One of Luigi Colani's designs that is particularly confusing to me is the second design iteration of the C-309 propeller racing airplane. Allegedly, its two propellers are designed to be supersonic and they have a very peculiar shape, as shown in the photo below.
The leading edge of the C-309 propellers is both forward-swept and twisted in a circular fashion, given the propeller blades a helical appearance. This is a very different approach from real-world supersonic propellers found in e.g. the Republic XF-84H Thunderscreech.
Assuming the propeller material to be indestructible for a moment, and that the propeller design is not guided by aesthetics alone, what would be the aerodynamic reasoning behind creating a propeller of such an absurd shape? Is it equivalent to a forward-swept wing that takes into account the relative velocity from the propeller rotation?