The first prototype of the "San-shiki-Sentohki ichi gata" ("Type 3 Fighter, Model 1", the official IJAAF designation) first flew in December 1941 at Kagamigahara Airfield. Although test pilots were enthusiastic about its self-sealing fuel tanks, upgraded armament, and good dive performance, the wing loading of 146.3 kg/m2 (30 lb/ft2) at an all-up weight of 2,950 kg (6,500 lb) was viewed with scepticism by many of the senior officers of the "Koku Hombu", who still believed in the light, highly manoeuvrable, lightly armed fighter epitomised by the then new Nakajima Ki-43-I-"Hei" which had a wing loading of 92.6 kg/m2 (19 lb/ft2) (and even that was considered borderline compared to the earlier Ki-27).