Nakajima Ki-87

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.^[1] 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.^[2][3] 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.^[3] 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.^[4][5] The Ki-87 had a rearward folding undercarriage to accommodate the storage of ammunition for the cannons, which were mounted in the wing.^[1][6]

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.^[6][7]

A further variant, the Ki-87-II, powered by a 3,000 hp (2,200 kW) Nakajima Ha-217 (Ha-46) engine and with the turbo-supercharger in the same position as the P-47 Thunderbolt, never went further than the drawing board.

Production of five-hundred aircraft was planned, but the War ended before any more than the single prototype were built.

The sole completed prototype was in natural metal finish; some paintings show a black anti-glare area in front of the cockpit, but this is not seen on any of the known photographs of the plane.^[1][8][9] However, James P. Gallagher took a photo of the Ki-87 at the abandoned Japanese Army fighter base at Chofu after Japan's surrender. The photo clearly shows a black anti-glare area from the cockpit forward to the tip of the nose.^[10]

Data from Japanese Aircraft of the Pacific War;^[6] Japanese Army Fighters, Part 2;^[7] Famous Aircraft of the World, first series, no.76: Japanese Army Experimental Fighters (1)^[11]

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

1,600 kW (2,200 hp) at 1,500 m (4,900 ft)

1,530 kW (2,050 hp) at 6,000 m (20,000 ft)

1,380 kW (1,850 hp) at 10,500 m (34,400 ft)

• Propellers: 4-bladed constant-speed metal propeller

Performance

• Maximum speed: 706 km/h (439 mph, 381 kn) at 11,000 m (36,000 ft)
• Endurance: 2 hours
• Service ceiling: 12,855 m (42,175 ft)
• Time to altitude: 10,000 m (33,000 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 (0.79 in) synchronized Ho-5 cannon in the wing roots
• Bombs: 1 × 250 kg (550 lb) bomb under fuselage

Aircraft of comparable role, configuration, and era

• Blohm & Voss BV 155
• Curtiss XF14C
• Fisher P-75 Eagle
• Focke-Wulf Ta 152H
• Republic P-47N Thunderbolt
• Republic XP-72
• Tachikawa Ki-94-II