1/90 scale Virginia Drive shaft Question

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  • Michael McCourt
    Ensign
    • Sep 2020
    • 7

    1/90 scale Virginia Drive shaft Question

    I am building a fully custom 50" long and 4.5" beam Virginia class submarine.

    when it comes to the drive shaft of the submarine i was originally going to use a 1/8 brass rod and brass bushings i bought from bob martin. i have been told to use a stainless steel shaft.

    my Question is what size drive shaft should i use, are brass bushings ok to use, and how do i take the force from the propeller off of the motor?

    any other insights into drive shafts would be great! thank you very much!
  • He Who Shall Not Be Named
    Moderator
    • Aug 2008
    • 12256

    #2
    Rule one in running gear is to isolate the motor from any axil loads -- ahead and astern -- presented by the propulsor. The only load that motor should see is torque.

    Absorb the ahead and astern loads at the propeller shaft, either near the propulsor itself, or forward where the propeller shaft interfaces with the motor or intermediate shaft.

    In this example the propeller shaft is supported laterally and axially by flanged Oilite bearings set into the stern of the model:

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    Stainless steel washers between the Oilite flange and propeller hub (the ahead thrust bearing), and the Oilite flange and Dumas coupler (the astern thrust bearing) when lubricated with silicon grease produce a low friction bearing surface between stationary and rotating elements of the running gear.

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    Or, you can use a single Oilite bearing, glued into a suitable foundation, at the forward end of the propeller shaft, and secure the shaft from axil motion by the Dumas coupler aft, and a wheel-collar forward. In essence you're sandwiching the Oilite bearing between the two rotating elements of the running gear. Again, use stainless steel washers to reduce rotational friction.

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    The Dumas universal coupler (coupler-dog bone combination) delivers only torque, not axial force between motor and propeller shaft.

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    Or, in the case of this pump-jet, the axial force (thrust force fore and aft) is handled in the Oilite bearings set within the stator hub.

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    I recommend 3/16" diameter SS shafting for a model this size. You'll find both the shaft stock and Oilite bearings at the McMaster-Carr site.

    Go get 'em, Tiger!

    David
    Last edited by He Who Shall Not Be Named; 09-13-2020, 06:45 PM.
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    • Michael McCourt
      Ensign
      • Sep 2020
      • 7

      #3
      ok great! thank you for the insight! i will definitely use this in my submarine.

      Comment

      • He Who Shall Not Be Named
        Moderator
        • Aug 2008
        • 12256

        #4
        Originally posted by Michael McCourt
        ok great! thank you for the insight! i will definitely use this in my submarine.
        Keep us informed by way of a WIP.

        David
        task-master
        Who is John Galt?

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