Dr Hidemasa Kimura's 'Flying Fuel Tank'

This first hand account by Dr Hidemasa Kimura (1904-1986) of the development and flight of the Tachikawa Ki-77 under the project designation A-26, appeared as part of the 'Now It Can Be Told' series in the February 1964 issue of Flying Review International magazine. It is too interesting to remain buried in an old magazine and is therefore presented here in its entirety. The A-26 designation represented 'A' for the Asahi Shimbun newspaper which had first sponsored a non-stop Tokyo to New York flight and '26' for the Japanese Imperial year (Kōki - 皇紀) 2600 for 1940. The A-26/Ki-77 featured here in May 2014 as a superbly scratch-built model in 1/48 scale by John Haas (heading image) and was also the second kit as FSM-002 produced by the late Horatio Hernández in his Friendship Scale Models enterprise as featured here, here and here.  

The mysterious fate of the second prototype, lost on an inaugural Seiko (成功 - Success) flight to Germany via Singapore on 7 July 1943 remains unresolved. In June 2001 Larry deZeng posted at j-aircraft.com the information that in the same month RAF 'Y' Service personnel had intercepted the following Ultra signal from Berlin dated 7 July 1943 to Kdo.d.Flughafenbereich 6/VI (Airfield Regional Command) at Sarabus, Crimea, which exercised authority over the entire Luftwaffe airfield infrastructure at that time:- "On 8/7 an allied aircraft will fly via air grid squares 3420, 2560 and 2510 to Sarabus. It is a two engined low wing monoplane, wing span 30 metres, metal fuselage, natural colour, wings grey. The aircraft must not be fired on under any circumstances." The Ultra signals intelligence analyst at Bletchley Park had added the following note:- "This presumably refers to undertaking 'GOA' in which an aircraft was flying to Sarabus from Tokio (sic) via Singapore". Ultra Signal CX/MSS 2867/T8). 

According to Deniz Karacay also posting at j-aircraft.com the first (non-scheduled?) non-stop flight from New York to Tokyo was by Boeing 747SP in November 1975 with Dr Kimura as passenger!

 Dr Hidemasa Kimura 1904-1986

Image credit: Heading photo © 2014 John Haas via Aviation of Japan; Article scans © 1964 Flying Review International magazine published for Purnell & Sons Ltd by Macdonald & Co (Publishers) Ltd.; Dr Kimura photo via web, original source unknown.

   

Danilo Renzulli's 1/72 Kawaskaki Ki-61-I Tei Hien

Danilo Renzulli has very kindly shared these images and details of his impressive build of the RS Models Ki-61-I Tei Hien in 1/72 scale, looking splendid in the Italian winter sunshine. The model represents c/n 5262 of Hiko Dai 244 Sentai, assigned to Sentai Leader Capt Teruhiko Kobayashi as a reserve aircraft after he was wounded on 12 April 1945 and as illustrated by Ronnie Olsthorn in Osprey's 'Ki-61and Ki-100 Aces' (2015). 

Danilo reports that progress on this Ki-61 project remained 'trapped' by long interruptions due to his home move and was plagued by painting issues related to inconsistencies in paint quality - with Humbrol no longer the paint he was used to for a lifetime. It is true that long gone are the days when a single, smooth and  opaque coat of Humbrol enamel paint could be applied by brush straight from the tin and they call this progress! He found it compulsory to use a primer to avoid unwanted extensive chipping.

 The model was enhanced with some Eduard photo-etched parts for the cockpit and the use of Albion Alloys 0.3 mm and 0.5 mm telescopic tubes to make up the pitot tube. Danilo added extra detail to the undercarriage components with photo-etched links and wire brake lines, whilst the landing gear down indicators and drop tank connections were also added using metal wire. Navigation lights were added by drilling holes into the wingtips and vertical tail then adding a tiny drop of Crystal Clear. The navigation light on top of the fuselage was likewise carefully carved out in the plastic thickness and a drop of Crystal Clear added. Machine guns were replaced with Quickboost items. 

 The upper surface colour scheme was mixed using Humbrol paints and the undersurface using Alclad. The blue and white fuselage stripes were painted on as were the hinomaru using masks by Maketar. Danilo found the masks useful but a challenge, requiring patience and care when locating and removing them. He also warns that they cannot be used over a model sprayed with the hairspray technique as the upper paint layer will be removed as he discovered to his expense with a Ki-84 model. The anti-slip panels were added using # 2000 wet and dry sanding sheet.  

 Danilo found the RS Models kit not bad and recommends it as going together well with a fit requiring no great effort and the result an accurate appearance. Nevertheless he says that he has a whole Sentai of Tamiya and Aoshima Hiens waiting their turn to show up on his workbench!   

   

 With special thanks to Danilo for sharing the images of his splendid Hien model with Aviation of Japan and providing the details of his build.  

Image credit: All photos © 2019 Danilo Renzulli

Season's Greetings

 

With Very Best Wishes to All Aviation of Japan Contributors and Readers for the Christmas Season and New Year

Image credit: Atogoshita and Yabu Lane ('Snow in the City') No. 112 in the winter series of 'One hundred famous views of Edo' by Utagawa Hiroshige 1797-1858

Dragon Slayers and More from Rising Decals

Recently two new and very welcome sheets from the prolific Rising Decals for the popular Kawasaki Ki-45 Type 2 Two-seater fighter Toryu 'Nick' in 1/48 and 1/72 scales, together with a new 1/72 sheet for the K5Y1 'Willow' in the innovative 'Unknown and Less Known Units' series. And, as hoped for, a new AVI Models 1/72 kit of the Gasuden KR-1 Chidori-Gô based on their De Havilland DH.83 Fox Moth kit. 

Set RD48028 (heading image) contains markings in 1/48 scale for eight Ki-45 Toryu from seven units as follows:-

• Ki-45 Kai Hei '10' of 11th Hakko-tai 'Kokon-tai' at Hokota airfield, Japan in November 1944 - in overall olive brown or black(ish) brown colour.
• Ki-45 Kai Hei '1' of the same unit as dlown by unit leader 1Lt Kyoichi Miura
• Ki-45 Kai Tei c/n 4101 of Dokuritsu Hiko 25 Chutai at Liaoyang airfield, Manchuria in February 1945 - in dark green mottle over grey with individual aircraft name 'Tachibana'
• Ki-45 Kai Hei of 5th Sentai, Negros, Philippines in August 1944 - in dark green mottle over grey
• Ki-45 Kai Hei as flown by Sgt Yoshio Sakaguchi of 5th Sentai at Kyoshu airfield, Japan in April 1945 - in overall olive brown or black(ish) brown colour
• Ki-45 Kai Tei of Dokuritsu Hiko 71 Chutai at Kallang airfield, Singapore in July 1945 - in dark green mottle over grey
• Ki-45 Kai Ko of Dokuritsu Hiko 84 Chutai at Canton, China, May-June 1942 - in a heavy green mottle over grey-green
• Ki-45 Kai Tei of 53rd Sentai at Matsudo airfield, Japan in February 1945 - in dark green mottle over grey

This sheet offers some interesting and unusual choices including the 25th DHC example (about which more below), the mysterious 71st DHC Toryu at Singapore and the early Indo-China and Canton-based test Chutai bird, the first to engage the enemy in combat (although the 5th Sentai scrambled its six new Toryu to intercept the Doolittle raid they climbed per tactical doctrine to high altitude and did not make contact with the low-flying raiders).

Sheet RD72086 (above) contains markings in 1/72 scale for no less than 12 Ki-45 from seven units as follows:-

• Ki-45 Kai Tei c/n 4101 of Dokuritsu Hiko 25 Chutai at Liaoyang airfield, Manchuria in February 1945 - in dark green mottle over grey with individual aircraft name 'Tachibana'
• Ki-45 Kai Hei as flown by Sgt Yoshio Sakaguchi of 5th Sentai at Kyoshu airfield, Japan in April 1945 - in overall olive brown or black(ish) brown colour
• Ki-45 Kai Hei of 27th Sentai at Clark field, Philippines in August 1945 - in overall olive brown
• Ki-45 Kai Hei of Dokuritsu Hiko 25 Chutai at Shinkyo airfield, Manchuria in August 1945 - in dark green mottle over grey
• Ki-45 Kai Tei of 45th Sentai at Clark Field, Philippines in August 1945 - in overall olive brown
• Ki-45 Kai Tei as flown by Capt Totaro Ito of 5th Sentai at Kyoshu airfield, Japan in November 1944 - in overall olive brown or black(ish) brown colour with individual aircraft name 'Kuzuryu'. Ito was a Bukosho winner with claims for nine B-29s.
• Ki-45 Kai Tei of 53rd Sentai at Matsudo airfield, Japan in 1945 - in dark green mottle over grey; the white trim lines are included for the striking nose flash but the red will need to be carefully painted
• Ki-45 Kai Ko of Dokuritsu Hiko 84 Chutai at Canton, China, May-June 1942 - in a heavy green mottle over grey-green
• Ki45 Kai Ko of the Army Flight Test Centre at Fussa in January 1942 - an unarmed aircraft in overall grey-green 
• Ki-45 Kai Tei of 53rd Sentai at Matsudo airfield, Japan in February 1945 - in dark green mottle over grey

This sheet also includes partial markings for two more 53rd Sentai Toryu each bearing kill markings (adjusting the colour to better display the white markings the second 53rd insignia shown above appears near black but is cobalt blue on the decal sheet). Again an excellent sheet with some interesting and different subjects. The Hasegawa kit is recommended but the decals would probably work ok with the venerable Revell kit too. Regarding the two Dokuritsu Hiko 25 Chutai aircraft, the tail marking of the first subject, representing a stylised '25', was adopted from the beginning of 1945. Each aircraft was assigned an individual name and other names assigned were 武蔵 - Musashi, 桜 - Sakura, 伊予 - Iyo and 天竜 - Tenryu.  The tail marking of the second subject was designed by aircrew member Tsunetake Fujiki and adopted from the unit's establishment in August 1944 until the end of that year. The dual circles in the centre symbolised the '8' and '0's of the unit's coded designator - 'Manchuria Dai 800 Butai'. With the July 1944 2nd Air Army re-organisation this unit had been established as the 'Composite Twin-seat Fighter Squadron' under 15th Air Brigade HQ for the air defence of Anshan, until formally designated Dokuritsu Hiko 25 Chutai in August 1944. The unit also operated Ki-45 nightfighters in the overall black(ish) brown colour displaying the '25' unit insignia. The dual markings for this unit are especially welcomed by this reviewer. A Key Data Guide for Toryu colours is in preparation but has been delayed by  family commitments.

The Yokosuka K5Y1 'Willow' biplane trainer is catered for in 1/72 with a lovely set of markings (shown above) representing 'J-BCPQ' operated by the Kaigun Yobi Kokudan (海軍予備航空団 - Navy Reserve Air Group), a flying training unit for university students. The set is designed for either the AZ Models, Valom or Arii (ex-LS) kits and offers an attractive alternative to the usual Navy schemes for this type. The insignia is beautifully and crisply printed with the anchor design in metallic ink.
  

Last but not least is the AVI Models 1/72 scale Gasuden KR-1 kit (shown above), designed by Rising Models, which consists of the basic Fox Moth sprues with the addition of a replacement resin fuselage and crisply moulded seven part resin engine and prop. Kit decals by Rising offer a difficult choice between two very attractive examples - the silver doped and blue trimmed 'J-BBJI' operated by Nippon Koku Yuso Kenkyusho (Japan Air Transport Service) from 1935 to 1937 or a silver doped aircraft operated by the Manchukuo Kaijo Keisatsu Koku Butai (Maritime Police Air Unit) with the distinct Manchukuo roundels in six positions. The decal sheet is also by Rising and includes the blue fuselage trim for 'J-BBJI' although the wing leading and tailplane edge trim will need to be carefully painted. This neat kit should appeal to Japanese aircraft, civil aircraft and inter-war biplane enthusiasts.

With special thanks to Mirek of Rising Decals for kindly sending the review samples to Aviation of Japan.

Image credit: All images © 2019 Rising Decals

Kawasaki Ki-100 Type 5 Fighter Colours

Continuing a Goshikisen (Type 5 Fighter) theme this brief exploration begins with the University of Illinois example photographed in colour by Charles 'Chuck' J Graham in 1949 when he was in his third year at the University and attributed by both Chuck Graham and Jim Long with c/n 13012, manufactured by Kawasaki in July 1945 (at the Miyakonojo plant on Kyushu according to Jim Long, but at Kagamigahara's Ichinomiya dispersal plant according to Joe Picarella). The aircraft was one of four former 111th Sentai examples found at Komaki airfield and taken to the USA. It was allocated the 'Foreign Equipment' identifying code FE-314 (listed in March 1946 as FE-N314) and subsequently the 'Foreign Technology' code T2-314. It was on display at the Urbana airfield of the University of Illinois, Champaign, from August 1946 until 1959 when it was sadly scrapped as being beyond repair. Copies of Chuck Graham's colour photographs were provided to the late Al Makiel, Don Thorpe, Bill Thompson and Toda-san, the editor of Koku-Fan magazine. Some of the photos were reproduced uncredited in one of the Bunrin-do published Famous Aircraft of the World (FAOW) editions on the Ki-100, No.36 of 1973 (see heading image). The photos from the Al Makiel collection were subsequently provided to the late Jim Lansdale.

The first four colour chips shown above are rendered from Munsell comparisons of the exterior and interior paint provided to Jim Lansdale by Chuck Graham and shared with this author in 2008. Leaving aside for the moment the provenance of the paint finish (see below) they are indicative of the variegated and 'chalked' paint surface of a weathered aircraft standing exposed for four years. The lightest hue is similar to an FS 595 value attributed to the early Zero colour! The colour chip shown below is rendered from the Munsell value from a colorimeter measured sample of the aircraft's skin provided to Jim Lansdale by Chuck Graham. Note that Munsell 7.5 Y 4/2 is the same colour value as Thorpe's A2 Olive Green.

Opinions have differed as to whether the paint finish of this aircraft was original, either in whole or in part, or was the result of re-painting after capture. The airframe displayed a number of anomalies, not least a grey painted finish on the under surfaces not typical for the Ki-100 and similar in hue to the US Neutral Gray colour. The rear fuselage trestle location stencil appears to have been masked off to reveal a darker, greener finish but the wing stencils show no such evidence. The paint exposed by removal of the tail fairing also appears slightly darker, as would be expected of a protected paint surface. The yellow wing leading edge IFF strips were painted over in the airframe colour, leaving only 'stars' around the gun apertures. On the other hand the patches of bare metal from an unprimed finish reveal no clues as to the existence of a previous paint layer. Al Makiel was of the opinion that the aircraft had been re-painted with US Olive Drab as the University had plans to restore the aircraft as part of a plan to establish an aircraft museum - which was not achieved. In 2008 Chuck Graham opined differently that there were no signs that the University had re-painted the aircraft and the finish appeared original, although he thought that it was possible it had been re-painted when in US hands before that. The Aero Detail 32 book on the Ki-100 by Joe Picarella ((Kaiga/Modelkasten 2009) asserts that the aircraft was re-painted in US colours and in October 2005 this belief had been affirmed by him to the author with the observation that the fuselage hinomaru had been applied over an overpainted star and bar shape as well as noting the apparently masked off trestle stencil and overpainted fuel pressure regulator cover (originally red). He also noted the unreliability of colours as displayed in photos and that was reinforced by Chuck Graham who observed that the actual appearance of the colour was more 'greenish' than the photos suggest. It is possible that the aircraft had been only partially re-painted as the US Olive Drab and the Japanese Army Air Force's # 7 Ohryoku nana go shoku (yellow green) colour are similar, both having their origin in the PC10 'Khaki Drab' (an olive brown hue) of the Royal Flying Corps. The green vs brown paradox is endemic to the individually subjective viewing and assessing of this colour space.

The colour chip above is rendered from the Munsell value attributed by Joe Picarella and Helen Maiden to the original exterior and interior paint colour of Ki-100 c/n 16336, the surviving and restored example at the RAF Museum, which was manufactured at the Kawasaki Kagamigahara plant in June 1945. In Japanese Aircraft Interiors by Robert C Mikesh (Monogram Aviation Publications 2000) it is stated that "This color is believed to to be the Kawasaki standard factory-green of the late 1944-45 period, used both structurally and externally." The colour chip in the Aero Detail book is described simply as 'green' but the Japanese characters used are 暗緑色 (Anryoku shoku - dark green colour). The slightly more olive green finish of this example, still close to the # 7 colour standard, is consistent with information from a Japanese researcher 'Maru' that the Ki-100s were delivered in batches of varying colour, with an early batch finished in the # 7 olive brown colour sent to the 18th Sentai and a later batch in a 'dark green' finish sent to the 5th Sentai.  It appears that some late production Ki-45s were also solidly finished in this olive green colour on their upper surfaces, which is slightly more greenish than FS 33070 (@3.38). Bear in mind that FS 34083 is a very close equivalent to the wartime RAF Dark Green colour standard (@ 1.14).

The colour chip above is rendered from the Munsell value attributed by Katsushi Owaki to a Ki-100 artifact at the Kisarazu JGSDF (陸上自衛隊 Rikujō Jieitai) museum and attributed to the aircraft flown by Sgt Maj Yasuo Takeshi. The dark black(ish) brown colour is associated with both the Ki-100 and as an overall finish on some Ki-45s, attributed by several Japanese sources as a night fighting camouflage sometimes referred to as 'yokan iro' (羊羹色) from a type of Japanese sweet delicacy (the Ki-100 was also flown in night combat). This colour has been misleadingly referred to as 'charcoal' in some English language sources, resulting in illustrations of 'black' Ki-100s, whereas the Japanese colour name is Kuro Kasshoku (黒褐色 - black brown colour). At first believed to be an expedient variant of the # 7 colour (still possible - PC10 also showed this variance depending on the percentage of ferric content in the iron oxide pigment used) it also bears a strong resemblance to the IJAAF colour standard # 43 Tochi or Tsuchi iro (土地色 - earth or soil colour), the intended use of which is uncertain. However # 43 must have been of some importance to the IJAAF as it was carried forward in the February 1945 reconciliation of paint colours as standard 2-2 with no IJN equivalents.      

Therefore there appear to be at least three colour variations in which Ki-100 models can legitimately be finished, although attributing them to specific aircraft and units is more difficult: - the # 7 olive brown (olive drab) colour with all its variegation and weathering characteristics; a slightly more olive green (which could be approximately represented by the so-called 'Kawasaki Green' available in many hobby paint ranges); and the black(ish) brown colour which is similar to, but not quite as reddish and slightly more greyish than, the Luftwaffe RLM 81 Braunviolett colour (as measured from the 1941 Tafel 5). AK Interactive Real Colors RC323 RLM 81 is similar, whilst the Gunze H-421 RLM 81 is a little greener. 

This blog should be viewed as an updated revision to any previous Ki-100 colour discussions here and has been prepared in acknowledgement and with much gratitude for the input and valued data of Ken Glass, Chuck Graham, the late Jim Lansdale, Jim Long, Katsushi Owaki and Joe Picarella, as well as kind assistance with translation from Tetsuya Inoue.

Image credit: Heading photo © 1949 Charles J Graham via M Toda scanned from FAOW # 36 of April 1973 & reproduced for academic discussion; All rendered colour chips © 2019 Aviation of Japan   

Francesco Borraccino's Ki-100-II

In an appropriate follow-up to the last blog Francesco Borraccino has kindly shared these images of another of his excellent models, this time the Kawasaki Ki-100-II crafted from the 1/72 Aoshima kit. The Aoshima Ki-61/Ki-100 series has attracted criticism for the slightly slab-sided shape of the rear fuselage but nevertheless the appearance and 'sit' of Francesco's model are very convincing and there is a great deal to appreciate. 

The model was built from the box with just the addition of lead wire for the undercarriage hydraulic lines and the use of Dead Design masks. Francesco judged it as not a bad kit but the build was challenging and needed careful dry fitting and testing throughout for almost all the parts. He found the separate wing leading edge gun panels a poor fit and their muzzle apertures oversized.

The instruction sheet, especially the markings indications, gave him the most headaches and he found that:-

• The yellow wing IFF strips were wrongly shown in shape and length
• Position of the fuselage hinomaru were incorrectly shown too far to the rear
• No paint indications were given for most of the small parts
• The size of the decals did not tally with those as shown on the instruction sheet but the box art appeared correct
• No yellow tips or stencils were shown for the propeller blades and they were not provided as decals

 

Francesco devised his own mix by eye for the upper surface colour using AK Interactive RC330 (Ohryoku Nana Go Shoku), Tamiya XF-51 Khaki Drab, XF-52 Flat Earth and XF 90 Red Brown (a new colour for German WW2 armour which he found to be more olive than brown!). The undersurface was finished with Tamiya AS-12 Bare Metal spray, with some panels finished with AK Interactive Xtreme Metal Polished Aluminium and Dark Aluminium. The propeller blades were a mix of Tamiya XF-62 Olive Drab and XF-65 Field Grey, whilst the drop tanks were a mix of XF-19 Sky Grey and XF-23 Light Blue. The kit decals were used and Francesco found them strong and matt, a little thick but better than Hasegawa or Academy. 

 

Francesco freely admits that he made mistakes in the build, such as attaching the drop tank racks to the gun ejection slots after fixing the undercarriage with CA glue, but the instructions were no help with the attachment location unclear and no locating points on the parts. He attempted to rectify the damage but mindful of not wishing to spoil the natural metal finish or to break the undercarriage legs he opted to conceal it with a rather over zealous application of gun staining - which does not appear in photographs. However the heavy exhaust stains from the turbosupercharger were replicated from a photograph of the real aircraft. 

The Ki-100-II represented the final development of the fighter design that began life as the Ki-61, with the basic hybrid design of the Ki-100 fitted with a turbosupercharged engine to improve performance at altitude. Three prototypes had been built at the Kawasaki Gifu plant (where much experimental work was conducted) and were flight tested successfully from the adjacent Kagamigahara IJAAF airfield (the airfield was directly accessible from the Kawasaki flight engineering workshops) but plans to begin production in September 1945 (by both Kawasaki and Nakajima) were thwarted by the end of the war. Francesco's model represents the third prototype, found intact at Gifu but sadly not preserved.

With very special thanks to Francesco for sharing these images of his beautifully realised model.

Image credit: All model photographs © 2019 Francesco Borraccino; Box art © 2014 Aoshima Bunka Kyozai Co., Ltd. via Hobby Search, Japan  

Army Prop and Spinner Colours

Some recent correspondence on the subject of late war Army propeller and spinner colours raised interesting points and prompted this summary. 

At the start of the Pacific War Army propellers were generally of polished metal with only their rear faces painted dark brown as an anti-glare measure. The colour standard for the dark brown paint has not been confirmed but was referred to as Azuki iro (小豆色 - literally red bean colour from the Azuki bean but meaning reddish brown). The current JIS (Japanese Industrial Standard Z 8102: 2001 Object Color Color Name) conventional colour value for Azuki iro is given as Munsell 8R 4.5/4.5, significantly lighter than the typical appearance of the wartime propeller paint which was a rich chocolate brown with a maroon or reddish undertone. This may be the reason that some aircraft models are finished with spinners and props closer to a brick red colour. The closest colour in the Army KouKaku (航格 for 航空機規格 - aircraft specification) 39 to the actual appearance of the propeller paint is # 37 An Kasshoku (暗褐色 dark brown colour). Thorpe's A11 Dark Brown is comparable. The (infamous?) 'tea colour', Cha Kasshoku # 31 is a colour of slightly different character, more an earth brown in appearance and related to camouflage, although the two have been frequently confused and some of the extant prop and spinner artifacts exhibiting fading begin to approach it in appearance.

The front face of each blade had a red warning stripe painted 5 cm from the tip and 5 cm in depth Spinners were either painted aluminium or more usually painted to match the standard hairyokushoku (ash green) colour of the aircraft. Reportedly regulations of that time required aircraft in the multi-colour camouflage finishes adopted in the China theatre to have the entire propeller assembly and spinner painted Azuki iro, but photographs suggest that this practice was by no means consistent.  The Fine Molds Ki-15 kit instructions (FB23) suggest Mr Color 526 (Japanese Army AFV Early Camo described as 'Japanese Army Brown') for the spinner of the camouflaged 18th Independent Flying Company subject, which matches the brown of the upper surface camouflage, whilst the prop colours are suggested as silver (polished metal) for the front of the blades and Mr Color 191 Propeller Color for the rear of the blades.  Such a combination cannot be ruled out. The whole or partial painting of spinners to identify Chutai or Shotai was not general practice at that time but was not unknown in some cases.

After mid-1942 it became general practice for propellers and spinners to be wholly painted in Azuki iro which was not matt but had a lustrous or satin finish. There are indications that this paint became duller and faded with exposure to a lighter brown appearance. The warning stripes at the tips were painted yellow instead of red and a rectangular yellow data stencil was also applied to the front face of each blade near the root. Dimensions were unchanged except that the warning stripes on Ki-61 prop blades were generally 7 cm in depth. The colour standard for the yellow was # 14 Ki iro (黃色) a strong chrome yellow towards orange-yellow, close to FS 33538 and also approximate to RAL 1033 Dahliengelb (Dahlia yellow) which is slightly darker. Thorpe's A17 Deep Yellow is comparable whilst his A16 Medium Yellow probably documents a faded paint colour. A less frequently seen warning stripe variation was for a 5 cm yellow stripe bisected by a white stripe, the three stripes being each of equal depth and the whole also 5 cm from the tip.  In some units spinners were painted in distinguishing Chutai or Shotai colours, either the whole spinner of just the forward half. Spinners painted in a different colour to the Chutai colour used for the unit insignia on the tail are rare but not unknown.

After mid-1944 propellers were painted in a new green colour, the colour standard for which is unknown. However it is apparent that dark brown propellers continued in use on many aircraft until the end of the war. Former Tachikawa employee Noboru Shimoune prepared a colour sample of the green, assessing the late war prop color for the Ki84, Ki-87, Ki-43 III, Ki-94, Ki-100, Ki-102 & Ki-106 as 5GY 3.5/2.3 (reported match FS34094 ~ actual digital match FS 34082 good). Model Art # 28 on the Ki-84 has a colour chip which shows the prop colour as closer to Munsell 10GY 3/2 (reported match FS 34092 ~ actual digital match FS 34094 poor). This was recorded by the author Ichiro Hasegawa from the recollections of Tadamitsu Watanabe. However, another researcher Kenji Ishikawa, who provided input to Model Art # 329, disagrees with that colour. The Model Art book does not present a colour chip for the green.  FS 24172 has also been given for the greyish green props on the Tachikawa built Ki-43 III Ko but has a significantly more greenish appearance with the closest Munsell match being 10GY 4/2. 

The well respected Gakken book series colour researcher (and animation film director) Sunao Katabuchi has presented a colour which appears close to RAL 7009 Grüngrau (Green grey) but which is darker and greyer than the closest FS value 14159. This colour is perfectly consistent with the appearance of an extant Hayate prop blade.  Katabuchi-san also asserts that this new green colour was the same colour being applied to Ki-45 and Ki-84 cockpit interiors. Propellers painted in the new green colour had a 5 cm yellow tip instead of the previous warning stripe. 

The colour of propeller blades and spinners on the Ki-100 is contentious with Aero Detail 32 asserting that they were delivered to Kawasaki pre-painted (dark) brown (shown in the book in Japanese as 暗褐色 - An Kasshoku), contrary to Shimoune-san's data, but conceding that late production aircraft had spinners painted 'green' (presumably to match the airframe colour). The Gakken book on the Ki-61/Ki-100 series displays the prop and spinners of the Ki-100 and late production factory painted Ki-61-I Tei in the # 7 yellow green (olive brown) colour of the airframes and an extant Tei spinner in a Japanese museum appears to be painted in a similar colour but applied over a previous faded (?) brown on the exterior which is visible as a darker brown at the rear edges and on the rear mounting plate. The interior of the spinner appears to be matt black except for the central frame which is dark brown. The prop  blades on the University of Illinois Ki-100 appear from colour photographs taken in 1949 to be dark brown with yellow tips (not warning stripes) but it is unknown for certain if they were original to the airframe and/or re-painted (more on the subject of the UoI Ki-100 colours in a future blog). Spinner colour is unknown as it was missing from the aircraft in the photos. It is worth mentioning here that in some colour photographs the prop blades can be taken for black or dark grey but the recent FAOW Special Edition Vol.7 Army Type 2 Two-sear Fighter 'Toryu'  has a useful colour photo (on page 14) showing a collection of props in the rich and lustrous dark brown colour - and clearly a dark brown prop on the Ki-61 (with yellow roundels!) in the background. However, care must be taken as a close-up colour photograph of a Nakajima Ki-115 strongly suggests that it has black-painted prop blades!     

Who Did The Painting?

It has been asserted that prop and spinner assemblies were delivered pre-painted but it seems unlikely that this was done by the propeller manufacturers. Sumitomo Metal Industries Propeller Division (Sumitomo Kinzoku Kogyo K.K. Puropera Seizosho) manufactured nearly 40% of the propellers used by the Army but the production flow charts within the United States Strategic Bombing Survey (USSBS) report for this company give no indication of a painting process and no mention of spinners as manufactured products. The report also mentions that completed propellers were delivered to Army depots and not direct to aircraft manufacturers. 

The Japan Musical Instrument Manufacturing Company (Nippon Gakki Seizo K.K.) manufactured under licence from Sumitomo 28% of the propellers used by the Army, including those for the Ki-43 and Ki-48, averaging 241 and 120 a month respectively for those two types in the last three months of 1943. The USSBS report on the company gives a stronger indication that the manufacturing process did not include painting. Although the main plant did have a paint shop it is clear from the production flow charts that this was used only in the manufacture of plywood droptanks and not for propellers. Again there is no mention of spinners as a manufactured product and the report mentions that all propellers were delivered to the 'Munitions Ministry' (軍需省- Gunjushō) and again not direct to aircraft manufacturers. 

It would seem logistically clumsy for props to be painted at Army depots (but which would explain why they were painted to the same colour standard as the spinners) and then shipped to aircraft manufacturers. However post war photographs of newly manufactured Ki-84 Hayate at Ota and Utsunomiya show rows of prop-less aircraft with no indication of props on the ground as might be expected if they had been removed in conformity to surrender terms. The answer may lie with the Army Air Depots (Rikugun Kôkû Shô) responsible for equipping and supplying complete new aircraft and which were subordinate to the Department of the Director of Field Air Ordnance (Yasen Kôkû Heiki Chôkambu). In terms of ferrying replacement aircraft there was a depot to depot arrangement. Lt Shuho Kurita's 1943 photograph (below, from Ken Arnold's Home Page) of a Ki-43-I being ferried from Sadohara, Japan to Peitung (Heito?), Formosa (now Taiwan) reveals a natural metal aircraft with anti-glare panel and dark painted prop and spinner. Heito was an important Army Air Depot so it is not unreasonable to conclude that natural metal finish Ki-43-1 aircraft were subsequently camouflage painted there before delivery to units (which will be explored further in a future blog). Indeed after the fall of the Netherland East Indies the 64th Sentai collected some new Ki-43-I aircraft from Formosa which were completely and proficiently camouflaged with lacquer-type paint on all surfaces.   

This selection of rendered chips for the brown propeller and spinner colours from extant artifacts are based on Munsell comparisons provided by Japanese researcher Katsushi Owaki and the late Jim Lansdale. The closest FS and where appropriate RAL colours are displayed adjacently and as usual a value of 2.0 or less denotes a close match. The colours should not be taken as precisely indicative of the original paint colour as the paint appears to have been prone to fading towards lighter shades (and as mentioned above towards the # 31 Cha Kasshoku colour), but they do provide a guide as to the general dark reddish brown character of the colour - and not a brick red (Methuen 7D7) which is a much lighter colour closer to the Army # 4 Seki Kasshoku (red brown colour), the IJN red-brown primer paint and the modern JIS Azuki iro!

Suitable and specific hobby paint colours are available from Gunze (GSI Creos) as Mr Color C131 Propeller Color and Sovereign Hobbies Colourcoats ACJ23 Propeller Brown. In standard ranges Humbrol 98 Matt Chocolate is an approximate match but just a little too greyish, Revell 84 ‘Leather Brown’ being a better and reasonable match. Xtracolor X807 ‘Schokoladebraun’ (RAL 8017) is also acceptable. Vallejo Model Color 822 ‘German Camouflage Black Brown’ matched to RAL 8019 is a little too dark and 985 ‘Hull Red’ matched to FS 30059 is probably a better alternative for smaller models. Other more recent acrylic contenders have not been assessed or measured yet so suggestions are welcome!

Image credit: Heading image of RAF Museum Ki-100 © 2019 Ronnie Olsthoorn; All rendered colour chips © 2019 Aviation of Japan; Ki-43-I photo © Shuho Kurita via Ken Arnold.