| Mitsubishi J8M1 |
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| Description |
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| Role | Interceptor |
| Crew | one, pilot |
| Dimensions |
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| Length | 6.05 m | 19 ft 10 in |
| Wingspan | 9.50 m | 31 ft 2 in | | Height | 2.70 m | 8 ft 10 in |
| Wing area | 17.7 m² | 190 ft² | |
| Weights |
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| Empty | 1,505 kg | 3,311 lb | | Loaded | 3,885 kg | 8,547 lb |
| Powerplant |
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| Engine | 1x Toko Ro.2 rocket | | Power | 14.7 kN | 3,307 lb |
| Performance |
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| Maximum speed | 900 km/h | 560 mph |
| Endurance | 5 min 30 seconds |
| Service ceiling | 12,000 m | 39,370 ft |
| Rate of Climb | 2,858 m/min | 9,374 ft/min |
| Armament |
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| Guns | 2x 30 mm Type 5 cannons
Ki-200 - 2x 30 mm Ho-105 cannons |
The Mitsubishi J8M Shusui (Japanese: 三菱 J8M 秋水, "Sharp Sword") was intended to be a licence-built copy of the German Messerschmitt Me 163 rocket-powered interceptor aircraft. Difficulties in shipping an example to Japan meant that the aircraft eventually had to be reverse-engineered from a flight operations manual and other limited documentation. A single prototype was tested before the end of World War II.
The J8M project resulted as a direct response to the imminent deployment of the B-29 Superfortress in 1943. The development of the US bomber was known to Japan, and it was correctly anticipated that it would be used to raid the Japanese home islands. In Germany, Japanese military attachés had become aware of the Me 163, and after a visit to the squadron evaluating the aircraft, (Erprobungskommando 16), negotiated the rights to licence-produce the aircraft and its engine.
An initial set of materials, including a complete dis-assembled aircraft, technical documentation, and a sample engine were loaded onto two submarines, one of which was sunk en route, meaning that only the engine and a small amount of paperwork eventually reached Japan. With the first B-29 raids already taking place, it was decided to proceed immediately rather than wait for the missing material to be replaced. The fighter was assigned the J8M1 designation by the Navy and Ki-200 by the Air Force, the only significant difference between the aircraft being the choice of different 30mm cannons as armament. While Mitsubishi developed the airframe, Yokosuka developed an engine based on the Walter HWK 109-509 and training gliders, the Yokosuka MXY8 (army designation Ku-13).
On January 8 1945 glide-tests of the J8M1 commenced, pending the arrival of an engine. These were judged a success, with the ballasted aircraft performing very much like an Me 163 while gliding. The first of the Toko Ro.2 powerplants was delivered in June, and after final glide tests with the engine installed, the first powered flight took place on July 7. The take-off was normal, with the aircraft climbing away strongly, but at around 400 metres (1,300ft), it abruptly nosed over and dived straight into the ground, killing its pilot, Lt Cdr Toyohiko Inuzuka. Subsequent analysis found that the fuel tank design was unsuitable for the steep angle of climb. During Inuzuka's flight, an air-bubble had been created in a fuel line, leading the engine to stop abruptly and causing the crash. All testing was suspended while modifications were made. In the meantime, Mitsubishi began mass-production of components for the aircraft. Before flight testing could resume, however, Japan had surrendered, and the war was over.
A total of seven airframes were completed. Two were taken to the United States for evaluation, and one of these is now exhibited in the Planes of Fame Museum. In the 1960s, a nearly complete (but badly damaged) fuselage was discovered in a cave in Japan. This was on display at a Japanese Air Force Base near Gifu until 1999 when it was restored and completed by Mitsubishi for display in the company's internal museum.
English-language sources invariably translate this aircraft's name as "sword stroke" or "swinging sword", which is not correct. The tradition of this translation apparently stems from work done by Robert C. Mikesh in the 1950s and repeated by many others over the decades. Even more literally, 秋水 means "autumn water", but is a widely-recognised poetic metaphor for a well-sharpened sword, possibly because the brightness of the sword blade and the wavy pattern in the metal recall that of a clear body of water.
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