Not a good design. Cantilever everything. Puts a side load
on the rear main that it is not designed to accept.
I am not talking about pre load tension. Has nothing
to do with pre load. Anytime you are transmitting HP
with a belt or chain there is a side load. Best to
stradle mount everything like this Ken Welter belt drive.

Paul Lamar ...No rotor no motor.

There's a lot of extra (and unnecessary) mass on the Welter drive.  He's
got the right idea, though.

A combination of Welter's and Valley's design is the best set of
tradeoffs.  Add an outboard bearing straddle support to the Valley unit,
made of a 1/2" x 2" bar that goes out past the big pulley to a couple of
blocks bolted to the engine, and you have solved the problem without
adding another 10lbs of deadweight.

Drive designers usually base their stuff on auto designs.  Carmakers
have to overdesign, because they know that someone will take it to the
limit and because a car takes many sharp shocks just in being driven
around on the streets.

Aircraft prop drives don't get those shocks.  If you study other, proven
aircraft structures, you will see ways to design things which are
nothing like the original (car-based) idea.  In the case of my
suggestion, I remember when I was interested in Gyrocopters -- which
hung the entire aircraft, fuel load and pilot from a rotor head attached
by a couple of aluminum blocks such as I've described.  If it will take
that kind of load, a similar structure will do just fine with any load
your PSRU can generate.

BTW, a large chunk of the planetary PSRU weight can be eliminated by
some re-engineering.  Again, Ford designed it to allow a 300 HP engine
to  push a 10,000 lb load over many years' worth railroad crossings,
potholes, etc.  The prop load is less than about 250 lbs and all
twisting forces on it are much longer and softer than just a drive to
the grocery store.  The only inherently fragile parts of the whole drive
are the gears, but there are extra pounds of carrier, housing and so on
which could be rethunk.

Consider that all you really need for a housing is a sealed "can" for
the carrier assembly to spin in, that you pump cooling oil through.  The
carrier itself can be lightened.  All you need for an output shaft is a
SEAMLESS TUBE long enough to attach a prop mount to.  With a
straddle-mounted bearing at the prop end of the output shaft, your
housing could be a couple of layers of CARBON FIBER.  The common input
shaft is likewise way to big and heavy, so go to seamless tubing for
that, too.  *POOF* your 40 lb reduction is now a 20 lb reduction.

Keith




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