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| The Mitsubishi J8M1 Shusui (Sword Stroke) During the war, Japanese military attaches in Germany were aware of the existence of the Messerschmitt Me 163B Komet rocket-powered interceptor, and in late 1943 Japan arranged to purchase a license for manufacture of the Komet. For the sum of 20 million Reichmarks, Japan also purchased the manufacturing rights to the Walter HWK 109-509 rocket engine together with one completed example. Faced with the onset of B-29 raids on the Japanese home islands, the military was in desperate need of an effective interceptor to counter the Superfortress. In July 1944, the Japanese Navy issued a specification for a rocket-powered interceptor based on the Me 163B. The task of designing and producing the aircraft was assigned to Mitsubishi Jukogyo K.K. Both Army and Navy versions were planned--- the Army designation was to be Ki-200 Army Experimental Rocket-Powered Interceptor and the Navy designation was to be J8M1 Navy Experimental Rocket-Powered Interceptor Fighter. The popular name for both versions was Shushi (Sword Stroke). The Japanese-built version of the HWK 109-509 rocket engine was designated Toko Ro.2 (KR10), and had an estimated thrust of 1,500 kg (3,307 lb). It was quite similar to its German inspiration, but did have some modifications to adapt it to Japanese production techniques. Progress on the aircraft proceeded rapidly under the direction of Mijiro Takahashi of Mitsubishi, in spite of the fact that a submarine bringing an example of the Me 163B and a set of full technical data back to Japan had been sunk en route. The team at Mitsubishi had only a simple instructional manual to work with, but a mock-up of the Shusui was completed and ready for inspection in September 1944. A glider version of the Shusui was also designed. It was to act as a trainer for pilots who would be flying the J8M1. The glider version was designated MXY8 Akigusa (Autumn Grass), and was built by the Dai-Ichi Kaigun Koku Gijitsusho (First Naval Air Technical Arsenal) at Yokosuka. The MXY8 was taken to Hyakurigahara Airfield in Ibaragi Prefecture for tests upon completion. It flew for the first time on the 8th of December 1944, towed into the air by a Kyushu K10W1 of the 312th Kokutai and piloted by LtCdr Toyohiko Inuzuka. Despite its unusual configuration, it handled well. Two additional MXY8 prototypes were built at Yokosuka. A heavier version of the MXY8 was planned, fitted with water ballast tanks to simulate the characteristics of a fully loaded J8M1. It was to be built for the Navy by Maeda Koku Kenkyujo (Maeda Aircraft Institute) and for the Army by Yokoi Koko K.K. (Yokoi Aircraft Co) as the Ku-13 Training Glider. Some 50-60 of these gliders was finished by the time of the Japanese surrender. The Navy also planned to built the MXY9 Shuka (Autumn Fire), a modified powered version powered by a 200.03 kg thrust (441-lb) Tsu-11 ducted fan engine. However, no examples were completed before the Japanese surrender. The first two J8M1s to be built were completed with ballast replacing the rocket motor and its fuel. Gliding flights of the J8M1 began on the 8 th of January 1945. The aircraft were towed into the air by a Nakajima B6N1 and released to glide back down. These flights confirmed the basic soundness of the design. The first Toku Ro.2 rocket motors were delivered to Mitsubishi in early June of 1945. The first powered J8M1 was ready for its first flight test later in June. Unfortunately, on its first powered flight on 7 th July, the rocket engine failed during the steep climb after takeoff and the aircraft crashed, killing its pilot, Lt.Cdr Toyohiko Inuzuka. The cause of the engine failure was thought to have been the shifting of the hydrogen peroxide fuel to the rear of the partially empty tank, allowing air to enter a fuel pipe and causing a blockage. No other test flight ever took place. The fuel system of the sixth and seventh prototypes were in the process of being modified when the war ended, bringing the Shusui programme to an abrupt halt. Shusui production was already underway at the end of the war, with Mitsubishi, Nissan, and Fugi all participating in the programme. By the time of the Japanese surrender, Mitsubishi had built a total of seven Shusui aircraft. Three MXY8 gliders and some 50-60 Akigusa and Ku-18 Shusui heavy gliders had also been built. Two Navy versions of the Shusui were planned, the J8M1 armed with two 30-mm cannon and the J8M2 with one of the cannon being replaced by additional fuel tanks. An enlarged version of the Ki-200 Army version with increased fuel, the Ki-202, was to be the Army's priority interceptor project. A J8M1 was captured by US forces after the war and was returned to the USA for evaluation. As far as I am aware, it was never flown. It was acquired by Ed Maloney from a scrap yard in 1950, and is now on static display at the Planes of Fame museum in Chino, California. |
