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WKM Cinestar issues!

Discussion in 'Electronics' started by Tristan Twisselman, Apr 21, 2014.

  1. Tristan Twisselman

    Tristan Twisselman Active Member

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    Having an issue or two with my wkm X8. Cinestar 450mm booms, 6s, 3515-400 motors and 15x6 or 16x8 props. Changing props has no effect. Gain settings don't seem to change my issue either. AUW is around 26 pounds

    1st issue is motor temps and yaw issue.

    My bottom motors are twice the temp as my top motors using the standard dji mix. If i use the MK Mix then only two of my bottom motors, opposite of each other are twice as hot...too hot. I also notice when i yaw to the left after letting go of the stick it isn't a hard stop and it even travels a little past where i tell it to stop slowly. If i pan right and let go it stops instantly as it should.

    2nd issue is the heli is almost like pulsing the motors as if the gain is too high and it makes the heli rapidly bounce or pulse up and down. Not smooth at all. Major issue.

    HELP
     
  2. Daniel Gowland

    Daniel Gowland New Member

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    G'day Tristian, I have the same or very similar set up, so hopefully I may help. My craft has the same blades on top and bottom. APC 14x4.7.
    After double checking CG and that I have it recorded correctly in the GUI.
    If the WK (Wookong) has had many reincarnations with out a reset or reload back to the defaults perameters... Then if so, reload the firm/software.
    When turning the gains, I put them on sliders/pots or the like. I have two at the rear of my JR 11X. I've found roll and pitch to be the first gains to be turning. Then I've paired those two on a slider and put the altitude gain on the second slider, before swapping the altitude gain slider to the Yaw gain.
    Are you getting any flashing lights...?
    Check the blades are all tight and spinning in the same direction on the bottom & the blades all spinning the same direction on top. As well all blades the same way up, top and bottom.
    Is there a iOSD installed and if so how are the motors comparing to each other...
    Regards, Dan...
     
  3. Tristan Twisselman

    Tristan Twisselman Active Member

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    No flashing white lights, all props are spinning correct directions and tight. No iosd but the top motors are all around 100 degrees f and the bottoms are all around 200. I have tried it with my gimbal attached and without. With the gimbal there is an added 13 pounds to the heli and it pulses much faster and gets much hotter. Without the gimbal and flying just the airframe the motors aren't as hot but the bottoms are still twice as hot as the tops and the pulsing is a slower pulse without weight than with but the gains don't really affect it.
     
  4. Ryan McCrae

    Ryan McCrae Member

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    Check your motors are levelled, sounds like one or more motors might not be perfectly level, which causes the motors to fight each other. I used to have a very uneven amp draw and yaw issues, this was the main issue for me.
    Also what is your throttle % during hover?
     
  5. Tristan Twisselman

    Tristan Twisselman Active Member

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    I checked level but Ill check it again. Also, my hover percentage is right at 50%. Im about to switch back to flat octo
     
  6. Daniel Gowland

    Daniel Gowland New Member

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    Have you tried smaller props...?
    Dan...
     
  7. Tristan Twisselman

    Tristan Twisselman Active Member

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    I have tried 14 inch slow fly props even. When taking the gimbal weight off the bottom motors aren't as hot but are still twice as hot as the tops. Also the pulsing is still there but it's in a lower slower type frequency and not as fast as with weight.
     
  8. Michael McVay

    Michael McVay Active Member

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    Is there any chance you put all of the bottom props on upside down? I'm not sure what would make all the bottom motors double the temp of the tops. The props all should face upwards (same orientation as if they were on a flat 8) even if they are on an upside down motor.
     
  9. Tristan Twisselman

    Tristan Twisselman Active Member

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    Good thought but the props are on correct. Motor temp issue was motors not completely level. I thought they where but some where a degree or two off and now all the motors are very close to the same.

    My last issue is this pulsing. I have no idea why it is doing it and I am starting to think it may be the FreeFly ESC's. Whether my wkm gain is 60 on vertical or 175 there isn't much change and it is unflyable the motors pulse so bad. Now I am wondering how low the gains can safely be. I am going to try and lower my pitch and roll gains to 80 instead of 100 and see if that helps.
     
  10. Michael McVay

    Michael McVay Active Member

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    To get the motors perfectly aligned, I got a cross hair self leveling laser. I put it on a tripod and get the height set to put the horizontal line down the center of the booms and the vertical line right down the center of the prop adapter bolts. If you have your 3 axis gimbal attached, you might need to shim the legs a bit to offset the play in the vibration dampeners to get the laser line centered at the far ends of the booms.

    The outcome is very good, and I have actually gone back and done this on both of my flat Cinestars as well. Attached are a couple of photos for you.

    This is the one I purchased:
    http://www.amazon.com/gp/product/B001U89QEC/ref=wms_ohs_product?ie=UTF8&psc=1

    There are certainly many other choices. Self leveling and cross hair are the 2 key features to get.

    photo 1.JPG

    photo 2.JPG
     
    hugo burns likes this.
  11. Michael McVay

    Michael McVay Active Member

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    Another couple questions for you:

    1. What is you AUW?

    2. Which version of the IMU do you have (v1 is the original with plastic case, v2 is metal like the A2 has)?

    The X8 I have is flying DJI WMK (built prior to MK's 6S option) and is flying with the Freefly ESCs.
     
  12. Ozkan Erden

    Ozkan Erden Distributor

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    I'm no DJI expert but lets look at the numbers:

    Your AUW is around 13 kg. In a flat Octo configuration, each motor has to provide around 1.65kg thrust to hover. And if we look at the Mt3515-400 data sheet ( http://www.rctigermotor.com/html/2013/Professional_0912/50.html ), with 16x5.4" props the throttle level will be around %65 to provide this thrust.

    X8 congfiguration has %20-25 efficiency loss compared to flat octo. This means, your throttle level should be close to %80 with 16x5.4 props. This is too much for these motors. Eventually they will get very hot. Even with 16x8 props, they will get hotter.

    (The reason you think the hover throttle is %50, I think DJI FC works with altitude mode so whatever the gas stick will be %50 to hover all the time.)

    You will be more comfortable in terms of efficiency with flat Octo, or you move to more powerful motors (KDEXF4014 with 18" props for instance) to overcome heat problem.
     
  13. Tristan Twisselman

    Tristan Twisselman Active Member

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    AUW with RED is around 23-24 pounds.

    I have the V2 IMU

    Ozkan, In manual mode I am hovering at around 50 percent throttle. When there is no gimbal I hover around 15-20% Throttle in manual mode. Atti and GPS will hover at 50% throttle stick INPUT but that doesn't mean the throttle percentage is 50%. It could be more or less.

    Heat is also no longer a problem. Motors are around 100 Degrees all around now that I made sure they are more level.

    At this point I am wondering what the causes of low gains could be. I have to have all of my gains around 80 for it to not do the pulsing. All gains at 100 causes the pulsing but the problem is, at 80 gains, the heli needs higher gains and better reaction times. I tried remounting my imu as well to see if that helped. SO, does anyone know the possible causes for gains needing to be so low or what I can change or try to change to allow my gains to be higher without the pulsing.
     
  14. Justin John

    Justin John Member

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    Have you made any further progress with finding a solution to this problem?


     
  15. Tristan Twisselman

    Tristan Twisselman Active Member

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    Unfortunately no
     

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