Namtong Type 37 bomber

Namtong Type 37 bomber
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Type 37-I and Type 37-II, the most common wartime variants.
Role	Twin-engine bomber
National origin	Greater Menghean Empire
Manufacturer	Namtong Aviation Group
First flight	1936
Introduction	1937
Primary user	Imperial Menghean Army Air Force
Produced	1937-1941

The Namtong Type 37 bomber (Menghean: 남통 37식 폭격기 / 南通三七式中爆擊機, Namtong sam-chil-sik pokgyŏkgi) was a Menghean twin-engined front-line medium bomber designed in the mid-1930s. It saw extensive use in the early years of the Pan-Septentrion War. At the time of its appearance, it was a major improvement over Menghe's existing bomber aircraft, in part due to the use of the Dayashinese Mitsubishi Kinsei engine. Its main drawback, common to other bombers of its generation, was a lack of self-sealing fuel tanks, which left it vulnerable to faster fighter aircraft at the height of the war.

Development

When Menghe launched its military intervention in Dzhungestan in early 1933, it did not possess any modern twin-engine bomber aircraft. Its main ground-attack aircraft was the Type 26 bomber, a single-engine biplane with poor range and payload. The lack of a long-range tactical bomber became a serious complaint among the Army's high command, leading Menghe to purchase 26 Mitsubishi Ki-1 bombers from Dayashina in 1934. The Donghae Heavy Industries Group also developed its own twin-engine, high-wing monoplane design, which was accepted for service as the Donghae Type 35 heavy bomber, but its speed and range were disappointing and in the end the design was repurposed for transport duties.

Already anticipating flaws with the Donghae design after its flight tests, the Namtong Aviation Group began work on its own prototype in late 1935. They opted for a more modern cantilever monoplane configuration, and made greater use of aluminium frames and skin. Throughout the design process, they drew inspiration from contemporary bomber aircraft in development elsewhere, with the goal of producing a world-class bomber which could compete with anything in the Columbian or Tyrannian arsenals.

Their main obstacle was engine power. The Namtong Gi-8 radial engine, originally slated for use on the new bomber, suffered from reliability and quality control problems, which threatened to slow down development. Under pressure to meet the Army's tight deadlines in the context of an escalating conflict with Sylva and Themiclesia, Namtong negotiated the purchase of Mitsubishi Kinsei engines from Dayashina, with plans to license-produce them as the Donghae Gi-20. A Kinse-powered prototype made its first flight in late 1936, and by early 1937 the Army had approved it for mass production as the Type 37 medium bomber (the "medium" was later dropped).

Design

The Namtong Type 37 is easily recognizable by its broad wings with a nearly straight leading edge, which earned it the nickname "gliding eagle" (활공 독수리, hwalgong doksuri) among ground troops. The wings followed a cantilever configuration, eliminating the external struts present on the Donghae Type 35, and were of all-metal construction using an aluminum cover (the tail control surfaces still used stretched fabric). To further reduce drag, the main landing gear could retract into the engine nacelles in flight, though the tail wheel was not retractable.

The main payload was carried within an enclosed internal bomb bay, which could accommodate a total of 1,000 kilograms of bombs - usually 4x 250kg or 10x 100kg. There were also four additional external hardpoints, two under each wing between the engine nacelles and the fuselage, each of which could carry a 250kg or 100kg bomb. These were only used in short-distance missions, as they hindered the bomber's speed and range. The Type 37-II could carry a single 1000-kilogram bomb, an option not present on earlier models. The bombsight was relatively crude, relying on manual input for speed, wind, and altitude, and the Type 37 could not drop bombs accurately from high altitudes, hamstringing it in its intended role as a front-line tactical bomber.

Defensive armament consisted of three 7.5mm machine-gun mounts: one in the nose, one in a turret over the fuselage, and one in a downward-facing mount in the fuselage rear. This latter gun was mainly added to cover a blind spot, and was awkward to aim and operate. The turret, by contrast, was fairly effective, and offered a wider field of fire over the shielded pintle mounts on the contemporary Ki-21 and G3M.

Operational history

The Type 37 bomber arrived on the front lines right as the Pan-Septentrion War was escalating into a major conflict. It made its debut in the Menghean invasion of Maverica, and also saw extensive service in the Khalistan campaign, as it was one of the few Menghean aircraft capable of reaching northern Khalistan and Portcullia from airfields in Innominada.

During the early war, the Type 37 earned a favorable reputation among its crews, who regarded it as an effective tactical bomber. On a light or empty bomb load, it could outrun early Maverican and Themiclesian fighters such as the P-6 Hawk, and Gladiator pilots who lacked an initial height advantage struggled to keep up. It was also sturdier and better-defended than the Type 35 before it, and broadly comparable to allied Dayashinese bombers. Its main threat came from Tyrannian and Rajian monoplane fighters, which also outperformed its escorts until the arrival of the Type 40 fighter.

As the war progressed, threats to the Type 37 grew more numerous, and its shortcomings became more prominent. The lack of self-sealing fuel tanks and internal armor plates made it especially vulnerable to incendiary machine-gun fire. These flaws, combined with better Allied fighter tactics, caused Type 37 bombers to suffer heavy losses in 1939 and 1940, forcing the Imperial Menghean Army Air Corps to shift them away from front-line service. Many Type 37-Is were converted into transport planes, and late in the war some were repurposed for suicide operations against enemy warships.

Variants

Namtong WH-42

First prototype, using the Namtong Gi-8 engine.

Namtong WH-44

Updated prototype with the imported Kinsei engine.

Type 37-I

Initial production model.

Type 37-II

Late 1938 variant with moderately improved engines and a new defensive turret carrying a 12.7mm heavy machine gun.

Type 37-III

Extended-range version capable of mounting an auxiliary fuel tank inside the main bomb bay. Bombs could only be carried on the wing hardpoints.

Type 37 transport aircraft

Type 37-I rebuilt with a modified interior, used to move supplies, transport high-ranking officers, and insert small commando teams behind enemy lines.

Type 37 inline-engine testbed

1939 prototype using DB 601 inline engines. The formal Army designation, if it had one, is unknown. It was found to possess slightly superior performance, but was not adopted for service.

Specifications (Type 37-I)

<imgur thumb="yes" w="700">wo0H7S1.png</imgur> General Characteristics

• Crew: 5 (pilot, copilot/bombardier, three gunners)
• Length: 15.23 m (excluding nose MG)
• Wingspan: 21.23 m
• Height: 4.14 m to antenna, parked
• Wing area: 62.88 m² (346 sq ft)
• Empty weight: 6,520 kg
• Loaded weight: 8,230 kg
• Powerplant: 2 × Mitsubishi Kinsei 14-cylinder air-cooled radial engine, 791 kW (1,061 hp) each

Performance

• Maximum Speed: 420 km/h (261 mph)
• Cruise speed: 360 km/h (224 mph)
• Range: 2,400 km (1,490 miles) one-way with 1,000 kg payload
• Service ceiling: 8,800 m (28,870 ft)
• Rate of climb: 6.3 m/s (1240 ft/min)
• Wing loading: 130.41 kg/m² (26.71 lb/sq ft)
• Power-to-mass ratio: 0.193 kW/kg (0.117 hp/lb)

Armament

• 3× flexible 7.5mm machine-gun
• up to 1,500 kg of bombs

• 1,000 kg internal (basic load)
• 500 kg external (supplementary load)

See also

• Namtong Type 36 attack plane
• Chikai Type 34 fighter