Nakajima Ki-84

Ki-84
275px
Type	Fighter
Manufacturer	Nakajima
Maiden flight	March 1943
Retired	1945, Japan
Primary user	Imperial Japanese Army Air Force
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. The Allied codename was "Frank"; the Japanese Army designation was Type 4 Fighter (四式戦闘機).

It was the last in Nakajima's line of classic fighters and considered one of the best-performing craft from any country.

Design and development

Design of the Ki-84 commenced in early 1942 to meet an Imperial Japanese Army Air Service requirement for a replacement for Nakajima's Ki-43 Hayabusa, which had just entered service. The specification recognised the need to combine the manouverability of the Ki-43 with performance to match the best western fighters and heavy firepower. The Ki-84 first flew in March 1943. Although the design itself was solid, the shortage of fuel and construction materials, poor production quality, and lack of skilled pilots prevented the fighter from reaching its potential. A total of 3,514 were produced.

The Ki-84 addressed the most common complaints about the popular and highly maneuverable Ki-43: insufficient firepower, poor defensive armor, and lack of climbing power. The Ki-84 was introduced with two 12.7 mm (.50-in) machine guns and two 20 mm cannons, a considerable improvement over the single 7.7 mm and single 12.7 mm machine guns which equipped the Hayabusa. Defensive armor offered Hayate pilots better protection than the unsealed wing tanks and light-alloy airframe of the Ki-43. In addition, the Ki-84 used a 65 mm armor-glass canopy, 13 mm of head and back armor, and multiple bulkheads in the fuselage, which protected both the methanol-water tank (used to increase the effectiveness of the supercharger) and also the centrally located fuel tank.

It was the powerplant that gave the Hayate its high speed and prowess in combat. Derived from the Homare engine common to many Japanese aircraft, the Hayate used a direct-injection version of the engine, using water injection to aid the supercharger in giving the Ki-84 a rated 2,000 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-51D Mustang and P-47D Thunderbolt (with top speeds of 433 and 426 mph, respectively). Initial testing of Hayate 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).

The complicated direct-injection engine, however, 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 type's designed performance. Compounding reliability issues was the Allied submarine blockade which prevented delivery of crucial components such as the landing gear. Many Hayate consequently suffered strut collapses on landing.

Versions

Ki-84-a

Prototype.

Ki-84-b

Evaluation model.

Ki-84-c

Pre-production model.

Ki-84-Ia Hayate

Fighter Type 4 of Army. Armed with 2 × 12.7mm Ho-103cannons and 2 × Ho-5 cannons in wings

Ki-84-Ib

Version armed with 4 × 20mm Ho-5 cannons

Ki-84-Ic

Version against Bombers, with 2 × 20mm Ho-5 cannons and 2 × 30mm Ho-105 cannons in wings.

Ki-84-Ia (Manshu Type)

Manufactured in Manchukuo for Mansyu by Nakajima License.

Ki-84-II

Similar to models mentioned above (Ki-84-Ia, -Ib, -Ic).

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.

Operators

Wartime

Template:JPN

• Imperial Japanese Army Air Service

Post-war

Template:PRC

• People's Liberation Army Air Force operated captured aircraft from 1945 until the 1950s.

Template:China as ROC

• Chinese Nationalist Air Force held some Ki-84 in reserve in case American aid was cut.

Template:Country data Indonesia

• In 1945, Indonesian People's Security Force (IPSF) (Indonesian pro-independence guerrillas) captured a small number of aircraft at numerous Japanese air bases, including Bugis Air Base in Malang (repatriated 18 September 1945). Most aircraft were destroyed in military conflicts between the Netherlands and the newly proclaimed-Republic of Indonesia during the Indonesian National Revolution of 1945-1949.

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 wing leading edges ("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; planes belonging to interception forces in Japan proper placed the insignia inside a white square (colloquially known as the "Homeland Defense bandage"), so antiaircraft 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.

Specifications (Ki-84-Ia)

General characteristics

• Crew: One
• Length: 9.93 m (32 ft 7 in)
• Wingspan: 11.23 m (36 ft 11 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

• 2 × 12.7 mm Ho-103 machine guns in fuselage (350 rounds each)
• 2 × 20 mm Ho-5 cannon in wings (150 rounds each)
• 2 × 250 kg (550 lb) bombs
• 2 × 200 L Drop tanks

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 the Browning M2 design; however, they lost 50%+ of its 900 rpm cyclic rate when synchronized with the prop; consequently, their cyclic rate was but 400 rpm. Each carried 350 rounds 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 12.7x81mm 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.

Production

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

Survivors

After the war a number of aircraft were tested by the allied forces, two at the Technical Air Intelligence Unit South-West Pacific Area (SWPA) as S10 and S17 and a further two in the Unites States as FE-301 and FE-302 (Later T2-301 and T2-302).

The aircraft now on exibition at the Tokko Heiwa Kinen-kan Museum at Chiran in Japan is the former S17 This is the same aircrat that used to be found in the Planes of Fame Museum and later in the Arashiyama Museum in Kyoto.

See also

Related development

• Nakajima Ki-43
• 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

References

Bibliography

• Aeronautical Staff of Aero Publishers Inc. Nakajima KI-84 (Aero Series 2). Fallbrook, CA: Aero Publishers, Inc., 1965. ISBN 0-81680-504-0.
• Bueschel, Richard M. Nakajima Ki.84a/b Hayate in Japanese Army Air Force Service. Reading, Berkshire, UK: Osprey Publishing Ltd., 1971. ISBN 0-85045-044-6.
• Francillon, René J. The Nakajima Hayate (Aircraft in Profile number 70). Leatherhead, Surrey, UK: Profile Publications Ltd., 1966.
• Francillon, René J. Japanese Aircraft of the Pacific War. London: Putnam & Company, 1970 (2nd edition 1979). ISBN 0-370-30251-6.
• Green, William. War Planes of the Second World War, Volume Three: Fighters. London: Macdonald & Co. (Publishers) Ltd., 1961 (seventh impression 1973). ISBN 0-356-01447-9.
• Green, William and Swanborough, Gordon. WW2 Aircraft Fact Files: Japanese Army Fighters, Part 2. London: Macdonald and Jane's Publishers Ltd., 1977. ISBN 0-354-01068-9.
• Sakaida, Henry. Japanese Army Air Force Aces 1937-45. Botley, Oxford, UK: Osprey Publishing, 1997. ISBN 1-85532-529-2.
• Thorpe, Donald W. Japanese Army Air Force Camouflage and markings World War II. Fallbrook, CA: Aero Publishers, Inc., 1968. ISBN 0-8168-6579-5.
• Wieliczko, Leszek A. Nakajima Ki-84 Hayate. Lublin, Poland: Kagero, 2005. ISBN 83-89088-76-2. (Bilingual Polish/English)
• Unknown Author Review in "AIRVIEW".
• Various Authors. Yon-Shiki Sentoki Hayate (Pacific War No.46). Tokyo, Japan: Gakken, 2004. ISBN 4-05-603574-1.

Scale Modelling

• Tamiya Nakajima Ki-84 Hayate 1/48 Scale Model Aircraft, Kit No. 6413 (Instruction paper)

Hasegawa 1/48 and 1/32 scales

External links

• Miyakonojo Hayate Special Attack Shinbu Corps Monument
• Review of Japanese Ki-84 Hayate publications
• Angelfire's overview of the Ki-84 Hayate

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Nakajima Ki-84".