LEGO® IJN I-400 Submarine MOC

Downloadable Content: PDF Instructions Book & Parts List

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The I-400 was requested many times and there’s a reason why. First of all, yes that’s a micro airplane sitting on the deck prepping for take-off. Secondly, it was the biggest submarine project in WW2 and the biggest submarine class at the time. A big ambitious project led by the Imperial Japanese Navy, which eventually failed because of costs, flaws and the war ending sooner.

The LEGO® IJN I-400 Submarine MOC was built at a 1:500 scale, the same one I used for my other submarine MOCs. It is effectively the largest one in the collection and will be the largest one among the WW2 submarines in the Sea Monsters series…

The Bobby Brix Channel 2021.

This product contains a fully detailed instructions book with a parts list.

Product License use:
Personal or non-commercial use with attribution required.

Additional information

File Type

PDF File

File Size

12 MB

Model Designer

The Bobby Brix Channel

Software Compatibility

Adobe Acrobat Reader, Microsoft Edge


The I-400-class submarine Imperial Japanese Navy (IJN) 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. The IJN called this type of submarine Sentoku type submarine. The type name was shortened to Toku-gata Sensuikan. They were submarine aircraft carriers able to carry three Aichi M6A Seiran aircraft underwater to their destinations. They were designed to surface, launch their planes, then quickly dive again before they were discovered. They also carried torpedoes for close-range combat.

The I-400 class was designed with the range to travel anywhere in the world and return. A fleet of 18 boats was planned in 1942, and work started on the first in January 1943 at the Kure, Hiroshima arsenal. Within a year the plan was scaled back to five, of which only three (I-400 at Kure, and I-401 and I-402 at Sasebo) were completed.

Source: Wikipedia

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