Hallo: by serendipity, 'chiripa' in Spanish, I've found these
comments by one of the engineers who were involved in the development
of OMC Wankel engines. Hope it's of some interest to you. Have a good
season. Best regards.

Salut       Jose Gros-Aymerich; Madrid, Spain

http://vintageomc.webs.com/theomcproduction.htm
<http://vintageomc.webs.com/theomcproduction.htm

"Max Bentle of Curtis Wright is credited with the kinematic inversion
of the engine allowing the housing to remain stationary with a
rotating crankshaft."

Untrue. It was a person at NSU. The name later.

"The pressurized oil system allowed the use of conventional babit
bearings and with the addition of an oil cooler to maintained
internal temperatures adequately."

Are you listening you Wankel heads in Europe? :)

"Curtis had use “D-Gun” tungsten carbide from Linde as their coating,
which was very effective, but extremely expensive."

Interesting.

"It was also hundreds of pounds lighter than the V-8 being used and
as such would out accelerate them even with 100 less hp."

"Both versions meet the design requirement of 100 hrs @ WOT."


"The trochoid coating was still “D-Gun”, as research hadn’t developed
a lower cost suitable coating yet."

"After several months of work, it became apparent an oil-cooled
engine could not be made cost competitive with a 2 cycle and work on
oil cooled engines stopped."


" Unlike a piston engine, the rotor is a captive heat source with
very little heat rejected to the housing walls. As such most of the
cooling had to come from the incoming charge to cool the rotor. The
result is a significant reduction in volumetric efficiency, the
actual amount of air going thru the engine vs its theoretical
capacity. This is due to the significant heating of the charge as it
passes thru the engine."

"Unfortunately he had designed a 2 stage axial blower running at
30,000 RPM and took 35 hp to drive to cool the CW design."


"We knew an axial fan could not generate sufficient pressure that
would result in the velocity required to cool the engine."


"The rotor bearing was the weak link of this engine. Being inside the
rotor, it is completely dependent on the incoming charge for cooling
and lubrication. The bearing was already pretty special. It had a
silver plated retainer and a high temperature temper of the outer
race. Steel grows; get larger, as it gets hotter. That is until it
exceeds the temper temperature where in it gets smaller. As I figured
out after 100’s of tests, there was a lubrication breakdown between
the retainer and the outer race. The result was steel running on
steel at very high speeds generating extreme heat. The result was the
bearing shrinking onto the crank eccentric stalling the engine. It
took a hydraulic press or a sledge hammer' to get them apart. I took
several samples to SKF Research and talked to the chief metallurgist.
He told me this was impossible to do. When I suggested he come to
Waukegan and see for himself, he said the bearing had to be reaching
1800 F for this to happen. This type failure was self-destructing.
When the bearing got near its thermal breakdown temperature it would
self generate additional heat causing further oil breakdown, causing
additional heat, etc, etc,etc. "

The European Wankel builders have yet to learn a lot of these
lessons. Not Mazda. Mazda is the gold of the Wankel world.

Paul Lamar



Kinematic inversion. The Gentleman at NSU was Mr. H, D, Paschke, Hans
Dieter.

http://www.der-wankelmotor.de/Wankelmotor/wankelmotor.html

Rolf Pfeiffer

How do we get that in English Rolf?

Paul Lamar

          I'd say Rolf=Rudolph, for translation from German
   to English, Google translator is quite good, and above
  all, very fast in translating texts and web pages, however,
   as the Grammar of German is complex, you need knowing
   a bit of German and having at hand a dictionary that includes
  exploded verb tenses in order to detect mistakes of the
  automated translation and get the right sense.

      I guess I discussed here before the outcome of one of
   the first attempts of computerized translation, the
    sentence: 'Spirit is strong, but flesh is feeble' was
   translated into Russian, and then went through
   a back-translation process, that resulted in:
     'Vodka is good, but Goulash is inedible'
     Have a good week, best regards. Salud †

      Salud †   Jose Gros-Aymerich

                    Madrid, Spain



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