Paul, what can you tell us about the Woelfle/AIXRO engine? It looks
really interesting for a single-seat project.
David Josephson
It is a good engine.
Paul Lamar
Here are some pictures.
Paul Lamar
Paul and Poul,
The Center Needle Bearing cage, it looks like a light brownish
plastic, is that the material "PEEK" that the 2 stroke guys are using
now as coating or in total as a bearing race material?
Poul, I read where you can get Ceramic Bearings for the Center
Bearing , how is that working?
My best, Anthony
I have not idea.
Paul Lamar
Paul, I noticed the AIXRO rotor face looks more like a square and not
a rectangle, do you have any literature on the length and width of
the rotor face and how it changes engine performance?
Aaron Buster
I have not found any data on that yet. The AIXRO was based on the
Norton geometry. So was the Midwest engine. That became the Austro
Engines rotary used in motor gliders. There are plenty of UAV engines
with the same geometry.
The wider rotor make sense to me as the surface area to volume ratio
is better than the Mazda Geometry. There is a company in Germany
called Wankel Supertec.
http://www.wankelsupertec.de/ That went for a
narrower rotor than Mazda. So too is the Mazda 16X. Why is a mystery
to me.
I under stand the Wankel Supertech has a higher compression ratio.
They were making some fantastic claims of low BSFC numbers at Aero
but I never saw one run let alone saw one in private hands. I suspect
they are lying.
I suspect the surface to volume ratio is not the main problem. I
suspect the heavy fuel molecules are being thrown out towards the
rotor housing and become near stationary while half of the mixture is
attached to the rotor and moves with it. It is a similar aerodynamic
situation to that of a car moving over a stationary road. The air on
the ground is stationary while the air attached to the bottom of the
car moves with the car. So far I have not found a rotary CFD that
addresses this issue.
It is well known fact that a lot of fuel is NOT being burned in the
rotary. AKA high hydrocarbon emissions. Currently that is handled by
the catalytic converter. I suspect that two plugs side by side with
multi strike ignition would ignite some of that unburned fuel. Mazda
achieved a 3% improvement in the Lemans engine by using 3 spark plugs
per rotor with another one above the top plug.
Any time you put a spark plug BTDC you lose a little compression due
to small leaks above the apex seal near the plug hole. In theory a
flush surface plug would be better but apparently nobody has been
able to develop one that worked over a long period of time or that
was truly flush and did not leak compression.
Hopefully my new ignition will burn more of that fuel.
Paul Lamar
Paul check out the NGK surface gap plugs used in the 1969 Kawasaki H1
500cc 2 stroke. Might work with the multi spark ignition.
Bill Jepson
Poul Woelfle, head of the company that produces the Aixro engines and
sends sometimes comments to this site, can tell you about the advantages
and disadvantages of ceramic rotor bearings, but their engines are
designed
mainly for kart use, that is a different functioning regime than in
an experimental
airplane, it seems ceramic bearings once reached a certain limit of
load and
temperature, that can be found under certain faulty engine operation, is
totally destroyed, all of this is described in the Aixro engines ads and
operation manuals, down-loadable from Aixro.de Once inside their
web page, you can choose between German and English versions of
texts. Good week. Regards. Salut † Jose Gros-Aymerich
Madrid, Spain
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