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Desending from a great height

Discussion in 'Phantom 2 Discussion' started by cokeaddict, Aug 23, 2014.

  1. cokeaddict

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    Hey guys,
    Some of my favourite footage is hovering at around 4 meters and then take off straight up with the GoPro facing the ground. Sadly though the down side to this is the amount of time it takes to come back down. Does anyone know if there is a fix to allow the decent to be faster than what I get when I pull the stick back? The scary part is, you always worry that if you pull back too far you might switch the motors off so to compensate that happening I have my thumb between the stick and the base to stop the stick pulling right back.
    Anyone been able to get a quicker decent?
     
  2. dragonash

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    I heard if you downgrade, you can have the restriction removed - although I do not believe you can successfully downgrade from what I know.

    The currently firmware restricts descent speed as to stop a vortex effect (wobble then crash)

    Also, if you hold down on the stick, as long as your altitude decreased, the motors will not turn off.

    FYI, I also try to stay at 2 meters per second when descending. The decent is always the most stressful part.
     
  3. FlyingHigh

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    I downgraded from 3.06 to 1.08 just fine. You need to have copy of the original phantom 2 assistant software, and use that the "upgrade" and it'll put 1.08 on.
     
  4. cokeaddict

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    dragonash.... so let me get this right.
    Your saying that I CAN pull the stick all the way back while desending?
    Doing that WONT stall the motors?
     
  5. FlyingHigh

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    Theoretically it only cuts the motors when the stick is all the way down AND the quad senses a zero altitude change. So in other words only if it thinks it is on the ground. However I've never tested it
     
  6. harbourside

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    Read the manual.
    Holding the throttle all the way down will only turn off the motors once the Phantom has stopped descending for 3 seconds. In other words, once it has landed or been hand caught. The only way to stop the motors mid flight is to do the CSC.
     
  7. sijbren

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    Just be careful, do not descent straight down fast. You can get into a vortex ring state (VRS) The props get in their own downwash, and then they have zero lift...
    If you want to descent fast, also move forward, back, left or right when doing this!
    Example of VRS here (action at 1:05):
    [youtube]https://www.youtube.com/watch?v=eZIuO66WjDY[/youtube]
     
  8. HarryT

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    I strongly suspect that the problem there was your CF props. There have been all sorts of reports of problems with them!

    Personally speaking, I regularly descend straight down from 100+m altitude, and haven't had any problems. My understanding is that the 2m/sec descent rate limit imposed by the current firmware should pretty much eliminate the problem.
     
  9. sijbren

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    The CF could be the problem. It's not my video and I only have genuine DJI blades.
    But there are a lot of stories about VRS and descending too fast straight down. But as you mentioned the latest firmware could have eliminated the problem.
     
  10. HarryT

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    Apologies - I didn't realise it wasn't your video.

    From what I've read, CF props can cause real problems when ascending and descending. The stock DJI plastic props are designed to flex, thus changing their pitch, during ascent and descent. CF props are rigid and can't flex, thus causing problems. I very strongly suspect that was the cause of the problem in this video, rather than VRS. But that's just a guess, of course :).
     
  11. sijbren

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    No problem ;)
     
  12. ussvertigo

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    If in manual mode, doesn't holding throttle all way down while at altitude indeed cuts motors off?
     
  13. macheung

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    If you are indeed in manual mode and hold the throttle all the way down, you are essentially almost shutting the throttles off already. I flew it a bit in manual mode today and hover was like 70% throttle and can descend much faster than I had ever wanted without full down throttle.

    So, if you want to come down fast, switch to manual mode and leave throttle around 50%, it will bring a loaded (1350g) phantom 2 down really fast, like 6m/s+ fast.
     
  14. cokeaddict

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    Thanks guys so much.
    Very good info here.
    I have learnt something which will come in very handy in future.
     
  15. UAVDD

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    I've noticed this myself with the prop guards on. That if you descend faster with prop guards it creates the vortex effect and causes it to wobble to a crash. Also having nothing attached to the bottom of your phantom also helps the decent time. Lighter weight more aerodynamics on the bottom allows for the air to rush past the frame of the Phantom 2. I also thought of a really great idea to put air flow holes in the wings of it. Of course this voids the warranty as I should advise so does opening the shell of the phantom 2. The trick to any modifications if you do it to one side you have to do it to the other side evenly and precisely. The prop guards are great if you want to try out some new tricks and flying stunts, but don't leave them on all the time. Take some risks and get used to flying without the prop guards.
     
  16. macheung

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    The prop guards are a liability for a fpv go pro gimbal Phantom 2 because it would add too much weight and put it over the 1350g max load (which is already a little too high for this quad)
     
  17. OI Photography

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    The prop guards do add weight and rob lift, both of which will make VRS a much bigger factor for a loaded Phantom. I'd highly suggest that anybody using them on a fat P2 consider trying the new 9450 props to help prevent (but still never eliminate) VRS.
     
  18. HarryT

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    I must partially disagree. Prop guards are a useful aid when you're learning to fly. In my first week I must have hit the ground pretty hard half a dozen times, and the prop guards saved my props. You shouldn't be flying high when you're learning, so fast descent rates and VRS aren't really a factor.

    But certainly you should take them off when you start flying for real. They make the Phantom harder to fly.
     
  19. noiseboy72

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    So here's a little video of a VRS moment!

    Basically, a bunch of people turned up at my flying site, so being responsible, I headed in to land. Descending at about 2m/s and with some forward flight, the bird started to become unstable. I gave it a bit of forward stick and then some power and ALMOST caught it before the ground turned up... A very light bump and we headed back into the air!
    [youtube]http://www.youtube.com/watch?v=dFd3WpnFCqI[/youtube]
    No harm done, just some pride. The air currents around this location can be a little unpredictable and the sudden incursion took my attention away a little bit. Lessons learnt!
     
  20. offcamber

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    I use manual mode. Just flip it to manual and dive. I can scrub a couple hundred meters of altitude in about 10 seconds. If you aren't comfortable flying in manual mode for the recovery, just flip it back to GPS and it'll stop its dive.