Jim Logajan writes:

Myth:

It is impossible to perform a barrel roll such that the pilot feels exactly
1 gee of force perpendicular to the floor of the cockpit.

No maneuver that involves a change in altitude can maintain exactly 1 G along
the net acceleration vector (including perpendicular to the cockpit floor).
This is not a myth, it's a fact.

The only roll you can perform that does not involve more than 1 G of net
acceleration is one that involves no change in altitude, such as a roll
precisely about the longitudinal axis. But no roll that maintains the net
acceleration vector perpendicular to the cockpit floor is in this category.