To All:

I've always appreciated my father's explanation, which some of you may
find suitable if you have a nine-year old who is just getting into
free-flight.

Model competitions were quite popular up until WWII but never regained
their past glory after. My dad and several of his friends were
discussing a new wing for an existing fuselage and Reynold's number
was mentioned several times. When I asked what it was his friends
started to grin; a couple even laughed but he told me there were
somethings that we couldn't scale, such as the size of a molecule of
air. so a fellow named Reynold came up with a way of calculating a
number that could be used as a kind of artifical scaling factor.

-R.S.Hoover

(Do they still use Banana Oil?)