Hey there. I have the first 2 pics of which first one is my great grandfather and second is great great grandfather. I know the first one he was a pilot but that is about it and the other one I know nothing at all. I love to learn about my families history so if anyone can help that would be great. Thanks! http://imgur.com/a/OFcL0
Looks like lower enlisted. The collar tabs in the first pic might be for a corporal (or other junior NCO), though.
For your great grandfather, it's a little more difficult, because the rank systems pre-1940 of the red army were not comparable to those of western militaries. Because socialism.