Do we have any archaelogical finds of them? Absent that, are there any detailed drawings of them dating from those periods?
I can find tons of pictures of these things online, but they all look like modern versions. I want to see original versions, because it's very critical to see the blade shape. In particular, I want to know if the blades were plain rectangles, or had some curves in them, especially washout twist like you see in modern propellers.