As well as being formidable fighters, K-84 fighter-bomber models also entered service. On April 15, 1945, 11 Hayates attacked US airfields on Okinawa, destroying many aircraft on the ground.
The final American pilot to score five aerial victories was Capt. Abner M. Aust, Jr, of the 506th Fighter Group making him the last American ace of World War II. His kills included two Zeros and three Ki-84 Hayate (Gale) fighters.
Firepower – The combination of two 30mm and two 20mm cannon with good ammo loads gives the Frank-Ic a firepower as good as any other single-engine fighter.
Speed – Though somewhat slower than Frank-Ia, the -Ic is still one of the faster prop planes in the game.
Bomb Load – With a capacity of only two 551 lb bombs, the Frank-Ic has to rely on its guns to make it a capable ground-attack fighter.
Ki-43s were only just starting to see action when the Koku Hombu ordered Nakajima to develop a replacement. The specifications called for a top speed of at least 640 kph (398 mph) and range long enough to allow it to operate at combat settings for 1 1/2 hours 400 km from base. Provisions for pilot armor and self-sealing fuel tanks were required and the armament was to consist of a pair of 12.7mm Ho-103 machine guns in the cowl and a pair of 20mm Ho-5 cannon in the wings.
Design work began in early 1942 and in April 1943 the first prototype, powered by the 18-cylinder Ha-45 radial engine, took to the air. Testing proceeded smoothly and by June the first machines were handed over to the JAAF for Service Trials. Pilots by now were recognizing the value of speed and durability and although the top speed was a bit lower than required, at 624 kph (388 mph) it was the best plane the Army had available for immediate production.
Eighty-three pre-production machines were built between August 1943 and March 1944, with minor changes to the structure being made throughout the process. Upon completion of Service Trials, the Ministry of Munitions ordered the plane into production as the Ki-84-Ia. A second batch of pre-production machines was then started with the final changes to the airframe structure, which included a rack under each wing capable of carrying a 300 liter drop tank or a 250 kg. bomb. The experimental Chutai, which had operated the Ki-84 during Service Trials, was disbanded with most members being used to form the 22nd Sentai, which was equipped with Hayates and shipped to China to face off against Chenault’s 14th Air Force.
Five weeks after being sent to China, the 22nd Sentai was transferred to the Philippines where they joined five other Hayate Sentais in head-to-head combat with the best Allied fighters of the time. Quickly dubbed the “Frank” by the Allies, it was found to be slower than the P-51s and P-47s it faced, but could climb and turn much quicker than either American fighter and was therefore considered a formidable opponent. However, the engine was difficult to maintain and the hydraulic system suffered from sudden failures. This combined with a weak main gear that often collapsed on landing, caused by poor manufacturing standards rendered many aircraft unserviceable without even having seen action.
Shortly after the introduction of the Ki-84-Ia to combat, the company introduced another two variants to the production line, which would be assembled in parallel with the Ia. The Ib model had the two cowl mounted 12.7mm machine guns replaced by pair of 20mm Ho-5 cannon, while the 1c model replaced the wing mounted Ho-5s with 30mm Ho-155s instead. The Ic model was intended to be used as a heavy bomber interceptor, with its 30mm cannon capable of bringing down a B-29 with only a few hits.