Targit, I'll bet the answer is something like "Because it looks cool!" or "Because I wanted to see if it could be done..."

The other answer, of course, is that with one motor (presumably?) and four rotors to spin, variable pitch is the only reasonable answer for controlling the rotors. The necessary transmission to allow for RPM-based control would be fairly complicated, I'd think.

I'd love to hear more about this, but the original posts are from January, so who knows...?

Will