I have extracted the critical parts of the propeller design for my whirligig do make derivatives easier.The most complex part of the whirligig propeller was actually the quick lease spiral mount in the hub. Most derivatives don't need this feature, so I removed it from the scad file to make the design less confusing.Download .scad file. Modify as needed. Publish you new thing.You can print the included sample stl if you want. It has a double-d mount and will fly just fine.