The Ki-61 Ib Hien, code named Tony by the Allies, was designated Army Type 3 Fighter powered by an unreliable Kawasaki Ha-140 providing 1,175 hp for takeoff. In fact, when attacking B-29s Hiens often had to be protected by Ki-100s. The Ki.61-Ib overall however had good performance, especially at high altitude, the maximum speed reaching 589 km/h(366 mph).
The armament consisted of 3 possible configurations; two fuselage-mounted 12.7-mm (.50 cal)and two wing-mounted 7.7-mm (.30 cal) machine guns, four wing-mounted 12.7 mm (.50 cal) or four German-supplied Mauser MG 151/20 20 mm cannons. With its armor protection, self-sealing tanks, good armament and excellent diving speed, the Ki.61-Ib became much more of a problem for allied pilots than the Nakajima Ki.43
The armament consisted of 3 possible configurations; two fuselage-mounted 12.7-mm (.50 cal)and two wing-mounted 7.7-mm (.30 cal) machine guns, four wing-mounted 12.7 mm (.50 cal) or four German-supplied Mauser MG 151/20 20 mm cannons. With its armor protection, self-sealing tanks, good armament and excellent diving speed, the Ki.61-Ib became much more of a problem for allied pilots than the Nakajima Ki.43