The Kawasaki Ki-61 Hien or Type 3 Fighter remains to this day one of the most recognizable Japanese fighters of the World War II era. What makes Hien unique is the powerplant - it was the only mass-produced Japanese fighter powered by an inline, liquid cooled engine. The Ki-61 began to arrive at the frontlines in large numbers in the summer of 1943 and took part in battles over New Guinea and later over the Philippines and Okinawa, as well as in the...