Does anyone have any ideas on the following

question?  I send it out previously but haven't had
any responses.

What usually limits the RPM on a 13B engine?
e.g. airflow, rotor bearing load, stationary

gear failure, lubrication problems, apex seal
dynamics?

KQ

In an airplane it is the prop. A practical fixed
pitch prop with a 2.17:1  PSRU is
limited to about 6300 RPM wide open throttle.

In a car with a gear box the RPM is limited by the
rotor bearing loads  right at the moment. 

At one time it was the phasing
gears but they have been improved.
The loads on the rotor bearing limit the engine to
about 10,000 RPM.

The new rotor for the side exhaust port engine are
reported to be
14% lighter in weight and the load on the bearing is
m*V^2/r
m is is in slugs so you need to divide the rotor
weight in pounds by 32
to get slugs. r is the radius of the eccentric and V
is the tangential velocity
of the CG of the rotor in feet per second.

Current rotors weigh about 8.5 to 9 pounds.

This is probably more than you wanted to know :-)

Paul Lamar

Vance Jaqua wrote:

Gee! a rotary will "throw a rod"! just like those old
fashioned piston engines :-) Vance

No Vance they don't have rods but you can destroy the bearings. I imagine the 
engine would seize if you persisted in running it at 10,000 RPM with shot
rotor bearings. I have never heard of a person seizing the engine by running it
at 10,000 RPM continuous. I have heard of early engines with phasing gear
failure punching the rotor through the rotor housing however. I guess you
could call this "throwing a rotor" :-)

We had a guy on here who ran his engine up (probably) to about 10,000 RPM
with no oil pressure. He replaced the damaged bearings and the engine ran 
just fine.

BTW more and smaller rotors would improve the power to weight ratio as
the engine could be run much faster than 10,000 RPM. Just like a smaller
piston engine with more cylinders.

I have asked Juergen Bax why he does not run the smaller Wankel GmbH engines faster
than 6000 RPM and get more power. He said they were being real conservative.

Paul Lamar
 
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