Two types of rotary external combustion air engine are under development

• The first is semi rotary using a combination of reciprocating piston and rotating/spinning displacer
  Details of rotary displacer engines can found at :
  1. On the model engineering pages
  2. .

• The second is truly rotary. To date no fully rotary engine has been successfully tested.

  Details of current research can on the following web pages.

  1. The Quasiturbine in Canada
  2. Rotary Stirling engines in Australia
  3. Univ. of Karlsruhe: Institute of Reciprocating Engines who are experimenting with modified rotary i.c engines, similar to the Wankel rotary engine. Two engines are coupled together via a regenerator.