Complex sentence: Bek flew a homebuilt category version of the Me 109 in 1996, powered by a Hirth F30 and later a Subaru automotive conversion, which became the prototype of the Me 109R kit aircraft.
Split into simpler sentences: Bek flew a homebuilt category version of the Me 109 in 1996, powered by a Hirth F30 and later a Subaru automotive conversion. This was the prototype of the Me 109R kit aircraft.