"Robert M. Gary" wrote:
Did I miss some context? Was there a debate about this? There are
videos on youtube of people doing barrel rolls with a cup of coffee in
their lap.

Most everyone agrees that keeping the coffee in the cup is possible. What
some people don't seem to believe is possible is that the force felt by the
pilot (or tea/coffee) can be 1 gee during the entire roll. They believe it
has to vary during the roll. I'm hesitant to name names. ;-)

So yeah, I think there is some need to clear the air.