Paul,

    Perhaps Lynn can answer this one easily.  I am wondering if the
    transmission spline size and shaft was enlarged when Mazda went from a
    13B to  the 20B.   Do racers use over sized shafts and splines to handle
    the larger amounts of torque and power.

    Doug in Japan

    Those pro road racers using 3 rotors are using $50,000 Emco
    transmissions. http://www.emco-gears.com/GT46.html
    That is the least of their worries :)

    Most of the airplane people are using the same input shaft Tracy is
    using on the
    two rotor. I think it is from a Ford V8 or some such. It mates up
    with a clutch
    disk center. I don't know what Mazda did on the 3 rotor Cosmo. Your
    buddy should be able to answer that question.

    Paul Lamar

I used the Tilton sport discs for a Volvo in my Mazda input shaft Saenz
transmission. And Chevy 15/16 fine spline on the richmond gear
transmission. The rotary, even the three rotor, have dismal torque and
there is little problem with shaft size. Drag racing with a heavy
flywheel would need a deeper evaluation. Nice pictures.

Lynn E. Hanover

Thanks Lynn.

BTW Tilton is my old Lamar Engineering company with a name change.
I sold it too cheap around the early 70's and retired for awhile
on my sail boat :)

Paul Lamar

Lynn,

Thanks.   Interesting you mentioned "Drag racing with a heavy flywheel
would need a deeper evaluation."  This is exactly my concern because I
will have a 55 lb prop that essentially has a direct load path to the
spline with only the planetary gears and prop to absorb any sudden
gyroscopic loadings.

Resonance engine induced torque is handled by a dampener between the
engine and the spline female coupling.
Paul the spline I have now from the early 13B appears to be 19mm  OD or
3/4"    Do  you have an idea what dia. the spline is in the picture of
Tracy`s Ford unit?


Cheers

Doug in Japan

Are you lucky. I just happened to have one here in the office.
One inch OD.

Paul Lamar

Paul,

Thanks for the info.  I just measured the bearing on my (semi auto) RX-5
bell housing and the ID is 32mm or 1.259 inches.  That will accept a
shaft  large  enabling a one inch spline to be cut on it.   Perhaps I
can find the female collar in some parts bin so I don't have to have
that made as well. Perhaps just pressed tack welded to a plate and
normalized. The Bell 47 PSRU is spine hell and I am concerned all of
those splines combined with the gear lash is going to add up to a lot of
slop and that means severe stress. I believe I can eliminate the sun
gear and prop shaft spline connection even though it means machining
some new parts.


Doug in Japan.

Here are some shots of Doug's Bell 47 Helio magnesium case final drive he is using for a PSRU.

If you had to buy one of these today it would cost you upwards of $30,000.
Despite the 1000 HP capability the whole thing is about the weight of one of Tracy's psru. About 47 pounds.

Paul Lamar

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