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Our Cinestar 8 bites the hand that feeds it!

Discussion in 'Cinestar 8' started by Sebastian Meredith, Jan 29, 2013.

  1. Sebastian Meredith

    Sebastian Meredith Active Member

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    Hi all ... thought I might share our recent "wobbly" we experienced on a photoshoot this weekend. :(

    We were up at 4:30 am to catch the morning light. Shoot was going smoothly as was the norm ... then at about 9am disaster struck!! I landed CS8 after a low battery warning. Shut the motors off with the assigned switch. Started walking towards it to disconnect the battery, when suddenly the motors powered up, throttled up to a high speed which lifted the CS8 into a swirling ascent to about 5 meters, then plummeted back to earth landing squarely on the rear landing gear which shattered. It then shot up again to about 20 meters still swirling (during this moment of chaos I was trying everything to get control .... but nothing was responding) it then plummeted back down to earth and straight back towards me.

    Not sure what went through my head at that exact moment, but it definitely was not going to be my CS, so what I presume was totally out of instinct I raised my had to block my face and grabbed one of the booms. Unfortunately so did a prop grab my hand ... splitting me open and kindly offered me the opportunity to receive 14 stitches.

    Have not began a postmortem on the CS yet to ascertain the full extent of it's damages and the exact cause thereof! I'll continue to lick my wounds and rerun the scenario through my brain a million times in the hope of trying to understand what went wrong! The CS's SD card

    I have not ruled out pilot error ... 4.5 hours of filming without a coffee or breakfast break (the morning light was just too fantastic to leave with the threat of rain on the horizon) ... but what that error was, if any, is clouded in mystery.

    I can only hope that is was pilot error, as that would be much easier to fix than trying to entangle an electrical web of circuit boards and electronics in the hopes of unraveling the alternative! Which includes the limited capabilities of my current use of only one hand ... which is taking me forever to type this message!

    Attached some pics of the splintered landing gear and splintered hand. My Graupner that was in my other hand also managed to get in the way ... somehow?. I'll upload some more pics of the CS when I get to operate on it. We also managed to capture some of the initial carnage on our GoPro that was on the ground ... should be interesting!

    (PLEASE BE ADVISED - SENSITIVE VIEWERS might loose their lunch! ... but I thought it necessary to enlighten CS users of the dangers and powers which lay behind those thin little plastic blades)

    pixair-01.jpg pixair-02.jpg pixair-03.jpg pixair-04.jpg
     
  2. Gary Haynes

    Gary Haynes Administrator
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    Sebastian. Sorry to hear of your mishap. So as you start the post mortem see if you have the following and will share.
    1. SD card, your sentence cutoff so not sure of the status on that item.
    2. If you use an MX-20 and have the flight timers activated then the SD card will also have a log of the flight.
    3. Video from the cameras.

    Hopefully we can help you determine what transpired from all of those data points and the sound/audio from the camera.
     
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  3. Steve Maller

    Steve Maller UAV Grief Counselor

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    Holy smokes! That's a frightening-looking cut. I'm sure I'm not the first or the last person to tell you that you are lucky it didn't end even worse. Yikes. I hope you recuperate fully, and are not too uncomfortable. Give it time to heal!
     
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  4. Sam Slape

    Sam Slape Member

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    As you said. Better your hand than your head!
    Interested to know how...
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Wow, Sebastian. That is bad. You were right to put up a "Sensitive Viewers" warning for the images. That is a very graphic image as to what a prop blade can do. You certainly have my full attention and best wishes for a speedy recovery.

    In addition to what Gary said, the one sentence that caught my eye was: Shut the motors off with the assigned switch.
    There is a serious safety issue behind that statement because this is an uncommanded motor start and those, as you discovered, can be exceedingly dangerous.

    Can you give us more details, please?

    Apologies for the Spanish Inquisition:
    1. Was this the Motor Safety Switch?
    2. Do you recall anything about where the throttle stick was?
    3. Were you walking with the transmitter, or had you put it on the ground or somewhere where no accidental switch settings/stick movement could have occurred?
    4. Would it be possible that accidentally nudging the throttle stick might have caused a motor re-start?
    Andy.
     
  6. Howard Dapp

    Howard Dapp Active Member

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    Wow, glad you're ok now. It could have been much worse. I can only suggest to anyone in the event an out of control multi is flying towards you the best thing to do is drop into a tight ball and never swat at it...could end up with a severed artery. I have a similar injury but on the thumb side, the prop cut clean through the apl extensor.

    Curious to hear what cause the uncommanded start.

    Heal quickly sir!
     
  7. Ben Hall

    Ben Hall New Member

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    wow thats deep. first and most importantly of all i hope you make a full recovery . secondly i hope you find the root cause and share it with us . maybe it will help avoid a similar situation in future.
     
  8. Dave King

    Dave King Well-Known Member

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    Sorry to hear!!! I"m glad it wasn't worst. I think its commendable that you shared these pictures as this will put that little extra careful reminder in the back of all our heads. I wish you a quick recovery.
     
  9. MIke Magee

    MIke Magee Active Member

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    A local colleague had almost the exact same thing happen, stitches on the hand and all, although it got him on the first hop. His post analysis suggested that there was nothing hardware related and that the lanyard had tangled up on the TX as he approached and started it all going. (not calling the lanyard hardware) He said it all happened very fast but after some thought he could explain it. We hope you recover quickly and get back in the air. Safety first. As Andy stated, you have my attention with this.
    Best ! -m
     
  10. Sebastian Meredith

    Sebastian Meredith Active Member

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    Hi all...
    Thanks for all the positive responses and support.
    I've pulled the SDcard out the CS and the TX and had a quick look. All the data is there. I'll go through it this evening and decipher. I'll also upload the clip that the GoPro captured.
    I have my suspicion as per Mikes comment above about a dragging lanyard ...
    Anyone know the best place to source spares for the Graupner TX? I need to replace the antenna and one of the large switches that were chopped off in the incident.
    The hand is feeling great. Feels like its on the mend.
    Thanks again for all the concern.
     
  11. Gary Haynes

    Gary Haynes Administrator
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    Sebastian

    I would suggest www.Altigator.com. They always seem to have parts in stock and it's where I got my antenna when I busted mine. Quick delivery.
     
  12. Sebastian Meredith

    Sebastian Meredith Active Member

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    Awesome. Thanks Gary. Had a look and they have exactly what I need!
     
  13. Brad Meier

    Brad Meier Active Member
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    First, glad to hear you are doing ok and hope for a quick recovery. In your comments "shut the motor off with the assigned switch" makes me think you were using a motor safety switch as your primary means of startup/shutdown. Is this correct?
     
  14. Marty Ferris

    Marty Ferris New Member

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    Hope you make a speedy recovery Sebastian. That looks very nasty.
     
  15. Sebastian Meredith

    Sebastian Meredith Active Member

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    This clip is from landing to disaster ... apologies for the language at 0:28
    Damage at the moment seems to be limited to the rear landing gear only. Busy dismantling at the moment.

    When referring to the "switch" I used to shut the motors off I was referencing the SW8 Switch on the rear left of the Graupner MX-20 which has been assigned as the motor safety switch for startup and shut down of the motors when the Gas is at Zero. See pic below.

    mx-20.jpg

    The log files on the CS & TX revealed what was running through my head last night instead of sleeping ... I suspect that I became a victim of the greatest NO NO - "to never switch off the TX before disconnecting the CS battery" - the log reveals a "loss of signal" then it kicked into "Altitude Hold" " Fail Safe" and then "Coming Home" ... which would explain the sudden climb to 25m and then the sudden drop to ground zero due to Low Battery (which is why I had landed initially) ... does this sound like a logical order of events should the TX have been switched off?

    I must have hit the "Motor Safety Switch" and without thinking powered off the TX ... which I have never done even when the CS has been on the work bench without props during buildup and testing etc. Never .. not even with our tiny quadro. Baffles me as to why I done it this time!?! Perhaps the lack of coffee through the morning - which is something I live off!


    kill-for-coffee.JPG
     
  16. Ben Hall

    Ben Hall New Member

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    does your motor switch only start motors at low throttle ? could it be the switch is set in the motor on position at rx signal loss. ( sorry dont know to much about Graupner MX-20 but was thinking if its like spektrum the position of switch at bind is where it will fail safe to at rx signal loss ) just watched the video looks like to motors never did shut off fully . can still hear them running at idle
     
  17. Gary Haynes

    Gary Haynes Administrator
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    Sebastian some thoughts, and I point out that I don't use the motor safety switch. Do you use the centering spring on the throttle? Just thinking if you use centering the motors shouldn't have started since the throttle wasn't at zero, unless of course you were still holding it.

    Post the log when you get a chance. Add .txt to the end so that it can be uploaded. It would look something like this GPS00001.gpx.txt

    And in the video the MK beep tones are the pattern for loss of signal towards the end.

    Note in the video after landing that the motors never shut off. They appear to go to idle but not stop. At about the 10 second point you start walking towards the copter but the props do not change speed. Not sure when or if you turned off the transmitter. Your logs indicate what we would expect to happen with a loss of signal from the AH,PH,CH all coming on. Were you flying with AH/PH on and do you keep those on during landing?

    Other note, as it took off there is no sound from the beeper indicating loss of signal. Actually don't hear it until it hits the ground. That could be that the motor sounds drown it out.

    I did a bench test and tried to simulate your conditions. Powered up the copter (no blades), added a bit of throttle, turned on AH and PH, throttle to idle and then turned off the transmitter. Ship sat with the motors running and after about 5 seconds started to speed up rather quickly.

    Last thought/question. The motors do stop after hitting the ground off screen. Did someone pull the battery cable to shut it down at that point?
     
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  18. Sebastian Meredith

    Sebastian Meredith Active Member

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    Gary ... the Centering spring has been removed for the throttle .. so 0 gas is at the bottom. I'll upload the log in a moment.
     
  19. Sebastian Meredith

    Sebastian Meredith Active Member

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    Gary ...

    The props were probably drowning out the sound as there should have been the low battery tone during the landing.
    With reference to flying with PH and AH I was landing totally on manual. I never land using either settings.
    After the crash the first thing I did was pull the plug on the battery to cut all power.

    In your bench test the results sound similar to those in my scenario ... A few moments of idle and then great acceleration.

    Perhaps in my moment relapse of reason I in fact turned off.the RX instead of flicking the motor safety switch. Which does make me feel like a complete idiot!!!!
     
  20. Tabb Firchau

    Tabb Firchau Administrator
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    Wow! Horrible accident and I wish you a speedy recovery. Thanks for being brave enough to share on the forum, I am sure doing so will prevent someone else from having a similar incident.

    Best,

    Tabb
     

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