Graupner Mini Hydro

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  • Chop
    Senior Member
    • Nov 2007
    • 504

    #1

    Graupner Mini Hydro

    I have a Graupner mini hydro (16” long, 8” beam) that I want to put a slightly bigger motor into. It is a brushed system with a Graupner Speed 400 in it. I have a 3S, 1100mah battery and an Electrifly C-35 Mini ESC (6 – 12 NiCD/NH, 2S – 4S Lipo 5v/1.5 BEC).

    Will the Graupner 480bb Race 7.2 (http://www.offshoreelectrics.com/pro...?prod=grp-6327) work well in this application? With the 400 in it, it handles very well. I let my 11 year old run it when I’m playing with other boats.

    What other (reasonably priced) options would you suggest?
    Attached Files
    There is a fine line between "hobby" and "mental illness."
  • Dr. Jet
    Fast Electric Addict!
    • Sep 2007
    • 1707

    #2
    The Graupner Speed 400 6V motor has a Kv of about 2675 rpm/V and usually runs on about 10 to 15 amps maximum. That is why I have chosen to run similar setups in my 15" micros with the Chinese outrunner that has a Kv of 3000 rpm/V. The performance is about the same or a bit better than the Speed 400 on 2S, probably due to the increased efficiency and the slightly higher Kv and Kt of the brushless outrunner. This motor/ESC combo can be had for under $25 on ebay. It is a screaming deal, plus it is a bolt in replacement with no modifications required (other than allowing room for the spinning can of the outrunner). If you want to run 3S, I would recommend a lower Kv, maybe around 2500~2600 rpm/V. The 3000 rpm/V motor is best suited for 2S or 6 to 7 round cells. The Speed 480 motor has a reputation of eating brushes faster than the Speed 400 motors.
    A nation of sheep breeds a government of wolves

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    • Chop
      Senior Member
      • Nov 2007
      • 504

      #3
      Thanks Dr. J.

      Is there a brushless alternative?
      There is a fine line between "hobby" and "mental illness."

      Comment

      • Dr. Jet
        Fast Electric Addict!
        • Sep 2007
        • 1707

        #4
        The $25 brushless outrunner/ESC combo from ebay. It is a drop-in replacement for most Speed 400 applications. Slightly more rpm, slightly more torque.
        A nation of sheep breeds a government of wolves

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        • Chop
          Senior Member
          • Nov 2007
          • 504

          #5
          Originally posted by Dr. Jet
          The $25 brushless outrunner/ESC combo from ebay. It is a drop-in replacement for most Speed 400 applications. Slightly more rpm, slightly more torque.

          I will give that a try, thanks for the info.
          There is a fine line between "hobby" and "mental illness."

          Comment

          • Ocean Racer
            Senior Member
            • Sep 2007
            • 502

            #6
            did you find the motor combo on ebay?
            Failure is the First step to SUCCESS

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            • Avanti
              Fast Electric Addict!
              • Nov 2007
              • 1280

              #7
              The Manx has been sitting dormant, but I think I finally have my motivation back. I hope to see it float soon.

              Comment

              • dostacos
                Member
                • Jul 2008
                • 76

                #8
                Originally posted by Ocean Racer
                did you find the motor combo on ebay?

                Comment

                • Chop
                  Senior Member
                  • Nov 2007
                  • 504

                  #9
                  Originally posted by Ocean Racer
                  did you find the motor combo on ebay?
                  Yup, I ordered two sets (spares you know).

                  I’m still waiting for delivery. 8 to 14 days from China.
                  There is a fine line between "hobby" and "mental illness."

                  Comment

                  • j.m.
                    Senior Member
                    • Jul 2008
                    • 838

                    #10
                    You can also go to http://www.hobbycity.com/hobbycity/store/uh_index.asp
                    They have great deals on all things brushless.

                    Here is a good motor that would have a bit more power than what you are currently running: (and what's on the 'bay)


                    Esc:


                    Beware that some esc's used for airplanes and heli's may not be compatible with pistol style Tx's. Also, they aren't waterproof, and outrunner motors cannot be watercooled around the can. (it spins)

                    An outrunner (even the one on ebay) will have signifigantly more torque than the speed 400. You should be able to increase the prop diameter by a few milimeters and the pitch without worrying at all.

                    Comment

                    • Chop
                      Senior Member
                      • Nov 2007
                      • 504

                      #11
                      I received my parts today. I had ordered two 3000 kv motors but received one 3000 and one 5000 kv motor. Do I keep the 5000 kv moter or do I send it back?

                      What advantages/disadvantages does it offer?
                      There is a fine line between "hobby" and "mental illness."

                      Comment

                      • Dr. Jet
                        Fast Electric Addict!
                        • Sep 2007
                        • 1707

                        #12
                        If the 5000 rpm/V motor is the "Short Can" version, there is not much you can do with it in a boat. I have one and I finally built a little gearbox for it,; the resulting assembly gave similar performance to the 3000 rom/V motor in my micros. While it worked well, it wasn't really worth the extra effort and complexity of a gearbox.
                        Attached Files
                        A nation of sheep breeds a government of wolves

                        Comment

                        • stablgr
                          Member
                          • Sep 2008
                          • 93

                          #13
                          I was looking at these motors for a couple of Hydromites I'm about to start building. One is going to be for my 7yr old son and I was wondering if the 1700kv motor would power this hull. I'm not looking for blistering performance.

                          Any help would be greatfully received
                          By the time a man realizes that maybe his father was right, he usually has a son who thinks he's wrong.

                          Comment

                          • j.m.
                            Senior Member
                            • Jul 2008
                            • 838

                            #14
                            I don't know how well that would do. It might not even get the back of the hull out of the water.

                            You would definitely have to use a bigger prop to get it to perform well.

                            As for your son, a hydro might not be the best boat for a beginning driver.
                            (with a turn fin, he will only be able to turn one way at when he's going at any descent speed. Not ideal for a no-so-good driver.(as you make him seem))
                            A mono would be great, though.

                            As for you, check out the motor i linked to a couple of posts up. Should have a lot more power than the one most people are using, but it's not that much bigger.

                            Comment

                            • peells
                              Senior Member
                              • Jan 2008
                              • 716

                              #15
                              Ok I have seen these motors on ebay and do these speed controls that they come with work properly with a pistol grip radio? and one more question where do you get a coupling for a 2.26 mm shaft? I have found the 3mm shafts but no luck on the 2.26mm shafts (maybe I am not looking in the right places) and how do we know if the speed controllers are or are not compatable with P.G. Radios before we get them or is it just a crap shoot? just wondering since the pistix are no longer available and not being produced any more, that is a bumber those things work great so start making them again RC Hydros!!!!
                              Peter Eells; Fun, and Helping others To Have Fun!!!
                              http://rcboatsbypetere.blogspot.com/
                              [email protected]

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