Aviation of World War II

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  • Light bomber
  • First flight: 1937
  • Mitsubishi

In May 1936, Koku Hombu commissioned the Mitsubishi and Kawasaki firms to design a single-engine light bomber, which was supposed to replace the obsolete Mitsubishi Ki-2 and Kawasaki Ki-3 aircraft in the troops. In accordance with the requirements of the specification, the new combat vehicle, designed to directly support the ground forces on the battlefield, was supposed to gain an altitude of 3000 m in no more than 8 minutes, develop a maximum speed of more than 400 km / h at this altitude, carry a bomb load within 300-450 kg. Armament was to consist of two synchronized 7.7-mm machine guns: one firing forward, and the second - on a mobile mount at the shooter. To equip the aircraft, the developers were offered three types of engines: two air-cooled engines (Mitsubishi Ha-6 with a capacity of 825 hp and Nakajima Ha-5 with a capacity of 850 hp), the third - liquid (850-horsepower Kawasaki Ha-9-IIB).

At Mitsubishi, design work on a new machine, designated Ki-30, was carried out under the leadership of Colonel Komamura. Initially, it was planned to use a landing gear with retractable struts, but blowing in a wind tunnel showed that the increased mass of the machine and the complexity of the cleaning system were not fully compensated by the gain in speed, and this idea was abandoned. As a layout scheme, a mid-plane was chosen, which made it possible to equip a bomb bay inside the fuselage - for the first time on Japanese light bombers.

The first Ki-30 took off on February 28, 1937. It was powered by a Mitsubishi Ha-6 engine with 825 hp and showed very good performance. However, it was decided to install a more powerful Nakajima Ha-5 engine on the second prototype. As a result, flight performance improved even more, and the maximum speed at an altitude of 4000 m reached 432 km/h, which exceeded the most optimistic expectations of the customer. The Ki-30 was declared the winner of the competition, and Mitsubishi received an order to build a batch of 16 aircraft for operational testing. Their assembly was completed in January 1938, and they differed from the prototypes in engines - they were equipped with improved Nakajima Ha-5 KAI engines with a capacity of 950 hp. In addition, the design of the landing gear fairings was changed, which facilitated the use of bombers from field airfields, and the fixed forward-firing machine gun was moved from the landing gear to the wing.

In March 1938, the Ki-30, which received the official designation "Light Army Bomber Type 97", was put into mass production. Until April 1940, 618 aircraft were produced at the Mitsubishi plant in Nagoya. Another 68 vehicles were built at the 1st Army Aviation Arsenal in the city of Tachikawa.

In combat, the Ki-30 was first used in 1938 in China, where it proved its high efficiency, however, provided that it was accompanied by fighters. Ki-30 bombers achieved some success at the initial stage of the war in the Pacific. But after Allied fighter aircraft stepped up operations in this theater of operations, the Ki-30 (codenamed "Anne") began to suffer huge losses and were soon withdrawn from the first line units. At the end of the war, many of the surviving vehicles ended their combat path, piloted by kamikaze pilots.

Ki-30 Specification
Crew 2
Wing span, m 14.55
Wing area, m² 30.58
Length, m 10.34
Height, m 3,645
1 × PE Mitsubishi Ha-6, HP 950
Weights, kg
Empty weight 2230
Loaded weight 3322
Maximum speed, km/h 432
Cruise speed, km/h 380
Maximum rate of climb, m/min 500
Service ceiling, m 8570
Service range, km 1700

Armament. One wing type 7.7 mm machine gun and one 7.7 mm type machine gun. 89 on a mobile unit at the end of the cab;

Normal bomb load - 300 kg, maximum - 450 kg.

Design. The mid-wing of the Ki-30 consisted of a rectangular center section and trapezoidal consoles, under which there were four external hardpoints. In addition, a 7.7 mm Type 89 machine gun was installed in the left console.

A distinctive feature of the fuselage was the presence of an internal bomb bay, which was not available on all light bombers of those years.

The wheel landing gear to simplify the design of the aircraft were made non-retractable. In order to reduce aerodynamic drag, the wheels were covered with massive fairings. On prototypes, they were solid, and on serial machines, the casing was removed from the outside - to facilitate takeoff from field airfields.

Photo Description
Drawing Ki-30

Drawing Ki-30


  • Carrier-based torpedo bomber
  • First flight: 1937
  • Mitsubishi

Kaichun Koku Hombu for a long time sought from domestic developers to create a carrier-based torpedo bomber, the characteristics of which would correspond to the world level. The Mitsubishi B1M and B2M aircraft that appeared in the 1920s did not meet the set requirements, and by the beginning of the next decade, the quality and performance of Japanese aviation technology had declined even more. All new competitions held between Nakajima and Mitsubishi did not bring the expected results, and the Yokosuka B3V and B4Y bombers put into service should only fill the gap resulting from the obsolescence of the B1M and B2M aircraft, and therefore were considered only as a transitional option.

Formulated in 1935, the design requirements of 10-C became a real challenge for developers. In accordance with them, the new carrier-based torpedo bomber was supposed to be a cantilever low-wing aircraft and have high performance, and its dimensions were limited by the dimensions of a standard aircraft carrier deck elevator. The maximum speed was determined at 330 km / h, the flight duration was 4 hours, with additional tanks - 7 hours. The aircraft was supposed to be able to carry torpedoes or up to 800 kg of bombs in various combinations. No attention was paid to defensive weapons, it was planned to be limited to only one machine gun - based on the thesis popular at that time in Japan that high speed is the best defense. As a power plant, it was supposed to use a Nakajima Hikari or Mitsubishi Kinsei radial engine.

The project of the aircraft, developed by Mitsubishi, received the factory designation Ka-16 and military B5M1. In November 1937, the first prototype was built with a Mitsubishi Kinsei 3 engine with an 840 horsepower. With. and a three-bladed propeller, the pitch of which was manually changed on the ground. The aircraft was an all-metal low-wing aircraft with a non-retractable landing gear, the wheels were covered with massive fairings, similar to those used in the Aichi D3A dive bomber. Wing consoles were folded manually at half span.

Introduced by competitors from Nakajima, the B5N1 aircraft had a more modern design. It was equipped with retractable landing gear, hydraulically folding wing panels and an automatic pitch change propeller. It is not surprising that the characteristics demonstrated by him turned out to be higher than that of the B5M1. At the same time, problems with hydraulic equipment revealed during the tests of the B5N1 caused doubts among the customer's representatives about the performance of this machine. Since the failure of the extremely important program for the fleet to create a modern torpedo bomber could not be allowed, Kaigun Koku Hombu decided to put both aircraft into mass production.

The Ka-16 project went into production under the designation Type 97-2 carrier-based torpedo bomber (B5M1 Number 2). The first production vehicles, as well as competing aircraft, were sent to China, where hostilities were going on at that time. The experience of using Nakajima B5M bombers in China confirmed the rather high performance of these aircraft, as a result, the production of B5M1 bombers was stopped after the manufacture of approximately 125 aircraft. About half of them received new 14-cylinder Mitsubishi MK8D Kinsei 43 engines with a power of 1000 hp instead of Kinsei 3 engines. Thanks to the new engine, the maximum speed of the aircraft increased to 381 km / h (30 km / h more than the B5N1). But this circumstance did not change the decision of Kaigun Koku Hombu to curtail the production of B5M1. Perhaps the military considered the Nakajima car more promising, moreover, at that time the B5N2 variant with a more powerful engine appeared.

During the Pacific War, B5M1 torpedo bombers operated from ground bases in Southeast Asia for a short time, after which they were transferred to the second line in training units and used to solve auxiliary tasks. In 1942, they received the new designation B5M1 Model 61. Allied intelligence services initially identified the B5M1 aircraft as an early version of the B5N. and therefore assigned him the code designation "Kate". Later, the mistake was corrected and the designation was changed to "Mabel", but soon the Americans returned to the old name "Kate", adding the index 61 for clarity.

B5M1 Specification
Crew 3
Wing span, m 15.30
Wing area, m² 37.95
Length, m 10.23
Height, m 3.12
1 × PE Mitsubishi MK8D Kinsei-43, HP 1 × 1080
Weights, kg
Empty weight
Loaded weight 4000
Gross weight 4400
Maximum speed, km/h 381
Время подъема на высоту 3000 м, мин 7,1
Service ceiling, m 8260
Service range, km 2187

Armament. One 7.7 mm Type 92 machine gun on a turret at the end of the cockpit; sometimes two wing-mounted 7.7 mm Type 97 machine guns; 800 kg torpedo or 750 kg bombs.

Design. The low-lying wing of the B5M had an elliptical shape. Its consoles were folded by hand at about half the span.

The cockpits of the pilot, bombardier / observer and gunner / radio operator were closed by a common long lantern. Under it, in the rear, a mobile 7.7-mm machine gun type 92 was installed.

The power plant is a 14-cylinder air-cooled Mitsubishi MK8D Kinsei 43 engine with a capacity of 1000 hp. With.

As with most other aircraft with fixed landing gear, its struts and wheels were covered with massive fairings.

Photo Description
Drawing B5M1

Drawing B5M1


  • Multipurpose Attack Aircraft
  • First flight: 1939
  • Mitsubishi

In December 1937, at the suggestion of one of the leading pilots, Captain Yuzo Fujita, Koku Hombu prepared requirements for a close support aircraft designed to replace the Ki-30 light bomber. Particular attention in the specification was paid to the maneuverability of the machine, its reliability and the possibility of using it from poorly equipped field airfields. Compared to its predecessor, the new aircraft, which received the designation Ki-51, was supposed to be much smaller, and the requirements for its characteristics, formulated in its final form in February 1938, were as follows; maximum speed at an altitude of 2000 m - 420 km / h, take-off weight - 2700 kg. bomb load - twelve bombs of 15 kg or four of 50 kg, small arms - three machine guns (two for firing forward and one for firing backwards). It was supposed to equip the new machine with an air-cooled Mitsubishi Ha-26-II engine with an HP 940 power.

The task of designing the attack aircraft was entrusted to Mitsubishi, where the designers who created the Ki-30 took up its development. It is not surprising that the Ki-51 turned out to be very similar to its predecessor, however, it was not a medium wing, but a low wing, since a small bomb load made it possible to abandon the bomb bay. In addition to the reduced landing gear, the double cabin, covered by a common canopy, has also become noticeably shorter. This ensured closer interaction between the crew members and made it possible to install a device for dual control of the aircraft and the minimum necessary set of instruments at the gunner-radio operator. Two Type 89 7.7 mm machine guns were placed in the wings, the third in the rear of the cockpit, to protect against attacks from enemy fighters from behind.

The first of two ordered Ki-51 prototypes was completed in June 1939. Its flight tests immediately began, but even before they were completed, Mitsubishi was instructed to build another eleven aircraft of the pilot batch by the end of the year, intended primarily for operational testing in the army. According to their results, a number of changes were made to the design of the aircraft, the main of which was the installation of fixed slats, which improved controllability at low speeds, and armor plates 6 mm thick under the cockpit and engine. One of the experimental machines was converted into a reconnaissance aircraft by placing several aerial cameras in the rear of the cockpit. Despite the positive test results of the reconnaissance variant, which received the Ki-51A index, it was not launched into the series, and changes were made to the design of the serial attack aircraft, which made it possible to install Photo equipment on them in the field. The standard Ki-51 received the official designation "Army attack aircraft Type 99". In the period from 1940 to 1944, 1459 aircraft of this type were produced at the Mitsubishi plant. During the entire production period, only two significant improvements were made to the design of the machine: two tanks with a capacity of 68 liters each were placed in the wing consoles, and 7.7-mm wing machine guns were replaced with Type 1 machine guns of 12.7 mm caliber.

Ki-51 attack aircraft, which the enemy assigned the code designation "Sonya", took part in the fighting in the skies of China, and then in all areas of the Pacific Ocean. In general, they coped well with their duties, although they suffered heavy losses, primarily due to insufficiently high speed. Pilots and technical personnel fell in love with the Ki-51 for its reliability, maneuverability, ease of operation and maintenance, and the ability to operate from unprepared airfields. The aircraft was so successful that for its production at the 1st Army Aviation Arsenal in the city of Tachikawa, they even launched a new assembly line, from which another 913 attack aircraft left by the end of the war. In recent months, Ki-51s have been used frequently by kamikaze pilots. On the last flight, they took on board one 250-kg bomb.

In 1941, the engineers of the Manei Hikoki Seizo KK company, transferred to Tachikawa, were instructed to create a special tactical reconnaissance aircraft based on the Ki-51. Received the index Ki-71, the aircraft was equipped with a Mitsubishi Ha-112-II engine with an HP 1500 power. s, which allowed to reach a speed of 470 km / h. The aircraft was equipped with a landing gear retractable in flight and had reinforced offensive weapons, two 20-mm No-5 cannons installed in the wing. The aircraft was not launched into the series, however, the Allies assigned the Ki-71 the code name "Edna".

Ki-51 Specification
Crew 2
Wing span, m 12.10
Wing area, m² 24.02
Length, m 9.21
Height, m 2.73
1 × PE Mitsubishi Ha-26-II (Army type 99 model 2), hp 1 × 940
Weights, kg
Empty weight 1873
Loaded weight 2798
Gross weight 2920
Maximum speed, km/h 424
Cruise speed, km/h 320
Maximum rate of climb, m/min 505
Service ceiling, m 8270
Service range, km 1060

Armament. Two 7.7 mm type 89 wing-mounted machine guns and one 7.7 mm Te-4 machine gun on a mobile mount at the end of the cockpit; normal bomb load - 200 kg, maximum - 250 kg.

Design. Low-lying, unlike the Ki-30, the Ki-51 wing had an all-metal two-spar design similar to its predecessors and also consisted of a rectangular center section and two consoles.

Like all other Japanese aircraft of this class, the Ki-51 had a non-retractable undercarriage, and its main struts with wheels were covered with massive fairings.

All-metal semi-monocoque fuselage. Due to the small bomb load, the internal bomb bay was abandoned.

Photo Description
Drawing Ki-30

Drawing Ki-51


  • "World War II Japanese Aircraft" /O.V. Doroshkevich/
  • "Encyclopedia of military equipment" /Aerospace Publishing/
  • CD encyclopedia. "Military Aviation" /Media 2000/