Instead of casting a steel or iron rotor housing would it not be
easier to wire edm one ?

O r if using the steel liner your picture 20121110_170021 6/11/2015
wire edm from aluminum plate complete with cooling fins,

This liner could allow twin spark plugs  thus allowing dual ignition

if the inner profile matched the external of the liner the aluminum
could be heat shrunk to fit

On another post there was a four rotor which seemed to be air cooled
but without cooling fins or was this a development by Tony Taghiem

Peter Whitehead

Wire EDM would be cost effective on the raw billet steel rotor
housing I think. Just to get rid of the mass of unneeded steel.

I am not sure of the finish quality however. The final finish, after
heat treating I suspect, would have to be done with a NC mill and a
grinding tool.

The EDM air cooling fins are totally out of the question as the EDM
cost would be astronomical. It would take too long and time is
money.

The real cost breakthrough here is using high fin density, mass
produced, extruded low cost aluminum heat sinks. These fins are on
the order of 1/16th" thick and on a 1/8th" inch pitch. The OMC
engineers would have given their right arm for that fin density and
the power of the  air cooled OMC snow mobile engine would be up by
150%.

Probably a patentable idea but I am giving it to the news letter
subscribers for nothing :-)  Its free. Just like the welded P-port
now viewed by 170,000 people on You Tube. God only know how many
people are now welding their rotary engine  p-ports to the steel
liner. :-) We have pictures of it being done in the Netherlands.

Paul Lamar


Hi Paul, can you explain this,

The OMC engineers would have given their right arm for that fin
density and the power of the  air cooled OMC snow mobile engine would
be up by 150%.

How would the power increase that much with fin density?  Could this
fins go radially around the housing, and still be effective ?

Steve Carlisel

To quote  OMC SAE Paper 730110

"The bmep  of an air-cooled RC is limited by the ability to cool the area between the minor axis at tdc and the major axis 90 deg after it. Approximately 80% of the heat is rejected in this area. Unlike a reciprocating engine, this area never receives any cooling from the inlet charge. "

"For maximum heat dissipation per unit volume, cooling should be proportional to the heat flux: there should be maximum fin area and high mass flow in areas of high heat flux, and no cooling where there is no heat flux. This idea has been used by others; in fact, Curtiss-Wright demonstrated it with their air-cooled, oil-cooled RC 2-90. But 0.050 in thick fins, machined on O. I 00 in centers, and a two-stage axial compressor running at 30,000 rpm was not economically feasible for OMC. To be cost competitive, we needed to die-cast the fins to size. Experience showed that O. I 00 in thick tapered fins, 1.5 in long, placed on 0.220 in centers, could be die-cast in production. "

"Early NACA work has shown that cooling fins can be mathematically modeled satisfactorily. In general, thin, closely spaced fins provided maximum heat rejection at all velocities tested (1, 2). With a projected heat flux, and manufacturing fin constraints, mass flow and pressure heads could be calculated. This quickly limited our options. "

BTW Steve please sign your message's with your full name. That adds work for me when you don't do that.

Paul Lamar


The Rotary Engine free News Letter. Powered by Linux. If you want
off the list PLEASE let me know and I will remove  you.  ACRE NL web
site. http://www.rotaryeng.net You Tube http://tinyurl.com/beqqxas
Copyright 1998-2016 All world wide rights reserved.