Info: Mitsubishi J8M1 Shusui (Sword Stroke)

[Robert Hurst]

Hi

The arrival of the B-29 Superfortress over Japan suddenly created an urgent need for a fast-climbing interceptor fighter, a weapon long neglected by the Japanese armed forces. Fortunately for them, their Military Attache in Germany had been aware of the development of the Messerchmitt Me 163B, a spectacular rocket-powered fighter and, in late 1943, for the sum of twenty million Reichmarks had acquired for Japan the manufacturing rights for the German fighter and the Walter HWK 109-509 rocket motor, together with one example of this power plant. Unfortunately, one of the two submarines taking to Japan technical data on the Me 163B and its engine was sunk en route and only incomplete data was taken back by Cdr Eiichi Iwaya. In spite of this setback the Japanese Navy issued a 19-Shi specification, in July 1944, covering the development of a rocket-powered interceptor fighter inspired by the German aircraft. The task of designing and producing the aircraft was assigned to Mitsubishi. From its inception the project became a joint Navy-Army venture as the Army intended to adopt the aircraft, while modifications of the Walter HWK 109-509 motor to Japanese production techniques as the Toku Ro.2 was carried out as a joint Navy-Army-Mitsubishi project.

Design of the aircraft, designated J8M1 by the Navy and Ki-200 by the Army, proceeded rapidly under the direction of Mijiro Takahashi of Mitsubishi, and a mock-up was completed in September 1944. Three weeks later the final mock-up was inspected and approved by both Services, clearing the way for construction of prototypes.

Shortly after instructing Mitsubishi to undertake the design of the J8M1, the Navy had initiated at their Dai-Ichi Kaigun Gijitsusho (First Naval Air Technical Arsenal) in Yokosuka, the development of a full-scale glider version which was intended to provide data on the handling characteristics of the tailless J8M1 and to be used for the training of J8M1 pilots. The first prototype of the tailless glider, designated MXY8 Akigusa (Autumn Grass) , was completed in December 1944, and the aircraft was transported to Hyakurigahara Airfield in Ibaragi Prefecture where its flight trials programme began on 8 December.

For its first flight the Akigusa was towed to altitude by a Kyushu K10W1 of the 312th Kokutai, and was piloted by Lieut-Cdr Toyohiko Inuzuka, the J8M1 project pilot. Notwithstanding its unusual configuration, the MXY8 handled satisfactorily and two additional prototypes were built at Yokosuka, one being delivered to the Rikugun Kokugijutsu Kenkyujo (Army Aerotechnical Research Institute), at Tachikawa, for evaluation by the Army. Production of a heavier version of the MXY8, intended as a training glider for J8M1 pilots and fitted with water ballast tanks to approximate the weight of the operational aircraft, was undertaken for the Navy, by Maeda Koku Kenkyujo (Maeda Aircraft Institute) and for the Army by Yokoi Koku K K (Yokoi Aircraft Co) as the Ku-13 Training Glider. The Navy also planned to build the MXY9 Shuka (Autumn Fire), a modified version powered by a 200 kg (441 lb) thrust Tsu-11 ducted fan engine, but none were completed before the Japanese surrender.

To assess more extensively the handling charactersitics of the fully-loaded Shusui. Mitsubishi completed the first two J8M1s with ballast replacing the rocket motor and its fuel. Towed by a Nakajima B6N1 the first aircraft was flown at Hyakurigahara beginning on 8 January, 1945, and confirmed the soundness of the design whilst powered prototypes were being readied under the designations J8M1 Navy Experimental Rocket-Powered Interceptor Fighter Shusui and Ki-200 Army Experimental Rocket-Powered Interceptor Fighter Shusai. The first prototype for the Navy was completed at Nagoya in June 1945 and was transferred to Yokosuka for final checks. On 7 July, 1945, the J8M1 was ready to start flight trials, but on its maiden flight after the aircraft had attained a height of 397 m (1,300 ft) in a steep climb after take-off, the engine failed and the aircraft crashed, killing its pilot, Lieut-Cdr Toyohiko Inuzuka.

The cause of the accident was variously explained as the result of the hydrogen peroxide shifting to the rear of the partially empty tank and cutting the fuel supply, and owing to air entering a fuel pipe and causing a blockage. However, the fuel system of the sixth and seventh prototypes was being redesigned when the war ended, and no further J8M1 or Ki-200 was tested. At the end of the war Shusui production was already under way, and the Navy had instructed Mitsubishi, Nissan and Fuji to produce two versions of the aircraft, the J8M1 armed with two 30 mm Type 5 cannon, and the J8M2-Shusui-Kai in which one of the wing-mounted cannon was replaced by additional fuel tanks. An enlarged version of the Ki-200 with increased fuel tankage, the Ki-202 developed by the Rikugun Kokugijutsu Kenkyujo, had been selected by the Army as their priority interceptor project.

Technical data

Type: Single-seat short-range rocket-powered interceptor fighter (J8M1, Ki-200 and Ki-202) or tailless glider (MXY8 and Ku-13).
Accommodation: Pilot in enclosed cockpit
Powerplant: One 1,500 kg (3,307 lb) thrust Toko Ro.2 (Kr.10) bi-fuel liquid rocket (J8M1, Ki-200 and Ki.202)
Armament: Two wing-mounted 30 mm Type 5 cannon (J8M1); One wing-mounted 30 mm Type 5 cannon (J8M2); Two wing-mounted 30 mm Ho-105 cannon (Ki-200 and Ki-202)
Dimension (J8M1): span: 9.5 m (31 ft 2 in); length: 6.05 m (19 ft 10 3/16 in); height: 2.7 m (8 ft 10 5/16 in); wing area 17.73 sq m (190.843 sq ft)
Weights (J8M1): empty 1.505 kg (3,318 lb); loaded 3,885 kg (8,5465 lb); wing loading 219.1 kg/sq m (44.9 lb/sq ft)
Performance (J8M1): max speed 900 k/hr at 10,000 m (559 mph at 32,810 ft); climb to 10,000 m (32,810 ft) in 3 min 30 sec; service ceiling 12,000 m (39, 370 ft); powered endurance 5 min 30 sec.
Production: Seven Shusui aircraft were built in 1945 by Mitsubishi Jukogyo K K, three MXY8 light gliders were built by the Dai-Ichi Kaigun Koku Gijitsusho and some fifty to sixty Akigusa and Ku-13 Shusui heavy gliders were built by Maeda Koku Kenkyujo and Yokoi Koku K K.

The photos were taken from"Warplanes of the Second World War Vol.3: Fighters", by William Green.

Regards

Bob

[Cantankerous]

I have a photo I took of a Mitsubishi J8M Shusui at the Planes of Fame Museum in Chino, California, in April 2019.

Mitsubishi J8M Shusui at Planes of Fame Museum