Re: Is 'centrifugal force' applicable without friction?

first, let me qualify slightly a statement you make: Centrifugal 
force will hold a person on the inside surface just like gravity 
would - provided the person "sticks" to the surface of the cylinder, i.e, 
moves along with it. 

Secondly, I would recommend you to think about rotation problems in terms 
of centripetal forces rather than centrifugal forces. A centrifugal force 
is considered to be a "pseudo force" - you do not know who exerts that 
force. Instead, it's easier to think of it as follows: to make a mass move 
in a circular path, something has to exert a force on it directed towards 
the centre of rotation-  the centripetal force.

Gravity provides this force to make the moon and satellites rotate around 
earth. If the person sticks to the cylinder, the cylider surface would have 
to exert this force on the person to make him rotate. The person would 
perceive this as "weight".

When the person is not in contact with the cylinder, it cannot exert this 
force and so the person would be "weightless". I doubt that even if the 
cylinder were air filled, the air mass would have the capacity to exert 
this force on him. Even if the air mass was spinning, friction would be 
tangential to the rotation axis and could not have provided him with the 
necessary centripetal force.