Cinestar X8 Build - Needing some help

Discussion in 'Cinestar 8' started by georgemcnabb, Dec 1, 2014.

  1. georgemcnabb

    georgemcnabb Member

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    Hi all,

    You may have seen me on these forums trying to sell this rig, however if I am going to take a loss on this gear that I am looking at I may as well just build it out and enjoy it! Now that I have some free time over the holiday season I can spend some time completing the project.

    The first wall I have come up against is mounting the DJI A2, there isnt really much room, and if I mount over the battery plate in the centre there wont be much contact with the frame and IMU. Any suggestions on this?

    The next is connecting the motors to the FF power distribution board. My other rig from quardrocopter came with color coded wires. From the motors all 3 are black, how do I know which way they go around, this also controls which way the motors spin as I understand so is an important thing to get right.

    Lastly, building X8 config, with the A2 electronics mounted in the center leaves no room for batteries, how have you mounted your batteries on setups like this?

    Thanks for your help, I know these questions are quite basic but I am a bit of a perfectionist and like to do everything right the first time.

    George
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Sorry, George -- I'm not running the DJI A2, so I'll let someone else answer that.

    Just connect the wires up to each motor any which way, and then (without the props on), spin up the motor and notice which way it is spinning. If it's the wrong way, then swap over any two of the three wires. If it's the right way, no further action required.

    Obviously, for the long term you might want to some color coding heatshrink so you know which way round is the correct way. I'll also use a Sharpie pen to identify the motor number for each group of three wires.

    Can't help you on that one either. Sorry.
    Andy
     
  3. Steve Maller

    Steve Maller UAV Grief Counselor

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  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Please note Steve's ghetto copter stand in the background against the car.
    Also the wooden fencing which is designed to prevent the invasion of California by Oregonians.....or, given climate change, the other way around. :rolleyes:

    Andy.
     
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  5. georgemcnabb

    georgemcnabb Member

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    Thanks guys! Appreciate the help.

    Andy, will do that and get that all sorted!

    And Steve, nice solution! I will organise the same for my battery trays. May have to get someone to make me some carbon plates.

    The build is progressing nicely, a few hurdles with the A2 - In terms of powering the FC through the FF motor control set to still give me accurate readings on my IOSD. Am thinking will have to run a wire off the FF motor controller from where the 6S lipo connects.

    The next hurdle is mounting the Movi M5. As you can see I have my copter set up in the tricycle type config, I have the toad in the hold and am wanting to be able to just put the movi on and off easily, I will be flying this single operator also hence why I have not bought the MR kit. The drawback is, now I must somehow extend the legs, and this is going to make for awkwardly long landing gear...

    SIGH...
     

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  6. Steve Maller

    Steve Maller UAV Grief Counselor

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    You'll want the MR kit even for single operator. It makes no sense to not use it, and it solves the landing gear problem with its extensions. I use mine solo all the time. It's a little tricky to learn how to get it in the air (it'll spin when on the ground if you power it on too soon), but once in the air, it works perfectly for me.

    Oh, and I used ordinary Freefly CS8 battery trays. Just had to drill holes to mate up with the boom clamps. I used the old plastic clamps so that they'll actually give a little if they have to. And sometimes they have to. :eek:
     
  7. georgemcnabb

    georgemcnabb Member

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    Hmm, may have to get the MR then. I just primarily use my M5 handheld so wanted to keep it setup in that configuration!
     
  8. Steve Maller

    Steve Maller UAV Grief Counselor

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    Get a Toad in the Hole while you're at it. You're welcome. :D
     
  9. Nick Adams

    Nick Adams Member

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    Steve; Do you know if you can you build an X8 config with 4s? it seems that everyone seems to be going to 6s. (Is it more power / less heat?) I am thinking about converting mine. Its a Cinestar 8 and it will be flying the M5 with a GH4 or 5D's
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Nick: it's all about providing power -- which can be expressed in Watts. For electrical units power in Watts is = volts x amps. So if you increase the voltage (by going from 16 v to 22 v say), then you reduce the amount of current needed to provide the same number of watts.

    The heat produced is proportional to the square of current. Voltage has nothing to do with it (other than it alters the amount of current). Thus if you use a higher voltage, the motors require lower current for the same power, and thus produce less heat.

    Hope that helps.
    Andy.
     
  11. Nick Adams

    Nick Adams Member

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    OK thanks Andy, makes sense.

    So 4s would not provide enough power for an X8? I understand they are a little less efficient than the flat 8

    Nick
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Nick:
    Sure 4S will provide "enough" -- at least to get it off the ground with some payload, but, as you point out, you loose power from having the coaxial configuration and the fact that the lower prop is ingesting the turbulent, fast moving, air from the upper prop.

    So 6S is the better way to go. If some is good, more is better. :)

    Andy
     
  13. Nick Adams

    Nick Adams Member

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    Got it Thanks!

    Nick
     
  14. Steve Maller

    Steve Maller UAV Grief Counselor

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    I'll echo what Andy said, and add a little of my own experience.
    A year or so ago I decided to convert my Cinestar 8 with MK electronics (standard Quadrocopter setup) to an X8 for a variety of reasons. But what I found immediately was that the 4S setup did not provide enough power for my payload. The efficiency loss was noticeable. I tried to install larger props, but that made it worse (the QC motors really can't spin bigger props).
    So I went down the 6S route, and was one of the first adopters of the Mikrokopter BL3.0-based system. I began with Avroto 3515 motors, but was a little disappointed with their performance. So I ended up with the KDE 4012-400 motors. I experimented with different prop sizes, and ended up using the T-motor 16" CF props.
     
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