Wednesday, July 22, 2015

“Body-Crashing”: the Ramming Interceptors - Tai-atari

A NICK (Toryu) twin engine fighter (number 63) in close to A Square 22 experiencing heavy fire power from lower front gun turret of A Square 22. Apparently this is a ramming attempt by the Nick. The artist is Hideichi Kaiho.

On 14 June 1944, Boeing B-29 Superfortresses struck for the first time at the Japanese home islands. Most early raids were made at high level (above c.30,000ft, 9150m), but although Japan’s air defence was deficient in both AA guns and aircraft with the speed and combat ceiling successfully to intercept the Superfortresses – of 414 B-29s lost, only 147 fell to Japanese interceptors or AA fire – it was felt that the results of such operations did not justify even the lowest loss rate.

Early in 1945, MajGen Curtis LeMay took over the Marianas-based 21st Bomber Command from BrigGen Haywood Hansell, adopting a policy of low-level incendiary raids at c.5–6,000ft (1500–1800m) by B-29s virtually unarmed for extra speed. By August, LeMay could claim that fire raids had completely shattered some 58 major cities and that by bombing alone Japan would soon be “beaten back into the dark ages”. Fire raids indeed caused far greater material and moral damage than the two atomic bombs: on 9–10 March, in a raid by 325 B-29s, 15.8 sq miles (41 sq km) of Tokyo were gutted and c.84,000 killed and more than 100,000 injured (compared to c.78,000 dead and 68,000 injured in the atomic blast at Hiroshima). In a fire raid on Toyama on 1–2 August, no less than 99.5 per cent of the city was devastated. And when Prince Konoye told the USSBS that the major factor in Japan’s decision to surrender was “fundamentally ... the prolonged bombing by the B-29s”, he was speaking of the fire raids. One Japanese statesman, however, referred to the atomic destruction as “the big kamikaze that saved Japan”; meaning that the terrible civilian casualties sustained in just these two strikes afforded a decisive argument to the peace faction.

With fuel stocks low, factories and repair facilities dislocated, and many aircraft lacking trained pilots or held in reserve for the final kamikaze onslaught, the Japanese air arms proved unable to deal effectively with the low-level raiders and thus increasingly resorted to suicidal aerial ramming interceptions. Isolated instances had occurred earlier in the war. On 4 July 1942, Lt Mitsuo Suitsu, enraged when his naval air squadron’s field at Lae, New Guinea, was badly damaged by US bombers, fulfilled a vow of vengeance by destroying a Martin B-26 Marauder in a head-on collision with his Zero. The first Army pilot credited with such self-sacrifice was Sgt Oda who, also flying from New Guinea and unable to maintain the altitude conventionally to engage a B-17 that was “snooping” a Japanese supply convoy, brought down the Fortress by ramming with his Nakajima Ki-43 “Oscar”.

Tai-atari (“body-crashing”) tactics were not invariably fatal: a few US bombers were destroyed by Soviet-style Taran attacks, their tail assemblies chewed away by fighters with armoured propellers. USAAF personnel reported the first cases of what they judged to be deliberate ramming during a raid on the steel works at Yawata, Kyushu, on 20 August 1944. Of four bombers lost over the target area, one fell to AA, one to aerial gunfire, and two to a single Kawasaki Ki-45 Toryu (Dragon Killer; “Nick”): the “Nick” rammed one B-29 and the debris of the two aircraft brought down another.

In February 1945, an IJA manual stated that against B-29s (and the expected B-32 Dominators, of which only a handful became operational) “we can demand nothing better than crash tactics, ensuring the destruction of an enemy aircraft at one fell swoop ... striking terror into his heart and rendering his powerfully armed planes valueless by the sacrifice of one of our fighters”. The manual noted that only partly trained pilots need be used and recommended as rammers the Nakajima Ki-44 Shoki (Demon; “Tojo”) and Kawasaki Ki-61 Hien (Swallow; “Tony”), on the dubious grounds that their designs gave the pilot a faint chance of baling out immediately before impact.

Earlier than this, in November 1944, the 2nd Air Army’s 47th Sentai formed the volunteer Shinten Sekutai squadron, dedicated to ramming attacks in “Tojos”. Their successes included the destruction of a B-29 over Sasebo on 21 November by Lt Mikihiko Sakamoto; another B-29 on 24 November (one of only two Superfortresses brought down in a 111-strong raid); and two B-29s (out of only six lost from a 172-strong force over Tokyo) on 25 February 1945. Fighters of the Kwantung Army also adopted ramming tactics, bringing down two B-29s over the Mukden aircraft works on 7 December 1944 and another on 21 December. On both occasions, Japanese aircraft also attempted air-to-air bombing, releasing time-fuzed phosphorus bombs above the US formations. At least one B-29 was destroyed by this method, which was also used in the defence of the homeland.

A less extreme measure than ramming was the formation at Matsuyama NAFB, Shikoku, in January 1945 of a fighter wing led by Capt Minoru Genda and including Saburo Sakai and other “aces”. Flying the Kawanishi N1K2-J Shiden (Violet Lightning: “George”) – probably Japan’s best interceptor; only c.350 were built – they achieved especially good results against Allied carrier strikes. On 16 February, WO Kinsuke Muto was credited with engaging single-handed 12 F6F Hellcats from USS Bennington over Atsugi, Tokyo, shooting down four and driving off the rest.

Japan sought German aid

Kawanishi Baika

 Mitsubishi J8M1

Unable to produce in sufficient quantity such advanced interceptors as the Kawasaki Ki-100 (396 of all models built), the Kawasaki Ki-102 (“Randy”; 238 built) and the Mitsubishi A7M3-J Reppu (Hurricane; “Sam”; prototype only), or to bring to operational status the Funryu (“Raging Dragon”) surface-to-air guided missiles, Japan sought German aid. Plans, and in some cases completed models, were acquired of the Bachem Natter, the Reichenberg piloted-bomb (built as the Baika), and the Messerschmitt Me 262 twin-engined jet fighter-bomber. A prototype based on the latter, the IJN’s Nakajima Kikka (“Orange Blossom”), flew on 7 August 1945; if production had been attained it was to have been deployed in concealed revetements as a “special attack” bomber.

A major effort at a point-defence interceptor was the joint IJN/IJA project for the Mitsubishi J8M1 (Navy) or Ki-200/202 (Army) Shusui (“Swinging Sword”), a near-identical version of the Luftwaffe’s Messerschmitt Me 163 Komet. Rights to produce a version of the Komet’s airframe and Walter HWK 509A bi-propellant (T-Stoff and C-Stoff, which the Japanese called Ko and Otsu liquids respectively) rocket engine, with a completed example of the aircraft itself, were purchased as early as March 1944; but only one Walter unit and an incomplete set of blueprints reached Japan. Germany’s final effort to provide her ally with more material on the Komet and other “special weapons” was made on 2 May 1945, when U.234 (Cdr Johann Fehler) sailed from Norway for Japan with high-ranking Luftwaffe officers, technicians, and two Japanese scientists aboard. En route, Fehler received the news of Germany’s collapse and, as he headed for the USA to surrender his boat, both Japanese committed seppuku.

In Japan, training with the Komet-replica MXY8 Akigusa (“Autumn Grass”) glider began in December 1944. The first powered flight was attempted on 7 July 1945 at Yokoku airfield, Yokosuka. Successfully jettisoning the takeoff trolley, LtCdr Toyohiko Inuzuka had reached c.1,300ft (400m) when, probably because of a fuel line blockage caused by the steep climb, the engine flamed out and the Shusui stalled and crashed, mortally injuring Inuzuka. Later that month, an explosion of the volatile fuel mixture during ground testing killed another of the project’s officers. Many similar fatalities – especially during the hard skid-landings that often brought the liquid propellants violently together – had occurred in Germany, where the “Devil’s Egg” was regarded by many Luftwaffe personnel as semi-suicidal at best.

The Japanese rocket interceptor differed little from its German pattern. The J8M1 had a span of 31.2ft (9.5m), a length of 19.86ft (6.05m) and a height on its jettisonable trolley of 8.86ft (2.7m). Powered by a Toko Ro.2 motor giving 3,307lb (1500kg) thrust for up to c.5.3 minutes, it was estimated to be capable of a maximum 559mph (900kmh) at 32,810ft (10,000m); thus probably having a range at optimum flight profile of less than 60 miles (96km). Its armament was to be two wing-mounted 30mm cannon – although if the planned production of more than 1,000 examples by August 1945 had been achieved, it is likely that many would have been expended in ramming attacks after exhausting their ammunition of 50 rounds per gun. In the event, only seven Shusui, which were to have been operated by the 312th Naval Air Group, were completed by the war’s end.

Friday, July 10, 2015

“Fukuryu”: the Suicide Frogmen

Suicide divers (Fukuryu "Crouching dragons") were a part of the Special Attack Units prepared to resist the invasion of the Home islands by Allied forces. They were armed with a mine containing 15 kilograms of explosive, fitted to a 5 meter bamboo pole. They would dive and stick the pole into the hull of an enemy ship, destroying themselves in the process. They were equipped with a diving jacket and trousers, diving shoes, and a diving helmet fixed by four bolts. They were typically weighed down with 9 kg of lead, and had two bottles of compressed air at 150 bars. They were expected to be able to walk at a depth of 5 to 7 meters, for about 6 hours. 

It was estimated that the mass onslaught would destroy some 35–50 per cent of the Allied armada before any troops could be put ashore. Offshore, a last line of maritime defence would be provided by the least-known of the “special attack” forces: the demolition frogmen called fukuryu (“crouching dragons”).

Their training had begun at Kawatana in November 1944 (see here), although the IJN had employed teams of swimmers on hazardous missions since early in the war; notably at Hong Kong, where skindivers defuzed Allied mines to prepare a way for landing craft. A Japanese prisoner taken at Peleliu, Palaus, late in 1944, claimed that he belonged to a 22-strong Kaiyu unit of swimmers trained to attack landing craft. Each swimmer was armed with three grenades, a knife and a simple demolition charge: a wooden box of c.160in3 (2620cm3) packed with trinitrophenol (Lyddite) with a fuze cut to the required length. But the kaiyu units, credited with damaging an LCI in the Palaus and a DE and an attack transport at Okinawa, were surface swimmers rather than frogmen.

The fukuryu appear never to have been deployed outside the home islands. Their role in the final defence would have been suicidal – as was, to some extent, their training. Their equipment – a loosely-fitting wet suit; a clumsy helmet not unlike that of a deep-sea diver; bulky air circulation and purification tanks strapped to chest and back and linked by a tangle of hoses – was most unsatisfactory. “There were very many [fatal] accidents during the training of fukuryu”, a Japanese veteran told me, “because the twin-tank oxygen re-breathing equipment was no good – but nothing better was available”. Nevertheless, some 1,200 fukuryu graduated from Kawatana and Yokosuka Mine School by the war’s end, when 2,800 were still in training.

To destroy inshore landing craft, each fukuryu was armed with a 22lb (10kg) impact-fuzed charge, incorporating a flotation tank, mounted on a stout pole (much like the anti-tank “lunge mine” described above). If his equipment functioned perfectly, the frogman could stay at an optimum depth of 50ft (15m) for up to 10 hours, sustained by a container of liquid food. Construction was begun of underwater pillboxes, concrete with steel doors, in which fukuryu would shelter from a pre-landing bombardment while awaiting their opportunity to sally forth and thrust their explosive lances against the bottoms of landing craft.

The fukuryu would form part of a network of beach defence. Farthest from the beach were moored mines, electrically detonated from ashore; then three lines of fukuryu deployed so that each man guarded an area of c.470sq yds (390sq m); then lines of magnetic mines; and finally beach mines. Capt K. Shintani, commanding the fukuryu, was somewhat optimistic in hoping that his men might “cause as much damage as the kamikaze aircraft”.