"David L. Burkhead" wrote in message
How would something like the Hiller flying platforms, the Piaseki
"AirGeeps"
or, for that matter, the Avro Aircar, done as a homebuilt be licensed?
They
don't seem to fit any of the normal categories I'm familar with.

They all derive their lift from rotating airfoils. They would therefore
likely be categorized in a little known category called 'rotorcraft'. They
may not even need to be licensed, if they can't rise above ground effect.

D.