Hi,
Can you please explain the problem and solution of balancing when
using a cut down e-shaft with single rotor 1/2 Mazda 13b engine.
Regards Zahid
Balance is controlled by these equations. The Wankel is not just
tatically balanced but dynamically balanced as well.
In a single rotor engine the counterbalance weights must provide a
STATIC balance for the e-shaft eccentric and its rotor and must also
account for the DYNAMIC wobble caused because the static counter
weights are not located at the mechanical centres of the rotor and
the eccentric. It is impossible to do this.
They must be mathematically sized relative to their lateral position
from the rotor and eccentric centre line.
Paul Lamar
the Tracy ISO is physically attached to the flywheel. Does that need
to be brought in to balance equation as extra mass to mF (front
counter weight) or mR (mass Rear Counterweight)?
Regards Zahid
The rear counter weight is hiding behind the ISO.
Paul Lamar
Here is how I solved some of the balancing issues. There are a whole
lot of issues interacting when building a new engine configuration.
Weight control influences almost everything. A single rotor engine
certainly requires a considerable flywheel, if one wants the idle
speed somewhere below 3000 RPM. I integrated the rear balance
weight in the flywheel (picture). The front balance weight I modified
with tungsten inserts before dynamic balancing. I ended up with a
clean rotating setup. My engine is based on 12A rotor and housing, so
I do not have any direct comparison to 13B size parts. FWIW.
Richard Sohn N2071U
http://www.fairpoint.net/~res12/home.html
Hi Richard, I have read some postings where some have machined a
single rotor eccentric shaft from a 2 rotor unit. Paul mentions the
shaft needs to be hardened after machining. Could you give a
overview of the process you used to build your shaft ?
Thanks, Steve Carlisle
Here is what I did.
On the first e-shaft I concerted, I left the oil pump side of the
shaft with the front lobe unchanged. After machining the rear end of
the shaft to my mods, I only had one bearing surface to create. I
picked an inner ring of a INA needle bearing with an outer diameter
the same as the original MAZDA bearing, and pressed it on the shaft.
As it turned out, it was a solution, which never failed during all
the ground testing of the first engine I build, with a run time of
around 50hrs. I did not consider this a solution for a final,
flyable configuration. The solution I have in the engine now is a
case hardened bearing section. The biggest problem was finding
someone for the case hardening and grinding who was willing to do it
for and affordable cost. FWIW
Richard Sohn N2071U
http://www.fairpoint.net/~res12/home.html
I misunderstood the last email by Richard Sohn. He was referring to
case hardening process for e shaft . I thought he was referring to
case hardening for bearing. So please do not publish my last email.
Zahid Rahman
Centrifugal force of a rotating object is MVVR. Where V is the velocity,
and R the radius and M is mass.
This means that unless C.G. is matched exactly, it is impossible to
ballance the engine at different speed.
Fortunately, I think the C.G. Of the rotor travels in a circle. Therefore
it is van be balanced by a weight at the C.G. path of the rotor. The same
goes for the imbalance of the eshaft.
Since counter weight is located only at the end of the engine, I think you
will get from limited twisting on the shaft.
That's IMHO. No guarantee on accuracy.
Henry Nee
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