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Rapid Descent with no control

Discussion in 'Phantom 2 Help' started by Gautam Pandey, May 21, 2015.

  1. Gautam Pandey

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    Hi,

    Have been flying the P2 for a few months and have had 1 crash which now when I think about was similar but with an older firmware and a much lower altitude.

    This time I was flying at 10,200 ft above sea level and was very cautious and was expecting it not to fly, though there is a video of a P2 flying at everest base camp!

    So I did a compass calibration and had a battery at 60%

    I took off in GPS mode. all looked good. As I slowly began to descend the phantom suddenly started coming down really fast. Full throttle up no change in sound, I tried maneuvering.. no response. Luckily nothing broke. After a quick check I decided to try another flight and with a friend ready to grab it incase it fell again.

    same thing happens.

    Next I moved lower down the mountain at about 8,800 ft and fly on the same battery just to see if it's a battery issue. Compass calibrate.. Take off in ATTI mode.. fly for a minute and then I tried to very slowly descend. I was being careful to avoid the Vortex Spin situation so was coming down real slowly and at an angle. At first it seemed like it wasn't descending and then quite suddenly just starts coming down.. I jump to full Manual mode and throttle up all the way.. no change. Had a big blanket stretched out and caught it in it :)

    Inspite of 3 'crashes' now I decided to do 1 more test with a fresh battery and ATTI mode. It flew.. it came back.. it landed. It didn't sound great though and it felt like it was a little less responsive and it yawed all of a sudden while flying in a straight line. I panicked and and got it back.

    Have had perfect flights at 7,600 ft with a controlled descent because of the latest firmware with throttle all the way down and felt like it would be a great feature at a higher altitude where the air is thinner.

    Sorry for the long post but just wanted to give all the details - Any ideas.. anyone?
     
  2. IflyinWY

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    Welcome to the forum Gautam.

    I have done all my flying between 5,000 and 8,000 feet above sea level. Yep, the air is less dense and the performance drops off pretty good around 8,000 feet. It sounds like you were having more problems than just altitude though.

    I'm going to ask questions and really do want to know the answers so I will know the cause as well.

    Were you flying in a canyon where you were having difficulty with GPS?
    How heavy is your bird? I can't get much flight time at high altitude if the weight is anywhere near the max take off weight. My max takeoff is 1,200 for my FC40. What is it for your P2?

    Did the Phantom descend at an angle moving forward? If the answer is yes, and you have a camera mounted forward of the COL (center of lift), then it sounds like you just ran out of power.

    High altitude flights suck a lot of juice from the batteries and if the battery is cold, or your bird is heavy, you can draw more power than it can supply... down it comes. I keep the batteries in my pants pocket before I fly, to keep them warm. I won't fly with anything less than a full battery when flying at 8,000 feet. Flight times are drastically reduced if you are heavy.

    On the other hand, I have had many great flights when the bird did well, climbing and descending.
    When the battery can't keep up, it's coming down. Keep the blanket handy. :)

    This is a great way to find things. Google Custom Search for our forum.
    Enter your text in the middle of the screen, not at the top.
    https://cse.google.com/cse/publicurl?cx=014775389315664725445:ejku2ysgyhi
     
  3. Gautam Pandey

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    Hi.. Thanks for responding!

    Have answered your questions below

    It wasnt very cold.. maybe around 20 C, in anycase the batteries were warm but like you mentioned perhaps at this height the power draw was more than what the battery could give out.

    But whats really got me scratching my head is the guy zipping around his phantom at 17,000 feet at the everest base camp!! How is THAT possible?
     
  4. IflyinWY

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    It was a P1 and the flight lasted 1:39 before he ran out of power. I would say that's a pretty quick battery drain.

    Everest base camp P1: 17,500'/5334m


    Can't really help you beyond that without answers. o_O
     
    #4 IflyinWY, May 21, 2015
    Last edited: May 21, 2015
    N017RW likes this.
  5. Gautam Pandey

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    Yup.. very quick drain but it flew!! Found another post with a similar issue .. Seems some can fly and some cant.

    Maybe they have the newer wider props on them
     
  6. IflyinWY

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    The P1 was fitted with P2 props. I don't know if they are 9443s or 9450s.
     
  7. Gautam Pandey

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    aha.. so a little glimmer of hope!! Thanks :)