Neutraalipiste

Neutraalipiste, or neutral point, is a stability concept used in engineering to describe a longitudinal location along a vehicle where the net restoring moment due to changes in attitude is zero. At this point a disturbance does not produce a restoring moment to return to equilibrium nor a further diverging moment; the configuration is said to be neutrally stable.

In aviation, the neutral point is often defined as the aerodynamic center of the entire aircraft. It is the point about which the pitching moment does not change with angle of attack. If the center of gravity (CG) lies forward of the neutral point, the aircraft is statically stable; if the CG lies behind the neutral point, the aircraft is statically unstable. The static stability margin is the distance between the CG and the neutral point, usually expressed as a percentage of the mean aerodynamic chord.

In naval architecture, the neutral point is the aftmost CG position at which a vessel remains statically stable. It corresponds to the condition where the metacenter coincides with the center of gravity; moving the CG forward of the neutral point yields positive stability, while moving it behind the neutral point yields neutral or negative stability. The neutral point depends on hull form, superstructures, loading, and can shift with speed, trim, and displacement.

The neutral point is a theoretical construct used for design and safety analysis. It is related to concepts such as the aerodynamic center, the center of gravity, and the metacenter, and is used to assess and ensure adequate stability margins in aircraft and ships.