As an addendum to
weasello's excellent writeup above, and for
contrast, I offer the following list of aircraft
classes as they are (or soon will be) recognized by the U.S.
FAA:
Note that aircraft must be certified to be flown in the U.S., with the exception of
experimental aircraft. Recognizing the continuing debt owed to the garage
tinkerer by
general aviation (and, by extension, everything up to and including the
Space Shuttle - thanks
Orville and Wilbur!) the FAA allows homebuilt and even home designed airplanes restricted use of the nation's
airspace. The tradition of experimental aircraft designs flown by their inventors is going strong - see
Bert Rutan for an example.