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Thread: Brushless motor for feather spinner?

  1. #11
    maddox10's Avatar
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    Valkiri2 had a meassured top speed of 6000 rpm with a 405mm disk. Tip speed 450 km/h .

  2. #12
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    That motor is a tad low on power . 18.5V*60A= 1.1kw

  3. #13
    overkill's Avatar
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    That SK3 motor should be fine for a smaller diameter weapon like a drum or a small disk, maybe not enough power for a larger diameter. As long as you gear the motor down, it will probably be fine to over-volt the motor on a 6S pack to get a more power out of it; power will be almost 1.6Kw on 22.2V. With a 2:1 belt reduction and running on 22.2V, the no-load speed at the weapon is a respectable 7,000 rpm.

  4. #14
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    Quote Originally Posted by maddox10 View Post
    That motor is a tad low on power . 18.5V*60A= 1.1kw
    Which one would you recommend for a 1.8kg bar, about 300mm across? And what gear ratio? I already know I'll be running a 5s lipo.

  5. #15
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    It is almost impossible to find a higher powered out-runner designed for 5S; manufacturers have discovered that with new FET technology it is cheaper & easier to make low Kv, high voltage motors. Just a few years ago, it was rare to find medium to large motors for 12S batteries, now they are everywhere and motors above 1.5Kw designed for 6S and lower are becoming scarce.

    For a high powered motor on 5S, you will probably have to turn to in-runners like this: https://hobbyking.com/en_us/dt38-620...ner-motor.html. The smaller diameter means they have less torque than a similar power out-runner but that's the compromise you have to make to run at 5S.

  6. #16
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    I suppose I could run a 6s at a push, would that be any better?

    Scratch that, I noticed your earlier comment and see a 6s can work ok.

  7. #17
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    What batteries do most high-powered spinners use these days then? Are they mostly 12S to match the motors?

  8. #18
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    More bots still use 6S packs that are easier to use with drive motors. I am headed towards 10 or 12S packs and I think other builders will too. The trick is to either run a small secondary pack for the drive motors or to dump brushed motors completely and find some small, high voltage brushless motors for drive.

  9. #19
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    Valkiri 2 used a 4S 8000mAh monster to power everything.

    Valkiri 3 went for a 6S 3300mAh pack for weaponpower and a 4S 2700mAh pack for the drive.

    Both used the NTM 5060, a motor suited up to 8 S .

    6S because the ease to find cheap packs and chargers and the fact we use the cheap SS190-200 ESC, what in theory should do 7S.

  10. #20
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    True - its mush easier to make a 10 or 12S pack from two 5 or 6S packs. They are more common and much easier to recharge - I don't think there are many 12S chargers around just yet.

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