Hey Paul and all,

   Ok I have been going thru the Sachs, I must have put it in a dozen different positions and stared at it for hours on hours just thinking.

   Now a question for you Paul specifically:

   1.  So the Teflon seals impregnated with glass and or carbon fibers, what was the temperature limit for these seals?

   2.  Do you think it could take the temps as apex seals? (just looking thru the papers from Mazda about combustion chamber temps) it would be close.


   3.  We had talked before, and you had suggested using a thin steel and shaping it and letting it spring into place or anchor it in place. What about using a thicker say .125 stainless steel sheet, put it through a roller to shape it properly and then freeze it, heat the rotor housing and slip the two together using Hysol or some other structural adhesive that will take high temps?  The SS will help raise the BSFC and keep more of the heat in the combustion chamber.
   The only problem I see is welding the two ends ends of the SS sheet in such a manner to try and prevent it cracking and coming free.

   For everyone:

   I have been mulling around the bearings and cooling oil and lubrication. I have quite a bit of experience with turbine engines and bring some of that to the mix on this project. I am thinking about using turbine oil like we used in the lycoming turbines (T53-13B, T53-703, T55) and the GE700 series, 23699 mil spec. I think it is thin enough that it will flow very well, in the case it should froth/mist enough coming off the rotor to cool the rotor, also will probably have to cover 50 to 60% of the bearing to prevent over oiling and floating the balls and rollers, but enough of the misting oil should lubricate them fine. Plus the oil is specifically designed for high temp.

   The charge cooling ports are on the bottom side of the end plates, so the oil injectors can be placed there plus can be used as the oil drain ports too. I have though the rotor might need some modification to keep oil from pooling inside, but after thinking about it no mods to the rotor will be needed.

   Also been thinking about the oil pump, I have been looking at the georotor pump from the Onan generator. They are cheap and easy to find, one on each end of the motor driven by the e-shaft and pumping directly to the oil injector that is in the end plate. This set up should give us the oil flow needed to cool the rotor without requiring too much power from the engine.

   Moving to oil cooling the rotor and away from charge cooling should improve power. then having the housings water cooled will increase the engine weight but with more power being produced and sustained is worth it.


   Ok, so open to comments, suggestions and more ideas.

   David Mikesell

   Quest 1: 500F. Carbon and glass will go higher than that. Carbon
   possibly higher than glass.

   Quest 2:  I think it is worth a try. Compared to some other solutions
   it might be less expensive.

   Mazda tries to keep the apex seals less than 500 F.
   Steel ball bearings and iron starts to lose it's strength.

   Silicon Nitride ball bearings are good to 1000 F.

   I suspect the same thing is true for silicon nitride apex seals.

   In that case there is something to be gained by alloying the combustion
   chamber walls to run higher than 500 F. This would let out aluminum.
   The Mazda walls are of course steel so a steel liners for the Sach and
   OMC are advisable. The steel liners in the Mazda are grooved on the
   out side. This allows a higher heat transfer rate to the aluminum.

   If one pressed a steel liner in the OMC or Sach it would run higher
   temperature. Combined with silicon nitride seals that combination
   might work and show better BSFC in the bargain.

   If you made it .125 one could machine the trochoide part in an
   NC mill and the outside part could be simpler shape like two circles
   with a straight part between them. It would be best if the inside
   would be reverse chrome plated. This was done in WW II for Navy
   radial engines. Same as the Mazda. The side housing could be a simple
   sandwich of flat steel chrome plated and the original aluminum.

   As far as I know nobody has tried this combination with less
   cooling so far and did any data gathering.


   Paul Lamar



If you are going to build aircraft engines let's think a bit like how Mazda engineers think.
The main production engines all shared an eccentricity of 15 mm and rotor radius of 105 mm. That is a 7:1 ratio. Different ratios give different trochoid shapes.
Mazda also produced the rare 13A engine used in the front wheel drive R130 Luce based car. This had eccentricity of 17.5 mm and radius of 120 mm. The rotor width was the same as the 100 engine at 60 mm. The radius to eccentricity ratio was 6.857:1
If you used the 13A dimensions with the 70 mm rotor width used for the 13A engines you get a displacement of 1308 cc which is identical to the 13B displacement. This should provide slightly more torque.


If you stretch the radius to the 7:1 ratio the displacement jumps from (for racing calculations) 2618 cc to 3119 cc. If you push the radius to 125 mm the displacement jumps to 3183 cc. Close to what Mazda' 16X could be. On power per liter basis the RX8 power of 240Hp would be about 290 to 295Hp. Also close to the claims for the 16X.
Copying the 13A rotor gears and rotor bearing dimensions would simplify design. The rotor width makes Ianneti apex seals easily available. Then it is just a matter of building wider rotors and housings.


With power recovery 365Hp is probable with exceptional economy. Using a turbo set up to cruise at 6000RPM could give 500 HP for takeoff and power recovery off the turbine shaft. Sequential turbos to normalize the engine to fl280  could give very efficient flight.
The advantage to copying Mazda production dimensions is they work and would lower design expenses. These engines are old enough that patents have pretty much run out.

Dale Davies



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