When design work had progressed far enough to allow it, Kawasaki built a full-scale mock-up of the Ki-88, which bore a strong resemblance to the P-39. After inspection of the mockup, the Japanese calculated a maximum speed for the aircraft of 600 km/hr (373 mph) at an altitude of 6,000 m (19,685 feet). This was only slightly faster than the Kawasaki Ki-61 Hien fighter, which already was in production. As a result, Kawasaki discontinued design work on the Ki-88 less than a year after beginning it.
