Kawasaki Ki-61

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Ki-61 Hien

Type	Fighter
Manufacturer	Kawasaki Heavy Industries
Designed by	Takeo Doi Shin Owada
Maiden flight	December 1941
Introduced	1943
Retired	1945
Primary user	Imperial Japanese Army Air Force
Number built	3,159
Variants	Ki-100

The Kawasaki Ki-61 Hien (飛燕, "flying swallow") was a World War II fighter aircraft used by the Imperial Japanese Army Air Force. The allied code name was "Tony", given by Allied pilots who initially thought it was a derivative of the Italian Macchi C.202. The Japanese Army designation was "Type 3 Fighter" (三式戦闘機). It was the only mass-produced Japanese fighter of the war to use a liquid-cooled V engine.

1 History
2 Variants
3 Specifications (Ki-61-I-KAIc)
4 References
5 External links
6 Related content

[edit] History

The Ki-61 Hien was designed in parallel with the Kawasaki Ki-60 interceptor by Takeo Doi and Shin Owada. Created around the Kawasaki V12 engine with denomination Ha-40 engine, a license-built version of the German Daimler-Benz DB 601A, Ki-61 improved on the Ki-60 design by incorporating a revised wing and various streamlining and weight-saving measures. The aircraft first flew in December 1941. Although test pilots were enthusiastic about self-sealing fuel tanks, upgraded armament, and good dive performance, the wing loading of 146.3 kg/m² (30 lb/ft²) was considered excessive by Japanese standards (92.6 kg/m² (19 lb/ft²) in Ki-43-Ia was considered borderline). To address these concerns, Kawasaki staged a fly-off between the Ki-61 prototype and Ki-43-II, Ki-44-I, Bf 109E-3, and captured P-40E Warhawk. Ki-61 proved the fastest of all the aircraft and was inferior only to Ki-43 in maneuverability ^[1].

Ki-61 entered combat for first time in the Spring of 1943 during the New Guinea campaign. The aircraft was utilized in South and Southwest Pacific, Philippines, Southeast Asia, Okinawa, China, Manchuria and Japanese Metropolitan defense against American B-29 Superfortresses. Some were also used in Kamikaze missions toward the end of the war. The Ki-61 was delivered to fifteen Sentai (squadrons), State Major Chutais and other operational training units in the IJAAF. The aircraft was largely trouble-free in service except for the liquid-cooled engine which tended to overheat when idling on the ground and suffered from oil circulation and bearing problems.

Ki-61-II was a high altitude interceptor with 10% larger wing area, more armor, and a more powerful engine. After initial fuselage and wing stability problems, the new interceptor reverted to the original wing and was put into service as the Ki-61-II KAI. However, engine reliability problems with the improved version of the Ha-40 engine named Ha-140 were never resolved. After a US bombing raid on 1945-01-19 destroyed the engine factory in Akashi, Hyogo, the 275 Ki-61-II KAI airframes without engines were converted to use the Mitsubishi Ha-112-II radial engine, resulting in the Ki-100.

[edit] Variants

Ki-61-Ia: The first production variant, 2x 7.7 mm (0.303 in) and 2x 12.7 mm (0.50 in) machine guns, some fitted with a pair of German 20 mm MG 151 cannon instead of wing machine guns
Ki-61-Ib: Armed with 4x 12.7 mm machine guns, some fitted with a pair of German 20 mm MG 151 cannon instead of wing machine guns
Ki-61-I-KAIc: Reinforced wings to permit carrying bombs or external fuel tanks, 190 mm (7.5 in) fuselage stretch, fixed tail wheel, revised rear fuselage, 2x 20 mm cannon in the nose.
Ki-61-I-KAId: Interceptor variant with 2x 12.7 mm fuselage machine guns and 2x 30 mm wing cannon
Ki-61-II: Prototype with 10% larger wing area, Ha-140 engine with 1,120 kW (1,500 hp) for takeoff; first flight December 1943, 8 built.
Ki-61-II-KAI: Pre-production version with the original wing, 220 mm (8.7 in) fuselage stretch, enlarged rudder, and Ha-140 engine, 30 built.
Ki-61-II-KAIa: 2x 12.7 mm machine guns in the wings, 2x 20 mm cannon in the fuselage.
Ki-61-II-KAIb: 4x 20 mm cannon.

A total of 3,159 Ki-61 were built.

[edit] Specifications (Ki-61-I-KAIc)

Data from The Great Book of Fighters^[2]

General characteristics

Crew: One
Length: 8.94 m (29 ft 4 in)
Wingspan: 12.00 m (39 ft 4 in)
Height: 3.70 m (12 ft 2 in)
Wing area: 20.00 m² (215.28 ft²)
Airfoil: NACA 2R 16 wing root, NACA 24009 tip

Internal fuel capacity: 550 L (145.2 US gal)
External fuel capacity: 2x 200 L (53.8 US gal) drop tanks

Empty weight: 2,630 kg (5,800 lb)
Loaded weight: 3,470 kg (7,650 lb)
Powerplant: 1× Kawasaki Ha-40 liquid-cooled inverted V-12, 875 kW (1,175 hp)

Performance

Maximum speed: 580 km/h (360 mph) at 5,000 m (16,405 ft)
Range: 580 km (360 mi)
Service ceiling: 11,600 m (38,100 ft)
Rate of climb: 15.2 m/s (2,983 ft/min)
Wing loading: 173.5 kg/m² (35.5 lb/ft²)
Power/mass: 0.25 kW/kg (0.15 hp/lb)

Time to altitude: 7.0 min to 5,000 m (16,405 ft)

Armament

2x 20 mm Ho-5 cannon, 120 rounds/gun
2x 12.7 mm (0.50 in) Ho-103 machine guns, 200 rounds/gun
2x 250 kg (550 lb) bombs

[edit] References

^ Francillon RJ (1966). Aircraft profile 118: Kawasaki Ki-61 Hien. Profile publications. ASIN B0007KB5AW.
^ Green, W, Swanborough, G (2001). The great book of fighters. MBI Publishing. ISBN 0-7603-1194-3.