Cinestar 8 Upgrade for Medium Heavy Lift (8-10kg)

Discussion in 'Cinestar 8' started by Steve Maller, Jan 3, 2014.

  1. Steve Maller

    Steve Maller UAV Grief Counselor

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    A couple updates.

    First of all, like Dave King, I found that the Double Quadro XL board won’t work with the existing Cinestar mounting hardware because the board’s too thick. I searched around, and found some metric spacers and screws that should work. I ordered them from Digi-Key. The part numbers are in the order below.

    Secondly, I completed soldering up my built-in parallel splitter for the main LiPo connections. As I mentioned before, I am going to mount the batteries on outriggers, so I need longer leads. I hooked it up to the bench power supply, and I have lights on it. Very exciting! :)
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  2. Dave King

    Dave King Well-Known Member

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    Steve it will be interesting to see if the longer lipo wires give you any headaches. Many people have said to keep them as short as possible. One thing I would definitely do is to heat shrink the positive and negative wires together so that you don't induce magnetic fields. I heat shrink everything together such as motor wires, lipos, and even navigation lights. If you don't want to remove the EC5 connector I would at least electrical tape them together.
     
  3. Steve Maller

    Steve Maller UAV Grief Counselor

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    Yeah, Dave, I am wondering if this is going to introduce a gigantic electromagnet into the copter, which would be a bad thing. I should have twisted the wires. I will go back and do that. Still not 100% certain of the length, so I made them really long. They’re likely to end up a lot shorter.
     
  4. Steve Maller

    Steve Maller UAV Grief Counselor

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    I just got an email from Holger with an answer to the question of what is involved in installing heat sinks onto the new MK power distribution boards.
    ---
    Yes, the heatsink would be inbetwwen the two boards.
    You (or we) would have to desolder the points.
    Regards,
    Holger
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Steve: I think you'll find that as long as the two wires are heatshrinked together, their magnetic fields will cancel out. If you want to twist them, you need to twist them tightly (as in one or two turns per inch) for it to really cancel out the induced field.

    So short and tightly parallel's the word, IMO. I could be wrong, of course, but I'm rarely uncertain. ;)

    Andy.
     
  6. Steve Maller

    Steve Maller UAV Grief Counselor

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    Ok, I just hacked together the two battery outriggers for my coax build. I wonder whether I should turn the batteries 90° so that they are closer to the copter's center of gravity. Any thoughts?
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  7. Chris Fox

    Chris Fox Active Member

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    G'Day Steve,
    I have been thinking along the lines getting the batteries in closer. I have been looking at how Kopterworx place the batteries on there U8 monster copter, and by spinning them 90 they can get four on board, with the weight being relatively closer to the CoG.

    Having the batteries of to the side though does create an asymmetrical weight distribution.

    How much room is left on the centre hub with the MK PDB installed, is there any room left to clamp or attach alternate battery mounts to?

    Cheers
    CHris
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Having the batteries that far out also creates a fairly large moment arm (mass x distance from GoG) so it will make the copter much harder to move in roll (assuming the batteries lie on the roll axis). There's more inertia to overcome at the start of a roll, and more momentum to overcome once they are moving.

    So I would move the batteries closer in, Steve.

    Andy.
     
  9. Steve Maller

    Steve Maller UAV Grief Counselor

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    Thanks, Andy. I have been looking at it and I concur. I actually was toying with the idea of doing 4 smaller batteries in a ring, but 4 batteries in parallel sounds like a Bad Idea WRT balancing cells and other issues.

    I think I’m going to re-do the outriggers to position the batteries 90° to their current position, closer to the hub.
     
  10. Steve Maller

    Steve Maller UAV Grief Counselor

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    Thanks for the feedback, Chris.
    My decision to move the batteries was based on two factors:
    1) The 6S LiPos are so damn heavy that the CoG was going to be riding really high with the battery tray up so far from the center.
    2) The weight also made me worried about having them on the single tray, so I thought splitting the batteries would distribute the load.
    As I wrote in the previous note, I do think I will rotate the trays by 90° to get the batteries closer to the center.
    I also think this will provide additional magnetic isolation with the relocated Navi board (above the FC).
     
  11. Chris Fox

    Chris Fox Active Member

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    G'Day Steve,

    I have been running two FF 6S 9000 batteries on single tray, and they would be of a similar weight, I added self adhesive velcro to all the batteries and to the battery tray, which prevents them from sliding, and a half decent velcro strap will hold them all in place.

    the tray seems to hold up fine, I have not used 4S batteries, so I am not sure how much heavier the 6S is compared to the 4S setup.

    Cheers
    Chris
     
  12. Dave King

    Dave King Well-Known Member

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    Andy I believe you are correct. Its the gap distance between the two wires that matters. If there is a gap between the wires that can create magnetic fields. So if the wires are heat shrunk tightly together its all good. The only problem is that you need to remove the EC5 connector because any size tubing that will fit over the EC5 connector will not shrink down tightly enough in order to prevent any small gaps.
     
  13. Dave King

    Dave King Well-Known Member

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    I think its going to be challenging to CG the copter in that configuration but I can be wrong. Personally if I was trying this I would mount the batteries closer to the hub and have them front to back. I like your idea of using the extra booms but I would try fabbing something up where you use two of the functional booms and the two booms that would in reference to 3 and 9 o clock where you can have the battery plate close to hub and front to back. I'll see if I can draw something up very crudely of course. :D
     
  14. Dave King

    Dave King Well-Known Member

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    Something like this? I think it would be easier to CG the copter and you can have the lipo wires go straight back away from the GPS. I know it might not easy to come up with something you already have but I think one of these options will give you the best CG and best options to adjust the CG as needed. I just think putting them out like you have will require a lot of offset weights to get the CG right. One thing I noticed with these big ass batteries is that the heavier they are the harder it is to counter balance it to get it right.


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  15. Steve Maller

    Steve Maller UAV Grief Counselor

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    Actually, IMHO the big LiPos are going to want to be centered front/back, so offsetting them is going to create difficulty. They weigh about 10x the Navi/GPS.

    Here’s a hacked up drawing of what I have in mind. And remember, I’ve re-done the Navigation and GPS so that they sit directly above the center hub (but 8-10 inches higher. So I think the battery cables will be sufficiently far away (they’re down at the level of the hub) to avoid interference. I guess my only issue with this configuration is that it will require two batteries, unlike the regular config where I could still mount a single battery on the tray. Cinestar-Technical-Drawing.jpg
     
  16. Dave King

    Dave King Well-Known Member

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    Steve

    Thats a great design. I just wander about flex in the battery plate on the ends with the weight of the big batteries. That's why I was thinking having the plates over 2 booms. The drawing you just whipped up would definitely be the way to if you don't have to worry about any flex in the battery plate.
     
  17. Steve Maller

    Steve Maller UAV Grief Counselor

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    I think as long as the batteries are properly centered on the plates, and the plates are centered on the little booms, it should be fine. The amount of flex will be minimal, especially because of how short the booms are.
     
  18. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    You can also use spiral wrap to hold the two conductors together, Dave. That way, you don't have to remove the EC5.

    Andy.
     
  19. Jose Luis Ocejo

    Jose Luis Ocejo Active Member

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    Hi Steve I hava a Skyjib8 and here are 2 possible solutions one from Droidworx Aeronavic and the other from allied drones
    the one from Droidworx may be your solution but it requires you or some one to cut a custom CF battery plate to fit a CS frame base on this idea
    http://aeronavics.com/products/shop/skyjib-accessories/boom-battery-mounting-plate-skyjib/

    The other are from Allieddrones here in the USA check them out talk to Josh he is very helfull and can do custom plates for you

    http://www.allieddrones.com/collect.../products/droidworx-skyjib-dual-battery-mount
    http://www.allieddrones.com/collections/accessory-plates/products/boom-accessory-mount
     
  20. Steve Maller

    Steve Maller UAV Grief Counselor

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    Outriggers now modified, and motor mounting commences...
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