Imperial Japanese Navy

Imperial Japanese Navy

The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

 submarine I-402, was one of three completed Sen Toku I-400

I-400 class submarine

The Imperial Japanese Navy submarines were the largest submarines of World War II and remained the largest ever built until the construction of nuclear ballistic missile submarines in the 1960s. They were submarine aircraft carriers able to carry three Aichi M6A Seiran aircraft underwater to their...

 class submarine aircraft carriers, which proved to be the largest prior to nuclear submarine development. Each were able to carry three Aichi M6A

Aichi M6A

The Aichi M6A Seiran was a submarine-launched attack floatplane designed for the Imperial Japanese Navy during World War II...

 Seiran floatplanes. In 1942 18 of these vessels were planned, however after increased shipping losses and the rising scarcity of alloys, only five were expected to be built. By 1944 only three had been completed (I-400 at Kure

Kure, Hiroshima

is a city in Hiroshima prefecture, Japan.As of October 1, 2010, the city has an estimated population of 240,820 and a population density of 681 persons per km². The total area is 353.74 km².- History :...

, I-401

Japanese submarine I-401

The Sen Toku-class I-401 was once the largest submarine in the world. It was commanded by Lieutenant Commander Nobukiyo Nambu of the Imperial Japanese Navy during World War II...

 and I-402 at Sasebo

Sasebo, Nagasaki

is a city located in Nagasaki Prefecture, Japan. As of 2011, the city has an estimated population of 259,800 and the density of 609 persons per km². The total area is 426.47 km². The locality is famed for its scenic beauty. The city includes a part of Saikai National Park...

). Although I-402 never saw combat it was intended for attacks on the eastern seaboard of the United States and the eastern locks of the Panama Canal

Panama Canal

The Panama Canal is a ship canal in Panama that joins the Atlantic Ocean and the Pacific Ocean and is a key conduit for international maritime trade. Built from 1904 to 1914, the canal has seen annual traffic rise from about 1,000 ships early on to 14,702 vessels measuring a total of 309.6...

.

Characteristics

I-402 was powered by four 3,000 horsepower diesel engines. The massive I-400 class submarine displaced 6,500 tons and had an overall length of 380 feet compared to the most numerous IJN submarine type, the B1 which only displaced 2,584 tons and had a length of 356 feet. The most notable characteristic of the I-402 was its ability to carry three Aichi M6A

Aichi M6A

The Aichi M6A Seiran was a submarine-launched attack floatplane designed for the Imperial Japanese Navy during World War II...

 Seiran seaplane dive bombers. I-402 had a figure-eight hull shape for additional strength to handle the on-deck hangar for housing the three aircraft. The wings of the Seiran folded back, the horizontal stabilizers folded down, and the top of the vertical stabilizer folded over so the overall forward profile of the aircraft was within the diameter of its propeller. The planes were launched from a 120-foot catapult on the deck of the giant submarine. In addition, it had four anti-aircraft guns and a 144 mm 40 caliber deck gun

Deck gun

A deck gun is a type of artillery cannon mounted on the deck of a ship or submarine.The deck gun was used as a defensive weapon against smaller boats or ships and in certain cases where torpedo use was limited. Typically a crew of three; gunner, loader, and layer, operated the gun, while others...

 as well as a suitable complement of twenty Type 95 torpedo

Type 95 torpedo

The Type 95 torpedo was a torpedo of the Imperial Japanese Navy.It was based on the formidable Type 93 torpedo but had a smaller warhead, shorter range and a smaller diameter...

s for commerce raids.

Post War Inspections

I-402 along with her sister ships were captured by the United States Navy after the war. They were taken to Sasebo Bay for evaluation. While there, the Soviet Union planned to send inspectors to also study the unknown vessels. To keep the technology out of the hands of the Soviets, Operation Road's End was instituted. I-402 along with twenty other submarines were filled with C-2 explosive

Composition C

The Composition C family is a family of related US-specified plastic explosives consisting primarily of RDX. All can be moulded by hand for use in demolition work and packed by hand into shaped charge devices. Variants have different proportions and plasticisers and include C-2, C-3, and C-4.The...

 charges and scuttled off the Gotō Islands

Goto Islands

The are Japanese islands in the East China Sea, off the western coast of Kyūshū. The islands are a part of Nagasaki Prefecture.- Geography :There are 140 islands in total, including five main islands:,,,, and....

.