Good in-flight shot of a Ki-30 in flight over China, apparently
returning from a mission (note the empty underwing bomb racks).
The Ki-30 was a type of
airplane — a single-engined, multi-seat land-based light bomber – that
was steadily becoming obsolete by the beginning of World War II. It was
the first Japanese aircraft of its kind that was fitted with a
double-row air-cooled radial engine, split flaps, an internal bomb-bay,
and a variable-pitch propeller, but it was fated to spend most of its
operational career toiling in the obscurity of China, at a time when
almost no aerial opposition faced Japan’s Imperial Army Air Force.
However, though it was never famous, the Ann, as it was code-named by
the Western Allies, was notably easy to fly and maintain and possessed
hardly any vices, for which its flight and ground crews regarded it
An in-flight shot of one of the prototypes or service-test Ki-30s
during a test flight (note the two men in the rear-seat position!).
During the mid-1930s
the Japanese Army began implementing an ambitious modernizing and
expansion program based around aircraft wholly designed and built by
Japan itself. From this program sprang the Nakajima Ki-27 fighter, the
Mitsubishi Ki-21 "heavy" bomber, and the Mitsubishi Ki-15
reconnaissance plane. The Army also wanted a suitable replacement for
the Kawasaki Ki-3 then equipping its light bomber units, so in May 1936
the Army Air Staff (Koku Hombu) asked the Mitsubishi and Kawasaki
companies to build two prototype light bombers apiece by December of
the same year. The requirements set out by the specification included
the following: (a) a top speed of 248.5 mph at 9,845 feet; (b) a normal
operating altitude of between 6,560 feet and 13,125 feet; (c) the
ability to climb to 9,845 feet in 8 minutes exact; (d) engine to be one
of the following – the 825-hp Mitsubishi Ha-6 radial, 850-hp Nakajima
Ha-5 radial, or 850-hp Kawasaki Ha-9-IIb liquid-cooled inline engine;
(e) a normal bombload of 661 lbs. and a maximum of 992 lbs.; (f)
defensive armament of one forward-firing machine gun and one flexible
rearward-firing machine gun; (g) the ability to perform 60-degree dives
for glide-bombing; and (h) a loaded weight not to exceed 7,275 lbs.
Colonel Komamura of the JAAF was to supervise the Mitsubishi design
team — engineers Kawano, Mizumo, and Ohki.
Preparing for a mission, somewhere in China.
Originally, the new
aircraft was to have had a retractable main undercarriage, but
wind-tunnel tests with models indicated that the gain in speed would be
offset greatly by a retractable landing gear’s extra weight and
complexity. As a consequence, a sturdy fixed gear with “spatted" main
wheels was chosen instead. The wing was mounted at a point above the
line of the aircraft's belly in order to give the prototype a fully
enclosed bomb bay within the fuselage. The pilot sat just above the
leading edge of the wing, and the rear-gunner/radio-operator just
behind the wing trailing edge, in a long, extensively-framed
“greenhouse" canopy which gave both crewmen excellent all-around
vision. Oddly, there was no onboard intercom radio; the pilot and
gunner communicated using a primitive “gosport tube" instead. The Ha-6
engine was chosen, driving a three-bladed variable-pitch propeller
(this kind of propeller was retained throughout the aircraft’s service
lifetime), and the first prototype took off on its maiden flight on
February 28, 1937, from Kagamigahara airfield. A second prototype,
differing from the first solely in being powered by the Nakajima Ha-5
engine, was completed during the same month. Although they were
slightly behind schedule and were somewhat overweight, the two
prototypes met or exceeded every other requirement. The second
prototype’s top speed of 263 mph at 13,125 feet so impressed the Army
that the Ha-5 engine powered the Ki-30 throughout its service life.
Compared to its rival, the Kawasaki Ki-32, it was more reliable,
simpler to maintain, and could also sustain more battle damage and
continue flying, all largely due to its having an air-cooled radial
engine and not a liquid-cooled vee type.
A fully-loaded Ki-30 over China, late 1930s.
Sixteen service test
examples were completed by January of 1938, all of these being powered
by the Ha-5-KAI radial. Only two other changes were made – the
forward-firing 7.7mm machine gun was moved from the left main
undercarriage leg to within the left wing, and the outboard main wheel
covers were removed to ease operations from muddy, unpaved forward
airfields. Once these first sixteen planes were built and tested, the
new aircraft was placed into production as the Army Type 97 Light
Bomber (Ki-30) in March 1938. The parent company built 618 production
machines through April 1940, and the First Army Air Arsenal at
Tachikawa built 68 more by the time production ceased in September
1941. Including prototypes and service-test types, a grand total of 704
Ki-30s were built.
The Ki-30 swiftly built up a reputation as one of the JAAF’s most
reliable machines once it was committed to combat over China in the
spring of 1938. Losses were low as it nearly always operated within the
range of escorting Ki-27 fighters. When the Pacific War begin in
December 1941, the Ann was committed to operations in the Philippines
once Japan gained local aerial superiority, but it quickly became clear
that the Ki-30 was no match for modern Allied fighters. By the end of
1942, the Ann was relegated to training, and others were transferred to
the Royal Thai Air Force, which had already used the Ki-30 as early as
January 1941, against the French in Indochina. And in 1945, along with
other obsolete aircraft, the Ki-30 was used as a suicide attack plane
as Japan desperately tried to stave off defeat.
Bombs away! Two Ki-30s release their lethal loads over China.
Mitsubishi Ki-30 (Ann)
Single-engined light bomber, of all-metal construction with
fabric-covered control surfaces.
Crew of two seated in tandem in an enclosed cockpit.
(First prototype) One Mitsubishi Ha-6 fourteen-cylinder air-cooled
radial engine, developing 825 hp for take-off.
(All other Ki-30s) One Nakajima Ha-5-KAI fourteen-cylinder air-cooled
radial, rated at 950 hp for take-off and 960 hp at 11,810 ft.
One wing-mounted 7.7mm machine gun and one flexible rear-firing 7.7mm
machine gun; bomb load -- normal, 661 lb.; maximum, 882 lb.
Dimensions, weights, and performance:
Wingspan: 47 ft. 8 27/32 in.;
length: 33 ft. 11 3/32 in.;
height: 11 ft. 11 ½ in.;
wing area: 329.159 sq. ft.;
empty weight: 4,916 lb.;
loaded weight: 7,324 lb.;
wing loading: 22.3 lb./sq. ft.;
power loading: 7.7 lb./hp;
maximum speed: 263 mph at 13,125 ft.;
cruising speed: 236 mph;
climb to: 16,405 ft. in 10 min. 36 sec.;
service ceiling: 28,120 ft.;
range: 1,056 miles.