I would be more curious about folding rotor system developed by Dutch Aerospace Laboratory (NLR) for the PAL-V Europe helicar. If this does allow a low diskloading and affordable means of getting rotor time then i wish John Bakker well. Of course the average car driver will not be aware of vortex ring state and/or need to drop collective sharpish for engine failure. In general teetering rotor handling qualities take time to master, so i would be interested what control measures are put in place. Finally machine will potentially need to meet automobile and helicopter crash requirements.
These are the more practical aspects that potentially make this project more difficult than say the
Aquada amphibious car...
Mart