They are the initials of Miezyslaw Foltynski, designer of devices such as the MF-08 autogyro.

-The power plant had two puller propellers.

"The MF-08 gyrocopter with the MF-06 engine"

-The powertrain is surprisingly original as the two propellers are driven by a common shaft after the transmission made a turn towards the engines that were a set of two joined WSK-175 motorcycle engines.

“MF gyroplane power plant” (PiP-SP)

-See WSK for a photo of a single motorcycle engine.