| J8M | |
|---|---|
 | |
| General information | |
| Type | Rocket-poweredInterceptor |
| Manufacturer | Mitsubishi Aircraft Company |
| Primary users | IJA Air Service |
| Number built | 7[1] |
| History | |
| Manufactured | 1944–1945 |
| First flight | 7 July 1945 |
| Developed from | Messerschmitt Me 163 Komet |
| Variants | Yokosuka MXY8 Yokosuka MXY9 |
TheMitsubishi J8MShūsui (Japanese: 三菱 J8M 秋水, literally "Autumn Water", used as a poetic term meaning "Sharp Sword", deriving from the swishing sound of a sword) is aJapanese World War IIrocket-poweredinterceptor aircraft closely based on theGermanMesserschmitt Me 163Komet. Built as a joint project for both theNavy and theArmy Air Services, it was designatedJ8M (Navy) andKi-200 (Army).
The J8M1 was intended to be a licence-built copy of the Messerschmitt Me 163Komet, but 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 aware of the results of thestrategic bombing of Germany, and they knew that theB-29 Superfortress would be bombing Japan and that there would be problems trying to combat this. Japanese militaryattachés had become aware of theKomet during a visit to theBad Zwischenahn airfield ofErprobungskommando 16, theLuftwaffe evaluation squadron charged with service test of the revolutionary rocket-propelled interceptor. They negotiated the rights to licence-produce the aircraft and itsWalter HWK 509A rocket engine. The engine licence alone cost the Japanese 20 millionReichsmarks (equivalent to 81 million 2021 euros).[2]
The agreement was for Germany to provide the following by spring 1944:
The broken-down aircraft and engine were sent toKobe, Japan in early 1944. It is probable that the airframe was on the Japanese submarineRO-501 (ex-U-1224), which leftKiel, Germany on 30 March 1944 and was sunk in the mid-Atlantic on 13 May 1944 by the hunter-killer group based on theescort carrierUSS Bogue. Plans and engines were on the Japanese submarineI-29, which leftLorient, France on 16 April 1944 and arrived inSingapore on 14 July 1944, later sunk by thesubmarineUSS Sawfish on 26 July 1944, near thePhilippines, after leaving Singapore.
The Japanese decided to attempt to copy the Me 163 using a basic instructional manual on theKomet in the hands of naval mission member Commander Eiichi Iwaya, who had travelled to Singapore in theI-29 and flown on to Japan when the submarine docked. Germany tried to send anotherKomet inU-864, but the submarine was sunk nearBergen by British submarineHMS Venturer in February 1945.
From its inception, the project was a jointImperial 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 GermanKomet because it had already proven to be a stable aerodynamic body. It was the JNAF which won and issued the19-shi specification in July 1944 for the design of the rocket-powered defence fighter. The contract went to MitsubishiJukogyo KK, which would produce both the JNAF version the J8M1Shūsui and the JAAF version Ki-200.
The project was headed by Mijiro Takahashi. The JAAF, however decided to undertake their own design to meet the19-shi specifications, working at theirRikugun Kokugijitsu Kenkyujo (JAAF Aerotechnical Institute) in secret.
At the 1st Naval Air Technical Arsenal inYokosuka, in association with Mitsubishi and Yokosuka Arsenal, work began to adapt the Walter HWK 509A engine to Japanese manufacturing capabilities and techniques. This was also where efforts were underway to produce a glider version of the J8M to provide handling data. While working on this glider, theMXY8Akigusa (秋草, "Autumn Grass"), Mitsubishi completed a mock-up of the J8M1 in September 1944.
Both the JAAF and JNAF approved its design and construction, and aprototype was built. In December 1944, the MXY8 was completed and, on 8 December 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 theKomet. Two additional MXY8 gliders were constructed in the naval yard at Yokosuka, and one was delivered to theRikugun Kokugijitsu Kenkyujo (JAAF Aerotechnical Institute) at Tachikawa for evaluation. The JNAF initiated the construction of another prototype, production designation Ku-13. This was to use waterballast to simulate the weight 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 be constructed byYokoi Koku KK (Yoki Aircraft Co). The JNAF also proposed a more advanced trainer, designated theMXY9Shūka (秋火, "Autumn Fire"), which would be powered by a 2 kN (450 lbf) thrust Tsu-11 ducted-fan engine. However, the war ended before this model could be built.
Mitsubishi and partnersNissan andFuji proceeded with development of the airframe, and Yokosuka Arsenal was adapting the engine for Japanese production, designated the Ro.2. The Japanese succeeded in producing prototypes that outwardly looked very much similar to theKomet. The J8M1 had a wet weight that was 400 kg (880 lb) lighter, the aircraft having aplywood mainspar and wooden vertical tail. The designers had also dispensed with the armoured glass in thecockpit, 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 30 mm (1.18 in)Type 5 cannon (with a rate of fire of 450 rounds per minute and a muzzle velocity of 920 m/s (3,000 ft/s)), while the J8M1 was armed with two 30 mm (1.18 in) Ho-105 cannon (rate of fire 400 rounds per minute, muzzle velocity 750 m/s (2,500 ft/s). The Ho-105 was the lighter of the two and both offered a higher velocity than theMK 108 cannon of the Me 163 (whose muzzle velocity was 520 m/s (1,700 ft/s). 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 J8M1 would not offset this. Performance would not be as good as that of theKomet but was still substantial.[3]
The engine used the German propellants ofT-Stoff oxidizer andC-Stoff fuel (hydrogen peroxide/methanol-hydrazine), known in Japan asKo andOtsu respectively.
Sixty training versions (Ku-13, Ki-13, MXY-8 & MXY-9) were produced byYokosuka, Yokoi andMaeda. Seven of the operational version (J8M1/Ki-200) were built byMitsubishi.
On 8 January 1945, one of the two J8M1 prototypes was towed aloft, water ballast added in place of thefuel tank and rocket engine to test itsaerodynamics. The test flights confirmed the design.Training courses for JAAF and JNAF pilots began on the Ku-13glider, which shared a similar configuration to the J8M1. The 312th Naval Air Group was selected to operate the first J8M1. Mitsubishi, Fuji Hikoki, and Nissan Jidosha all had tooling for mass production well into the advanced stages, ready to produce both the J8M1 and the J8M2 variant, which differed from the J8M1 in sacrificing one of the Type 5 cannon for a small increase in fuel capacity. The first J8M1 prototype to be equipped with the Toko Ro.2 (KR10) was ready in 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 J8M took to the air for its first powered flight on 7 July 1945,[4] with Lieutenant Commander Toyohiko Inuzuka at the controls; after his "sharp start" rocket-powered takeoff, Inuzuka successfully jettisoned the dolly upon becoming airborne and began to gain speed, climbing skywards at a 45° angle. At an altitude of 400 m (1,300 ft), the engine stopped abruptly, and the J8M1 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 aircraft to burst into flames. Inuzuka died the next day.[5] While Mitsubishi and naval technicians sought to find the cause of the accident, 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 activate because of an air lock in thefuel line. Requests to continue flight testing were denied pending the modification of thefuel pumps in the aircraft. The sixth and seventh prototypes were to be fitted with the modified Ro.2 engine.
Contractors were already manufacturing components, and almost ready for full-scale production. Despite another explosion of the fuel mixture during a ground test days after Inuzuka's crash, flight testing was to resume in late August 1945, and the J8M2 design was finalized. But on 15 August 1945 the war ended for the Japanese, and all work on the J8M ceased. The end of the war also spelled the end of the JAAF'sKi-202Shūsui-Kai (ModifiedShusui), 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 before Japan's surrender.
As with many other Japanese fighter types combating air raids over Japan, the Ki-200 was considered for use inramming attacks against B-29s. The envisioned mission profile was to make one or two firing passes and then, with the remaining energy, conduct a ramming attack. Any fuel left on board would most likely detonate, increasing the effectiveness of the attack but also meaning the pilot had little chance of survival. Nevertheless, the cost was deemed to be worth it, and plans were being drawn up to form a "Hagakure-Tai" (Special Attack Unit), similar to the GermanSonderkommando Elbe, when the war ended.
In November 1945, two aircraft were taken fromYokosuka to theUnited States for evaluation aboardUSSBarnes. FE-300/T2-300 (USA ident) (Japanese ident 403) is now exhibited at thePlanes of Fame Museum inChino, California.
The other was atNAS Glenview in October 1946 (identity 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 Self Defense Force base nearGifu until 1999, when it was restored and completed by Mitsubishi for display in the company's internal Komaki Plant Museum.[6]
| Specifications[7] | |||
| J8M1 | J8M2 | Ki-200 | |
|---|---|---|---|
| Manufacturer: | Mitsubishi Jukogyo K.K | ||
| Type: | Interceptor | ||
| Crew: | 1 | ||
| Span: | 9.50 m (31 ft) | 9.47 m (31 ft) | |
| Length: | 6.03 m (20 ft) | 5.88 m (19 ft) | |
| Height: | 2.68 m (9 ft) | 2.68 m (9 ft) | |
| Wing area: | 17.72 m2 (191 sq ft) | 17.69 m2 (190 sq ft) | |
| Wing loading: | 219.22 kg/m2 (44.9 lb/ft2) | 219.70 kg/m2 (45 lb/ft2) | |
| Empty weight: | 1,445 kg (3,186 lb) | 1,510 kg (3,329 lb) | 1,505 kg (3,318 lb) |
| Loaded: | 3,000 kg (6,614 lb) | 3,650 kg (8,047 lb) | |
| Maximum: | 3,870 kg (8,532 lb) | 3,900 kg (8,598 lb) | 3,870 kg (8,532 lb) |
| Useful load: | 1,545 kg (3,406 lb) | 2,140 kg (4,718 lb) | |
| Fuel capacity: | T-Stoff = 1,181 L (260 imp gal) C-Stoff = 522 L (115 imp gal) | ||
| Armament | |||
| Gun: | 2xType 5 30mm autocannon | 1xType 5 30mm autocannon | 2xHo-155 30mm autocannon or 2xHo-5 20mm autocannon |
| Capacity: | 53 rounds per gun | ||
| Performance | |||
| Powerplant: | One Toku-Ro.2 (KR10)bipropellant rocket engine developing 1,500 kg (3,307 lb) of thrust | ||
| Liquid-propellant: | T-Stoff = 80%hydrogen peroxide + 20%water withoxyquinoline andpyrophosphates C-Stoff = 30%hydrazine hydrate + 70%methanol, water and potassium cyanocuprate catalyst | ||
| Max speed: | 900 km/h (559 mph) at 10,000 m (32,808 ft) | ||
| Cruise speed: | 699 km/h (434 mph) | 351 km/h (218 mph) | |
| Landing speed: | 150 km/h (93 mph) | ||
| Range: | 3 min 06 seconds of powered flight | 2 min 30 seconds of powered flight | |
| Max range: | 5 min 30 seconds of powered flight | 7 min of powered flight | |
| Climb: | 2,000 m (6,562 ft) in 40 seconds 4,000 m (13,123 ft) in 2 minutes 08 seconds 8,000 m (26,247 ft) in 3 minutes 08 seconds 10,000 m (32,808 ft) in 3 minutes 50 seconds | 10,000 m (32,808 ft) in 3 minutes 40 seconds | |
| Rate of climb: | 43.47 m/s (8,557 ft/min) | 45.45 m/s (8,947 ft/min) | |
| Ceiling: | 12,000 m (39,370 ft) | ||
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