Torsional Vibration on a long shaft?

Discussion in 'Mazda Rotary' started by RSD, Jun 1, 2019.

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  1. Jun 8, 2019 #81

    RSD

    RSD

    RSD

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    Yep apparently. There are some 12 rotor engines out there in a weird V formation with four rotors on each of three shafts.

    I don't know the answer to this one, but I don't believe that anyone has built a five rotor - seems to be one, two, three, four, six, twelve.

    I have heard a figure of 94 SHP for that which came from Tracy Crook I think, but I don't know whether that was for an all aluminium engine and what the porting was.
     
  2. Jun 8, 2019 #82

    BBerson

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    The animation is on the left side of my wiki link.
    In your video they have a one piece eccentric shaft (with two eccentrics).
    So for a six rotor, I assume a custom one piece eccentric shaft (with six eccentrics) would be made?
    Or some sort of press fit, as Charlie said.
    Fitting three separate complete engines together with couplings would obviously be extra heavy.
     
  3. Jun 8, 2019 #83

    wsimpso1

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    Tracy Crook's info is 13B production with cast iron end plates and intermediate plates and side ports, intended to meet emisdions rules and give wide torque bands.
     
  4. Jun 9, 2019 #84

    RSD

    RSD

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    One piece. I'm fortunate that I have plenty of room for a long straight engine, a six rotor in all alluminium is a similar weight and length to the Allison turbine that it is replacing.
     
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  5. Jun 9, 2019 #85

    RSD

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    Ah OK - a 13B with the aftermarket alluminium end and intermediate plates is considered to cool considerably better but I don't know precisely how much by.
     
  6. Jun 12, 2019 #86

    rv7charlie

    rv7charlie

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    I don't recall Tracy being being quite that specific (94HP), but his ~90-100 HP number (using 'stock' Mazda housings) came purely from worries about keeping the engine cool enough to avoid either short or long term damage. Nothing related to road use/emissions/torque bands. Racers groove the rotor housings to help turbulate water flow & sweep nucleate boiling off the water passage surfaces, and these are 50-60% duty cycle.

    RSD, do you have hard info on aluminum cooling better, or is this interweb lore? I wouldn't bet on an all-aluminum engine cooling any better without data. The 'stock' engines have been known to have issues at higher outputs in road racing with the aluminum rotor housings getting 'soft' and shrinking under the through-bolt loads, causing the housing stack to get loose. Other than Mazda themselves (using proprietary housings), I haven't heard of anyone using all-aluminum versions in anything other than drag racing. The current time-to-climb record holder RV-Rocket engine was all-aluminum, but it was really just a drag racer, running methyl alcohol and <deleted; invalid info was here>.

    Charlie
     
    Last edited: Jun 13, 2019
  7. Jun 12, 2019 #87

    rv7charlie

    rv7charlie

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    Quoting myself...
    I'll try to attach an image of the original RWS coupler/damper plate, and the page from the install manual showing detail of one damper 'donuts'. The mounting radius is closer to 4" than 6".

    RE: quill shaft operation, There's at least one turbo'd 13B (well over 200 HP) flying in an RV-6 that is using a lightweight steel racing flywheel (in place of the auto-trans flex plate), and I *think* the spline coupler shown in the pic is attached directly to the steel flywheel. I'll update if I discover that I'm in error. Same input shaft to the gearbox. The input shaft is around 1" dia and no more than 3" from the damper plate splines to the sun gear.
     

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  8. Jun 13, 2019 #88

    mm4440

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    Hi, Two truck radiators in series under engine, not total loss cooling.
     
  9. Jun 13, 2019 #89

    rv7charlie

    rv7charlie

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    OOPS; you're right. I'll edit my post. Don't know what I was thinking about, but it was obviously the wrong plane.
    Thanks for the correction!

    Charlie
     

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