"The up and down bobbing triangular center body."

   There is no up and down Roger. A common mistake many make.
   The rotor CG orbits around the center of the e-shaft much like
   the earth orbits the sun. That is why it is sometimes called
   a planetary engine. Have you read the Kitplanes article yet?

   Here is a good one to read as well.

   http://www.rotaryeng.net/how-wank-works.html

   "Actually what is happening is the center or CG of the rotor is
   moving in a
   circle around the center of the output shaft while the output
   shaft rotates."

   "Since there are no reciprocation parts what so ever it is
   possible to   completely balance the Wankel engine just like a
   turbine or electric motor and   unlike any piston engine despite
   some claims to the contrary. The rotor is   balanced around it own
   axis. The front rotor balances the rear rotor as they are   180
   degrees apart on the output shaft. That leaves a small couple which
   is   finally completely balanced by the counter weights."

   Also go on youtube and watch many Wankel animations as there are
   dozens.

   The only limitations on the RPM of a rotary are due to centrifugal
   load of the rotor weight on the e-shaft rotor bearing.

   Paul Lamar
   --
   I'm no expert, but the two areas in which the Wankel would need to
 be  improved to significantly improve BSFC are  1) Reduction of
 waste energy in the exhaust (higher in the rotary than  in a piston,
 as evidenced by higher EGTs)

   2) Reduction of waste heat lost to the housing due to the
 relatively  inefficient shape of the combustion area (long, wide,
  and very thin  in a rotary= lots of surface area-to-volume,
 relatively compact and  cylindrical in a piston engine=less surface
 area per volume.

   It seems 1) could be reduced by turbocompounding, and 2) might be
   somewhat reduced by optimizing the engine geometry, but real
   improvements here await development of a practical ceramic engine
 or  other material breakthrough  (or some miracle way of recovering that
   low-quality waste heat in the cooling water--very unlikely).

   Mark W.

   The higher EGT is due to the fact there are no exhaust valves
   to absorb some of the heat. The RX8 engine is proof as the exhaust
 must  make a right angle to exit so some of that waste heat goes
  into the cooling system and the EGT is a couple of hundred  degrees
 F cooler.

   In the R3350 turbo compound engine 22% of the total energy in
   the exhaust went into the exhaust valve. Almost 50% of the kinetic
   energy went into the exhaust valve. That is why a rotary is so
   noisy. It is also why it makes an ideal turbo compound engine.

   I am beginning to think the old surface area to volume ratio reason
   is invalid. Both the 16x and the Wankel SuperTec engines have
   worse  surface area to volume ratios yet are more efficient
   than the current geometry.

   Paul Lamar

 There could be a difference in the area if it is the end plates or
 the rotor housing. If the fuel has a tendency to be pushed to the
 rotor housing causing poor burn the solution may be in a narrower
 housing with greater eccentricity. The side housing area is larger
 but may not affect the burn the same. Also in reading, the flame
 does not get all the way to the sides of rotors more than 76mm wide.
 This seems to explain a lot of why Mazda would narrow the housings.
 It gives more complete burn the same as the 3rd plugs in the 26B Le
 Mans engine.

 Dale Davies

 Actually the fuel being pushed to the rotor housing is an advantage
 as the engine will run with 20:1 air fuel ratio unlike a piston
 engine and gain BSFC in the bargain.

 I think you are right on the rotor width but that does not take
 into consideration  two sparks plugs side by side in the leading
 position. Austro engines use this trick on their wider rotors.

 Read Norton geometry.

 Paul Lamar


You mean I am not the only one to come up with the idea to put spark plugs
beside each other, say at 1/4 and 3/4 of the rotor width?  :-)))

Dale Davies

I am afraid not Dale. Sorry :)

Paul Lamar