Small point about ultralights…
There has long been a view, advanced by certain members of the aviation press, to the effect that ultralights are “vehicles” but not “aircraft” under the regulations.
A literal reading of the regulations suggests they are both - although admittedly there’s enough ambiguity that a judge could rule the regulations intended to exclude them from being “aircraft”.
The wording in 14 CFR 103 carefully sticks to “ultralight vehicle” and never once implies that these vehicles are “aircraft”; and in several places the wording seems a bit odd, if ultralight vehicles are “aircraft”.
Still, the authors of Part 103 never actually said ultralight vehicles are NOT aircraft for the purposes of the regulations.
14 CFR 1.1 defines both “aircraft” and “airplane”. Ultralight vehicles clearly meet the definition of “aircraft” and powered fixed-wing ultralight vehicles clearly meet the definition of “airplane”.
Just sayin’.