Kawasaki Ki-102 Army Type 4 Assault Plane

The Kawasaki Ki-102 Army Type 4 Assault Plane was a twin-engined heavy fighter developed from the Ki-45 Toryu via the single-seat Ki-96, and which saw limited service over Okinawa.

Work on the single-seat Ki-96 began in the summer of 1942, originally as the Ki-45-II, a larger version of the standard Ki-45, and retaining the earlier type's two crewmen. In December 1942 the Japanese Army ordered Kawasaki to develop the new aircraft as a single-seater, with the new designation of Ki-96. The first prototype was by then quite close to completion, and so it was completed with the original forward cockpit while the rear cockpit was faired over. Two further prototypes were completed with a purpose-built single-seat cockpit and canopy, but by the time the first prototype made its maiden flight in September 1943 the Japanese Army had changed its mind again, and Kawasaki were ordered to produce the aircraft as a heavily armed two-seat close support and ground attack fighter.

This didn't cause the Kawasaki design team, led by Takeo Doi, many problems. They simply reverted to the original layout of the Ki-45-II, restoring the second cockpit faired over on the first Ki-96 and retaining the same Mitsubishi Ha-112-II engines. Armament was increased, with the 37mm cannon of the Ki-96 replaced by a 57mm Ho-401 cannon in the nose. The two 20mm cannon in the fuselage were retained, while the second crewman was given a rear-pointing flexibly-mounted 12.7mm Ho-103 machine gun.

The first of three Ki-102 prototypes made its maiden flight in March 1944. They were followed by twenty pre-production aircraft, before production of the main Ki-102b Army Type 4 Assault Plane Model B began in October 1944. A few aircraft saw combat over Okinawa, but most were retained in Japan.

Kawasaki were also ordered to produce a high altitude pressurized version of the aircraft, as the Ki-108. It was obvious that this would take some time to produce and so in February 1944 work began on an unpressurised high-altitude version of the Ki-102, the Ki-102a. This was given the same turbo-supercharged engines as the Ki-108, and the first aircraft was completed in June 1944. Six prototypes were followed by twenty further aircraft, all produced by modifying existing Ki-102s or Ki-102bs, but the type never entered production.

The same was true for the Ki-102c night fighter, of which four prototypes were built before the end of the war.

Variants

Ki-102

The Ki-102 was the designation given to the three prototypes of February-March 1944 and to the twenty pre-production aircraft of April-October 1944. These aircraft were all originally built as ground attack aircraft, although six of the pre-production aircraft were later modified to become Ki-102a high altitude fighters. As originally built the Ki-102 was powered by two standard Mitsubishi Ha-112-II radial engines, and were heavily armed, with one 57mm Ho-401 cannon in the nose, two 20mm Ho-5 cannon in the fuselage and one flexible rear-firing 12.7mm Ho-103 machine gun controlled by the second crewman.

Ki-102a

The Ki-102a was a high-altitude fighter version of the Ki-102a developed in an attempt to fill the gap left by the long development time needed to produce the pressurised Ki-108. Work on the Ki-102a began in February 1944. It used the same turbo-supercharged Mitsubishi Ha-112-II Ru engines as the Ki-108. These engines could operate at full power at up to 26,900ft, an improvement of 8,000ft on the standard Ha-112-II. The Ki-102a was more lightly armed than the ground attack versions, replacing the 50mm cannon with a 37mm Ho-203 cannon and removing the rear-firing machine gun. The two 20mm Ho-5 cannon were retained.

Six prototypes were produced by modifying six of the Ki-102 pre-production aircraft. These were followed by twenty further aircraft produced by modifying standard production Ki-102bs. Only fifteen of this batch of twenty aircraft reached the Army. 

Engine: Two Mitsubishi Ha-112-II Ru fourteen cylinder radial engines
Power (each): 1,500hp at take-off, 1,250hp at 26,900ft, 1,000hp at 32,810ft
Crew: 2 - pilot and radio-operator
Wing span: 51ft 1in
Length: 37ft 6 25/32in
Height: 12ft 1 21/33in
Armament: One 37mm Ho-203 cannon in fuselage, two 20mm Ho-5 cannon mounted obliquely
External stores: Two 44 gallon drop tanks

Ki-102b

The Ki-102b Army Type 4 Assault Plane Model B was the only version of the Ki-102 to enter full production. A total of 215 were produced between October 1944 and July 1945, of which twenty were later modified to become Ki-102as and two became the prototypes for the Ki-102c.

The Ki-102b closely resembled the original Ki-102 prototypes and pre-production aircraft, with the same Mitsubishi Ha-112-II air-cooled radial engines, and an armament of one nose mounted 57mm Ho-401 cannon, two fuselage mounted 20mm Ho-5 cannon and a rear-firing flexibly mounted 12.7mm Ho-103 machine gun. The only significant change on the Ki-102b was the introduction of a longer tail wheel strut, which reduced the time it took for the tail to settle to the ground during landing. This was introduced because the aircraft suffered from directional instability during the landing approach - the new strut reduced the amount of time that the pilot was exposed to this problem.

The Ki-102b saw very little active service. A small number were sent to Okinawa, where they were given the Allied code name 'Randy', but most were kept back in Japan, where they were to be used against the expected Allied invasion.  

Engine: Two Mitsubishi Ha-112-II fourteen cylinder air-cooled radial engines
Power (each): 1,500hp at take-off, 1,350hp at 6,560ft, 1,250hp at 19,030ft
Crew: 2 (pilot and radio operator)
Wing span: 51ft 1in
Length: 37ft 6 25/32in
Height: 12ft 1 21/33in
Empty Weight: 10,913lb
Max Speed: 16,094lb
Service Ceiling: 32,810ft
Range: 1,243 miles
Armament: One 57mm Ho-401 cannon in the nose, two 20mm Ho-5 cannon in the fuselage, one flexibly mounted rear-firing 12.7mm Ho-103 machine gun
Bomb-load: Two 551lb bombs or two 44 gallon drop tanks

Ki-102c

The Ki-102c was a night fighter based on the Ki-102a. It was given a longer fuselage, a new tail and both the wing span and wing area were increased to improve high-altitude performance (a similar wing was used on the Ki-108 KAI). Turbo-supercharged Ha-112-II Ru engines were used. Radar was carried, wit the revolving antenna mounted in a Plexiglas radome above the fuselage. The Ki-102c was armed for the night fighter role, with two forward firing 30mm Ho-105 cannon and two obliquely mounted 20mm Ho-5 cannon carried behind the cockpit (to allow the aircraft to sit below an American bomber, avoiding most of its turret guns).

Two prototypes were built by modifying Ki-102b airframes. The first was completed in July 1945 and the second in August, but the end of the war meant that their flight trials were never completed.

Engine: Two Mitsubishi Ha-112-II Ru fourteen cylinder radial engines
Power (each): 1,500hp at take-off, 1,250hp at 26,900ft, 1,000hp at 32,810ft
Crew: 2 - pilot and radar operator
Wing span: 56ft 7 1/8in
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: Two 30mm Ho-105 cannon in the nose, two 20mm Ho-5 cannon carried obliquely in the fuselage
External stores: Two 44 gallon drop tanks

Ki-108

A high altitude single-seat fighter, with two prototypes based on Ki-102b airframes and two Ki-108 KAI prototypes with expanded fuselage and wings.

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How to cite this article: Rickard, J (21 October 2010), Kawasaki Ki-102 Army Type 4 Assault Plane, http://www.historyofwar.org/articles/weapons_kawasaki_ki-102.html

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