For my wind mill project I wanted to do something unconventional, and as I have spent countless hours making turbines before I wanted something different  ,so I made a Lilly impeller.  Below are the step by step instructions of how Iw did it.

 

 

 

 

 

 

 

 

 

 

 Above are pictures of the 3d model made in a software called Onshape ,

It is my preferred software, an online version of solid works with built in simulation capability. I started by making a golden ratio spiral ,this can be made by using a grid of square boxes each one with the length of the last two added together to form a grid like this.  Then in Onshape do the same thing ,like this.

Now using the center point arc form the spiral by connecting the boxes like this ,you will get a lot of errors but you can solve them by finding the place with unnecessary the  dimension’s.

         Once you are done do it for the other side and it should look some thing like this.

After that I extruded the central shaft and used the helix tool to add the curve. 

Next I swept the golden ratio spiral sketch along the curve I made in the last step.

 

Then I made a new sketch with an area that I will use to cut the spiral in to the right shape.

  After that I use the sketch and a “remove revolve” to cut it into the right shape

For the next step I extended the central shaft and extruded bits so the petals and shaft touched turning them in to one piece

lastly I used transform to scale it to the right size and I finished

Thanks for reading