Center of gravity (CG)

The Center of Gravity, or CG, is the point at which an aircraft would balance if it were suspended at that exact point. It is the theoretical point where the entire weight of the aircraft is assumed to be concentrated. The CG location is crucial as it affects the aircraft’s stability during flight.

The CG point changes depending on the distribution of weight in the aircraft, including fuel, passengers, and luggage. Therefore, each aircraft has specific CG limits determined by the manufacturer. If the CG of the aircraft is outside of the specified limits, it can be unsafe to fly as the control surfaces will not have enough authority to safely control the aircraft. For instance, if the CG is behind the aft (rear) limit, the aircraft may stall.

The CG may be expressed in inches from the reference datum or as a percentage of the mean aerodynamic chord (MAC). The MAC is a reference chord line used to determine the wing’s aerodynamic center. It is the average distance from the leading-edge of the wing to the MAC.

Aircraft specifications indicate forward and aft CG limits, which must be adhered to during flight. These limits ensure that an aircraft remains within its safe operating envelope. The distance between the forward and aft CG limits is also specified and must be considered when determining an aircraft’s loading configuration. Overall, the importance of understanding the CG cannot be overstated, as it affects both the performance and safety of an aircraft during flight.