occur should be taken into consideration or a mention in the documentation and ways to avoid it.

    My original Phantom FC40 was flown with Prop Guards and in some instances when descending at speed it did start to oscillate but when this happened I reduced the descent rate and induced forward momentum which stopped the oscillation.
     
  8. JWarren

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    To avoid this again, and I happen to agree it was a VRS with maybe prop guards contributing, take back control of the aircraft from Fail Safe as soon as possible. You were plenty low enough when this occurred to have taken control again. Just my 2 cents. Glad your craft is OK!!!

    Best wishes,
    J.
     
  9. Werz

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    For what it's worth, I had my first RTH this evening. I got a "control signal lost" warning at only about 1,000 feet away. However, I had lost sight of the Phantom over trees and buildings (which may be why the signal dropped at such a short distance), and I was monitoring it by FPV and the radar icon. I immediately flipped S1 down to failsafe, and I could hear it coming back to me at its last altitude of 200 feet. As soon as it stopped overhead and started to descend, I switched S1 back to GPS and rocked it back and forth as it descended. I had prop guards (trees + breeze = prop guards), but I managed to catch-land it like I always do.
     
  10. Jason Church

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    Listen to Geert and HunterSK,

    I never descend in a hover, always descend while traveling in some sort of direction.
     
  11. Brent

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    Just to be clear, this was in RTH when it happened. As soon as I noticed the VRS, I tried to regain control by cycling the right switch. Someone mentioned "pilot error". I make a lot of mistakes and do some risky things with all of my aircraft but the only pilot error I see here is using the RTH feature. I never once used RTH on my hexacopter (with over 50 flights) because I read too many horror stories in the forums about it.

    So what have I learned...
    I should have stuck with my initial thoughts on RTH which were "don't use it unless you have to".
    Today I will take the prop guards off.
    I will never descend straight down again.
    If I have to use RTH I will regain control when it is in sight.

    I think dji should program RTH a little different on descent to avoid this. I nearly lost $1400 on flight number 5 testing their feature. If someone truly wants to test RTH of course they want to see if it returns to home and not regain control at 300-400 feet.

    Thank you guys for all the input. I feel so much better about it now. Scary stuff indeed! I was lucky to not have gimbal damage here.
     
  12. Mako79

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    Did you catch any fireworks Brent? I noticed the vid was uploaded on the 4th July.
    And yes it is VRS. Don't be boring on a decent and go straight down. Fly like a hero when you land. I come down spiralling.

    Anyways, just off topic..

    Can every one please stop "testing" the RTH/Failsafe.
    It should be always refered to as FAILSAFE!.
    My Car has ESP and this predicts if im going to spin out of control. Do i dare test this? No. If I was, I would be doing it under very strict controlled environments.

    I've owned the Phantom for 3 months and i cannot say that I'm a guru or knowledgable. In those 3 months, I have never let her go into Failsafe. Why? because it's called failsafe. I know the feature is there and it WILL WORK! I always fly her back and never use the Failsafe feature.

    I know some will argue and use the "Failsafe to bring her home and lazy-land" method.
    There are 2 methods i use to bring her home without using Failsafe (NAZA-M and IOC must be on):
    1. Home Lock (Dont get this confused with RTH). This is where you click S2 all the way down and pull the right stick back and it doesnt matter which orientation or where the phantom is, it will come back to the set home point. Spiral down and catch land like a HERO.
    2. Radar. Bottom left hand corner, tap it so it becomes larger. The red arrow is the phantom and its direction. The centre is the home point/you (provided thatyou didnt set a new one in mid flight). Spin the arrow so it points to you. Push fwd until you can hear the phantom. And just to reiterate, Spiral down and catch land like a HERO.

    Just make sure you have enough altitude on both the methods above to clear obstructions/obstacles on the way back.

    On a side note, If you want to test out if the HOME POSITION is set correct, fly her up (so it records the HOME), and then fly her fwd (this records the direction for Course Lock) for more than 10 meters and then rotate her 90 degrees in any direction. Flick on IOC HOME LOCK and pull the right stick back. If she comes back sideways, then home lock is working.

    Stay safe!
     
  13. Double-D

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    +1
    I do this after take off EVERY TIME before I fly into the wild blue yonder.