Wookong X8 Near Crash - Footage

Discussion in 'Cinestar 8' started by Alex Fuller, Oct 11, 2015.

  1. Alex Fuller

    Alex Fuller Member

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    Had quite the glute workout today. Went for a test flight of my Cinestar X8/Wookong flying a Ronin-M, A7s with Tokina 11-16, and Connex Amimon. I have put about 60 minutes of actual flight time with this copter switching off between 5lb weights and the Ronin M, but today was the first day with the Sony and Connex. Never have I had any crazy behavior like this before, she has been rock solid. Note: I have V1 IMU, which may be part of the issue.

    Before the flight I calibrated the compass with payload powered up and had success. Flying in Atti, she took off just fine, hit the retracts and moved forward over a practice target, thats then things got weird. I started to pull the bird back in the same direction after passing over the target, and noticed it was going a lot faster than my stick input. From what I recalled (it happened very quickly), I saw the Yellow/Green LED of Bad Compass Health and the 3 White flashes of Bad Atti Status all back to back on the indicator. It then climbed and took off forward of home position, which is when I lowered retracts and switched to Manual Mode. I was able to bring it back safely, albeit a rough landing. Extremely lucky nothing was damaged and I think I owe the safe recovery to flying FPV quads in Acro mode. Great training, I highly advise practicing with them. Ronin got bounced around from the abrupt movements as seen in the video showing it was not a pleasant flight.

    Upon inspection of the craft, my buddy noticed the power lead from the battery was touching the GPS mast/cable, and I think that's the main cause of the erratic behavior. The 3 white flashes for Bad Atti status have occurred before but never caused any changes in flight characteristics. I plan to move the GPS further away from batteries since its way to close. Although I am almost certain it was the power lead/old IMU, I am very nervous to fly it again and would love some input on other Wookong users.

    My questions:
    Is there a way to read data logs of the FC?
    Should I ditch Wookong all together or try IMU V2?
    Should I switch to A2 or another FC?
    Could the Connex/Sony be putting off an unwanted signal?
    Does anyone have a fresh pair of underwear?

    Attached a photo of copter to see GPS placement, and Video Link here, password: yikes



    Side note: Anyone have suggestions for smoothing out the "bounce" in the footage? I have the blue dampeners and a Cinemilled adapter plate hard mounted using the 4 point Cinestar ninja star. Switch to the 8 point ninja star perhaps?
     

    Attached Files:

  2. Steve Maller

    Steve Maller UAV Grief Counselor

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    Good job getting her down in one piece. Quite a few folks like Dave King fly the WKM, so maybe they can help you out. Meanwhile, it goes without saying that you should ground the bird until you've got a positive ID on your gremlin(s).
     
  3. Dave King

    Dave King Well-Known Member

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    Wookong is extremely reliable, probably more reliable than anything out there (alta still doesn't have enough field time for that to be determined IMO). For Wookong the firmware is the critical factor. The safe versions are 5.16 and 5.20, anything else is not reliable. My main rig is flat 8 Wookong with the upgraded IMU V2 and I fly a Movi and 5D and MOVI Sony A7s. Its my work horse that I use all jobs for. I literally have 600 flights on it this year, not one issue or hi-cup other than a couple bad KDE motors. It is 5000% better than my previous MK rigs as far as performance and reliability. I only use MK rigs now for waypoint flying. I always make my lipo wires as short as possible and I have them taped together. Can you tell me what firmware you are using and share any pictures? Did you make sure your measurements between the CG and IMU/GPS are close? Do you set your copter CG with the landing gear in the up position? I take a lot of time to balance my copters and gimbals to make sure the CG is perfect. I set them up on test gigs in my basement and suspend them from the ceiling.

    Please beware of using the A2, I have heard nothing but bad things about the A2 even with the newest software thats supposed to have the bugs worked out.
     
  4. Steve Abrams

    Steve Abrams New Member

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    I can't comment on your Cinestar issues, but I agree whole-heartedly with your experience flying FPV250 racing machines. I have been piloting RC heli's, planes, and now multi-rotors for about 35 years - and my flying skill has improved at least 100% over the past few months after building four FPV racers. Flying these little rockets in acro mode, is like the difference between driving a Bugatti Veyron and a 1956 Chevy Station Wagon. You'll be able to fly your big aerial video multi's in your sleep - not to mention having complete command and control during emergencies. An FPV250 only costs a few hundred dollars and, when you crash, it's usually only about $5.00 worth of props that have to be replaced. You'll be amazed at how tiny, cheap, and advanced Flight Controllers and Power Distribution Boards have become. I highly recommend it.
     
  5. Alex Fuller

    Alex Fuller Member

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    Alrighty, I think I figured out what happened. Thankfully I took a photo before flight (attached), and I have determined the power lead from battery was pushed down and against the GPS mast probably after the first pass. That explains the smooth flight up until the error. Still going to do some more testing before she's working again, but I'm pretty sure that was the issue. Dave: running 5.2 on the FC and CG is good, haven't tried with retracts up but I'll give it a go.
     

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  6. Dave King

    Dave King Well-Known Member

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    It looks like your radio receiver is right on top of your GPS puck? If that's the case that could cause an issue. I have mine right on the hub and have never had a problem with it (specktrum receiver and radio).
     
  7. Steve Maller

    Steve Maller UAV Grief Counselor

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    I'd rotate your battery 180° and get those leads away from your GPS antenna. It's also a good idea to twist the LiPo wires a bit to reduce the interference that these wires can cause.
     
  8. Steve Maller

    Steve Maller UAV Grief Counselor

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    I think his radio RX is on top of a different mast than the GPS receiver.
     
  9. Alex Fuller

    Alex Fuller Member

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    Steve is correct, there is a second mast for the radio RX.

    Going to change battery and GPS placement now, hope this scenario doesnt happen again!
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    By either twisting or cable-tie-ing the Lipo cables together, the magnetic fields that they create at high current will be cancelled out. This will certainly affect the compass, and, to the degree that there is electrical noise on the LiPo wires, may also affect the GPS radio frequency reception. (Note to self: I wonder how much electrical noise there is on the Lipo wires -- hunch is that it will be sizzling with all kinds of noise.)

    Andy.
     
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  11. Jose Luis Ocejo

    Jose Luis Ocejo Active Member

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    Dave I have been flying custom CS X8 with a A2 many many different flights over a year never ever had an issue with the A2 for me solid..... Unknown.jpeg
    I regularly check and calibrate the IMU, it sits on top in the middle of the frame it has its own dampers I also extended the GPS puck so it sits higher than everything the 2 lipos sit on the booms i calculated the IMU CG pretty carefully considering the the M5 I probably could find some improvement in shortening the cables.

    IMG_4508.jpg
     
  12. Dave King

    Dave King Well-Known Member

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    Hello Jose what do you mean you calibrate the IMU regularly? How many flight hours do you have on the A2?
     
  13. Jason Herring

    Jason Herring Member

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    Very nice rig, the arms look so nice and compact, how many inches long are they? Are those u7 with 18inc props?
     
  14. Jose Luis Ocejo

    Jose Luis Ocejo Active Member

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    Hi Dave I probably have about 100 flights more or less 8 minutes each in different conditions hot Miami, damp Cost Rica and some altitud Mexico no issues with the A2 before a new location I go trough the settings and do a IMU test it usually say that I don't need to calibrate it but I do it the advance calibration anyway with the copter level with out any disturbance like I said my IMU sits on top right in the middle of the frame and it sits on its own vibration dampers

    Jason the arms are 500mm the motors are Tiger U5, the PDB is a Power hungry, props are 16 inch, I get about 8 minutes with 38% left I guess I could do 10 minutes but I don't want to push the Lipos on 2 10k 6S, AUW 24LBS
     
  15. Jason Herring

    Jason Herring Member

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    Thanks so much Jose, did you see dji has a new small battery for the Dji ronin m, should be great
     
  16. Shaun Stanton

    Shaun Stanton Active Member

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    About two weeks ago we were having some serious CME events causing kp indexes up to 8. These are solar events well above the levels for reliable GPS. The cause of the Atti issues could be due to vibrations. Certain vibrations on 5.26 causes issues where the gyro gets jarred a little and can cause some errors I. Atti.

    I have been flying x8 for a whole with WKM it has been fairly reliable. The only time I had a gps go offline was during a nominal CME with a kp of 6. I have not had any issues since.
     
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