The Tower info on the prop for the OS 120 AX in my earlier threath was incorrect. The manual itself proposes a 15x10-12 or 16x8-10. It would rev at 9.000 for 3.1 BHP. I'll go for this one for the size; fits with standard muffler in cowl. Weight 865 gramm including muffler. This engine has a lot of torque for a two stroke. And the last reason, I.ve got one already.
When I fly the bird I'll let you guys know if it has enough power.

Regards,

Eric Schumacher, Netherlands