Abstract: An internal combustion (IC) engine with at least one pair of aligned and opposed cylinders has a reciprocating double-headed piston in each cylinder pair. The axis of the double-headed piston is perpendicular to a driveshaft. The reciprocating motion of the double-headed piston is transmitted to the driveshaft by a rotating crankdisk. The crankdisk is rigidly mounted to the driveshaft, which is rotably mounted to a crankcase. The resulting IC engine has a low engine profile, as well as simpler engine construction with fewer moving parts and fewer bearing surfaces compared to conventional IC engines and yoke-type engines.