Rolssi is a true Finnish classic originally designed back in 1936 at Vyborg Finland by Urho Purhonen and Aarne Heikkinen.
My friend and model engine builder colleague KalleR made the CAD model couple of years ago and built a fine example of this same design about a year ago. This is the second succesful replica of the original engine that I built. The build started in October and the first run of the engine was achieved first of February 2024.
Rolssi seems to be quite sound design given its age and is an easy starter and puts out over 0,2HP at around 6800rpms.
My example has ran now 8th times in total on cdi ignition and future plans hold a proper vintage spark ignition with coil and points and also a vintage style period correct wooden propeller.
The performance with Master Airscrew 12x5 Scimitar propeller is 7000rpms (0.24bhp) and fuel consumption around 236ml/h!