Finding the perfect color for undersides of Russian aircraft during WW2 is hard and it varies between internet sources.
My question is what would your color of choice be for undersides of WW2 Russian aircraft?
RLM 78
Vallejo 906 (Pale Blue) [FS35352]
Vallejo 972 (Light Green Blue)
Vallejo 961 (Sky Blue) [FS35466]
Whatever is a closest match to this:


RLM-78 would not be a bad choice at all. Testors has the Russian Sky Blue in the MM Line, but apparently only in enamel. Humbrol discontinued their Russian underside blue many years ago. And we all know the fate of Polly Scale who also made the color.
stik - Yeah I saw Testors had Model Master Russian Underside Blue in enamel. I have yet found a bottle anywhere to really get a good look see. Polly Scale seems almost too blue from the looks of it and my LHS didn’t have that color on hand to speak of.
At some point this weekend I’m going to try to stop over to a Hobby Lobby in my area and take samples of the Vallejo colors on paper and compare with RLM 78 I had bought yesterday at a LHS.
I managed to stop by Hobby lobby during my “pick up the stuff for the birthday party” run this morning. Vallejo 961 (Sky Blue) [FS35466], is way too bright for Russian undersides color… So that one is out, Unfortunately they didn’t have the other two Vallejo blues I wanted to compare with. The more I llok at the pic posted by Nathan T, the more I’m leaning towards RLM 78. I still want to see a sample colors of Vallejo 906 (Pale Blue) [FS35352] and Vallejo 972 (Light Green Blue).