That makes perfect sense. Neat that power cycles overlap and now I see why.

Pressure per rotor face doesn't make its way out to the eccentric
shaft, just the net total pressure on all faces. The eccentric shaft
is isolated from this reversed loading.

So I've heard of having gearbox issues due to torsional vibration with
specific reduction drives, and the problem sounds unique to the
rotary. If I recall correctly, the issues are solved with dampeners or
increased flywheel mass, but what is the cause of these issues if a
reciprocating engine does not have them?

Thanks,
-Chris

On Sun, Aug 24, 2008 at 2:57 PM, Rotary Engine <rotaryeng@earthlink.net> wrote:

>Paul,
>
>Here is what Charlie Airesman has been up to.  He has dual altenators,
>Fiberglass pan dual crank senors.  Intake is plasic tube wraped in glass
>with carbon fiber tapes in strategic locations.   It's painted black.
>
>Joe Berki
>Limo EZ

>Does Charlie live near you Joe? Tell him I said hello. Great guy.
>Very creative. Here is an old picture of his composite prop extension.
>
>Paul Lamar
>

Joe,

Ok I give up.  The two engine mounts on the rear of the engine look
intriquing.  How and where do they mount to the metal frame shown
attached to the frame.  Perhaps there are two more near the flywheel?
Also is lateral cross bracing to be added or is the engine locked secure
(no rubber isolators) to the frame?

Thanks.

Doug in Japan

Doug,
This Photo should clarify the mount.  The rubber mounts are in the
vertical
axis for both front and rear ends of the engine.

Joe Berki
LimoEZ

It is easy to do it that way but the main source of vibration in the
rotary engine is torsional. So you want to rotate the mounts 90 degrees.

Joe, please pass these charts on to Charlie. The Barry mounts are ten
times
stiffer radially than they are axially. Also the vertical load is ten
times
higher near the flywheel than at the front (car) cover.

Paul Lamar

Paul,

Can you describe the last chart (rotary-torque-v-4-cyl-2) in some detail?

What causes the 270-degree period for one full cycle, and what does
the overlap indicate? Is the dotted line representing per-face force
on the eccentric shaft, while the solid line represents net resultant?
Does this cause zero net torque reversal (seems to be shown that way)
on the output?

I imagine zero torque reversal would be desirable, but is this the
source of gearbox problems?

Thanks,
-Chris

Yes. What causes the 270 degree expansion period is the rotor is rotating
2/3rd as fast as the E-shaft.

The torque pulse follows the pressure diagram in the rotor chamber.
For a two rotor engine the torque pulses are 180 degrees out of phase.
Due to the 270 degree period of the expansion stroke in a rotary unlike
a four cylinder piston engine the torque pulses overlap.

Here is the torque pulse from a one cylinder aircraft engine.
Next is a smoothness comparison.

The rotary is an extraordinarily good engine.


Paul Lamar

That makes perfect sense. Neat that power cycles overlap and now I see why.

Pressure per rotor face doesn't make its way out to the eccentric
shaft, just the net total pressure on all faces. The eccentric shaft
is isolated from this reversed loading.

So I've heard of having gearbox issues due to torsional vibration with
specific reduction drives, and the problem sounds unique to the
rotary. If I recall correctly, the issues are solved with dampeners or
increased flywheel mass, but what is the cause of these issues if a
reciprocating engine does not have them?

Thanks,
-Chris

I cannot imagine why. The two rotor side port is only about 165 foot pounds
of torque and the p-port is about 200 foot pounds. Given the same RPM
there should be less of a problem with the rotary say compared to a four cylinder. The main reason we use a damper is the resonant frequency
of a planetary with a prop is about 2000 engine RPM. Any time you separate
a large rotating mass (prop) with a gear train or long shaft you are
going to have torsional problems at some RPM.

Paul Lamar