Another A2 Crash - Pictures, Graphs, and Video

Discussion in 'Cinestar 8' started by Josh Lambeth, Aug 5, 2014.

  1. MIke Magee

    MIke Magee Active Member

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    Sorry to hear Josh. You did a good job of minimizing impact damage and avoiding injury.
    -m
     
  2. Dave King

    Dave King Well-Known Member

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    HI Josh

    I have not had any issues with my combo using MK electronics. I have the same exact setup you do only with the cinestar frame and MK electronics and have about 70 flights on my rig. It's not my main rig as my flat 8 rig is my main setup but I have put it through the passes pretty good and used it on a few jobs working flawlessly. I had an issue with altitude hold but it appears it was just the sensor being exposed to light and a quick cover for the sensor fixed it.

    Thanks for posting and sorry to hear.
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Josh: Please check your inbox for a PM from me.

    Andy
     
  4. Chris Schuster

    Chris Schuster New Member

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    Man this is terrible and didn't need to happen.
    What firmware versions were you running Josh ?
     
  5. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I was running 2.3.
     
  6. Jose Luis Ocejo

    Jose Luis Ocejo Active Member

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    Hi Josh sorry for your incident, how far back you go with that A2 copter, any issues on previous flights? did you have a good amount of successful flights ?
     
  7. Josh Lambeth

    Josh Lambeth Well-Known Member

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    It has about 35-40 flights on it which were all testing flights. The flight when it crashed was the first one on a job.

    Josh
     
  8. Jason Smoker

    Jason Smoker Active Member

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    Wow that really sucks. Its first job and it fails
     
  9. Dave King

    Dave King Well-Known Member

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    Josh

    What is your AUW?
     
  10. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Yeah I wasn't really happy about that Jason.

    Dave we were flying 27lbs AUW
     
  11. Rafal Plewa

    Rafal Plewa New Member

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    Hi, this is my first post here, but I had just the same problem.

    I use X8 frame and A2. After 14 minutes of flight (mainly hoovering for pictures) the whole platform started to spin ccw (yaw). I switched to ioc mode, and managed to move the platform over field of rye and lower the altitude. I couldn't make it stop spinning. The spin slowed down and almost stopped couple of times, but then every move of any stick, caused the spinning speed growing up again. The whole situation took almost 4 minutes, eventually it entered autodescend mode due to critical voltage level. Amazingly, after pretty hard touchdown (during the slight spin), there was no damage, as the platform didn't fall over. The rye was just flying all over the place.

    My X8 is new platform, we only have several flights, and total flight time of this setup is 1h 10min. This behavior of A2 never happened before. We grounded the platform because we don't consider it safe now. Our distributor blames communication between Futaba T14SG and A2 built in receiver. We plan to use bundled Futaba receiver instead of the A2 build in receiver and test the platform.

    Do you think it may solve the problem?

    The setup:
    X8 configuration and A2 controller
    DJI Ground Station
    8x NFS ESC 45A Multi-Rotor ESC SimonK Firmware
    8x Tiger Motor U5 400kv 850W
    2x 10.000 mAh Gens Ace
    alexmos 32bit - gimbal
    Teradek Clip 5.8 GHz with signal boosters for HD streaming
    Futaba T14SG (control), Futaba T7CP (gimbal and shutter)
    AUW is 10.5 kg (23 lbs)
     
  12. Dave King

    Dave King Well-Known Member

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    Too much for those motors. I just got some new motors in that I will be trying very soon :)
     
  13. Steve Maller

    Steve Maller UAV Grief Counselor

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    This almost certainly has nothing to do with your radios. There's a number of things that can cause uncontrolled yaw. One of them is a pair of motors that are not perfectly vertical on their boom. Another is an oscillation or other problem with your gimbal. Finally, your flight controller could be defective or improperly configured.

    Can you post a photo of your copter?
     
  14. Josh Lambeth

    Josh Lambeth Well-Known Member

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    How is that to much for the motors? I was only hovering at 46-48% throttle?
     
  15. Josh Lambeth

    Josh Lambeth Well-Known Member

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    That sounds just like our crash! Did you happen to have the iOSD to record flight data? Do you have video of the crash?
     
  16. Steve Maller

    Steve Maller UAV Grief Counselor

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    I agree with you, Josh. You had plenty of power on that rig.
     
  17. Dave King

    Dave King Well-Known Member

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    Flying at 26 pounds with the same motor and props I'm seeing 64 percent hover throttle. I guess its the inefficiency for KDE motors to run with any other ESC besides their own. That's a pretty huge difference and I'm at a pound less than you. I'm estimating that I would be around 67-68% flying 27 pounds like yourself.
     
  18. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Dave, what size props were you running? I was running in X8 and did a motor-out test. Had my motors been anything over 50% power it wouldn't have been able to fly since one motor has to take complete load from the one that stops. My copter never attempted to flip and looking at the data logs from the A2 for output to the motors it clearly shows they are below 50% at hover.
     
  19. Dave King

    Dave King Well-Known Member

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    Well my now "former setup" was X8 - KDE 4014 motors with 18 inch Tiger 18X6.1 props. I tried all phase timing from 18 to 28 degrees. Nothing made an impact. The copter was very stable, no yawing what so ever and very smooth just didn't have enough power. I am in the process of converting it back to a flat 8 with some new Tiger motors I am testing out.
     
  20. Steve Maller

    Steve Maller UAV Grief Counselor

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    I think we have to be careful with the hover throttle percentage numbers. I have a strong feeling that the better measurement is the hover current as a percentage of the max current of the particular motor/ESC combo. The throttle percentage is somewhat arbitrary depending on the PPM scaling factors and the radio, FC and ESC's interpretation of that number. For example, while Josh was hovering at 46% and Dave at 67%, the fact that you guys are running completely different electronic stacks (DJI/KDE vs MK/MK) makes those numbers truly apples vs. oranges. For example, I'd rather see a number that says that hover as a percentage of max output. In other words, full throttle climb out runs at 200A let's say, and hover is at 67A, then that's more interesting data.
     

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