Just for interest, trying to choose 100-200BHP and similar configs (2 "bangs" per crank rev). Using maximum powers and installed weights:
Mistral G-190 Rotary: 1.0 kW/kg - Avgas
Freedom Rotapower: 1.65 kW/kg - Avgas
Wilksch WAM-160: 1.0 kW/kg - TurboDiesel
Deltahawk DH160-V4: 0.68 kW/kg - TurboDiesel
Lycombing 0-320 D: 0.83 kW/kg - Avgas
Assuming that the Freedom figures are dry, installed specific power is probably also about 1kW/kg. The Deltahawk suffers because it is a loop scavenge 2-stroke, with nowhere near the volumetric efficiency of the Wilksch uniflow scavenge. Being very mean a VW TDI cast iron lump is probably about 0.5 kW/kg, but an aero redesign would approach the lycombing 4-stroke.
The practical upshot is that rotary offers little benefit over say a 2-stroke turbodiesel. This is why i feel that turbodiesel piston is the way to go, albeit requiring development to reduce weight. To my mind push the turbo boost way up and go for a small, but very solid, piston 4-stroke...
Mart
Last edited by Graviman; 23rd May 2006 at 22:00.