Tuesday, March 3, 2015
Preliminary discussions regarding a heavily armed high-altitude fighter were held between the Koku Hombu and Tachikawa Hikoki KK in mid-1942. At that time the Japanese Army wanted to obtain a fighter fitted with a pressure cabin and capable of reaching a top speed of 800 km/h (497 mph) and having a maximum range of 3,000 km (1,864 miles). As these performance requirements were rather stringent, the Koku Hombu decided to instruct Tachikawa to proceed with the design of the aircraft while they placed a contract with Nakajima for another high-altitude fighter with a less stringent range requirement. The aircraft proposed by Tachikawa, which received the designation Ki-94 (later Ki-94-I), was of highly unconventional design. The aircraft was a large twin-boom monoplane powered by two 2,200 hp Mitsubishi Ha-211 Ru eighteen-cylinder air-cooled radials which were mounted fore and aft of the pilot's cockpit and drove four-blade tractor and pusher propellers. Proposed armament included two 37 mm (1.46 in) Ho-203 cannon and two 30 mm (1.18 in) Ho-105 cannon, and a maximum speed of 780 km/h (485 mph) at 10,000 m (32,810 ft) was anticipated. A full-size wooden mock-up was completed late in 1943, but development of the aircraft was discontinued as the Technical Department of the Koku Hombu judged the project too complex and its calculated performance unduly optimistic.
Soon after, Tachikawa submitted a new proposal designed to meet the same requirements as the competitive Nakajima Ki-87. The new aircraft was a single-engined single-seat high-altitude fighter of conventional design with laminar-flow wings and featuring a pressure cabin mounted in the fuselage behind the wing trailing edges. The aircraft was to be powered by a fan-cooled turbosupercharged 2,400 hp Nakajima [Ha-44] 12 eighteen-cylinder radial, rated at 2,450 hp for take-off, 2,350 hp at 1,100 m (3,610 ft), 2,200 hp at 4,400 m (14,453 ft) and 2,040 hp at 11,000 m (36,090 ft), and driving a six-blade propeller, and the wing-mounted armament was to include two 30 mm (1.18 in) Ho-105 cannon and two 20 mm (0.79 in) Ho-5 cannon. The proposal was accepted by the Koku Hombu which ordered one static test airframe, three prototypes and eighteen pre-production aircraft under the designation Ki-94-II. The first Ki-94-II was scheduled for completion on 20 July, 1945, but eventually was completed two weeks behind schedule. The six-blade propeller planned for the Ki-94-II was not ready in time, and it was decided to begin testing of the first prototype on 18 August, 1945, by temporarily fitting a four-blade airscrew. A second prototype, intended to be fitted with the six-blade propeller, was under construction, but the end of the war prevented it from being completed, while the first aircraft was still being readied for its intended maiden flight three days later.
Manufacturer: Tachikawa Hikoki KK (Tachikawa Aeroplane Co Ltd).
Type: Single-engined high-altitude fighter.
Crew (1): Pilot in pressurised cockpit.
Powerplant: One 2,400 hp Nakajima [Ha-44] 12 eighteen-cylinder air-cooled radial engine, driving a (1st prototype) four-blade or (planned production aircraft) six-blade constant-speed metal propeller.
Armament: two wing-mounted 30 mm (1.18 in) Ho-105 cannon and two wing-mounted 20 mm (0.79 in) Ho-5 cannon. External stores: one 500 kg (1,102 lb) bomb.
Dimensions: Span 14 m (45 ft 11 3/16 in); length 12 m (39 ft 4 7/16 in); height 4.65 m (15 ft 3 1/16 in); wing area 28 sq m (301.388 sq ft).
Weights: Empty 4,690 kg (10,340 lb); loaded 6,450 kg (14,220 lb); wing loading 230.4 kg/sq m (37.2 lb/sq ft); power loading 2.6 kg/hp (5.8 lb)/hp).
Performance: Maximum speed 712 km/h (442 mph) at 12,000 m (39,370 ft); cruising speed 440 km/h (273 mph) at 9,000 m (29,530 ft); climb to 10,000 m (32,810 ft) in 17 min 38 sec; service ceiling 14,680 m (48,170 ft); range 2,100 km (1,305 miles).
Production: One prototype competed by Tachikawa Hikoki KK in August 1945.