Center of Gravity

The distribution of the mass of an object determines the position of its Center of Gravity.

CG Range

CG Range is the distance between the forward and back limits for the position of the center for gravity.

Specific aerodynamic principles apply to climbs, descents, and turning maneuvers. All maneuvering flight takes place around one or more of three axes of rotation. They are called the longitudinal, lateral, and vertical axes of flight. The three axes of flight pass through the airplane's center of gravity (CG). The CG is the theoretical point where the entire weight of the airplane is considered to be concentrated.

The ailerons, elevator, and rudder of an airplane create aerodynamic forces which cause the airplane to rotate about the three axes. The ailerons control roll movement about the longitudinal axis; the elevator controls pitch movement about the lateral axis; and the rudder controls yaw movement about the vertical axis.

Lateral Stability

Stability applies to all three axes of rotation. Various aspects of stability are designed into an airplane. Although no airplane is completely stable, all airplanes must have desirable stability and handling characteristics. If an airplane is laterally unstable, it has the tendency to climb or dive until a stall or a steep dive develops. Balance and center of gravity are among the key factors in determining the lateral stability of an airplane.

Center of Gravity

The position of the center of gravity (CG) is a key factor in lateral stability. Distribution of weight in an airplane determines the position of the CG. Since the weight of the airplane and the distribution of that weight are normally fixed, the CG location is largely determined by what you put into the airplane, and where you put it. For an airplane to be controllable during flight, the CG must be located within a reasonable distance forward or aft of an optimum position. All airplanes have forward and aft limits for the position of the CG. The distance between these limits is the CG range.

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