After battery change bird won't take off properly

Discussion in 'Cinestar 8' started by Mark Melville, Dec 27, 2013.

  1. Mark Melville

    Mark Melville Member

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    Cinestar 8 with MK electronics and 3 axis gimbal.

    Today we were doing some tests flights with no problems. We landed switched batteries and tried to take off. The bird would not take off evenly it wanted to tip over upon take off. It's as if there's more lift on one side that was forcing it to tip over much like what happens if you invert one of the props by accident.

    We initialized ACC and Gyros and reset the compass but it kept doing it. I even checked the props to make sure they were tight. All the motors seem to be running properly and the electronics are running cool. No problem there and I am at a loss as to why it flies great then suddenly I have issues.

    I really hate MK and wish I had gone with DJI. I have had nothing but reliability issues with their electronics and absolutely no faith in their system.
     
  2. Gary McCready

    Gary McCready Active Member

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    Sorry you had troubles. DJI is not any better, from what I've read. I had a bird totally ignore minor input and CF last week. Might have been a gust of wind from the side of the building but still hit a branch and had a minor crash. Minor, as in flew fine after I scraped the dirt off the cracked landing gear (just one side).
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Mark:

    Do you happen to have a Navi Control board installed that would have recorded a GPX file? (The recording usually starts when the throttle value exceeds 40 -- that is, when you start to throttle up).

    If you do have such a GPX file it will perhaps provide some insights as to what the problem is.

    Another strategy to try, but you have to be very careful, is to get a colleague to hold the Cinestar above their head, fire up the motors and see if they can sense (or you can see) motion that indicates this rolling will continue were the copter to get airborne.

    Obviously, all the safety precautions apply (like coordinating with the colleague to hold on tight, but allow roll and yaw to manifest, and to wait until *you* tell them that the prop blades have come to a stop).

    Andy.
     
  4. Howard Dapp

    Howard Dapp Active Member

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    Sounds like he might have mistakenly performed a gyro calb and the rig was not on level ground.
     
  5. Gary McCready

    Gary McCready Active Member

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    Howard: Yea I think I initiated the ACC calib accidentally once (or twice). If my rig is being weird I just redo the calibration!
    I now carry a small bubble level in my tool box, and have a small piece of custom cut plastic to put on the FC screw tops. It is square with a little tab sticking out at each corner, which fit in between the battery holder posts (CS6).
    I have this video imprinted in my brain permanently I've watched it so many times. Compliments of Ziggy:
     
  6. Mark Melville

    Mark Melville Member

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    Both ACC and GYRO calib were done on level ground. I unplugged the battery at least 5 times and redid the calib but to no avail. Maybe the ACC went out of wack but I find it odd considering it flew well, landed, changed batteries and the tried to take off when it started acting wierd all within a few minute time span.
     
  7. Mark Melville

    Mark Melville Member

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    Andy I'll upload the file from card in the next day or so. The rig is in Florence and I'm in Rome. How's that crappy Portland winter weather or are you making due with some bangers and mash and a pint of London Pride?
     
  8. Steve Maller

    Steve Maller UAV Grief Counselor

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    Can you upload the GPX file from the previous (healthy) flight? I strongly suspect something went wrong and went unnoticed. Or, the battery swap caused an electrical malfunction that took out part of the FC or other critical system. Can you hook the copter up to MK Tool or look at the info screen on the Graupner TX and see if there’s an error there?

    To be fair, these birds are all super sensitive to all kinds of things, and just looking at them the wrong way can cause lots of headaches. And we often end up in that old “devil you know vs. devil you don’t” situation. Sorry for the hassles.
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Ciao Mark: Tutto sta andando bene.

    Sounds good re: the GPX file. The crappy Portland winter weather is, errr...crappy. Well -- it's alternating between monochromatic grey (with varying degrees of cold and damp crap) and bright blue sunny and *really* cold. None of which are particularly tempting me to go out and fly.

    We're suffering through with turkey with 2006 Jack Larkin cabernet. It's a hard life.... ;)

    My good friend Steve "Yes, I have a copter on my head" Maller :) is quite right. It sounds like something may have failed. Did you happen to notice when the motors do their chirpy thingy (technical term) whether any of them sounded different. My first inclination, after checking that none of the props had worked loose, would be to start checking the electromechanical stuff -- motor connectors, etc. I realize that whatever happened appears to be coincidental with a battery change, but I've mislead myself several times by interpreting something coincidental as being something causal. Changing the battery might have nothing to do with it. Or it might have everything to do with it.

    If you feel so inclined, shoot a video of the motors starting up and idling such that we can see and hear it....I also have found that there can be useful information communicated by the audio from the copter -- to the point that I tell my camera operator, "Starting motors......everything looks good....everything sounds good...." before I take off -- more as a reminder to me to do a visual and acoustical check.

    Oh..and today it's, wait for it, Turkey Curry with a bottle or two of Fuller's Vintage Ale. Oh, the suffering....

    Andy.
     
  10. Shaun Stanton

    Shaun Stanton Active Member

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    I woulod check if you changed one of the flight profile modes and accidentally put it into Acro or something

    [​IMG]

    • To select the settings with the transmitter the proceed as follows:
      • Setting 1 => Roll left + Nick middle plus Gas up + Gier left
      • Setting 2 => Roll left + Nick up plus Gas up + Gier left
      • Setting 3 => Roll middle + Nick up plus Gas up + Gier left
      • Setting 4 => Roll right + Nick up plus Gas up + Gier left
      • Setting 5 => Roll right + Nick middle plus Gas up + Gier left
    Or Steve is right abd your Accel was re calibrated. Either way plug into Koptertools and see if the accelerometer is significantly off.
     
  11. Ozkan Erden

    Ozkan Erden Distributor

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    +1 to Shaun.

    If you accidentaly change the flight profile, it might have activated some functions which will prevent to bird to take off.

    At he misc tab (http://www.mikrokopter.de/ucwiki/en/MK-Parameter/Misc) :

    * Ignore magnet error on start up (Should be selected)
    * Not start without SD card (should be deselected)
    * Not start without GPS fix (I mostly deselect this)

    In addition to this, you might need to do compass calibration again which is described here:

     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Mark: Kudos to Shaun from me too. There is a chance that, unrelated to the battery change, you may have inadvertently operating the transmitter sticks to select a different Parameter Set that, in turn, changed the motor startup criteria.

    The description is here: http://www.mkmanual.com/mikrokopter-tool/mk-tools-tabs/configuration
    The relevant text is below. Unless you've made custom changes, you want Setting 3 (the so-called "Easy" setting, and usually the default setting). It's certainly worth making sure you *have* setting 3 before you go much further. You can also change the Parameter Set using MK Tool. The number is shown just by the red triangle/exclamation mark at the lower part of any MK Tool window.

    Select the single Settings with the transmitter

    • Setting 1 = Throttle up / Yaw left + Roll left
    • Setting 2 = Throttle up / Yaw left + Nick up / Roll left
    • Setting 3 = Throttle up / Yaw left + Nick up
    • Setting 4 = Throttle up / Yaw left + Nick up / Roll right
    • Setting 5 = Throttle up / Yaw left + Roll right

    If it's not this, the more I think about it, it's likely to be the ACC calibration that's the issue, or a failed ACC (which is probably the least likely of the two -- but still a possibility).

    Andy.
     
  13. Gary Haynes

    Gary Haynes Administrator
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    Also during the power up cycle the controller will beep the same number of times as the setting.
     
  14. Michael McVay

    Michael McVay Active Member

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    Another really simple answer could be that you bumped your AH or PH switch into the ON position after landing - or landed with them on. I did this once - do not recall which one it was - but when I went to take off again I had the same behavior you described. The Cinestar wanted to tip one direction on take off (presumably to get back to where it thought it was supposed to be). After a puzzled couple of moments I turned all my switches off like they were supposed be and took off normally.
     

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