Photo: Naval History and Heritage Command
Nakajima by February 1944. The gun armament
was improved and variants with magazines for
up to 150 rounds could be used on the Type 21.
Such a Zero may have been designated as Type
Here comes the Rufe
Wildcats aboard the USS Wasp prepare for an air strike against Tulagi and adjacent islands in the early morning
hours of August 7, 1942.
Photo: Naval History and Heritage Command
Floatplanes are a very old idea. Fighters of this
design had already been deployed in combat
during the First World War. After the war, their
priority gradually declined as the performance
of these seaplanes fell gradually behind that
of fixed landing gear machines. The Imperial
Japanese Navy returned to the idea in 1933
during preparation for a new seaplane tender.
IJN came up with a specification for a machine
that was to protect a coastal base during its
construction and was to be capable of reaching
speeds of 200 knots. Kawanishi had been
preparing a study of such a seaplane since 1934.
It was to operate from a tender, or launch from
a catapult, and be able to counter fighter aircraft.
The prototype was not built, and preparations
were halted in 1936. Subsequently, the concept
of a two-seat machine was considered, but even
this idea was abandoned.
In the late 1930s, the US Navy prepared a plan to
build 2,000 flying boats. The Japanese decided to
respond to this threat. Therefore, in September
1940, the IJN commissioned Kawanishi with
the specification for the 15-Shi fast interceptor
seaplane. Kawanishi had already been working
on a fast floatplane reconnaissance aircraft
(later designated the E15K Shiun) for several
months, and the Navy hoped for synergy from
this decision. However, at the same time, it
feared certain delays because Kawanishi’s
aircraft carried a number of innovative features.
Therefore, the IJN decided to convert the
Mitsubishi A6M2, which was currently
undergoing combat test deployment in China,
to a fighter seaplane. Mitsubishi was fully
occupied with the production of Zeros and other
types of aircraft. Therefore, the IJN turned to
Nakajima, which began licensed production
of A6M2 fighters at its Koizumi plant in late
1941. The company had some free design and
production capacity and was therefore awarded
with works on the seaplane.
Shinobu Mitsutake was appointed chief
designer. His team tried to make the most of the
A6M2 design. Some authors state that standard
fighter seaplane was based on the A6M2 Type 11,
which did not have folding wingtips. In fact, at
least the first few dozen production machines
had folding wingtips. On captured Rufes, this
design feature is still documented on the 37th
The designers added a metal central float to the
fuselage. The pylon was mounted to the main
wing spar and attached to the rear wing spar by
a “V” shaped strut. The pylon, with incorporated
the oil cooling system, was located roughly
This picture taken from Dauntless on August 7, 1942, shows smoke rising from burning fuel supplies
on Tanambogo Island, where the Rufe seaplanes were based. To the right is Gavutu Island and to the left
is Gaomi Island. Florida Islands can be seen in the background.
where the Zero had the auxiliary tank attached.
The absence of the auxiliary tank was replaced
by tanks in the float. The stabilizing floats were
mounted on separate pylons. Hatches were
added to the wing´s skin to allow access to the
internal wing structure and pylons.
This elegant solution for mounting the central
float was already used on the F1M Pete biplane
and contributed to the high aerodynamic purity
of Mitsutake’s design. The central float and
its dynamic effects on the fuselage structure
during take-off, high-G maneuvers, and landing,
necessitated the need to reinforce the fuselage
structure in the cockpit area by additional metal
On the first few dozen machines, a system for
purging the fuel tanks was installed on top of
the central float. The fittings of this system,
which protruded from the float at the top, were
protected by a hemispherical cover. The float
was also fitted with a rudder.
The last significant change from the Zero was
an increase in the vertical tail area for the
stability of the machine. Testing of the prototype
began on the day of the Japanese attack on
Hawaii and continued intensively during early
1942. The prototype was converted from the
land-based version of the Zero fighter, the A6M2
Type 11 c/n (6)69. The next nine A6M2-N aircraft
were to be produced at Nakajima by conversion
from Mitsubishi A6M2 Type 21 carrier fighters,
which were to undergo repairs due to damage
in combat. Among them were the machines c/n
(5)159 and (3)312, which took part in the attack
on Hawaii aboard the aircraft carrier Shōkaku.
However, the converted seaplanes suffered