Gulf: Japan's Battleship-Carriers
By Mike Bennighof, Ph.D.
At the Battle
of Midway in June 1942, the Imperial
Navy lost four of its six fleet aircraft carriers.
Shorn of these valuable ships, the Japanese
high command desperately tried to replace
them. Only one new aircraft carrier, Taiho,
was under construction.
At the time, two large liners converted
to aircraft carriers, Junyo and Hiyo,
were just entering service. Many nations
contemplated such conversions, and the Italian
Navy had its similar Aquila. But
the Japanese were not pleased with the results.
The ex-liners had poor internal subdivision
compared to a warship hull, their speed never
matched design specifications, and hangar
spaces were cramped. A converted warship would
solve at least some of these problems.
soon after conversion, 1942
Casting about for warship hulls that could
be converted to carriers fairly quickly, the
Navy ordered work stopped on the new cruiser
Ibuki, and her conversion to a carrier.
The seaplane tenders Chitose and
Chiyoda, designed with such an option
in mind, got the same treatment. The incomplete
battleship Shinano, third of the
massive Yamato class, would also be completed
as an aircraft carrier.
Naval engineers made a radical proposal:
Convert all 10 of the Imperial Navy’s
older battleships to aircraft carriers. Each
could carry, they estimated, 54 aircraft.
The high command removed the four Kongo class
battlecruisers from the list, as these elderly
but still fast ships would be needed to escort
the rebuilt carrier forces. The admirals also
vetoed conversion of the two battleships with
16-inch guns, Nagato and Mutsu.
before her conversion
That left just four eligible dreadnoughts,
two of the Fuso class and two more of the
similar Hyuga class. Limited resources would
have to be split between the conversions and
new construction of the Unryu class about
to be laid down in Japanese yards. A semi-conversion
would instead be attempted, removing the aft
armament and replacing it with a flying-off
Approval came in June 1943, and worked started
with Hyuga and her sister, Ise.
The slightly older Fuso and
Yamashiro, slated for the same work,
never received the conversion. Their turret
layout would have necessitated removal of
six of their twelve 14-inch guns, where the
Hyuga class would only lose four. And the
pair converted were slightly faster.
Initial plans called for everything aft of
the funnel to be removed, but the final version
only removed the two stern turrets. A hangar
took their place, with an aircraft handling
deck above it. This was not a true “flight
deck,” as aircraft were no longer intended
to fly off of it. Two catapults would launch
The two ships initially were intended to
carry the D4Y “Judy” dive bomber,
which we described earlier. This plane had good offensive
punch, but the battleships could not have
recovered them: they would fly one sortie,
then have to land at an airfield or on an
actual carrier. Thus the battleships could
not re-fuel or re-arm their aircraft, and
would have to enter a port to recover them.
Planners decided this was much too complicated,
and wanted the two ships to be able to fully
operate their air group.
Instead, the two ships would also operate
the Aichi E16 Zuiun (“Auspicious Cloud”)
seaplane, known to the Allies as “Paul.”
Eleven of each type would be carried. The
Auspicious Cloud carried a respectable bomb
load and had good range and armament.
As a final modification, each ship received
over a hundred 25mm anti-aircraft guns and
a number of rocket launchers.
The two ships had disappointing careers as
battleship-carriers. They participated with
the First Carrier Fleet in the Leyte Gulf
operation, and hundreds of American carrier
planes swarmed the force, sinking all of its
carriers but one. The massive firepower of
the two battleship-carriers spared them. They
undertook some transport missions in the last
year of the war, but never appear to have
actually operated their aircraft. American
planes sank them at their moorings just before
the war’s end, and both were scrapped
Gamers of course are never satisfied with
what was, and far more interested in what
might have been. We’ve provided more
rational air groups for the two ships. They
would have been well-suited to operating the
Ka-1 autogyro we detailed earlier.
With these craft on board, the battleship-carriers
could have provided substantial anti-submarine
capability. The aircraft handling decks would
have been sufficiently large to handle both
take-offs and landings. However, the Ka-1
was an army aircraft, and in Japan, Army and
Navy did not cooperate.
Fleet air defense required fighters, and
Japan had some very good seaplane fighters
that could have been operated by the battleship-carriers.
No other nation attempted to operate such
planes by the 1940s, as the floats created
such drag that it was believed no seaplane
could come close to a land plane’s performance.
Japanese designers first disproved this with
a seaplane version of the A6M “Zero”
fighter. While it did not equal the regular
version of the plane, it wasn’t that
far behind it. Requirements were issued for
next-generation seaplane fighters.
In 1943, Kawanishi produced the N1K “Kyofu”
(“Powerful Wind”), known to the
Allies as “Rex.” The Powerful
Wind, while not as good as contemporary land-based
fighters, had surprisingly good performance
for a seaplane. Kawanishi’s land-based
version, the N1K1-J Shiden (“Violet
Lightning”) was an excellent fighter,
equal to the American Corsairs and Hellcats.
These seaplnes would definitely have added
to fleet air defense, though of course recovering
them would have been far more cumbersome than
carrier landings, especially in action.
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