Nakajima Ki-84

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Ki-84
Type	Fighter
Manufacturer	Nakajima
Maiden flight	March 1943
Retired	1945, Japan
Primary user	Japanese Imperial Army
Number built	3,514

The Nakajima Ki-84 Hayate (疾風, "Gale") was a single-seat fighter used by the Japanese Imperial Army in World War II. It was the last in Nakajima's line of classic fighters and considered one of the best-performing craft from any country. The Allied codename was "Frank"; the Army designation "Type 4 Fighter" (四式戦闘機).

Contents 1 Design and development 2 Camouflage and markings 3 Versions 4 Operators 5 Specifications (Ki-84-Ia) 5.1 Production 5.2 Sources 6 External links 7 Related content

[edit] Design and development

The Ki-84 first flew in March 1943. While the design was solid, a shortage of fuel and construction materials, poor production quality, and lack of skilled pilots kept it from reaching its potential. A total of 3,514 were produced.

The Ki-84 addressed two of the most common complaints about Nakajima's previous fighter for the Japanese Imperial Army, the popular and highly manoeuverable Ki-43 or "Hayabusa" ("peregrine falcon"): insufficient firepower, poor defensive armor and a lack of climbing power. To this end, the Ki-84 was introduced with two 12.7mm (50-caliber) machine guns and two 20mm cannon, a respectable improvement over the single 7mm and single 12.7mm machine gun on the earlier aircraft.

Defensive armor offered Hayate pilots better protection than the unsealed wing tanks and light-alloy airframe of the Hayabusa. The Ki-84 used a 65mm armor-glass canopy and provided 13mm head and back armor, and multiple bulkheads in the fuselage protected both the methanol-water tank used to increase the effectiveness of the supercharger and also the centrally located fuel tank (which was supplemented by wing tanks as well).

But it was the powerplant that gave the Hayate its signature speed. Derived from the Homare engine common to many Japanaese aircraft, the Hayate was produced with a highly advanced direct-injection version of the engine, using water-methanol injection to aid the supercharger in giving the Ki-84 a rated 2000 hp at takeoff. This combination—in theory, at least—gave it a climb rate and top speed roughly competitive with the top Allied fighters of the late Pacific theater, the P-51 Mustang and P-47 Thunderbolt (with top speeds of 433 and 426 mph, respectively). The Hayate's initial testing at Tachikawa in early summer 1943 saw test pilot Lt. Funabashi reach a maximum level speed of 634 km/h (394 mph) in the second prototype, but after the war a captured example was tested by the U.S. Army using high-octane fuel and achieved a speed of 690 km/h (430 mph).

However, the complicated direct-injection engine required a great deal of care in construction and maintenance, and as the Allies advanced toward the Japanese homeland, it became increasingly difficult to support the Hayate's designed performance. And due to the Allied submarine blockade, Nakajima was unable to acquire proper materials for such crucial components as the landing gear, and many Hayates suffered collapse of the struts on landing.

[edit] Camouflage and markings

The Ki-84 basic colours are:

• dark green - top and fuselage sides, upper surfaces of main wings and horizontal stabilizer
• light grey or sky blue - lower surfaces
• orange yellow - identification colour on the inside half of the wings ("friend or foe marker")

Toward the end of war, some planes had a dark green "Special Attack Painting", while others had its silver duraluminium metallic surface mostly unpainted, save for the top of nose which was coated black to reduce reflection from the sun.

It was a general rule that Japanese planes in overseas territories had a narrow white line called the "border break through line" or "field identification mark" surrounding their hinomaru or insignia; planes belonging to interception forces in Japan proper placed the insignia inside a white square (colloquially known as the "Homeland Defense bandage"), so that ground Air defense units could more easily distinguish them from enemy planes.

The inside of the fuselage and the wheel cover wells were painted in a dark opaque bluish grey, and the propeller spinner was painted with a variety of colors based on the unit it belonged to.

[edit] Versions

• Ki-84 (prototype)
• Ki-84 (evaluation model)
• Ki-84 (pre-production model)
• Ki-84-Ia Hayate fighter Type 4 of Army (Mark Ia)
• Ki-84-Ib (Mark Ib) - four cannons Ho-5 of 20 mm
• Ki-84-Ic (Mark Ic) - Version against Bombers, with two cannons Ho-5 of 20 mm and Ho-105 of 30 mm in wings
• Ki-84-Ia (Manshu Type) - Manufactured in Manchukuo for Mansyu by Nakajima License.
• Ki-84-II (Army designation Ki-84-Ia, -Ib, -Ic) - similar to models mentioned above
• Ki-84 N/P/R - high altitude versions
• Ki-106 - Prototypes in total wood construction
• Ki-113 - Prototype similar at Ki-84-Ib in Steel
• Ki-116 - evaluation model, equipped with Mitsubishi 62(Ha-33), 1,500 hp (1,120 kW)
• Ki-117 - Redesigning of Ki-84 N.

[edit] Operators

Wartime

•  Japan

Post-war

•  People's Republic of China (used by the Chinese Communist Air Force until the 1950s)

[edit] Specifications (Ki-84-Ia)

General characteristics

• Crew: One
• Length: 9.93 m (32 ft 7 in)
• Wingspan: 11.23 m (36 ft 10 in)
• Height: 3.38 m (11 ft 1 in)
• Wing area: 21 m² (226 ft²)
• Empty weight: 2,665 kg (5,875 lb)
• Loaded weight: 3,616 kg (7,972 lb)
• Max takeoff weight: 3,898 kg (8,594 lb)
• Powerplant: 1× Nakajima Ha-45-21 18-cylinder radial engine, 1,485 kW (1,990 hp)

Performance

• Never exceed speed: 800 km/h (496 mph)
• Maximum speed: 627 km/h (392 mph)
• Range: 2,155 km (1,339 miles)
• Service ceiling: 10,500 m (34,450 ft)
• Rate of climb: 19.25 m/s (3,790 ft/min)
• Wing loading: 172 kg/m² (35 lb/ft²)
• Power/mass: 0.41 kW/kg (0.25 hp/lb)

Armament

• 2x 12.7 mm Type 1 machine guns in fuselage
• 2x 20 mm Ho-5 cannon in wings
• 2x 250 kg (550 lb) bombs

The Ho-5 cannon in the wings had 150 rpg. Projectiles weighed 112 g AP, and 79 g HE (HE=12%). The 20X94 cartridge had muzzle velocity of 820 m/s formerly, but was reduced to 700 m/s for AP and 730 m/s for HE due to alloy shortages in the guns. It still had a range of 900 m. Rate of fire was 850 rpm each. The twin Type 1 (Ho-103) 12.7 mm machine guns were based on a Browning design and therefore it lost 50%+ of its 900 rpm firing rate each when synchronized with the prop: Thus it's rate was 400 rpm each. Each carried 350 rounds of ammo in the cowl. The AP bullets were 35.4 g and the HE were 33 g (HE=2.3%) - Italian, together with 38 g HE - Japanese made. The 12.7x81 cartridge gave a muzzle velocity of 760 m/s for the AP, and 770-796 m/s for the HE and an effective firing range of 750 m. It was an unreliable gun earlier in the war. Sensitive rudder made it a poor gun platform at first.

[edit] Production

• Total production: 3,514 examples
  • 3,288 by Nakajima
  • 94 by Mansyu

[edit] Sources

• Review AIRVIEW
• Nakajima Ki-84 Hayate 1/48 Scale Model Aircraft, KIT NO 6413 (Instruction paper); TAMIYA MOKEI PLASTIC MODEL CO.50-1,OSHIKA, SHIZUOKA-CITY, JAPAN

[edit] External links

• Miyakonojo Hayate Special Attack Shinbu Corps Monument

[edit] Related content

Related development

Nakajima Ki-44 - Tachikawa Ki-103 - Nakajima Ki-113 - Nakajima Ki-116

Comparable aircraft

• Lavochkin La-7
• Focke-Wulf Fw 190
• Kawasaki Ki-100
• Republic P-47 Thunderbolt

Designation sequence

Ki-81 - Ki-82 - Ki-83 - Ki-84 - Ki-85 - Ki-86 - Ki-87