Crash video: X8 with KDE 4014 into the water!

Discussion in 'Cinestar 8' started by Bryan Harvey, Jun 21, 2014.

  1. Steve Maller

    Steve Maller UAV Grief Counselor

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    (moved my response here, too)

    Having experienced the loss of a BL on my flat 8 cinestar, I will assert that the flight control should do the hard work. Mine did. I could not tell that a motor had stopped. But there are many different scenarios to consider:
    1. Loss or impairment of a ESC
    2. Loss or damage to a prop
    3. Wiring or communication error
    4. Loss or impairment to a motor

    It's hard to simulate most of these because of the complex physics and the many variables. IMHO, somebody's going to have to step up and volunteer to do some real world testing and certification that this stuff works (or doesn't).
     
  2. Steve Maller

    Steve Maller UAV Grief Counselor

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    Apropos my comments, this guy seems to have weathered a motor failure in his NAZA-powered hex. One of his motors seems as though it went bad in the air, but his hex stayed up and he was able to land it.

     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I've emailed the author of AeroSimRC to ask whether there is a way to simulate a motor failure at a random point in time on the Cinestar 8 model.

    Andy.
     
  4. Steve Maller

    Steve Maller UAV Grief Counselor

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    I believe the standard mixer for the flat 8 Cinestar has 4 motors that do not contribute to some of the maneuvering, right? Do you think that losing one of those (or one of the other 4) would impact how well the FC could recover? I would think it would. But this is the MK mixer, and Bryan was using a coax with the A2 FC.
     
  5. Tristan Twisselman

    Tristan Twisselman Active Member

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    I lost a motor on my flat octo. I don't remember if it was setup i or x but it was in forward flight about 25mph, it dipped for a second and recovered quickly. It wasn't as controllable or as stable as it is with all 8 but it recovered and i was able to land it.
     
  6. Howard Dapp

    Howard Dapp Active Member

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    It really doesn't matter which mixer you use, they all will recover if one motor/prop fails. If your setup is near its thrust limit you will likely NOT recover. If you're flying an Epic or bigger you should be flying the most powerful system available, even then I don't know of any motor/prop combo that will still safely fly if one fails with a fully rigged out Epic strapped underneath.
     
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  7. Lanakila Young

    Lanakila Young New Member

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    oh man...bummed for you. i lost one of my cinestar8's in waimea bay due to a motor failure also.
     
  8. Gary Haynes

    Gary Haynes Administrator
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  9. Gary McCready

    Gary McCready Active Member

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    According to my son, Masters in Electrical engineering, all the motors contribute to the stability of the craft, all the time, in one way or another. Being a dentist I've "lost" some of my math skills, and this is beyond me, but I thought some of you might enjoy this mathematical explanation of a Quad's control characteristics. My son's specialty is robotics control theory, and he is currently working with a military contractor. This was his undergrad "Senior" paper.
    https://docs.google.com/file/d/0B4lHayyf4zkeLU1GVThzT1g0Tms/edit?pli=1

    He didn't even use pictures of MY Quad's in the paper....lol I've crashed my 3 year old FPV Quad (cheap Chinese parts) so many times, I've realize if I hit nearly full throttle and full yaw it will come down without much damage, just landing gear, as it spins into the ground.
     
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  10. Howard Dapp

    Howard Dapp Active Member

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    We're referring to 6 motors or more.
     
  11. Gary McCready

    Gary McCready Active Member

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    It actually applies for all multi-rotors with even number of motors over 4. Section three: Generalization to n-copters
     
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  12. Steve Maller

    Steve Maller UAV Grief Counselor

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    Here's another recent test of a copter with an A2 and one motor out. Josh Lambeth deliberately disconnected one of his motors and was able to fly just fine...

     
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  13. MIke Magee

    MIke Magee Active Member

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    Thanks Steve. JOSH! Thanks for running this test for us. Makes me feel a BIT better knowing that as you said, it won't flop over and fall out of the air. Also knowing that yaw control is severely compromised gives me food for thought for reacting to a similar scenario if I get a motor failure.

    Thanks for doing this.
    -m
     
  14. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Welll.....full rudder to stop it yawing and "wouldn't want to experience that in the air...."
    Not quite sure that's "just fine," but more like, "well, it didn't plummet out of the sky....."

    :)

    Andy.
     
  15. Steve Maller

    Steve Maller UAV Grief Counselor

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    I guess my definition of "fly" is modest. If you've seen me fly, you'd understand. :eek:
     
  16. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Wow you found that quick! I was just about to post that here! HA!

    I should mention that if you are running an x8 setup and your power system is NOT strong enough it will crash. The one motor will have to work twice as hard to keep it in the air if you loose one on the same boom. If you are already at 70% or more throttle in hover with all 8 working and you loose one there will not be enough power to keep it in the air.

    Josh
     
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  17. Dave King

    Dave King Well-Known Member

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    Thanks for the test Josh!
     
  18. Tristan Twisselman

    Tristan Twisselman Active Member

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    Also factor in it dying mid flight is harder for the flight controller to correct for/react and also going to spike your power system when it surges power to the motors having to make up for the one gone bad. I did the same test you did Josh and that is one of my main reasons for overpowering my new HL build, in case of motor failure. Thanks for posting
     
  19. Jose Luis Ocejo

    Jose Luis Ocejo Active Member

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    Question so the first flight charasteristic that gets compromise on a X8 loosing a motor is Yaw corect ?
    if so, assuming that it happens closer to the ground at the end of the flight the time it takes to notice and react are very small specially if the copter starts to Yaw, how fast some of us can orient and maneuver the copter to some kind of safety landing in so little time, I for one would like to have a stronger visual cue to tell orientation faster....... like this
     

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  20. Tristan Twisselman

    Tristan Twisselman Active Member

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    Led are the only orientation I've ever used on multis and occasionally colored tape. Plenty for me and having flown and still flying single rotor 3d definitely helps reaction time or even flying the single rotors on a simulator. Try in attitude first then manual mode to hold the yaw one way and then keep it in one spot and then once your good at that try flying it around while continuous yawing. I have been practicing that a lot after reading this thread
     

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