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Problem: Graupner MX20 Gr24 >50m range -> fly away

Discussion in 'Electronics' started by David Kellermann, Apr 21, 2013.

  1. David Kellermann

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    The password is "failure". I can't upload the log files here, since they are to big. But here's an other link.
     
  2. Gary Haynes

    Gary Haynes Administrator
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    David what are the files from? MK, Hoverfly, Graupner? You didn't mention what you are flying....
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Are they the GPX log files or the log files from a transmitter? I can't remember what file types the Graupner Tx's produce.

    Andy.
     
  4. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Graupner is a bin file.
     
  5. David Kellermann

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    I'm using a Graupner MX20 with a Gr24
     
  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks, Josh. Thought I remembered seeing .bin files.
    Andy.
     
  7. Gary Haynes

    Gary Haynes Administrator
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    I looked at the Graupner file and don't see that the receiver dropped offline. You did start losing RX strength starting at about the 260 second point. Prior to that it was running 80 or above. After that it started downwards and at 265 seconds starts showing single digits.

    At 280 secs it is back up into a more normal range where it stays for the remainder of the flight.

    No other data is available other than the receiver. With no other data points or way to align it to the video it is hard to tell when/where the signal strength dropped.

    David do you have the HF GPS installed and if so can you send the log file from the HF?

    The video is nice and clear but is upside down which makes interpretation a bit challenging.
     
  8. David Kellermann

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    Uploaded a flipped version. Unfortunately I don't have a Hoverfly GPS module, so there's no log of the Hoverfly.
     
  9. David Kellermann

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    Wow there seems to be an easy answer for the problem... one of the motor leads somehow got loose from the ESC. Can one motor drop be enough to let it fall that quickly?
     
  10. Dave King

    Dave King Well-Known Member

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    I use a GR24 (pilot) and a GR16 (gimbal) and I was able to trick it no problems. I used a GR12 for the 2nd set for the gimbal and it worked no problem. No telemetry being received to the camera operator TX. I've been 700 meters testing the distance of the 1.3 downlink and so far no issues.
     
  11. Gary Haynes

    Gary Haynes Administrator
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    David yes that could lead to a flip if the copter is under a load. The other motors would try to compensate but you would need to be quick on the controls to save and have a successful landing.
     
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  12. Dave King

    Dave King Well-Known Member

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    Really? I wasn't aware of that. I thought that was one of the benefits of the Octocopter. I guess it gives you better odds but you need to always be prepared.
     
  13. Gary Haynes

    Gary Haynes Administrator
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    Dave a CS8 does give you a safety factor but you need to be able to react quickly and fly through the incident. As you saw it can happen in the blink of the proverbial eye. The landscape is littered with real airplanes where the pilots forgot to fly the airplane first.

    As quickly as this happend in David's case not sure most of us could have saved the ship.
     
  14. David Kellermann

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    Thank you all again for the help! I'm now at least prepared, in case something similar happens again. I'm designing right now some carbon plates for my batteries and other stuff. I'll take the copter apart this weekend and then assemble it again differently (run the wire differently and so on), this time hopefully fixing all the earlier mistakes.

    If someone is interested in the CAD drawings, I can upload them when they are finished. Other than the battery plates next to the center plate where my Hoverfly is located, I'll replace the plate attached to the vibration dampers through a ring shaped plate, using eight instead of four dampeners. Hope that this will give the gimbal more stability.

    Cheers
    David
     

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