Good target RPM?

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  • FighterCat57
    "The" Fighter Cat
    • Apr 2010
    • 3480

    #1

    Good target RPM?

    I'm curious about the target RPM for a brushless setup.

    What is too high? What is too low? What is just right?

    How do I know?

    Right now I'm targeting 29 - 32k Peak RPM by V x Kv method.
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    Last edited by FighterCat57; 02-14-2011, 11:02 PM.
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  • FighterCat57
    "The" Fighter Cat
    • Apr 2010
    • 3480

    #2
    I guess this is a really silly question, or just too vague?
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    Last edited by FighterCat57; 02-14-2011, 11:05 PM.
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    • Jeff Wohlt
      Fast Electric Addict!
      • Jan 2008
      • 2716

      #3
      Those are good rpm levels as long as you do not over prop. I like 27-30,000. Also depends on the motor...some can keep it up while others can't.
      www.rcraceboat.com

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      • FighterCat57
        "The" Fighter Cat
        • Apr 2010
        • 3480

        #4
        Originally posted by Jeff Wohlt
        Those are good rpm levels as long as you do not over prop. I like 27-30,000. Also depends on the motor...some can keep it up while others can't.
        Is that actual or theoretical peak?
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        Last edited by FighterCat57; 02-14-2011, 11:05 PM.
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        • Jeff Wohlt
          Fast Electric Addict!
          • Jan 2008
          • 2716

          #5
          Based on non-loaded rpm so you will be down to 24,000 or so.
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          • FighterCat57
            "The" Fighter Cat
            • Apr 2010
            • 3480

            #6
            Originally posted by Jeff Wohlt
            Based on non-loaded rpm so you will be down to 24,000 or so.
            Nice.

            I've heard of a few running 4s 2700Kv without any problems, which is nearly 40k RPM.

            What is the main reason 40k is too high and 32k is not?
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            Last edited by FighterCat57; 02-14-2011, 11:07 PM.
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            • Jeff Wohlt
              Fast Electric Addict!
              • Jan 2008
              • 2716

              #7
              Well a good balanced motor can do that but the cheapos out there will throw parts, bearings or something. You can do it for a while but it will go.

              Now a NEU or Castle can probably handle it but they have more thorque than rpm in most cases.
              www.rcraceboat.com

              [email protected]

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              • FighterCat57
                "The" Fighter Cat
                • Apr 2010
                • 3480

                #8
                Originally posted by Jeff Wohlt
                Well a good balanced motor can do that but the cheapos out there will throw parts, bearings or something. You can do it for a while but it will go.

                Now a NEU or Castle can probably handle it but they have more thorque than rpm in most cases.
                Oh, so it's about shaft balance and the bearing system. That makes perfect sense. Really, I think spinning a dremel shaft at 30 KRPM is kinda surprising!

                Thanks for taking the time to clarify this, it's a bit confusing putting all of this together, I'm still wet behind the ears when it comes to building and calculating.
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                Last edited by FighterCat57; 02-14-2011, 11:09 PM.
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                • Brushless55
                  Creator
                  • Oct 2008
                  • 9488

                  #9
                  it also depends if your sport boating or going after a SAW record
                  take the SV27 has an unload rpm of about 27,000rpm
                  and the UL-1 is about 30,000rpm
                  and some SAW runs are 40,000rpm +
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                  • Simon.O.
                    Fast Electric Addict!
                    • Oct 2007
                    • 1521

                    #10
                    I am a solo boater and the pond I run mostly in is good for staight runs, I run anywhere up from high 20kprm to high 30krpm.

                    It is safe to say that some of my setups are close to SAW type.

                    I like small props and wicked rpms, it just sounds nice!
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                    • FighterCat57
                      "The" Fighter Cat
                      • Apr 2010
                      • 3480

                      #11
                      This really clears up the RPM range thing. I'll stay away from over 30k with anything that I don't feel is completely balanced and of good quality bearing/drive setup and shoot for 26k with cheap stuff. =)
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                      Last edited by FighterCat57; 02-14-2011, 11:10 PM.
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