Mitsubishi J8M

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Mitsubishi J8M1
Description
Role	Interceptor
Crew	one, pilot
Dimensions
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
Empty	1,505 kg	3,311 lb
Loaded	3,885 kg	8,547 lb
Powerplant
Engine	1x Toku Ro.2 rocket
Thrust	14.7 kN	3,300 lbf
Performance
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
Guns	2x 30 mm Type 5 cannons Ki-200 - 2x 30 mm Ho-105 cannons

The Mitsubishi J8M Shūsui (Japanese: 三菱 J8M 秋水, "Sharp Sword" turned from "Clear Autumn Water") was a rocket-powered interceptor aircraft closely based on the German Me 163 Komet.

Contents 1 Design 2 Flight Test 3 J8M Variants 4 Specifications (Ki-200/J8M-1) 4.1 General characteristics 4.2 Performance 5 Total Production 6 References 7 External links

[edit] Design

The J8M-1 was intended to be a licence-built copy of the Messerschmitt Me 163 Komet. 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 Japanese were quite aware of the results of the strategic bombing of Germany, and knew that the B-29 would be bombing Japan and the resultant problems which would arise from trying to combat this. Japanese military attachés had become aware of the “Komet” after a visit to the Luftwaffe squadron evaluation aircraft centre Erprobungskommando 16. They negotiated the rights to licence-produce the aircraft and its Walter HWK 509A rocket engine. The engine license itself cost the Japanese 20 million Reichsmarks.

The agreement was for Germany to provide the following by spring 1944:

• Complete blueprints of the Me163B "Komet" and the HWK 509A engine
• One complete "Komet"; two sets of sub-assemblies and components
• Three complete HWK 509A engines
• Inform Japan of any improvements and developments in the "Komet"
• Allow the Japanese to study the manufacturing processes for both the "Komet" and engine
• Allow the Japanese to study Luftwaffe operational procedures for the "Komet"

The broken-down plane and engine were sent to Kobe, Japan in early 1944. It is probable that the airframe was on Japanese submarine Ro-501 (ex-U-1224), which left Kiel, Germany 30 March 1944 and was sunk in the mid-Atlantic 13 May 1944 by the hunter-killer group around the aircraft carrier USS Bogue. Plans and engines were on Japanese submarine I-29, which left Lorient, France on 16 April 1944 and arrived in Singapore on 14 July 1944, later sunk 26 July 1944 after leaving Singapore by USS Sawfish near the Philippines.

The Japanese decided to attempt to copy the plane using a basic instructional manual on the Komet in the hands of naval mission member Cdr Eiichi Iwaya who had travelled to Singapore in I-29 and flown on to Japan when the submarine docked.

From inception the project became a joint Imperial Japanese Army Air Service (JAAF)/Imperial Japanese Navy Air Service (JNAF) venture The JAAF wanted a new design to be drawn up. The JNAF on the other hand, felt the design should mimic the German Komet because it had already proven to be a stable and ample aerodynamic body. It was the JNAF, who won and issued the 19-shi specification in July 1944 for the design of the rocket-powered, defence fighter. The contract went to Mitsubishi Jukogyo KK who would produce both the JNAF version the J8M-1 Shūsui and the JAAF version Ki-200.

The project was headed by Mijiro Takahashi. The JAAF, however decided to undertake their own design to meet the 19-shi specifications, working at their Rikugun Kokugijitsu Kenkyujo (JAAF Aerotechnical Institute) in secret.

At the 1st. Naval Air Technical Arsenal in Yokosuka, in league with engine partner Mitsubishi & Yokosuka Arsenalwork had begun on adapting the Walter HWK 509A engine to Japanese manufacturing capacity and technique. This was also the location, where work was underway to produce a glider version of the J8M to provide handling data. While work on this glider, MXY8 Akigusa (秋草, "Autumn Grass"), Mitsubishi completed a mock-up of the J8M1 in September of 1944.

Both the JAAF and JNAF approved its design and construction and a prototype was begun. In December of 1944, the MXY8 was completed and, on December 8 1944, at the Hyakurigahara Airfield Lieutenant-Commander Toyohiko Inuzuka took the controls of the MXY8, Once in the air, Inuzuka found the MXY8 almost perfectly emulated the handling characteristics of the Komet. Two additional MXY8 gliders were constructed in the naval yard at Yokosuka, one being delivered to the Rikugun Kokugijitsu Kenkyujo (JAAF Aerotechnical Institute) at Tachikawa for evaluation. The JNAF initiated the construction another prototype production designation Ku-13, this was to use water ballast to simulate the weights of an operational J8M complete with engine and weapons, this variant was to be built by Maeda Aircraft Institute, while the JAAF version was to constructed Yokoi Koku KK (Yoki Aircraft Co). The JNAF also proposed a more advanced trainer, designated the MXY9 Shūka (秋火, "Autumn Fire") which would be powered by a 441lb thrust Tsu-11 ducted fan engine. The war, however, ended before this model could be built.

Mitsubishi and partners Nissan and Fuji proceeded with development of the airframe and Yokosuka Arsenal were adapting the engine for Japanese Production designated Ro.2. The Japanese had succeeded in producing prototypes that outwardly looked very much similar to the "Komet". The J8M1 had a wet weight that was 900 lb lighter, The aircraft having a plywood main spar and wooden vertical tail, The designers had also dispensed with the armoured glass in the cockpit and the aircraft carried less ammunition and slightly less fuel.

The Ki-200 and the J8M1 differed only in minor items but the most obvious difference was the JAAF's Ki-200 was armed with two Ho-105 30 mm cannon (rate of fire was 450 round per minute, muzzle velocity of 2,350 ft per second) while the J8M-1 was armed with two Type 5 30 mm cannon ( rate of fire was 400 round per minute, muzzle velocity of 2,460 ft per second) The Ho-105 was also the lighter of the two and both offered a higher velocity than the MK 108 cannon of the Me163 ( whose muzzle velocity was 1,705 ft per second)

The Toko Ro.2 (KR10) rocket motor did not offer the same thrust rating as the original and Mitsubishi calculated that the lighter weight of the J8M-1 would not offset the lower thrust rating and thus performance was not as good as that of the "Komet" but it was still substantial.

The engine still used the German fuel of T-Stoff and C-Stoff (hydrogen peroxide/methanol-hydrazine), known in Japan as Ko and Otsu respectively.

[edit] Flight Test

In January 8, 1945, one of the two J8M-1 prototypes was towed aloft, water ballast in place of the fuel tankage and rocket engine to test its aerodynamics, The test flights confirmed the design. Training courses for JAAF and JNAF pilots was underway, training on the Ku-53 glider which shared a similar configuration to the J8M-1. The 312th. Naval Air Group was slated to operate the first J8M-1. Mitsubishi, Fuji Hikoki, and Nissan Jidosha all had their tooling for mass production well into the advanced stages, ready to produce both the J8M-1 and the variant J8M-2, which differed from the J8M-1 in sacrificing one of the Type 5 cannon for a small increase in fuel capacity. The First J8M-1 prototype to be equipped with the Toko Ro.2 (KR10) was ready in the June 1945. They were then transferred from the Nagoya plant to Yokoku for final checks before powered flight testing. After final glide tests with the engine installed.

The plane took to the air for its first powered flight on July 7, 1945, with Lt.-Cdr. Toyohiko Inuzuka at the controls; Inuzuka successfully jettisoned the dolly upon attaining the air and began to gain speed, climbing skywards at a 45 degree angle. At an altitude of 1,300 feet, the engine stopped abruptly and the J8M-1 stalled. Inuzuka managed to glide the aircraft back but clipped a small building at the edge of the airfield while trying to land, causing the plane to burst into flames. Inuzuka survived the crash, but died the next day. Mitsubishi and naval technicians sought to find the cause of the accident, and all future flights were grounded. The engine cutout had occurred because the angle of climb, coupled with the fuel tanks being half-filled for this first flight, caused a shifting of the fuel, which in turn caused an auto cutout device to kick in because of an air lock in the fuel feed line. Requests to continue flight testing were denied pending the modification of the fuel pumps in the aircraft. The sixth and seventh prototypes were to be fitted with the modified Ro.2 engine. Full scale production readiness was almost at hand and in fact, component construction had already gotten underway. Flight testing was to resume, despite another explosion of the fuel mixture during a ground test days after the crash, in late August of 1945 and the J8M-2 design was finalized. But on August 15, 1945, the war was over for the Japanese and all work on the J8M ceased. The end of the war also spelled the end of the JAAF's Ki-202 Shūsui-Kai (Modified Shusui), whose design had begun in secret months before. The Ki-202 was to offer improved flight endurance over the Ki-200 and was slated to be the priority fighter for the JAAF in 1946, but no metal was cut on this fighter before Japan's surrender.

Germany tried to send another "Komet" on U-864 but this submarine was sunk near Bergen by British submarine HMS Venturer in Feb 1945

[edit] J8M Variants

• J8M-2 Shusui Model 21(?). Long-range version for Navy, identical to J8M-1, but armament reduced to a single 30mm Cannon.
• J8M-3 Shusui Model 22 (Army designation Ki-202 Shusui-kai) Long-range version for Army and Navy, with fuselage and wingspan lengthened to 7.10m and 9.75m respectively. Powered by 2,000 kgf (19.6 kN) Tokuro-3, projected maximum speed 900Km/h.
• Yokosuka MXY-8 "Akigusa" (Army designation Yokoi Ku-13). Training glider using J8M airframe.
• Yokosuka MXY-9 "Shuka". Training version using J8M airframe, powered by Tsu-11 thermojet engine.

[edit] Specifications (Ki-200/J8M-1)

[edit] General characteristics

• Length : 6.05 m
• Wing Span : 9.50 m
• Height : 2.70 m
• Wing Area : 17.73 m²
• All-Up Weight : 3,000 kg
• Empty Weight : 1,445 kg
• Main Engine : 1 x Mitsubishi KR10 (Tokuro-2) Rocket, 1,500 kgf (14.7 kN)
• Crew : 1
• Armament : J8M-1 2x30mm Ho155-II Cannon, Ki-200 2x30mm Type 5 Cannon.

[edit] Performance

• Max Speed : 800 km/h
• Cruise Speed : 347 km/h
• Duration of Flight : 2.5 min (700 km/h)

[edit] Total Production

Operative Version:

By Mitsubishi:

• J8M1/Ki-200 (7 Units)

Training Version:

By Yokosuka, Yokoi and Maeda:

• Ku-13, Ki-13, MXY-8, MXY-9 (60 Units)

A total of seven airframes were completed.

Two were taken to the United States for evaluation from Yokosuka aboard USS Barnes in November 1945,

FE-300/T2-300 (USA ident) (Japanese ident 403) is now exhibited in the Planes of Fame Museum. The other was at NAS Glenview in Oct 1946 (ident unknown) but was scrapped.

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 (ident known).

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.

[edit] References

• 「秋水」と日本陸海軍ジェット、ロケット機, Model Art Co. Ltd., 1998. Edited by Takeo Yamashita
• Japanese Aircraft of the Pacific War -Rene J Francilion
• Komet The Messerschmitt 163 - Jeffrey L Ethell

@ (This Book Shows U-852 or U-68 being used to carry the ME163)

• War Prizes - Phil Butler

[edit] External links

• http://www.ijnafpics.com/jbwj8m1.htm
• http://www.ijnafpics.com/jbwj8m2.htm
• http://uboat.net/forum/read.php?f=3&i=44254&t=44254
• http://members.aol.com/pelzig/shusui.html
• http://www.asahi-net.or.jp/~KU3N-KYM/heiki5/mitsubi/mitsubi.html

Related content
Related Development	Me 163 - Yokosuka MXY8 - Yokosuka MXY9 - Mitsubishi Ki-202
Similar Aircraft
Designation Series	J5N - J6K - J7W - J8M
Related Lists	List of military aircraft of Japan - List of fighter aircraft - List of rocket aircraft