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Crash & Shake

Discussion in 'Phantom 2 Discussion' started by goldfishrock, Mar 17, 2014.

  1. goldfishrock

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    Hi Chaps, Took my P2 out for a spin a few days ago and was happily whizzing along when all of a sudden it tumbled out of the air. It was about 500m from me when it happened so all I could see was through the monitor. Luckily I was over private land and knew roughly where it had come down, a couple of large fields and it should be easy to spot......

    ..... 90 mins later after walking the perimeter of both fiends and still not finding it I was able to climb up onto a stone wall to get a better look and eventually spotted it, belly up on top of one of the hawthorn hedges. After them having to climb into the hedge to retrieve it (Devon hedges are about 10ft tall!), cutting myself up nicely in the process, I retrieved my baby.

    Quick check, Camera still rolling, main battery popped out, two broken blades (STBD side, front & back), little scuffed here and there but it seemed in good shape otherwise. The landing into the nice springy hedge I think saved it as it was a drop from around 200m.

    Back at home, further inspection showed bent gimbal mount but nothing else. Put some new blades on it (all four... genuine DJI) and took it outside for a little test and it seemed fine. However I noticed that in the hover there is a very slight shimmy / shake and it's not holding it's position as well as it did before. Initially I thought it was the bent gimbal throwing the balance so I removed it all together but it still happened.

    Ran through calibration / IMU + Sticks. Still no difference. I've had the top off and made sure everything inside is as it should be. GPS module seems in good shape, no damage to the sensor. Motors appear ok, nothing bent, all running smoothly, clips attached etc.

    To top it all, I then got flu and ended up in bed for the last five days.... even my P2 couldn't encourage me out!!!

    Reviewing the video of the actual point the tumble started it looks as though something hit the P2 on the STBD side (the same side as the failed props). The P2 clearly jolts a split second before the tumble starts. At this time of year there are many large birds starting to nest around here from Crows to Buzzards. I've certainly watched Crows attacking Buzzards while defending their area so possibly it was a punchy crow or maybe just a simple blade failure..... either way, it's not happy now!

    I am wandering if one of the motors is potentially to blame for the shake however not entirely sure what to try next. Has anyone got any suggestions?
     
  2. ianwood

    ianwood Taco Wrangler
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    Sounds like Kamikaze birds. I had a couple of close calls the other weekend. Post the video! Then, check the motors:

    • Check for smooth turning and any resistance or binding.
    • Props off, wiggle the tops of the motors and give them a pull. Should be very little play in it if any.
    • When you next run it, feel the motors and see if one is warmer than the others.
     
  3. Jaybee

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    Sounds hairy. I guess all the motors are straight and there isn't any small kinks at the end of the shell's arms?

    Be interesting to know if something definitely hit the Phantom. Sounds like a motor freaked out?
     
  4. goldfishrock

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    Thanks guys. I have just ordered a laser thermometer which should allow me to measure the motor temps (as well as ESCs) while they are running.... may give me a better idea!
     
  5. Paul K

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    I would say one of the ESC dos not work properly after the propeller hit something hard
     
  6. ianwood

    ianwood Taco Wrangler
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    Your hand makes a very good thermometer for this purpose. If there's a friction issue, you'll notice the difference in temp easily.
     
  7. Justgregg

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    Almost identical situation with me last Friday. 3rd flight with camera and zenmuse the P2 dropped out of the sky like a rock. Bounced off the roof of the house, bent the gimble plate and broke the back 2 limiting screws on the dampening plate. Destroyed all 4 props and prop guards.
    Put on new props and noticed a slight twitch and very hard to control. Loss of power on lift off. Imu/gps tests fine. 2 bad motors!
    I'm hearing that that stock dji motors are hit and miss on the quality side. I'm not sure if the stock motors can handle the cam and gimble. I'm waiting on a new set of tmotor anti gravity motors. This should fix the problem. There has been a few pilots here that have had the same problem.
     
  8. goldfishrock

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    I've now had a chance to check things over more.

    I ran it on my desk for 15 mins, blipping the controls to give the motors a work out and they are all pretty close temp wise (within 0.5 degrees C) however several times diring the test, one of the motors sounded like it stopped and started again. It's hard to explain but it sounded like the noise you'd get if you stuck something in the motor while it was running, it was almost a 'clunk'. This stop/start lasted milliseconds and was so quick you can't actually ascertain which motor was causing the problem.

    Anyway I beleive it's the rear right so I've ordered a new motor and ESC and will see if that helps.
     
  9. Peter Evans

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    I've just had a guy here fitting a new floor. It turned out that he's an r/c helicopter hobbyist and has a standard 'copter about one metre long. He said it had been destroyed the previous Sunday by some sort of raptor. Apparently the bird came out of nowhere, hit his copter and then flew off (injured or not he didn't know). Anyway, he says his copter fell from about 200 metres and is in a hell of a mess. It's made me a bit nervous as we have loads of buzzards, kites, harriers, and various species of hawks around here.
     
  10. goldfishrock

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    Wow! I'm not the only one then. They are definitely punchy at this time of year because they are starting nesting. The Buzzards don't seem to mind it too much and I've flown a few flights close up to a couple who were thermal soaring... they just ignored it and moved off elsewhere. It's the crows / rooks that are the problem; they are just suicidal in the spring.

    I think I've found the cause of the wobble after my crash. I found that the rear motor on the side of the 'strike' has a crack in the mount on the shell. I've got a new shell on the way which will hopefully fix the problem. I've also replaced the ESC and motor on that arm too after the strange 'clunk' that was happening too. I should have it back up and running in a day or so.
     
  11. ianwood

    ianwood Taco Wrangler
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    In LA, there are a lot of hawks but they seem to only flirt with the Phantom. There is always one where I practice who likes to lazily fly across the Phantom's path and then sit in a nearby tree and watch. You can see him here: https://vimeo.com/87061821

    The hawks are curious but they don't attack. Unlike these things (swifts) which are ridiculously fast and ridiculously bad tempered:

    [​IMG]