Mitsubishi Shusui (Swinging Sword ) Experimental Single-seat, Single-engine Rocket-powered Fighter, meeting specification 19-Shi; Navy designation: Mitsubishi 19-Shi J8M1 (no reporting name); Army designation: Mitsubishi Ki-200 Shusui (no reporting name)
When American Boeing B-29 Superfortresses began to raid the islands of the Empire on a mass scale, the need to create a high-speed, fast-climbing, powerfully armed interceptor became ever more pressing for the Japanese aircraft industry. The Japanese, however, completely lacked experience in creating aircraft of such a class, and some initial work in this field had no effect on the bombing's intensity, since the interceptors available to the Army and the Navy were inadequate.
As usual, help came from Germany. In the autumn of 1943, at Oldenburg Air Base proving ground, Japanese military attachés were presented with a new miracle weapon, the Messerschmitt Me.163 Komet rocket-powered fighter. Its capabilities greatly impressed the Japanese. After brief negotiations, a license to produce the aircraft was purchased for 20 million Reichsmarks. As early as April 1944, a package of documents was dispatched on two Japanese submarines bound for Singapore. Some things were shipped together with the documents, such as a functional Walter HWK 109-509 rocket engine, an airframe, a number of production assemblies, and equipment components. Things did not turn out too well: one of the submarines was lost on the way after being spotted by the Allies. However, the main body of the documents was able to reach the 1st Naval Air Technical Arsenal in Yokosuka.
Unfortunately, the Japanese industry was not ready to manufacture a product of such advanced technology. Changes still had to be made, although it had been decided to stick to the documents received from the Germans as closely as possible. The main reason for the difficulties was the poor strength standards the Japanese had for the materials used. The Japanese metallurgical industry was not able to provide the high-strength alloy steels to manufacture the engine injectors, and the chemical industry could not provide the required amount of hydrogen peroxide as an oxidizer and hydrazine hydrate as a fuel. The development of the interceptor, which Mitsubishi specialists delved into as early as late June of 1944, was significantly drawn out. It was necessary, first of all, to modify the design to match the overall technological level of development of the Japanese aircraft industry.
In addition to technological problems, the designers were faced with purely technical difficulties. They needed to install some powerful armament, such as two 30mm Type 5 cannons that were larger in size than their German counterparts, the Rheinmetall-Borsig MK 108 cannons. In addition, the Walter HWK 109-509 engine produced by Mitsubishi under the designation Toko Ro.2 or KR10 was extremely accident-prone and thus dangerous. The engines regularly exploded during trial starts, killing one engineer after another. It should be noted that military specialists from both the Navy and the Army took an interest in the interceptor at the same time, but, despite the competition, the development was a joint venture. The Navy designated the project as the J8M1, whereas the Army's specialists designated it as the Ki-200, and the aircraft had a common name: the Shusui (Swinging Sword). Nevertheless, it was the engine-related problems that made the developers divide again into Army and Navy. As a result, the Army's specialists managed to assure the engine’s stable operation for 4 minutes, while the Navy's engineers achieved nothing more than 3 minutes.
On July 7, 1945, the test pilot Toyohiko Inuzuka flew the J8M1 interceptor for the first time. After the aircraft reached a height of 380 m, the engine stopped abruptly; the pilot managed to level the plane out and head back on a return course, but the situation could not be saved: the machine nosed over and was completely destroyed; the pilot died the next day from injuries sustained in the fall. Several more engine-related accidents resulted in the designers having only one KR10 left, but they failed to install it on any of the four finished J8M1 airframes because the war ended, and the project with it. By this time, the factory in Okha had 6 more airframes in different stages of preparation, 6 finished engines, and 20 more on the production line. Thus, the Japanese never managed to improve the aircraft to any flyable condition.