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Stopping motors mid-flight for rapid descent?

Discussion in 'Phantom 2 Vision + Discussion' started by CoolDude, Mar 18, 2015.

  1. CoolDude

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    Hi,

    I have a strange question. Lets say I was up several thousand feet with my P2V+, and there's no time to bring her down due to low battery. Would it work if I try to stop the motors (sticks down center) so it would start to free-fall, then after I'm at around a few hundred feet, start them up again an regain control? This would all be done in a safe controlled environment and all that. No planes no people underneath etc.etc.

    This is something I'd like to try. Break an altitude record, then just let it fall down and start back up before crash. Anyone done it?
     
  2. landmannnn

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  3. Meta4

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    If you fly up several thousand feet and encounter a low battery situation - you deserve the logical consequences that will follow.

    Controlled environment? - no planes ??? How can you control your flying environment that far up?

    Has anyone shown what a dickhead he was by flying up so high we couldn't return safely?
    Yes - and it wasn't cool then either.
     
  4. SteveMann

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    Has anyone noticed that yours and the linked thread are both hypothetical, and most of the replies are, "don't go that high".
    Maybe it's not intentional, maybe you have a clear block from ATC, maybe you had a flyaway straight up. (Come to think of it, I've never heard of a vertical flyaway, but it could happen).

    If you shutdown the motors using the sticks, the Phantom will most likely tumble. At 200 ft you power up and the IMU should right the aircraft before it makes an unscheduled landing.

    Rapid maneuvers and descent are best performed in manual mode. Flip it on its back and throttle up and you will probably reach a 1000 fpm descent pretty quickly. Switch back to GPS or ATTI and the elevator ride stops. This is all purely theoretical - I haven't tried it.

    Let us know when you try it.
     
  5. SanCap

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    I do not know if mine was a fly away but as soon as I started the motors the Phantom 1 went vertical at full speed without my input. I almost immediately pulled both sticks down to stop it and actually tried to restart it as you can hear in the video. I did not have enough altitude. http://www.jimandsusan.com/crash.html
     
  6. Apparition

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  7. Mori55

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    That's the kind of bullshit that's going to ruin this hobby.
     
  8. terrylowe

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    This was posted months ago. It proves that a mid-fall motor restart can work.
     
  9. chapsrlz

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    maybe cooldude is extremely rich and doesnt care about turning an expensive investment into expensive junk :lol:
     
  10. n6vmo

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    It's a troll gentlemen....relax and stop posting to this thread.
     
  11. burlbark

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    Vertical flyaways can happen... This one is not a Vision but it decided to take on a mind of its own.

    https://www.youtube.com/watch?v=JxsUlU2 ... e=youtu.be
     
  12. cahutch

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    A quick bit of math on that scenario ...
    Assuming "several thousand feet" is ~3000ft. If you power back up at ~300ft that equals a fall distance of 2700ft

    Without considering air resistance ,
    You would be falling for about 13 seconds and be moving at ~284MPH when you restart the motors.
    I don't think you would be able to decelerate in time.

    With Air resistance is very difficult to calculate without knowing the specific air resistance of the Phantom 2,
    A skydiver free falling that distance would be falling for about 17 seconds and be moving at 135Mph at 300ft.
    If you can estimate the Phantom 2 air resistance, you can try different values here ... http://keisan.casio.com/exec/system/1231475371

    With the Phantom 2 max climb rate of 6m/s, you could decelerate at about 13Mph per second.
    At 300feet, you would need ~11 seconds to decelerate from 135Mph, but at that speed you only have ~1.5 seconds before you hit the ground.


    Good Luck. I wouldn't want to try it myself.
     
  13. flyNfrank

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    When I think of a vertical fly-away I would see it going straight up and up and so on.

    I went on a couple of higher then usual flights not quite a year ago and instead of shutting the motors down I just switched into manual mode. The quad actually remained prop side up. Once I reached the altitude I was comfortable with I switched back to gps mode and all was well. Shutting the motors down is not good regardless if someone feels like they are in control or not.
     
  14. CoolDude

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    You nailed it. I've broken 3 Phantoms in a year. I don't consider these "investments". They ain't supposed to give anything back except fun. One I flew into a lake. Another one busted up in a drunken stupor. I've got one now without the camera assembly which broke in a crash. It works fine just no camera.. I think I will try the motor restart and see how it goes. If I can repeat it enough times without crashing on someone's house or car, I'll go for an altitude record with a new Phantom, which is being delivered by DHL as I type.

    Anyway thanks for the info. Seems it's really just up to me to try it to make sure.
     
  15. Mori55

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    You are going for a altitude record , then free fall it ? Really ? How incompetent can you get ? Post it on you tube and make it even worse for us. Even better do it in a drunken stupor !
     
    snowghost likes this.
  16. CoolDude

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    Yea dat's right, tough guy. And you can bet I'll post it on youtube. And yes I will probably have had a few too.
     
  17. Mori55

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    Uhh ok Cool Dude....
     
  18. Spiritskeeper

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    As long as you clear the flight as needed to cya go for it. I would like to move to Utah or Nevada next to the desert. Great flying out there.

    Anyway I would go manual mode for the descent. The public YouTube altitude record is 6,000 feet up. If you are serious about this there are some considerations.

    1. You want to increase the thrust to weight ratio as much as you can. Probably carbon fiber 9450 props, removing landing gear and instead of a gopro and gimbal maybe remove that weight and strap/Velcro a keychain camera to the underside of the anti vibration plate.

    2. You want to go to the maximum flight level/ceiling of the phantom or just a little higher than the current YouTube champion?

    3. If you want to hit the ceiling this may be a one way flight. Think about an arresting chute attached to the top or side so upward momentum holds it against the bird and downward momentum would fill the sail. You may not want the weight of a full chute, just slow it down enough to retrieve the camera after impact.

    4. Redundancy. It may be you need more than one lightweight camera recording the phantom view. Having multiple cameras will increase your chances of recovering a video after impact/landing.

    5. You will need a stout lens to record the flight from the ground. There are some good cameras that mount to telescope eyepieces. It would take some practice to be able to follow a target of that size without over correcting the view back and forth. Maybe stiffer or tighter mounts on the telescope? And practice.

    If you do go ahead, plan ahead and give due consideration.

    PS does anyone know the height record? Or the theoretical maximum height of the phantom?
     
  19. N017RW

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    Regarding your final question, I have seen video of a P2 flying at Mt. Everest base camp (~18,000ft).