The Control Power refers to how quickly and effectively the rotor disk responds to cyclic movement to achieve a change in fuselage attitude.

The relationship of control power against the natural damping effect of the disc.

An uncomfortable oscillation of the tail in a combination of up and down and left and right, so it combines roll and sideslip at the same frequency, but not in phase, so the maximum sideslip does not occur at the same time as maximum roll, which is why it is uncomfortable. It arises from too little dynamic stability against yaw, so it happens at altitude. Helicopters may also include a pitching motion.

The ability of a statically stable aircraft to return to its original state.

An inverted aerofoil that creates a downward force to pull the nose up to keep the fuselage more level, so that the controls remain within their ranges of operation.

A phugoid is the path a particle takes when it is subject to gravity vertically, but is acted upon by a force at right angles and proportional to V2. Put another way, it refers to the size of the oscillation for dynamic stability (you could loosely call it porpoising). There is a large-amplitude variation of airspeed, pitch angle, and altitude, but almost no angle-of-attack variation. It is really a slow interchange of kinetic energy (velocity) and potential energy (height) about some equilibrium energy level as the aircraft attempts to re-establish the steady flight condition from which it was disturbed. The motion is so slow that the effects of inertia and damping are very low. Although the damping is very weak, the period is so long that you normally correct for it without realising. Typically it lasts for between 20–60 seconds.

The initial ability to return to the desired attitude.