1. Production data for the Ki 43-I cited in this report will follow those given by Long (RESEARCH REPORT, Japanese Army Type 1 Fighter (Ki 43) Record of Production, 1995) kindly provided by Mr. James I. Long. These are consistent with, but more detailed than, material collected by the United States Strategic Bombing Survey (USSBS Report, Pacific War, No. 17, pp.40-41) and figures published in Windrow and Francillon, "The Ki 43 Hayabusa" in Aircraft in Profile, vol. 2 (p.264).

2. The 59th and 64th FRs were equipped with this aircraft on December 8, 1941. The 59th at Konpong Trach, Indo-China, had an operational strength of 21 Type 1 fighters and three Type 97 fighters. The 64th at Duong Dong had 35 Type 1 fighters and six Type 97 fighters according to Japanese Monograph No. 55, Southwest Area Air Operations, Phase 1, (November 1941-February 1942), and p.6. A relatively recent book (1992) Shores, Cull and Izawa, Bloody Shambles vol.1, p.52, generally agrees with these figures but credits the 59th with 24 Type 1 fighters and does not mention any Type 97 fighters. The author of this paper suspects the monograph is correct, with all due respect to Messers. Shore, Cull and Izawa. Long (note 1) gives production to the end of November 1941 as 114 aircraft (Nos. 114-227) so fifty-six operational aircraft would equate to almost exactly one half of total production to that point. Since several aircraft had been lost in accidents (notably wing failures) this represented an even greater proportion of existing aircraft. The 64th began to receive the type in August 1941 when less than forty had been produced.

3. See for example, "The Nakajima Hayabusa", in Green, Famous Fighters of the Second World War pp.77-78 where it is stated "...receiving the designation Type 1 Fighter, Model 1A (Ki. 43-1a)*** The Model 1A variant of the Hayabusa carried an armament of two 7.7mm machine guns...The Model 1A was rapidly supplanted on the assembly line at Ota by the Model 1B (Ki 43-1b) in which a 12.7mm Ho 103 machine gun similar to the Colt-Browning, supplanted one of the 7.7mm weapons, while the Model 1C, the first large-scale production version of the Hayabusa, carried an armament of two 12.7mm guns." This was repeated in Green, War Planes of the Second World War-Fighters, vol. 3. Windrow and Francillon (note 1, op. cit.) are to the same effect and state, "The first mass production version was the Ki.43-1c with two 12.7mm guns..."(p.256). The same thing is stated in Taylor, Combat Aircraft of the World, p. 261. These were all published in the early to late 1960's. No sources are cited but they may be following information contained in General View of Japanese Military Aircraft in the Pacific War, p.17 (first published in Japanese in 1953 and English in 1956). Similar information is found in more recent books. Sakaida in the 1997, Japanese Army Air Force Aces 1937-1945, apparently adopts this view (pp.18 and 53) and specifically states that the 11th FR in New Guinea was equipped with the Ki 43-1hei (p.53). For a current internet website which apparently adopts this convention see, Joe Baugher's Hayabusa Files, http://www.warbirdforum.com/hayabusa.htm (visited August 15, 2001, originally posted 1995). One recent author who does not follow the convention (but is clearly wrong) is Bergerud, Fire in the Sky, p.221, where the Oscar is described as going from two 7.7mm guns to two 13mm guns with no mention of the mixed armament!

4. "Type 1 Fighter" undated handbook containing a description of the construction, assembly, maintenance and method of operation. Captured at Lae, New Guinea, September 1943. Allied Translator and Interpreter Section (ATIS), Southwest Pacific Area (SWPA). Enemy Publication No.91, pp.33-35, 67.

5. ibid., p.5

6. "Armorers' Manual: Reconnaissance Planes, Fighters, Light Bombers", undated mimeographed booklet issue by 8th Air Training Unit. Item 4 (No. 15568), ATIS Bulletin 1561 (though undated, internal evidence establishes its date as mid-1942).

7. Izawa, "64th Flying Sentai, pt.2", Aero Album (Fall 1971), p.2, reissued as "Combat Diary of the 64th Sentai", Air Classics (August 1972), p.38. The only aircraft serial number I have identified with these units is Ki 43 No. 206 (production date November 1941). The wreck of this aircraft was found near Kuala Lumpur, Malaya. Likely it is the aircraft of Lt. Tadao Takayama, a chutai leader in the 64th FR (see Shores, et al, note 2 at p.114).

8. Japanese Monograph No. 31, Southern Area Air Operations Record, December 1941-August 1945 (Army) (unpublished), p.5

9. Southwest Area Air Operations (note 1), chart 1, following p.104.

10. Japanese Monograph No. 69, Java-Sumatra Area Air Operations Record, December 1941-March 1942, p.102. The figures for machine gun and cannon ammunition for the 59th (39%) slightly exceeds the ratio of the ammunition load of the aircraft of the aircraft when fitted with mixed armament, which was 500 rounds 7.7mm and 270 rounds 12.7mm (note 4) or a 35% ratio. The ratio for the 64th shows they used nearly twice as much machine cannon ammunition as machine gun ammunition. Moreover, Japanese Monograph No. 65, Southeast Area Air Operations, Phase III, July 1944-August 1945, discussing ammunition shortages makes this statement: "In the early stage of the war the airplanes were equipped mainly with 7.7mm and 7.9mm machine guns and only the Hayabusa fighter planes were equipped with one 12.7mm gun." p.46. Hiroshi Ichimura (relying on information from 64th FR pilot Yoshita Yasuda) directly states that the 64th FR's aircraft mounted one 7.7mm and one 12.7mm gun. See footnote 26. Since the first version of this article (posted on the j-aircraft.com website) additional data on ammunition expenditure has come to light. This shows the 64th expended seven times as much machine cannon ammunition as machine gun ammunition in the first month of the war while the 59th expended only slightly more machine gun ammunition than machine cannon ammunition during the same period. Comparing this data with expenditures for the longer period clearly suggests a number of twin 12.7mm armed fighters were in use by both units during the first month of the war but that number rapidly declined in the succeeding two months either by aircraft being replaced or re-armed. Table C, Airplanes Used and Expenditures of Fuel and Ammunition, Selected Materials on Line of Communication Staff Duties (PACMIRS Special Translation No. 3).

11. Air Headquarters India, Weekly Intelligence Summary No.43, Nov. 11, 1942, p.4. According to Izawa, the 64th had sent pilots to Japan during the rainy season (June-October) to re-equip with new aircraft. The new aircraft arrived at Singapore during September and, despite losses en route, raised the Regiment's operational strength from 15 to 30 aircraft (note 7, p.6). Wrecks recovered in Bengal in December 1942 include Ki 43s No. 422 (April 1942) and 721 (October 1942).

12. Examples of this include the 64th contributing eight pilots to the Southeast Area (note 7, p.6) and 24th FR markings that were found painted over on 12th FB aircraft captured at Munda ("Munda Ki 43's PIC " posted by James F. Lansdale, at http://j-aircraft.com/, visited April 11, 2001, citing captured Enemy Aircraft Report No. 17, with an illustration of a sketch of tail markings of Ki 43 No.493). The author has since obtained the same information from documents in the National Archives.

13. Situation Report, 12th FB Headquarters, as of 31 December 1942; and notes found with operational reports for January 1943 (digest of translation), Fourteenth Air Force Language Officer.

14. Letter from Technician Yamanaka to Commanding Officer Funayama (14th Field Air Repair Depot), dated March 12, 1943. Item 1 (No. 11974) ATIS Bulletin No. 1174. The Akitsu Maru delivered thirty replacement Ki 43s to Truk on 31 December 1942 (Training Flying Brigade Operations Order No. 8, item 2, (No. 13531) ATIS Bulletin No. 1329). These had apparently already been delivered to Rabaul in a "first transportation" referred to in Yamanaka's letter as already having occurred. The remaining aircraft had been delivered by two aircraft carriers and by a second trip by Akitsu Maru on 23 February 1943.

15. With regard to ammunition supply see Japanese Monograph No. 127, Southeast Area Operations Record, Part IV, appended sheet 5. Regarding the Munda Oscars see Headquarters, U.S. Army Air Forces, Directorate of Intelligence, Technical Intelligence Report No. 169, 21 August 1943.

16. List of Airfields Used and Ammunition and Fuel Expended (note 13).

17. Note 15, T.I.R. No.169, p.3.

18. "Inspection Report of Fuselage, Engine, and Propellor", No. 2 Chutai, 31 December 1942, ATIS Bulletin No. 311.

19. Captured Enemy Aircraft Report, No.17

19a. HQ AAF, SWPA Intelligence Summary No. 184.

20. Prior to July 1942 the only Ki 43 equipped unit in China was the 10th Independent Air Squadron based at Hankou, Japanese Monograph No. 76, Air Operations in the China Area July 1937-August 1945, p.110. Apparently this unit only received its Ki 43's in May 1942 while temporarily in Japan. Molesworth, Sharks Over China, p.35 reports a Ki 43 captured near Kweilin but dates the incident about August 1st. A SWPA intelligence report (note 21, A.I.B. no.23) states such an aircraft was captured on May 1st. W.O. Tadashi Kawazoe who was attached to the 1st Yasen Hoju Hikotai flew this aircraft. Kawazoe became a prisoner of war (information from Hiroshi Ichimura but also stated in the Japanese language edition of Hata&Izawa, Japanese Army Air Force Fighter Units and Their Aces, Eng. Ed., Grubb Street, 2002). Ford, The Flying Tigers, p.364 suggests Ki 43's of the 10th were not encountered by the A.V.G. until July 1942. (It is interesting to note here that Ford also says that the 64th re-equipped with Ki 43-II's after the Java campaign and flew against the A.V.G. with them. He also states that the two 12.7mm guns were exchanged for the mixed armament at Chiang Mai, Thailand because "they were so slow."(p.282). What Ford suggests about the Type 1 fighter model II is not only not supported by Izawa but also impossible. Only four experimental Ki 43-II's had been completed by April 1942). Most likely P-5017 is the single Ki. 43-1 captured intact in 1942. Its production date was determined to be December 16th, 1941 (Pro Forma "C" [crash report], Fourteenth Air Force May 16, 1943) this would place it among the first one hundred fifty production Type 1 fighters. Finally, with regard to Ford's stated rationale for the change from two 12.7mm guns to the mixed armament see the text-accompanying footnote 26.

21. Pro Forma "C" foot note 20. Similar information is found in HQ USAFISPA, Air Information Bulletin No.23, 12 August 1943, reproducing information found in HQ AAF, SWPA Intelligence Summary No. 126.

22. Pro Forma Reports, 30 December 1943, regarding Oscars Nos. 776. 804 and 808 (in Technical Intelligence Report No. 220, Allied Air Forces SWPA). Remarking on the twin 7.7mm armament, an intelligence report says: "...this combination is the exception rather than the rule." HQ AAF, SWPA Intelligence Summary No. 176.

23. Operations Orders and documents related to the 14th Field Air Repair Depot, item 2 (No. 12521), ATIS Bulletin No. 1194 (chart 5 shows flight records for August 1943 indicating Type 1 fighter No. 793 engaged in test and liaison flights during the month). Ki 43 No. 750 was found damaged but potentially flyable after the War. It was reportedly in use long after 12th FB left the area (Wallis, "The Story of Nakajima Ki. 43-I No. 750 (Oscar)", http://www.nzfpm-co.nz/articles/oscar.htm).

24. Hata & Izawa (note 20), p. 114. The 11th FR returned to Japan in June 1943 and the 1st FR returned in August 1943. (Japanese Monograph No. 32, Southeast Area Air Operations, Chart 2.) Their remaining aircraft would then have been available for the purposes indicated. The crash reports on the Cape Gloucester aircraft (note 22) are far from complete as indicated in the author's "Tuluvu's Air War" (posted as a research article on the j-aircraft.com website) and the report on the Madang aircraft is a brief (but specific) reference in an intelligence summary. Photographic evidence of a Type 1 model 1 fighter (two bladed prop) at Wewak exists as late as October 1943 and as indicated in note 23 one remained in relatively good condition at Rabaul until the end of the war. The author does not claim certainty in this matter but suggests this as a likely explanation of an otherwise anomalous situation.

25. Figures for production of the 12.7mm fixed machine cannon (if accurate) show a rapid acceleration from fiscal 1942 to fiscal 1943, Table 13, USSBS Reports, Pacific War, No. 45. The same table shows production of the 7.7mm fixed machine gun declined from fiscal 1942 to fiscal 1943.

26. Hiroshi Ichimura messages of 11 and 12 December 2001, Warbirds Forum, http://forums.delphiforums.com/annals/messages/?msg+534. In addition to the unreliability of the early versions of the 12.7mm gun, it may also be that they were initially not available in sufficient quantity to equip all aircraft coming off the production lines. However, available data (see footnote 25) is not sufficiently detailed to support this conclusion (the table cited shows no 12.7mm machine cannon production in fiscal year 1941, April 41-April 43, suggesting the table is in error or the weapons fabricated at that time were still considered experimental and not "production" models.

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