When Admiral Yamamoto became commander of the Imperial Japanese Combined
Fleet, he brought a true appreciation of the importance of airpower. However, he
knew that carriers had some limitations. Any attack on the American west coast
by his carriers would be highly risky. They would too far removed from Japanese
controlled waters and any ship significantly damaged would probably not reach
the safety of home waters. To be able to attack those targets far removed from
the range of Japanese air power of land based or carrier based assets, Yamato
proposed large submarines carrying aircraft. One pet project was to use them for
attacks on the locks of the
the 1930s the IJN had built a few aircraft carrying submarines in the Junsen or
I-1 type. These were derivations of the large submarines designed for long range
reconnaissance. These variants could carrying only one small floatplane and the
wings would have to be added to the fuselage after the submarine surfaced in
preparation for launch. Clearly these would be insufficient for a significant
attack In 1938 a larger submarine the Type A, which could carry one aircraft but
with wings folded and which could be accessed while submerged. Therefore launch
preparation could be started before the boat surfaced. This was still a
development of the long-range reconnaissance mission. For an air attack mission
more aircraft were needed.
types of large submarines were developed for this purpose. One type was a
modified Type A, which reworked the initial Type A to provide for two aircraft.
However, the largest submarines of World War Two were designed from the keel up
for the long-range aerial attack mission. This was the Sen-Toku Type. Two
overlapping cylinders were used for the large pressure hull, which gave the
design a figure-8 cross section. The design was 400 feet long and displaced
5,223-tons surfaced and 6,560-tons submerged. The long hangar could carry three
Aichi M6A1 Seiran float planes to be launched from the catapult on the bow. The
design provided for a phenomenal range of 37,500nm at 14 knots surfaced.
Additional armament consisted of eight 21-inch (533mm) torpedo tubes with 20
torpedoes. Deck guns consisted of one 5/5-inch/50 (140mm) gun and ten 25mm AA
guns with three triple and one single mounts.
Seventeen units were
planned but with the death of Admiral Yamamoto in 1943, the construction program
was placed on the back burner. Only three were completed in 1944 and 1945. I400,
I401 and I402 never saw operations in their intended role and were inactive
after completion. I402 was subsequently modified to serve for fuel supply but
again never employed in this mission. All three were captured at the end of the
war. Construction on I404 was suspended in March 1945 when almost complete. I403
and the twelve boats of the 1942 program were cancelled.
has now produced a 1:700 scale model of this remarkable design. The box contains
five sprues of parts plus decals. One sprue has just the waterline base, while
another has the two hull halves. A third sprue contains the decks and aircraft.
There are parts for the main deck, conning tower deck and two aircraft. The
aircraft come with one version with wings extended, ready for launch, and the
other with wings folded. Since the hangar access door is a separate part and can
be assembled in an open position, the folded wings aircraft can be shown inside
the hangar, which has a detailed interior. Separate float parts are included.
One half of the upper superstructure is also on this sprue. A forth sprue
concentrates on the conning tower with both halves of the hangar, one of which
includes the upper superstructure. Also included on this sprue are the 5.5-inch
gun, single 25mm gun, periscope arrangement, propeller guards, hangar door and
snorkel. The last sprue is a standard armaments sprue from which only the triple
25mm AA guns are used, with a lot of other weapons and equipment for the spares
bin. Detail on the parts is good but not spectacular with deck access hatches
and knock out panels. It is a nice touch to have hangar interior ribbing, which
enhances the look of the boat with hangar door open and folded wing stored
aircraft. You may want to replace the 25mm guns with photo-etch pieces, as the
plastic parts are thick.
Where do you go to
get your long-range strike boats for your attack on the US Pacific coast? Well
of course the answer is simple. For Pacific coast attacks, go to Pacific
Front where Bill Gruner can outfit your 1:700 scale IJN with this unique