Kawasaki Ki-100

Ki-100
275px
A Ki-100 in the RAF Museum at Hendon, London
Type	Fighter
Manufacturer	Kawasaki Heavy Industries
Maiden flight	1 February 1945
Introduced	1945
Retired	1945
Primary user	Imperial Japanese Army Air Force
Produced	1945
Number built	395 .
Developed from	Kawasaki Ki-61

The Kawasaki Ki-100 was a fighter aircraft used by the Imperial Japanese Army in World War II. The Japanese Army designation was "Type 5 Fighter" (五式戦闘機).

The emergency measure of adapting a Ki-61-II-KAI fighter to carry a Mitsubishi radial engine resulted in an excellent interceptor fighter, one of the best used by the Army during the entire war. Missions began in March 1945; from the first engagements the Ki-100 showed its good qualities against the USAAF B-29 heavy bombers at high altitudes, and showed itself equally effective against U.S. Navy carrier fighters. A new variant, the Ki-100-Ib, was constructed during the last weeks of the conflict to equip five sentai for home defense.

Design and development

By mid-1944, one of the best fighters of the IJAAF was the Kawasaki Ki-61 Hien (飛燕、" Flying Swallow", named "Tony" by the Allies). It was the only production Japanese fighter to have an inline powerplant (the Kawasaki Ha-40, a Japanese adaptation of the German Daimler-Benz DB 601 engine) during World War II, as well as the first one with factory-installed armor and self-sealing fuel tanks. It had also a respectable performance, more in line with contemporary American and European designs of the time, with a focus on speed and rate of climb instead of maneuverability and range. It was an effective design, but suffered from engine shortages and reliability problems.

These problems as well as the performance advantage of enemy fighters, especially the F6F Hellcat, lead to the development of an improved model, the Ki-61-II (later Ki-61-II-KAI), powered by the new 1,120 kW (1,500 hp) Kawasaki Ha-140 engine which was unfortunately heavier than the Ki-61-I-KAIc it replaced . Maximum speed increased from 590 km/h to 610 km/h (368 mph to 379 mph) and general performance (except rate of climb) improved as well. However, it was never able to perform as planned due to the continued degradation of quality of the engine's assembly line. Production of this model ended at the beginning of 1945, when a B-29 raid destroyed the engine's production plant, leaving some 280+ finished Ki-61s without a powerplant. At this point of the war, the IJAAF was in desperate need of effective interceptors to stop the enemy bomber raids over the Japanese mainland, so it was ordered that a Mitsubishi Ha-112-H engine should be installed on those frames.

The Mitsubishi Ha-112-H was a powerful powerplant, in fact equivalent to the Ha-140, but was a radial engine and substantially lighter (the Ki-100 was 600 lb lighter than the Ki-61-II, in fact as light as a Ki-61-I). After the study of an imported Fw 190A, an example of an aircraft in which a wide radial engine had been successfully installed in an airframe with a narrow width, three Ki-61-II-KAI airframes were modified to carry this engine and to serve as prototypes. As a result, on February 1, 1945, the new model was flown for the first time. The army general staff was amazed by the flight characteristics of the plane, which surpassed the Hien's in all but maximum speed (degraded in a small degree by the larger drag area), and the model was order to be put in production as Army Fighter Type 5 Model 1a. The company's name was Ki-100-1-Ko and soon another 271 airframes were modified as well.

The engine was reliable in contrast to the higher-powered mechanical nightmares of the Nakajima Ki-84, Kawasaki Ki-61, and Kawanishi N1K-J that kept many aircraft grounded. Although slow in level flight for 1945, Ki-100 could dive with P-51 Mustangs (unlike most Japanese fighters) and hold the speed on pullout. The cannons had 250 rounds per gun (20x94mm shells, each weighing 112 g {armor-piercing} or 79 g {12% high explosive}}. Muzzle velocity was 700 (730 HE) m/s (2,300 ft/s; 2,400 ft/s) giving an effective range of 900 m (2,950 ft). The 850 rounds/min firing rate decreased by roughly 27% when synchronized through the propeller. Still, the weapon was effective enough (620.5 rounds/min) even by Western standards. The wings carried 250 rounds per gun (12.7x81mm ammunition). Each machine gun bullet weighed 35.4 g AP (33-38 g 2.2%HE) and had a muzzle velocity of 760 m/s (770-796 HE) (2,450 ft/s; 2,500-2,600 ft/s) giving an effective range of 750 m (2,460 m). Rate of fire was 900 rounds/min.

Improvement of the basic model lead to the Ki-100-II, with a supercharged engine for high altitude interception of the B-29s, but only three examples were built, and it never saw combat.

Operational history

Army units to be equipped with this model included the 5th, 59th, 200th and 244th sentai and the 81st Independent Fighter Company. At the same time, the army ordered the development of a new, slightly modified, type, which was called Ki-100 I-Otsu or Army Type-5 Fighter Model 1b. This model had a bubble canopy for improved visibility and was purposely built as a radial-engined machine. When the supply of engineless Ki-61-IIs ended, the new model came into production. Along with the previously named Army air units, the 17th, 18th, 25th, 111th, and 125th sentai were provided with training on this type.

File:Ki-100 at the RAF Museum front view.jpg

The same Ki-100 viewed from the front. Photograph at the RAF Museum at Hendon, London

The Ki-100 had its combat debut on 9 March 1945 and suffered its first loss in April 1945, however, Allied forces quickly assessed the new fighter as a first-class fighter. Fewer numbers of Ki-100s were available compared to Ki-84s, but were quickly assigned to 4h, 5h, 17h, 20h, 59h, 111t, 112d, and 244h Sentai (this deployment was a notable spreading out of the very few fighters that were operational, but many of these wings were only partially re-equipped). By 1945, the Ki-100 was perceived as one of the most important fighters in the inventory. However in intercepting the high-flying B-29s (at a point in the conflict, the B-29 raids became low-level missions), the new Japanese fighters struggled as the Ha-112-H engine performance decreased at high altitudes. The most effective way to attack the Superfortress was by making very dangerous head-on attacks, changing their approach path as they neared the bombers. A failure while attempting this was deadly, because of the concentration of defensive fire from the bombers. In this type of combat, the Navy's Mitsubishi J2M Raiden was superior.

On 25 July 1945, 18 Ki-100 fighters from 244h Sentai encountered ten F6F Hellcats of the Belleau Wood Air Wing in a monumental air battle where the Ki-100 pilots claimed 12 victories with only two losses. Claims and counterclaims regarding the "true" results still arise around this action; it was unquestionable the Ki-100 was a deadly adversary. The real losses were two Hellcats and two Ki-100s; one Ki-100 and one F6F were lost in a collision between Major Tsutae Obara and Ensign Edwin White in which both pilots were killed.

After the bombing of the Kagamigahara plant and the slow deliveries of components by the satellite plants, production rates of the Ki-100 began to fall more and more, and in the period between May and July, only 12 examples were delivered. Finally, production ended due to the bombing, with only 118 examples of the Army Type-5 Fighter Model 1b delivered, which was, in fact, very fortunate for the Allies.

The last loss of a Ki-100 occurred on 14 August 1945, a day before the surrender of Japan, when Sgt Tamagake was shot down by a Mustang.

An overall assessment of the effectiveness of the Ki-100 rated it highly in agility and a well-handled Ki-100 was able to out-maneuver any American fighter including the formidable P-51D Mustangs and the P-47N Thunderbolts which were escorting the B-29 raids over Japan by that time, and was comparable in speed especially at medium altitudes. In the hands of an experienced pilot, The Ki-100 was a deadly opponent and together with the Army's Ki-84 and the Navy's Kawanishi N1K-J the only other Japanese fighters being able to defeat the latest Allied types.

Variants

• Ki-100 (prototypes): one batch of Kawasaki Ki-61 II KAI with radial engine. 3 built as such.
• Ki-100 I-Ko: Fighter Type 5 of Army (Mark Ia) initial model of series, KI-61 II KAI modified. 271 built as such.
• Ki-100 I-Otsu: (Mark Ib) full-vision canopy. 118 built as such.
• Ki-100 II (prototypes): engine Mitsubishi Ha-112-II Ru with turbocompressor, 1,500 hp (1,100 kW). 3 built as such.
• Total production: 395 examples. .

References

Bibliography

• Bueschel, Richard M. Kawasaki Ki.61/Ki.100 Hien in Japanese Army Air Force Service, Aircam Aviation Series No.21. Canterbury, Kent, UK: Osprey Publications Ltd, 1971. ISBN 0-85045-026-8.
• Francillon, René J. Japanese Aircraft of the Pacific War. London: Putnam & Company Ltd., 1970 (2nd edition 1979). ISBN 0-370-30251-6.
• Green, William. Warplanes 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 1. London: Macdonald and Jane's, 1976. ISBN 0-356-08224-5.
• Januszewski, Tadeusz and Jarski, Adam. Kawasaki Ki-61 Hien, Monografie Lotnicze 5 (in Polish). Gdańsk, Poland: AJ-Press, 1992. ISSN 0867-7867.
• "Last Swallow of Summer." Air International October 1976.
• Mondey, David. The Hamlyn Concise Guide to Axis Aircraft of World War II. London: Bounty Books, 2006. ISBN 0-753714-60-4.
• Sakaida, Henry. Japanese Army Air Force Aces 1937-45. Botley, Oxford, UK: Osprey Publishing, 1997. ISBN 1-85532-529-2.
• Sakurai, Takashi. Rikugun Hiko Dai 244 Sentai Shi (History of the Army 244 Group [in Japanese]). Tokyo, Japan: Soubunsha, 1995. ISBN unknown.
• Sakurai, Takashi. Hien Fighter Group: A Pictorial History of the 244th Sentai, Tokyo's Defenders(in Japanese/English). Tokyo, Japan: Dai Nippon Kaga, 2004. ISBN unknown.
• Sgarlato, Nico. "Ki-100: il FW-190 Giapponese" (in Italian). Aerei Nella Storia N. 51.

External links

• KI-61 HIEN at Greg Goebel's AIR VECTORS

See also

Related development

• Kawasaki Ki-61

Comparable aircraft

• Focke-Wulf Fw 190
• Supermarine Spitfire
• P-51 Mustang
• Lavochkin La-7
• Nakajima Ki-84 "Hayate" (Frank)

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Kawasaki Ki-100".