The term “arm” refers to the horizontal distance from a specific reference point, known as the datum, to the center of gravity (CG) of an object. When measuring this distance, the sign matters. If the measurement is taken behind the datum or to the right of the centerline in a lateral context, it is considered positive (+). Conversely, if the measurement is taken in front of the datum or to the left of the centerline, it is negative (-). This distinction is essential in fields like aerodynamics, where precision is crucial.
