Hi JP, please post here again if that previous windmill wing discussion doesn't get you going.

One quick bit of advice - it can be a lot easier to make things like that if you don't worry so much about the rounded tip part at the very end during the initial modeling part.

I mean focus first on kind of the main body of the propeller, get some curves arranged out similar to this:



Then select them and run Construct/Loft to build a base surface like this:



That's the basic way to get started. Once you have that central form done then you can worry more about the tip and about joining that blade to a central hub, if you get stuck on parts please post a .3dm model file here with your current progress in it, that makes it a lot easier to give advice.

- Michael