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Thread: Large scale outboard design questions

  1. #1
    Join Date
    Jan 2008
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    IL
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    543

    Default Large scale outboard design questions

    Hi all, I am in process of designing an outboard that can handle 35000rpms and 4000+ watts. I plan on using a 1/4" flex system with it. My design goals are:

    5692 motor size
    Can use off the shelf flex cables (1/4 flex to 1/4 stub shaft or 1/4 flex to 1/4 stub reduced to 3/16 for different prop choices)
    Can use a standard flex hex
    Oiler system with oil reservoir
    Replaceable brass stuffing tube.
    Built in water pickup for motor
    Scale appearance (looks like a full scale outboard)
    Speedmaster style floating bushing system
    Can fit the MHZ 1/5 scale cowl over the motor.

    Anything else you guys think I should add to the list?

    I have one big problem with this project and that is the flex cable. I know it is best to have the flex as straight as possible but that will make the scale appearance hard to accomplish. It is possible to have the flex bend to a 90 degree angle and still be reliable.

    I am looking forward to the feedback.

    Thanks!
    Rich
    24 R/C vehicles and still counting...What budget?

  2. #2
    Join Date
    Jun 2011
    Location
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    789

    Default

    http://lawlessdrives.com/?c=225&i=2842

    Might be cheaper to not reinvent the wheel.
    Mic

    Mic Halbrehder
    IMPBA 8656
    NAMBA 1414

  3. #3
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    Quote Originally Posted by HTVboats View Post
    http://lawlessdrives.com/?c=225&i=2842

    Might be cheaper to not reinvent the wheel.
    Mic
    I don't see an electric version on the site. Is there one?

  4. #4
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    Default

    K&B has been using 90* degree bends on their outboards for many a long year with no issues, you have to try to break them, like putting them in backwards / upside down, the best way to break one is going fast forward slamming it into reverse to stop, sudden stops is bad for flexies. All my outboards are set up with no reverse. Most of today's existing nitro outboards have adapter plates to convert the lower unit to electric use.
    PROBOAT BlackJack 24", ShockWave 26"
    MRP U-31, 3 tunnels VS1, MRP Bud Light, Dumas HS Sprint

  5. #5
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    If you have the ability to consider making a complete lower making an FE adapter is pretty simple. Make a flat motor plate and use standoffs.
    Mic

    Mic Halbrehder
    IMPBA 8656
    NAMBA 1414

  6. #6
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    Quote Originally Posted by JestDanny View Post
    K&B has been using 90* degree bends on their outboards for many a long year with no issues, you have to try to break them, like putting them in backwards / upside down, the best way to break one is going fast forward slamming it into reverse to stop, sudden stops is bad for flexies. All my outboards are set up with no reverse. Most of today's existing nitro outboards have adapter plates to convert the lower unit to electric use.
    I remember K&B being around when I was younger. I think I would need a tighter bend than they have to keep the scale appearance that I am looking for. It also looks like they use a square flex apposed to a flex fused to a stub shaft.
    24 R/C vehicles and still counting...What budget?

  7. #7
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    Quote Originally Posted by HTVboats View Post
    If you have the ability to consider making a complete lower making an FE adapter is pretty simple. Make a flat motor plate and use standoffs.
    Mic
    An adapter would be very easy. I just want a scale look like the MHZ outboard, but with the reliability of a flex system.
    24 R/C vehicles and still counting...What budget?

  8. #8
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    Default

    20210110_111353.jpg20210120_193011.jpg
    Thought I'd test this idea first, we will see how it does in the test tank!
    24 R/C vehicles and still counting...What budget?

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