Essentially the planet carrier becomes part of the prop shaft doing
    two jobs. There are only two ball bearings in the entire PSRU. The
    forward ball bearing takes the prop thrust.

    It is only 7 inches long which is half the length of Tracy's redrive.
    Don't get too excited about the weight as that Allison planet is
    heavy being designed for over the road tractor trailer 450 HP diesels
    towing 50,000 pounds..

    The Allison planet and ring gear, sun gear, input shaft is 26.7
    pounds alone.

    The $30,000 Bell 47 weighs 35 pounds with out the Sonja :-) Tracy's
    is 45 pounds. But could be lightened if a 2 inch hollow prop shaft is
    used.

    This design  picks up 7 inches behind the engine for all aluminum
    rotary engines only. Other wise you would have a forward CG problem.
    I may not have to move the firewall back on the Glasair.

    This is also much cheaper to make as no long PSRU housing is needed.

    I got some of these ideas from the Bell 47.

    Paul Lamar


   That’s an awesome idea.  I just hope the planet cage and gears are up to
   resisting the gyroscopic forces from the prop.  If you extended the length of
   the prop shaft another couple inches, you could add another set of bearings
   to help with that.  But in either event, those front bearings have to be
   housed in something which can be opened for access.  Probably the front
   part of this housing would need to be detachable.

   Gene Kahn

   It is all in the steel planet cage. The gears are not involved.
   The steel planet cage is bolted solidly to front and back prop
   via their flanges..

   Actually it is better than the kludged up Bell 47 TX we have now.
   Some of the bending load is taken by a small double row bearing.

   Here is a 3D. Take a close look at this :-) A Sonja design.

   We have no intention of doing aerobatics or stalling the air-plane.

   Paul Lamar



   Which Allison TX are you thinking of using parts from?
   Dale Davies

I don't recall the model number but it is one of the smaller ones.

Paul Lamar

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