If you think there is 10 lbs to save in Tracy's PSRU, that's huge
considering CG and all...If someone is willing to get the necessary
components that can be whittled and you direct in the ares to be machined,
I
would be willing to do this for a very small sum to cover the tooling and
possibly the fixture material, about $200.  NO other machine shop would
touch something like this for under $1000 .................

thanks

jeff

I'm interested! My psru still in the crate.
C. Smith


Here is another way Jeff. We rejected this idea a few years ago because of
excessive cost. The cost on NC milling has come way down recently.

The big weight savings is it combines the schertz beam with the adapter
plate. A schertz beam alone weighs up to 9 pounds depending on the length.
Bob White tested it for us in a crash.

The right side can be much shorter to accommodate a rad on the cool side
of
the engine. I'll do a suggested dwg for you. It is a half inch thick.
Jerry
Hey tested it for deflection and Jarrett did an FEA.

Paul


I will have bottom Radiator, and what looks like 25.98 between barry
centers
if I read the drawing Paul made of the mount for me correctly.
So combo plate, then some shaving on the housing, what, 19 lbs saved????
8-D
C. Smith

Not quite that much as some goes and some stays. I would say 15 pounds is
possible.
We should standardize on the asymmetric mount as it can be used with a
bottom rad or a right side side rad.

It will look something like this. I'll have to redo that zenair dwg if we
use this plate.


Paul Lamar


I think I like this method. The strength is proven in the crash test. Can
you proceed with a new drawing for the Zenair mount?
Jeff, can you make these if Paul sends you the cad file? Cost to produce?

Paul, what was the depth of the cutaway for the gear housing in the image
Tracy-PSRU-10-2000-dwg, and how thick should the flanges created be? Can
the
RD-1C be safely disassembled by an average skilled person?
Jeff, with numbers from Paul, can you make the modifications to the gear
housings? Cost to modify?
I bought the 4130 sheet for the S-beam, but much of the cost is in the
fabrication, so I can eat $46 in material.
C. Smith

The max thickness on the housing should be 1/4 inch everywhere.
Tracy got carried away and made everything a 1/2 inch thick or thicker in
some
places.

The Ross gear box was 5 or 10 pounds lighter.

Tracy's older 2:17 PSRU comes apart rather easily. You take out the 10-32
screws
holding the front cover cover on and the large ball bearing should come
right out.
On mine Tracy glued it in with red RTV. Then you have to unbolt all the
long
1/4 28 screws holding the unit to the adapter plate.
After that it should fall apart. As I recall on the 2.85:1 the ring gear
is
pressed and keyed into the housing so you don't need to remove that. Power
is taken from the planet carrier. Ignore the green and red parts. Those
are just my idea for a built in torque meter.

Paul Lamar





Hi Paul
Is it possible to have counter rotating props through a PSRU it would take
out torque effect and max power could be used on T/O . Also would it counter
torsional vibration, if so maybe the PSRU may not have to be as rugged.

Paul M

But more complicated and expensive.

Paul Lamar