The main article on issue #10 of our magazine was on the Yokosuka K5Y "Akatonbo" (Willow) and included the very precise painting instructions by Fuji Aircraft Co. Ltd., dated January 10, 1942. According to the document the color for the fabric surfaces of the fuselage, tail and wings of the Akatonbo was ORANGE (daidai-iro). Repeat, ORANGE. NOT yellow.
Also, according to the document, the paint to be used for these surfaces was to be 94kg of orange-yellow (to-oshoku).
The document (the official painting instructions for the main trainer of the IJNAF) makes no distinction between the two colors.
Color researchers unfortunately seem to ignore the very precise painting process the aircraft underwent. For the Akatonbo the instructions for example call for:
"The temperature inside the paint workshop needs to be within the 20-30 degrees C range, with 45% to 70% humidity. Be sure to allow the measurement and recording of paint workshop temperature and humidity three times a day."
Until now, personally, I have never seen any research examining the effects the paint application process had on how the original paint looked. In other words, what was the difference, if any, between how the paint looked in the can and how the paint looked when applied on the aircraft.
Numerous Navy veterans I've interviewed call the color either yellow (kiiro) OR orange (orenji-iro). NEVER orange-yellow (to-oshoku) which in the Japanese language is more of a technical term that nobody would immediately use, and stress the fact that the color depends on how freshly painted each aircraft was. A Navy veteran who was a training instructor and regularly flew Akatonbo, even described the color as pink!
In any case all veterans agree that the Navy Akatonbo were always a lot dirtier than modern scale models or modern artwork they have seen.
Just some facts.
My personal conclusions are:
1. the color descriptions are attempts to describe what color the aircraft should be painted, not attempts to describe factory paints. In the Japanese language the perception of the colors "yellow" and "orange" are close and it's really subjective whether a color is simply yellow or dark-yellow, light-orange or yellow-orange. Another factor that should be kept in mind is the reluctance of the Japanese Army/Navy to use "western" terms, therefore instead of describing a color as "orenji" (orange) it is very possible they opted for the Japanese word "kiiro" (yellow).
2. The paint application process is an extremely important factor to consider when drawing conclusions and making suggestions about what color a particular aircraft type was. The Willow was mostly a fabric covered a/c. The paint instructions mentioned above call for 3 hands clear primer, one hand red-brown intermediate coat and on top of them two hands of orange paint, plus a clear coat for waterproof parts. Even if the original paint, straight from the can, was orange-yellow, two coats over red-brown would certainly make the color look darker; more orange than yellow.
3. Yes. The Willow wasn't just orange. Light orange or orange-yellow are fairly close enough. But it was certainly not yellow as some recently have been suggesting.
4. When talking about prototypes a very important factor is whether the overall color was properly applied with red-brown primer underneath or whether the overall color was applied directly on the metal. In the first case the result might be a darker orange-yellow, in the second a brighter color.
(Thank you Nick for the link)