Hi Paul, Do you have any more info on Tracy's box, like the shaft
and internals, I can't figure out where the thrust goes etc. The
box is very chunky, I would say overkill somewhat. Also I can't see
any oil supply, in or out. You wouldn't have to saw off the flange,
I would do my box and then remove it from the pattern before
casting others. From the side view it looks like the prop shaft is
one piece, is this right ? Also, is the box intended to be bolted
up to a plate or a bell housing. Chris.


Tracy used a cut down GM pick up truck rear axle and ball bearing.
The bearing was retained by a pressed on collar with  several tons
of force. Tracy fed the box with oil from the engine. So too the
Ross but the Ross had all needle bearing so it required less oil.

Very heavy at 9 pounds, I would not do it that way.

I would use a hollow shaft like the  Ross with a separate prop
flange. No forging required. The flange would be retained by
special set screws called  "Extended Point" . A relatively new
idea and much stronger  than pins that go all the way trough the
walls of the shaft (which is what Ross used for years) or splines
and much less cost. Easy to machine with a rotary table.

About a 2 inch OD steel tube with a .190 wall is about right. Just
like the Ross box. That is about the largest needle bearing you can
buy.

Use about eight or ten of these .25 inch screws and they are almost
as strong as a one piece shaft and flange. Here are some pictures.

Do you use a dwg program Chris? If not I suggest getting  Rhino. It
will save you money in the long run.

Paul Lamar

Paul, Refresh my memory, What was the problem with the springs in
the original flex plate? I always had the impression that springs
would absorb the torsional pulses and return the energy when pulse
subsided whereas rubber dampers would dissipate the torque pulse as
heat?

Erik


No damping. Ken  Welter destroyed a couple of them. Our new silicon
rubber coupling is the way to go. Chris, you will need something
like this.

Paul Lamar

Someone should design a pendulum style absorber to fit inside the
rotors. Gene Kahn

That works on aircraft piston engines but it would not help the rotary.
The rotary does not have an e shaft torsional vibration problem.
The problem is with  the gearbox.

Paul Lamar


Everett Hatch at Powersport did a pendulum dampener. They put it on their original superlight  engine. Steve Beckham said it would idle at 900-1000 rpm  smoothly. They discounted its use because it was very expensive to produce. That was on the superlight  with a custom planetary gearbox. They changed to the internal ring gear because it was a stiff solution, and backlash could be almost nil so the dampener wasn't needed.
Bill Jepson