Cinestar X8 Coax Updated

Discussion in 'Cinestar 8' started by Steve Maller, Dec 23, 2013.

  1. Steve Maller

    Steve Maller UAV Grief Counselor

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    First thing I tried today was to adjust the motor mixer from 64 up and 71 down to 64 up and 67 down. The current draws and BL temps are now more consistent, although my overall current draw is higher than I’d like. Time for bigger motors. :D

    Here’s the average current and temperatures for all 8 motors. 1-4 are the upper motors, and 5-8 are the lowers.
    Amps °C
    Motor 1 10.2 56
    Motor 2 9.5 56
    Motor 3 11.4 59
    Motor 4 11.7 66
    Motor 5 11.9 67
    Motor 6 11.3 66
    Motor 7 9.3 59
    Motor 8 10.4 62

    MK Version: FC HW:2.2 SW:2.02a + NC HW:2.0 SW:2.02a

    Flight date: 12/30/2013 12:50:24 PM
    Flight time: 12:50:24 PM - 12:56:30 PM (366 secs, 00:06:06)
    Batt. time : 363 secs, 00:06:03

    Elevation(GPS) : 0 14.31 62.487 m (min/avg/max)
    Altitude(Barom.): -0.05 15.38 61.3 m
    Vertical speed : -3.42 -0.04 5.31 m/s
    Max speed : 39.8 km/h
    Max target dist.: 8.5 m

    Sats : 11 12 13

    Voltage : min. 13.4, max. 15.7 V
    Current : 0.5 85 157.8 A
    Wattage : 8 1262 2130.3 W
    Capacity: 8644 mAh

    Motor1: 0.0 10.0 16.2 A Temp: 23 55 72 °C
    Motor2: 0.0 9.2 20.6 A Temp: 22 55 71 °C
    Motor3: 0.0 11.2 19.4 A Temp: 24 58 76 °C
    Motor4: 0.0 11.4 23.7 A Temp: 38 65 81 °C
    Motor5: 0.0 11.6 19.5 A Temp: 33 66 81 °C
    Motor6: 0.0 11.1 22.9 A Temp: 32 65 82 °C
    Motor7: 0.0 9.1 19.7 A Temp: 22 58 71 °C
    Motor8: 0.1 10.1 21.7 A Temp: 25 60 72 °C

    Magnet Field: 84 97 105 % (ok)
    Magnet Inclination: 49 54 62 deg

    No errors found ;)

    Parallels Desktop-snap001.jpg
     
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  2. Steve Maller

    Steve Maller UAV Grief Counselor

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    Jim from MontoRC wrote to answer a question I asked him (comparing the merits of the Avroto 3515 and 3520 for a 18-20 pound AUW copter). He said "3515 octo is perfect for 18-20lb all up weight. It will be more efficient at this weight than 3520 octo."

    So, how does your data line up for the 3515 vs U5?
     
  3. Sebastian Meredith

    Sebastian Meredith Active Member

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    Have been scratching my head on this with my camera guy.

    I was toying with the idea of dropping the lipos to below the hub by using two star plates, separated with +- 60mm ali stand-offs. This would lift the lower props by 60mm giving more clearance for the 360 gimbal and reducing the chance of getting them in a shot and I would imagine that having the lipos below might add to the stability?!? The current battery tray can serve as a dedicated cooling fan holder.

    Any thoughts on this configuration?

    lipo-placement.png
     
  4. Dave King

    Dave King Well-Known Member

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    Steve they look extremely close in data. If double checked it again in Ecalc thinking I might have plugged in the wrong data for one of them and they are coming out almost the same.
     
  5. Dave King

    Dave King Well-Known Member

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    Sebastian

    I could be wrong but I believe the gimbal needs to be bolted directly to the hub so that it can be bolted to the isolators on the hub?
     
  6. Sebastian Meredith

    Sebastian Meredith Active Member

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    Dave,
    I would leave the existing star plate connected to the isolators as is, then add the stand-offs and add the second starplate to the bottom of those which would attach to the gimbal as it does now. I would presume that the top star plate would have to be the full version with 8 points and have all 8 isolators on to accommodate the extra weight of the lipos?
     
  7. Ryan McCrae

    Ryan McCrae Member

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    On my skyjib i had it set up with the battery mounts that are level with the frame, so the battery sit just above the booms. with 2x8000 zippys and a total weight of 8.5kg it always felts horrible to fly, because it was so bottom heavy, it pendulum a bit and just didn't feel nice. Ive now mounted them about 3 inches higher lifting the cg, it flys a lot nicer now. From my experience so far i would say bottom mounting the batteries is not the way to go.
     
  8. Sebastian Meredith

    Sebastian Meredith Active Member

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    Thanks for the input Ryan!
     
  9. Shaun Stanton

    Shaun Stanton Active Member

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    Looks good Steve
     
  10. Dave King

    Dave King Well-Known Member

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    Steve

    I just realized that you put the GPS on top of the batteries. I can't believe nobody else noticed it. Looks good. Do you have any impressions of it making any difference?
     
  11. Steve Maller

    Steve Maller UAV Grief Counselor

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    Yup...did it a couple weeks ago. Position hold is very, very stable now (latest 2.02 firmware). However, there is definitely yaw drift, and I’m not sure why. I need to look into that. I have Compass Effect at its default setting of 64. I’ll try backing that off to 0 and see if that changes it. But I feel like the new location of the Navi board has improved position hold dramatically. It’s a little awkward to get the LiPos in underneath. I have to re-route the ribbon cables from the Navi board, but I just have to be delicate. I don’t have a good source for ribbon cable and connectors where I am right now.
     
  12. Dave King

    Dave King Well-Known Member

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    Very interesting. I wonder if the GPS external sensor and arm would improve it in the stock CS8 location. Do you have any pictures of your new GPS mount and setup?
     
  13. Steve Maller

    Steve Maller UAV Grief Counselor

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    Here you go. Kinda hacked up for now, but definitely seems to have improved things. I am going to get the external compass, too.
    The GR-24 is facing toward the front. The little boom on top makes a nice carrying handle, too! :D
    IMG_8849.jpg
     
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  14. Steve Maller

    Steve Maller UAV Grief Counselor

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    The boom clamps are from BrushlessGimbals.com. I like the new quick release levers!
     
  15. Steve Maller

    Steve Maller UAV Grief Counselor

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  16. Sebastian Meredith

    Sebastian Meredith Active Member

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    Steve, are you running the apc mr props? What size and config did you settle on?
     
  17. Steve Maller

    Steve Maller UAV Grief Counselor

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    Yes, been running the 14” MR props for several months. They’re great. However, my bird’s efficiency dropped dramatically (50% higher battery draw) in the coax config, and I’m wondering whether I need to go with wood or CF props for higher rigidity. I tried 4 16” props in the X8, but the 4S system just doesn’t have enough oomph to swing those big boys.
     
  18. kjetil tønnesen

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    hello
    i am now building a x8 with u7 motor and dji A2 fc ,i wounder if anyone have done that and have a pictures off the center plate how it is mounted?
     
  19. Steve Maller

    Steve Maller UAV Grief Counselor

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    Shaun Stanton may be doing that. Check with him.
     
  20. kjetil tønnesen

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