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Uncontrolled descent

Discussion in 'Phantom 2 Vision Discussion' started by Count, Aug 4, 2014.

  1. Count

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    Hello, It has been 6 months since i have been here-have not been flying much. I has a serious crash after an uncontrolled descent. I rebuilt, replaced main board, motors, ESC's, receiver, cables, all software and firmware upgrades and everything appears to be working well, EXCEPT:

    -If I climb to 400' and fly around for a few minutes, sometimes even without command, the quad will start a VERY fast, VERY wobbly (rocking back and forth from one side to another +/- 20-40 degrees, 2-3 times per second) descent. It always happens if I initiate a descent by reducing throttle. I have no apparent control over throttle (or the quad is not responding to throttle), and modest but not full control over pitch and yaw. I can usually guide it onto some grass, but even then it lands hard, usually with some damage. I have tried turning off the controller to activate return to home, with no result, and tried centering the X1 (right) toggle to the middle position. The only thing I have not replaced the antenna or GPS modules.

    It will fly perfectly if I stay near ground. One difference is that I have installed a LOT of lights on my quad, and fly with the prop guards, so I imagine I probably have 200-300 grams of additional payload over the stripped quad.

    I would be willing to send in for repair, but I have performed SO many modifications that I am afraid they may not work on it. Does anyone have an idea of what my issue may be, and what I may try to fix this?
     
  2. IrishSights

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    Almost certainly it sounds like VRS to me. Try descending slowly with forward flight and see if you get the same.
     
  3. Count

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    Thanks for your reply. Though I thought I was fairly conversant in Phantom Vision lingo, I have to admit ignorance to "VRS". I did a search here, but found nothing. Would you be kind enough to elaborate for me, or refer me to somewhere where I can learn what it is? Thanks!
     
  4. Count

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    I finally found some references on google to VRS. That is it for certain. Now I have to figure out why. Like I mentioned, I have installed a BUNCH if high intensity lights which may be negatively influencing CG/balance/aerodynamics causing this. I will strip it down and add on slowly until I find the reason! Thanks!
     
  5. IrishSights

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    Its more than likely it has been exaggerated by the prop guards. Its a well known insability cause in some conditions. Wikipedia has a good explaination on VRS or prop wash. Sorry I missed the prop guards mention in your OP. Lose them and it will get better plus forward flight descents or any direction just not straight down.
     
  6. IrishSights

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    Mods... another one for the ghostly FAQ Section :)
     
  7. Count

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    Irish, thanks again. Regarding the prop guards, do you think it is the additional weight outboard of the center which adds to the "rocking" due to VRS (mine seems to be much more violent that those I have watched on youtube), or do you think it is an aerodynamic issue where the prop guards physical presence somehow adds to the vortex ring? The reason I ask is that I also have added approximately 25-35g+ to the bottom of EACH engine pod and to the actual prop guard in the form of LED strip lights under the outside perimeter of the prop guards and high intensity LED spots to the bottom of the pods, adding a significant amount of weight WAY outboard of the center of the vehicle. It looks **** cool at night, and virtually brings daylight to an otherwise dark area, but I am not certain the negative influence is worth the loss in flight stability...
     
  8. IrishSights

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    I would say yes leds around the prop guards would almost certainly cause problems. So thats an extra 140g of Leds... good God man! It must be scary! Loses the lights and the prop guards and see how it goes IMO.
     
  9. Count

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    I removed the prop guards and LED's (210g total: I apparently underestimated), and everything works great. I am going to put 210g of dead weight on it, and give it a test, then slowly put things back on to the point where I start to encounter troubles again if it is not the weight alone causing the issue. Yes, Irish, it is a sight to see! 4 high intensity beams pointing forward from the prop guards (plus 4 more on the legs), plus red or green strips on the length and perimeter of each prop guard with a super bright programmable red or green flashing LED cluster on the bottom of each pod. You have NO problem flying high at night; in fact I Iike night flying more! The local police and fire depts have my number, and are going to call me next time they have a night time issue where a bright remote light source may be of value! I can't wait...
     
  10. IrishSights

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    Glad to hear you got smooth flying bird again
     
  11. Happyflyer

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    Count,
    Don't be shocked if some night you hear a loud shotgun blast from some "luna-tic" that thought it was a UFO. :lol:
     
  12. IrishSights

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    LOL!
     
  13. Count

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