The blades on the blackhawk aren't that complicated. You might be able to scratch them out of some styrene if the spinning look doesn't work for you. There aren't any curved lines, they'd all be straight edges.
If you want to try a spinning look in flight, you'll want to make the blades into a shallow cone (center downward, tips upward), if you look online for flying helicopter pics, you can see the way the blades flap upwards. If you want to do spinning on deck, the blades would be in a pretty much flat plane (no need to make it into a cone shape) but don't forget the 3 degree forward tilt on the rotor head.
Groot