Wednesday 15 March 2023

Grey Blue Cockpit Interior in Ki-61

Hat tip to Lorenzo of Italy for kindly alerting to this interesting Japanese video footage clearly showing the grey-blue # 3 Ash Indigo colour (Hai Ran shoku - 灰藍色) in the interior of a Kawasaki Ki-61 Hien 'Tony' recovered to Japan from New Guinea. The colour is similar to FS 36118 Gunship Gray, ANA 603.

From 1936 the grey-blue paint was to be applied as an overall primer to replace aotake, sometimes with the addition of # 17 Faint Blue colour (Tan Sei shoku - 淡青色)  as a middle coat before the grey green # 1 Ash Green colour (Hai Ryoku shoku - 灰緑色) was applied to external surfaces in top coats, sanded and polished. The whole interior, including the cockpit, was to be painted the grey blue colour and this was introduced with the Ki-15, Ki-21 and Ki-27. In practice this continued for the cockpit into the war years, certainly for early production Ki-61, whereas aotake continued to be applied to other parts of the interior. When the application of aotake to interior surfaces was discontinued in early 1943 in order to to speed production cockpits began to be painted in other colours in a more haphazard manner, including the # 1 grey green and another darker grey green paint similar to that used for Hayate propellers.     

The grey blue paint was also found inside the wing sections of the hybrid remains of Ki-61-I Ko/Otsu c/n 379/640 (379 constructed in Sep 1943 and 640 in Nov 1943), although the wheel wells appeared to be painted in a lighter grey colour, unspecified. Whether the lighter grey paint was very badly degraded, chalked or faded grey blue is now impossible to say. The problem, as referenced before, is that restorers take an inconsistent approach to measuring and recording extant paint in surviving airframes, often just stating that new paint 'matches the original' without actual providing colour values for it, the original paint being destroyed in the process. And laying standard paint swatches against the original paint surface and photographing them is not a valid scientific method for identifying the original colour value(s). 


Added some additional details of painting technique for the 11 March 2023 blog post featuring Guillermo's Fine Molds Ki-43-III Ko .


Michael Thurow said...

Very interesting. Another convention shattered ('all Hien are painted khaki in the cockpit area'). Taking the video evidence and the blue-grey Ki-27 cockpits into account this may also have applied to early Ki-43 and Ki-44 (?).

Thanks Lorenzo and Nick!

WK said...

How very timely, as I have acquired yet another 1/32 Ki-61 (ko/otsu) for my collection and future build (68/78 Sentai, of course). But before that I will be applying this knowledge to the cheaper and easier to find 1/48 Ki 61 ko/otsu.

Thank you for sharing.


Alex said...

Very useful and unique information! It's time to build an early Hien. Many thanks to Lorenzo and Nick!

Straggler 脱走兵 said...

Hi Michael

In Gakken 52 (2005) Katabuchi-san maintains that only the first Ki-43 prototypes had the grey blue cockpit interior and that from s/n 4312 all inaccessible interior parts and the cockpit were finished in aotake. Some confirmation of this was provided during restoration of the extant Oscar I # 750, From the Prue Walis write-up 'The Story of Nakajima Ki43i No. 750 (Oscar)':-

'A full surface corrosion removal was undertaken. Fortunately corrosion had not got a good hold on this aircraft and most was buffed off using Scotchbrite buffing wheels. The wash also brought the internal corrosion proof paint up beautifully. The colours inside now were brilliant green with some blue panels, and where it had not been exposed to ultra violet light, had proven itself to be extremely effective in its performance. The interior skins were remarkably well preserved.'

Images of the restored cockpit show this rather bright and metallic emerald green appearance emulating the original aotake found. However I remain a little sceptical about this, not least because of the evidence from this Hien, well into 1943. Ki-43-II cockpits examined by LAC Morton in Thailand were described as 'yellowish green' in colour, more on which in due course. Photos of a Ki-44 cockpit interior examined full size from the original prints during the writing of Ki-44 Aces show the appearance of a dark, opaque finish, which could be either grey blue or the unspecified, darker grey-green paint as described by Katabuchi-san (similar to the Hayate prop colour). But another photo showing the inside of an open side door suggests aotake. Because actual examples often refute the intention of official instructions the probability is that there was inconsistency in the interior finishing, so I think modellers will always have a legitimate choice.


Mark Smith said...

Lorenzo, Nick,
Finely written and presented, thank you for making this information available.

Kevin Bade said...

It amazes me how many decades ago we thought all Japanese aircraft interiors were painted some form of aotake or unknown green shade and thanks to you and other researchers we have much more clarity now. Thanks for the timeline of the use and then discontinuation of grey-blues, ect. Great info! :)

Dan Salamone said...

When I had started my Hasegawa Ki-61 back in 2005, it was going to be a 68th Sentai bird and I painted the cockpit this color based on some of the discussions at It wound up being a Ki-61 Hei of the 244th Sentai, but I kept the interior color the same. It's nice to see images showing the color on an actual aircraft, thanks to both Lorenzo and Nick for sharing it here.


Baronvonrob said...

Fascinating and impressive seems as though we all now have a legitimate choice of interior colors to apply

As the saying goes, variety is the spice of life

Gratitude to Lorenzo and Nick!

WD said...

Thanks so much for this Nick as I was just pondering this the other day. Now, after mid-43, what color/colors do we have to choose from for Ki-61 cockpits?


Fred Boucher said...

Lorenzo, Nick, grateful to you both for expanding our knowledge of interior colors, among other information. Wonderful work you are doing.

Thank you,

Fred Boucher

Ronnie Olsthoorn said...

Good stuff. Joe Picarella once told me he found this paint inside the Ki-100 cowling as well when they were restoring it for the RAF Museum.