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Stupid question from a newbie

Discussion in 'Phantom 2 Vision + Help' started by PhantomPhyler, May 13, 2014.

  1. PhantomPhyler

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    I have tried searching, but cannot find an answer to this.

    I have a Phantom 2 Vision+.

    After landing, holding the left stick down for a few seconds kills the motors. This is documented in the manual. My question is: what happens if I hold the left stick down while in flight? For example, if I am up 400', and want to descend quickly, can I hold the stick down at max descent rate, or, will I kill the motor after three seconds?

    I assume there is something in the software that says that as long as it is descending, holding the stick at max descent works, and holding it there while it is motionless initiates the shutdown. But, without finding it in the documentation, I figured I'd ask the experts.

    Thanks for any input anyone has.
     
  2. framedtrash

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    you would have to be really really high up to be able to hold the stick full down for longer then 3 seconds without crashing at full speed into the ground
    the phantom is aware where it is when its flying im sure it wouldnt allow itself to be turned off mid flight
     
  3. PhantomPhyler

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    I wasn't worried about descending for more than three seconds and crashing at full speed. I was worried about descending for three seconds at full speed and having the motors turn off at altitude and having it drop like a rock.

    And, like you, I suspect that because it knows when it is flying, that it is smart enough to not turn off the motors unless you do something really stupid like bring both sticks down and in, like the motor start-up motion.

    But...not being one to assume, and not being able to find it in writing, that's why I thought I would ask the community.
     
  4. AnselA

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    Have you tried "TAKEOFF/LANDING PROCEDURES" in user manual?
     

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  5. jimdenburg

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    Just an FYI you probably don't want to pull the left stick down full for a period of time while descending unless you're also moving along a horizontal plane or yawing at the same time. This can cause a ring vortex condition, uncontrolled descent, possible crash and stained shorts. Best to descend gradually, but no holding left stick back for a a few seconds while airborne won't cause engine shut off. Both sticks down and center (csc) I believe will though.
     
  6. PhantomPhyler

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    \
    Yes, however, it says nothing about whether holding it for 3 to 5 seconds while in flight will also cause the motors to stop. Hence my question.
     
  7. PhantomPhyler

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    Had not considered the effect of a straight descent at high speed. Thinking about the physics of it, I'm not sure that a vortex would form unless it was perhaps perfectly still, and, since I would be pulling away from it, I am hard-pressed to see how an uncontrolled descent would result. That and the fact that I can't descend without a little unintentional yaw probably will make that aspect safe.
     
  8. sar104

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    It will not kill the motors unless the FC detects no actual descent, determined by the barometric sensor, for 3 seconds. An actual CSC, in contrast, will kill them.
     
  9. PhantomPhyler

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    What I assumed, but thanks for the confirmation!
     
  10. sar104

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    The vortex bit is distracting. What happens is the craft is descending into its own prop wash, which is disturbed air with a downward particle velocity, and so it loses both lift and stability. It is very real, well documented, and the reason for the FC software limitations on descent speed.
     
  11. SilentAV8R

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    The descent rate is now restricted to 2 meters/second. So 3 second is 6 meters, or only about 18 feet or so. But the Phantom comes with Intelligent Cutoff as the default on the engine kill, so as has been noted, holding the stick full down will not stop the motors unless the Phantom detects it is not moving.
     
  12. PhantomPhyler

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    Makes perfect sense. Hadn't considered prop wash. I'd suspect even yawing would not help. It would disturb the prop wash, but now, you'd be making a potential vortex of four smaller vortexes. So...basic rule - fast descents only when coupled with some horizontal deflection as well.

    Thanks for the tips and thorough explanation.
     
  13. darwin-t

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    There is a setting you can set with Assistant for "Intelligent" shutdown of the motors. If that is set, the motors will only shut down if you hold the throttle all of the way down and it isn't descending (it is on the ground).

    If it is not set, I believe that the motors can be shut off while it is in flight.

    It's worth checking the setting.
     
  14. sar104

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    I'm not sure that setting still exists in the latest Assistant - at least I can't find it. It appears to be set to "Intelligent" with no way to change it.