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Jumpy Landings?

Discussion in 'Pro/Adv Discussion' started by Justin Namon, Jan 29, 2016.

  1. Justin Namon

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    Hey guys, not the biggest issue but it I'm concerned enough about it to make a topic. So almost every time I'm landing (always manually) just as I'm about to touch ground the p3a jumps all of the sudden, it reminds me of trying to fight 10% auto land. The jump is not very high, maybe half a meter, but it's sudden and unexpected and just about at that point where I'm about to relax my fingers off remote because it's literally on the ground and then jumps on its own. Anyone else deal with this? My VPS is off. I'm landing with over 30% battery each time. Let me know thoughts.
     
  2. happydays

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    Hand catching will avoid this totally.
     
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  3. shorttimer

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    I usually hand catch mine as well but when I was practicing landing and when I had it land itself when battery was low mine settles down nicely. It might go up a little then down but this is only when it is about 6" -12" off the ground and then it is only a couple of inches. I'm guessing because of the air cushion below. My VPS is off as well as I'm always outside.
     
  4. Justin Namon

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    Sounds exactly like the issue. Might be air cushion but it's so sudden it freaks me out. Ha. Will ride with it and expect it from here on out. Btw, I double checked VPS was turned on mysteriously. Must've been update I've heard it auto resets sometimes. Thanks for help yall
     
  5. eaglegoaltender

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    There is a fair bit of downward pressure from the props and the closer it gets to the ground there can be some "upward force" working against a clean landing. Ever watch real choppers land - they get that same upward force when landing. I haven't tried hand catching, but when I do land - I get that same force you mention and just when I am inches from the ground I kill the motors. Works for me when I have to do that. I haven't experienced it jumping back upward like you mention - however I would think perhaps you have higher throttle than needed to land and combine that with the downward (restricted) prop activity to ground it forces the Phantom back up again to a hover position where the downward force is limited. Just a thought!
     
  6. flyNfrank

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    What the OP described is called the Pogo Dance. It's caused from the barometer not being settled at that point of landing. Slow your landings down and you should be ok.
     
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  7. Albert D

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    I, personally, don't like hand catching. If my P3P is autolanding, there is always a little bouncing, usually no more than a foot (10-20 cm), but it always seems the vehicle is well in control and the bouncing stops as the props slow down, transferring more weight to the landing gear. When I land manually, there is much less bounce. Since I get that floating bounce when I try to do really gentle landings, I typically push the left stick all the way down, as soon as it touches the ground, until the motors shut off (2-3 sec). If I bring it down manually to where I think it is landed, then let go of the controls, sometimes it will jump back up and hover there, just a few inches from the ground (5-10 cm), until I complete the landing.
     
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  8. sdharris

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    Its normal and its called ground effect from memory, as the rotors get closer to the ground they encounter a bubble of pressure generated from their own wash bouncing up from the ground and actually become more efficient so you see that slight rise as less RPM is needed to maintain that alitude but the flight controller does not account for it and it rises back up.

    You just need a bit of practise to get used to it, don't over react with the sticks and slowly almost descend through it.
     
  9. henick

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    I often fly and walk behind my p3p because I have a park 2 blocks away to give myself some practice with close quarters control. I do the same to get home and usually fly over the car and land on my front step. When going over the car the compass always freaks out and when landing on a very closed space like a step the updraft is bad. Very slow careful stick movements usually negate any negative impact but any time flying in close quarters you will get updrafts. Careful reacting too fast and switching to atti. It will get noticeably more difficult to manage.
     
  10. dixter

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    I have seen this rabbit jumping also... wondering if it might be the ground sensors turned on ???
     
  11. robinb

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    Skill, practise.

    There is an air cushion as you come into land caused by the downdraft. Closer to ground greater the cushion and if the wind is blowing the cushion moves around and deforms.

    You dont need to hand catch (sorry Connor) but you need to have skill and it can kiss the ground like feather.
     
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  12. henick

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    I always assumed it was the consultation of VPS sensors coming into play at low altitudes. (Besides obvious up/down draft generated) You can test this in an open space by switching to atti and landing yourself without them. Switching to atti in a close space can be dangerous to your props if the craft drifts though so do it in a field the first time to understand it.

    Then again, I am admittedly guessing based on my own experience.
     
  13. Dirty Bird

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    You are just getting some ground effect turbulence when you approaching the deck. It's normal just keep slowly pulling down on the stick until she sets down. When you decide to land you have to be firm about it or it will dance around. Some of my early videos I was bobbing all over the place trying to be perfect but you just set your mark & commit to land.

     
  14. dixter

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    been doing this long enough to know its not ground effect.... it jumps like a rabbit... in the days before the phantoms you had to set the Z parameter so the quad was told where the ground was... if you set it just a little too high the quad wouldn't land and just jump around until you killed the motors... I'm now wondering if you need to calibrate from the launch site...
     
  15. CCDD

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    The issue with your landings is typical, a little bounce upwards right before touching down is likely the down burst of air from props. I just prepare myself for this and then just ease it down for a smooth landing nearly every time. A great landing, take off and flight adds to the "pure" enjoyment of these Phantoms. I don't see any need to hand catch or use any of the other "auto" features unless they're truly needed. There's no better feeling than to manually fly these birds from takeoff to landing.
     
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  16. Justin Namon

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    calibrate what exactly? the z parameter?
     
  17. CCDD

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    There's nothing wrong with it, just ease it down, let it do its "hop" and bring her to the ground slowly. One of the recent FW updates may have had something to do with this as I don't recall this occurring when I first bought my P3P. If it's not the "blast" of air from props, then perhaps it is FW related. I fly with others that have the exact same issue therefore, I would chalk this off as normal and be careful during those few inches before resting her down.
     
  18. Solar Deity

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    I'm not sure it's the VPS, or the barometer. I have noticed it, but the left stick will counter it. As soon as your skids are on the ground, hold down for 3 seconds ASAP. From experimenting, using auto land, the P3 accounts for the ground effect of the props. During its descent, when about 1 foot from the ground, the P3 lowers the rpm of all the motors and it settles in perfectly. It knows it's entering it from the VPS I assume.

    SD
     
  19. RichKleinforum

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    I have started to notice the same problem and it serious enough to cause a tip over. It is worst when i do autoland. In that case it jumps up a few inches after it lands. If it shut off the motors faster it would not happen. Again, intermittently it happens on manual landing as well. I have not tried turning off the VPS.
     
  20. JickMagger

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    Are you cutting the engines with CSC (both sticks diagonally down?) That causes the engines to rev up briefly and can cause tipovers.

    Best way to cut the engines is to hold down the left stick for 3 seconds once on the ground.

    But I always hand catch, get into a stable hover about 6 feet off the ground, grab the landing gear with the right hand hand and pull left stick down for 3 seconds with the left hand.