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Thread: 38KV Scarab scale build is back...God help me

  1. #1
    Join Date
    Sep 2014
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    NJ
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    47

    Default 38KV Scarab scale build is back...God help me

    So I'm back...
    A few years ago I started a scale build of a 38 KV Scarab, 1/6th scale. In a nutshell the project failed but in failure I learned. First, the boat was too big...72" My basement shop has two connecting rooms.
    Every time I moved the boat from room to room it took divots out of the wall...strike one.
    The molds I cast of the deck and hull had MAJOR gel coat issues...strike two.
    The final topper was a stupid design flaw that should have never happened...strike three.
    At this time, a little over three years ago a business venture presented itself which devoured most of my time. This was a blessing as it distracted from the boat failure...
    This new venture required me to become proficient in CAD and 3D printing.
    The business is on hold while we wait for some patent issues to get resolved...so with time on my hands what do I do with my newfound skills...attack the Scarab build again of course!
    Here's what I did.
    I had an 80's Monogram model of a Miami Vice 38 KV Scarab 1/34 scale.
    I sent the deck and hull out to get 3D scanned. The final scan was enlarged 444%
    The deck and hull were divided into 27 separate pieces in order to be printed the final size...61" It's big...but not as monstrously huge as the first one. The pieces went together precisely...so good it was scarey.
    These two components will be used to make a final gelcoat/fiberglass boat.
    So with the deck and hull ready to be molded when weather permits I turned to the drive train. I found outdrives from a German company called Bauer-Modelle. They fit the boat nicely.
    So before I go any further let me explain what I'm after. I'm not looking for a pond rocket. I want my boat to get up on plain and do a real life 18-20mph...that will give me a scale speed of 65-70mph if my math is correct. The folks at OSC recommended the motor and ESC combo.s The throttle will have to restricted as the outdrives can only handle a top rpm of 18-22,000.
    I built a plywood mockup of the Scarabs stern for component placement.
    I have the ESC's mounted above the motors for maximum air flow...also I'd like to have two small water pumps doing the cooling and have the water coming out of the exhausts while a sound module blasts the sound of twin V-8's...nothing with me is simple...I'm ok with all show and no go lol!
    So...batteries.
    The more I learn about lipo's the more I want the two I got from OSE out of my house. They are sitting in an steel ammo box in my basement at the moment. The more I tried to learn about them the more exploding videos I watch on YouTube.
    Since I'm after show, more than go, I went with nimh batteries. I soldered up two packs...14.4 volts at 4300mah. I'm assuming volts are volts...right? Does it matter to an ESC/brushless motor combo if the power is from a lipo or a nimh pack?
    This morning I attempted to hook up and spin the motors for the first time. I got juice to the steering servo and third channel...they worked fine but no throttle response...just non stop beeping. I immediately unplugged the batteries...hopefully no damage occurred. There was no smoke or smell...
    Any advice would greatly be appreciated...I'm no means an electronics guy...
    Anyway, here's some pics...no particular order.20180919_122256.jpg20180920_155443.jpg20180920_155443.jpg20180919_122246.jpg20181002_133414.jpg20181002_133551.jpg
    South Jersey Vice

  2. #2
    Join Date
    Apr 2007
    Location
    AZ
    Posts
    8,009

    Default

    Your fear of LiPos is totally unfounded, another example of why not to believe what you see on YouTube. Hundreds of thousands of modelers use them without burning down the house. That said, the motor/ESC won’t care where the voltage comes from, and your low-performance system will probably not cause excess voltage depression (which can cause the ESC to shut off).

    However, as mentioned in your other thread constant part-throttle is hard on the ESC and should be avoided. Better to remove a few cells and use lower voltage than to rely on ESC switching.
    ERROR 403 - This is not the page you are looking for


  3. #3
    Join Date
    Sep 2014
    Location
    NJ
    Posts
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    Default

    Thanks Fluid!
    South Jersey Vice

  4. #4
    Join Date
    Sep 2014
    Location
    NJ
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    Default So far so good!

    Well...enough for one day.
    I got the motors to finally turn but there's still issues...hopefully they are all software tweaks.
    Lots of beeping going on before they run...servos work immediately though. I have to learn what all the beeping means...
    I'm happy the drive shafts I machined spin true.
    The throttle is way off...motors engage in the neutral position and only one motor reverses when the throttle nudges forward. Maybe I need the program card for the OSE Raider ESC...hope thats not too complicated to tweak.
    I forgot to mention the motors are Leopard 4082's

    Last but certainly not least...thanks everyone for your expert advice!!
    South Jersey Vice

  5. #5
    Join Date
    Jun 2018
    Location
    ny
    Posts
    218

    Default

    Constant short beeps means the esc is not seeing what it believes to be neutral... try recalibrating the neutral point?

    Also, in the original post you mention being afraid of lipos, i have had the same 3s lipos for my boat and rc cars for 6 years... take care of them normally, dont drop or smash them, and they last a good long while...

  6. #6
    Join Date
    Mar 2011
    Location
    BC
    Posts
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    Default

    The beeping can be the ESC counting the cells that it recognizes.

  7. #7
    Join Date
    Mar 2011
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    BC
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    Ok after reading the thread I would say your ESC’s need calibration. Any chance of a parts list so that we know how to address the issue? I did not see an ESC brand.

    BTW, great project. Are you building a mould ?

  8. #8
    Join Date
    Jun 2018
    Location
    ny
    Posts
    218

    Default

    The OP appears to have OSE Raider 150s, which is the same as the flycolor 150 that i have, whenever my neutral gets off it just constantly beeps... as for the rest of the issues with the parallel escs i have no idea....

  9. #9
    Join Date
    Sep 2014
    Location
    NJ
    Posts
    47

    Default

    So it looks like I have to get a Programming Card for OSE Raider Esc's
    How complicated is it gonna be?
    I wish somebody lived close by thats good at electronics...
    South Jersey Vice

  10. #10
    Join Date
    May 2018
    Location
    TX
    Posts
    344

    Default

    It is very straightforward. The Ebay Flycolor cards work as well.

  11. #11
    Join Date
    Mar 2009
    Location
    NC
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    2,908

    Default

    Im going to want one of these once you have your molds done and ready to lay them up. That is probably the most perfect 38kv ever done as that Monogram hull was really spot on! Nice work so far! Mike
    Laser cut, birch plywood rc race boat kits- WWW.MLBOATWORKSRC.COM WWW.DINOGYLIPOS.COM

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