Sample A: http://i.imgur.com/gPzN5AN.png

Sample B: http://i.imgur.com/dUhGguS.png

There are many more but from what I saw they are basically alternations of or combinations of those two. I personally like sample A more myself and hope that's it, but I know there are so many versions of flags for empires from the past and it could be any one of them.

Edit* So sample A isn't working. It's basically the black, white, then red with the black Prussian eagle in the white and the white borders extend in a circular pattern going inside the red and black borders so the white surrounds the eagle. You can find it easily on Google image.