Kawasaki Ki-108

The Kawasaki Ki-108 was a twin-engined high-altitude fighter based on the Ki-96 and Ki-102 developments of the Ki-45 Toryu. Kawasaki had been working on the Ki-96, a single seat version of the Ki-45, since the summer of 1942, and so when the Japanese Army issued an operational requirement for a single-seat high-altitude fighter Kawasaki's chief designer, Takeo Doi, suggested that the new aircraft be based on the Ki-96.

The new aircraft required a pressurized cabin. In most aircraft this is achieved by combining a largely airtight cabin with a source of pressurised air. On the Ki-108 Kawasaki attempted to produce a hermetically sealed cabin, with a double-glazed canopy and airtight entrance door, in an attempt to eliminate the need for compressed air, which required engine power to produce.

By the time Kawasaki were ready to being work on the two prototypes for the Ki-108 work on the single-seat Ki-96 had been abandoned in favour of the two-seat Ki-102. The seventh and eighth Ki-102b (ground attack) airframes were taken from the production line during the spring of 1944, and were given the pressure cabin and a modified tail. Both were powered by two turbo-supercharged Mitsubishi Ha-112-II Ru fourteen cylinder radial engines, and were armed with one 37mm Ho-203 cannon and two 20mm Ho-5 cannon (the same as on the Ki-96 and the Ki-102a).

The first prototype was completed in July 1944 and the second in August. Both were used for flight trials, during which one aircraft suffered a pressurization failure when the door blew off. The pilot was able to safely land the aircraft.

The Ki-108 was followed by two prototypes for the Ki-108 KAI, with a longer fuselage and wider and larger wings. Both changes were designed to improve the aircraft's performance at high altitudes. The first Ki-108 KAI was completed in March 1945 and the second in May 1945, way too late to be of any use for the Japanese war effort. Both were used for tests, but these had not been completed by the end of the war. Despite the increase in loaded weight the two Ki-108 KAIs were faster at altitude than the Ki-108s, suggesting that the modified wings and fuselage had been a success.

Ki-108
Engine: Two Mitsubishi Ha-112-II Ru fourteen-cylinder air-cooled radial engines
Power (per engine): 1,500 at take-off, 1,250hp at 26,900ft, 1,000hp at 32,810ft
Crew: 1
Wing span: 51ft 4 15/16in
Length: 38ft 5in
Height: 12ft 1 21/32in
Empty Weight: 11,684lb
Loaded Weight: 15,873lb
Max Speed: 360mph at 32,810ft
Service Ceiling: 44,290ft
Range: 1,118 miles
Armament: One 37mm Ho-203 cannon in nose, two 20mm Ho-5 cannon in fuselage

Ki-108 KAI
Engine: Two Mitsubishi Ha-112-II Ru fourteen-cylinder air-cooled radial engines
Power (per engine): 1,500 at take-off, 1,250hp at 26,900ft, 1,000hp at 32,810ft
Crew: 1
Wing span: 56ft 11 1/16in
Length: 42ft 9 25/32in
Height: 12ft 1 21/32in
Empty Weight: 11,464lb
Loaded Weight: 16,755lb
Max Speed: 373mph at 32,810ft
Service Ceiling: 44,290ft
Range: 1,367 miles
Armament: One 37mm Ho-203 cannon in nose, two 20mm Ho-5 cannon in fuselage

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How to cite this article: Rickard, J (21 October 2010), Kawasaki Ki-108, http://www.historyofwar.org/articles/weapons_kawasaki_ki-108.html

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