Aviation of World War II

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  • Mansyu

Heavy attack aircraft and high-altitude interceptor fighters occupied a special place in the development of promising new aircraft designs to update the aging fleet. "Mansyu" tried to summarize for itself the optimal requirements for a new multi-role fighter. By July 1943, a working design for the Ki-98 was completed, and a full-scale wooden mock-up was built in December. However, design work continued into early 1944 with the aim of some refinement of the Ki-98 design. The model of the aircraft was sent to Japan for wind tunnel testing. Unfortunately for Mansyu, the deteriorating military situation in Japan meant that some of the company's employees were transferred to other jobs and other firms, and this, combined with many design changes, greatly slowed down work on the Ki-98. Nevertheless, tests in a wind tunnel showed excellent results and the "Mansyu" began preparations for the construction of a prototype.

In the spring of 1944, the Mansyu leadership was informed that the Ki-98 should be adapted for the role of a high-altitude fighter. Having received this news, "Mansyu" was forced to significantly change the existing structure to meet the new requirements, which further slowed down the work.

One of the most important changes was the need to use a turbocharged engine, as a result of which the Na-211-III was replaced by the Mitsubishi Na-211 Ru, of significantly larger dimensions. The turbocharger required additional piping to match, which of course was not originally included in the design. The new engine was much larger than the original, and this forced the fuselage to lengthen and widen. Since a new larger diameter propeller was used, the tail booms had to be spaced further apart and, as a result, the wings had to be redesigned as well. Finally, the glider had to be strengthened due to the increased weight of the structure. Another change was to make it easier for the pilot to escape in an emergency. Considering the great difficulties in this, the refusal to leave the aircraft through the nose landing gear compartment was provided, and explosive bolts were included in the design for emergency shooting of the propeller blades and tail. Thus, the pilot could get out of the plane in an emergency in a more traditional way. The Ki-98's armament remains unchanged. The redesigned project was ready by October 1944, followed by a new stage in prototyping the redesigned fuselage. Mansyu's management expected the first prototype to be completed and ready for flight tests in early 1945. These plans collapsed after an American bombing raid on Harbin on December 7, 1944. Thus, work on the construction of the Ki-98 prototype began only in mid-January 1945. Despite Mansyu's attempts to accelerate the pace of work, the reality still lagged behind plans.

On August 8, 1945, the Soviet Union declared war on Japan and the next day launched an invasion of Manchuria. The Imperial Army of Manchukuo and the Japanese Kwantung Army were unable to withstand the Soviet forces. In order to prevent the Soviets from seizing materials on the aircraft, it was decided to destroy all documentation, including models, mock-ups, fixtures, tools and an incomplete prototype of the Ki-98.

Mansyu Ki-98
Crew 1
Wing span, m 11.24
Wing area, m² 24.00
Length, m 11.38
Height, m 4.29
1×PE Mitsubishi Ha-211 Ru
Power, hp 1×2200
Weight, kg:
Empty weight 2880
Loaded weight 3442
Maximum speed, km/h 731
Cruising speed, km/h 654
Service ceiling, m 12,000
Service range, km 1000

Armament. Two 20mm Ho-5 cannons and one 37mm Ho-204 cannon, light bombs.

Photo Description
Drawing Mansyu Ki-98

Drawing Mansyu Ki-98

Structurally, the Ki-98 fighter was a single-engine fighter with a two-blade pusher propeller.

Ki-98 Layout diagram

The power plant is a radial 18-cylinder air-cooled Mitsubishi Na-211-III engine mounted in the fuselage behind the cockpit. A four-bladed pusher propeller located at the end of the central nacelle was driven by a two-meter shaft. To improve the aerodynamic properties for engine cooling, the designer abandoned the standard air intakes, using the original "gills" located behind the cockpit in the upper part of the fuselage-nacelle. To increase the air flow to the engine, it was equipped with a fan, also driven by the engine, but located in front of it. The cooling air passages ended behind the engine, just in front of the propeller, with a series of small nozzles. A wing with a profile close to laminar was located in the lower part of the fuselage, from each half-wing there was a long thin tail boom with keel washers at the end and with a stabilizer between them.

The aircraft used a three-wheeled landing gear with a front support, which was retracted back into a niche under the cockpit, the main struts were retracted inside the tail booms. Since the cockpit was high enough above the ground, access to the cockpit was through the niche of the front landing gear. In the event of an emergency exit from the plane, the pilot had two options to choose from. He could get out traditionally through a drop-off canopy to almost guaranteed to get into the plane of the propeller. Mansyu recommended a second escape route, through a hatch at the bottom of the aircraft. This allowed the pilot to avoid a collision with the stabilizer, and somewhat increased the chances of not being hit by the propeller.

A drop-shaped cockpit canopy provided excellent visibility in all directions. The armament was supposed to be very powerful, two 20-mm No-5 cannons and one 37-mm No-204 cannon. All the guns were concentrated in the bow of the central nacelle, with the barrels protruding strongly forward due to the relatively short fuselage-nacelle and lack of space.


  • Experimental Japanese aircraft of the Second World War / Evgeny Aranov /
  • Japan Aviation /Andrey Firsov /
  • Encyclopedia of Military Equipment / Aerospace Publising /

Add Comment

November 22, 2019
About leaving the aircraft through the niche of the front landing gear. Such a move is possible only with a working hydraulic system and the presence of pressure in it, because it is hardly possible to release the front support against the air flow in case of its failure. From here there is only one option - inverted aerobatics with the creation of negative G-forces for the forced leaving of the aircraft. However, even in this case, a safe leaving of the aircraft is only possible when the blades are fired.