Nakajima Ki-87

The Nakajima Ki-87 was a Japanese high-altitude fighter-interceptor of World War II. It was a single seat, exhaust-driven turbo-supercharged engined, low-wing monoplane with a conventional undercarriage.

The Ki-87 was developed in response to American B-29 Superfortress raids on the Home Islands. It followed up on earlier research by Nakajima and the Technical Division of Imperial Army Headquarters into boosting a large radial engine with an exhaust-driven turbo-supercharger, which had begun in 1942, well before the B-29 raids began. The efforts of the Technical Division of Imperial Army Headquarters eventually culminated into the Tachikawa Ki-94-I, while the Ki-87 was developed as a fall-back project, using less stringent requirements. Nakajima started in July 1943 with the construction of three prototypes, to be completed between November 1944 and January 1945, and seven pre-production aircraft, to be delivered by April 1945. The Technical Division of Imperial Army Headquarters made itself felt during the development of the Ki-87 prototype when they insisted upon placing the turbo-supercharger in the rear-fuselage, and from the sixth prototype the Nakajima fighter was to have that arrangement. The Ki-87 had a rearward folding undercarriage to accommodate the storage of ammunition for the cannons, which were mounted in the wing.

Construction was delayed due to problems with the electrical undercarriage and the turbo-supercharger, and the first prototype was not completed until February 1945; it first flew in April, but only five test flights were completed, all with the undercarriage in the extended position.

General characteristics

• Crew: 1
• Length: 11.82 m (38 ft 9 in)
• Wingspan: 13.423 m (44 ft 0 in)
• Height: 4.503 m (14 ft 9 in)
• Wing area: 26 m² (280 sq ft)
• Empty weight: 4,387 kg (9,672 lb)
• Gross weight: 5,632 kg (12,416 lb)
• Max takeoff weight: 6,100 kg (13,448 lb)
• Powerplant: 1 × Nakajima Ha219 Ru (Ha-44 Model 11) 18-cylinder air-cooled radial piston engine, 1,800 kW (2,400 hp) for take-off, 1,641 kW (2,200 hp) at 1,500 m (4,921 ft)1,529 kW (2,050 hp) at 6,000 m (19,685 ft)1,380 kW (1,850 hp) at 10,500 m (34,449 ft)
• Propellers: 4-bladed constant-speed metal propeller

Performance

• Maximum speed: 706 km/h (439 mph, 381 kn) at 11,000 m (36,089 ft)
• Endurance: 2 hours
• Service ceiling: 12,855 m (42,175 ft)
• Time to altitude: 10,000 m (32,808 ft) in 14 minutes 12 seconds
• Wing loading: 216.6 kg/m² (44.4 lb/sq ft)
• Power/mass: 0.3161 kW/kg (0.1923 hp/lb)

Armament

• Guns: 2 × 30 mm (1.18 in) Ho-155 cannon in the outer wing panels and 2 × 20 mm synchronized Ho-5 cannon in the wing roots
• Bombs: 1 x 250 kg (550 lb) bomb under fuselage

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