>>> I am looking for a drive for my single. Tracy's drive is too heavy
     >>> for this application so I assume so would be all attempts at a
     >>> planetary drive. Does that leave only belt drives? Can anyone
     >>> recommend a drive? Perhaps someone on this list (Paul?) could
     >>> design a belt drive that I could build? Any guidance would be
     >>> appreciated. Jerry
     >>>
     >>> ***************************************************************
     >>>
     >>> I can design one and they are pretty easy to build but I doubt you
     >>> would save much weight over Tracy's PSRU as the torque pulse
     >>> from a single rotor is severe. The big problem is getting a large
     >>> 12" dia. cog belt pulley made out of aluminum. Ken machined his
    own.
     >>>
     >>> Ken Welter can tell you what his belt PSRU weighs.
     >>>
     >>>
     >>> Weight can be gotten out of Tracy's
     >>> drive if you are willing to do a bit of machining on the housings.
     >>> A lot can be done with just a lathe.
     >>>
     >>> Perhaps Richard Sohn can fill us in on the weight of the PSRU he is
     >>> planning on using.
     >>>
     >>> -- Paul Lamar ...No rotor no motor.
     >>
     >> I am using a Hirth psru G40. The weight is 20.25lb with a donut
     >> coupler or
     >> 24.2 with a clutch. Ratio I am using is 3.3:3, however, there are
     >> four more
     >> lower ratios available with the lowest 2.03:1 .
     >> I am a few days away from running mine with a prop on it.
     >>
     >> Richard Sohn
     >
     > Looking for the Hirth, I found Autoflight. This "Universal" (via
     > adaptor plates) gear box is good for 7500 rpm in put and 160 hp out
     > put. Weight is 19 lbs. Sounds perfect. Made in Australia, I
     > think. George, do you have any knowledge about this? Jerry
     >
     > Beware Jerry. 160 HP at 7000 RPM is not a lot of average torque.
     > Particularly with a four cylinder engine.
     >
     > HP = RPM X Torque /5252
     >
     > HP X 5252 = RPM X Torque
     >
     > HP X 5252 / RPM = Torque
     >
     > Therefore:
     >
     > Torque = HP X 5252 / RPM = 160 X 5252 / 7000 = 120 foot pounds.
     >
     > The peak of the torque pulse out of the one rotor is about 35 Kg
     > per meter or
     >
     > about 253 pound feet or foot pounds.
     >
     > The question you want to ask is: What does the torque isolator look
     > like?
     > It is also not a planetary so you have mounting issues.
     >
     > Paul Lamar

    Thanks, I will beware. The company has both a Canadian and US
    distributer. Maybe they will be at Oshkosh. If I get 110 hp 6700
    rpm that would be fine. The gear ratio is 2.47.1 x 2750 ( max prop
    rpm) = 6737 rpm
    Jerry.


    You are a good welder and you have a lathe and mill Jerry. I think you
    could make your own out of thick wall 6061 tubing. If you do you could
    lengthen the snout and move the engine back closer to the firewall for
    better weight and balance. Here is one light weight design. I have
    others that use
    telescoping thinner wall tubing so there is not so much lathe work.
    This is a 2.17:1 design but I can redo it for 2.85:1. It will fit
    Larry's bell housing. If you use that you won't need the steel tube
    braces.

    The gear set and other parts are available from Slauson Transmission
    parts.
    http://www.slauson.com/


    Paul Lamar ...No rotor no motor.


Everyone,

Is there a way to use a manual transmission (stuck in the appropriate
gear?) and build one's PSRU?  Is it just not feasible?

Allen

It has been done but it is heavy and the rotary person that did it stripped
the gear teeth at least once. He reported spalling on the gear teeth
and high gear box oil temperature as well. I have not heard from him
in years. I also do not have any pictures. If anybody has some could
you send them to me?

Also it is IMHO dangerous as the prop shaft
does not have adequate size and support. Perhaps with a wood prop you
might get away with it for awhile. Losing your prop is not a good thing.
The CG may be so far aft you can't control the airplane.
The pdf explains it better.