Engines 2 or 4 stroke?

[twistedhickey]

I am researching a design for a gyro, I have a few questions about engines.

I have become informed of the Rotax 440, and others, My question is about rotary engines.
I have become aware of the rotary that are used for Para sailing. These engines are 4 stroke, light weight, less vibration,better gas consumption and come in 40hp designs.
Can these engines be used on Gyro copters?

 

[Dana]

 

[twistedhickey]

 

[charles]

 

[twistedhickey]