The COG range (Center of Gravity Range) of an aircraft defines the permissible range between the foremost and rearmost position of the center of gravity within which the aircraft can be operated safely. This range is defined by the manufacturer and certified by the aviation authorities. Compliance with the COG range is crucial for the safety and efficiency of flight operations.
Printout of the COG range
Distance from a reference point
The COG range can be expressed as a physical distance from a specified reference point, for example in inches or meters.
Percentage of mean aerodynamic wing depth (MAC)
For fixed-wing aircraft, the COG range is often specified as a percentage of the mean aerodynamic wing depth (MAC). This enables a standardized specification that is independent of the size of the aircraft.
Example
A typical COG range could be expressed as follows:
- COG range: 15 % to 35 % MAC
This means that the COG of the aircraft must be between 15 % and 35 % of the MAC under all loading conditions to ensure safe operation.
Significance of the COG area
Stability, control and performance
The COG range ensures that the aircraft remains stable and can be controlled well in all phases of flight. This is crucial for flight safety and the performance of the aircraft.
Protection from unsafe conditions
A COG outside the permissible range can lead to unsafe flying conditions:
Front center of gravity position: If the COG is too far forward, the aircraft becomes nose-heavy. This can lead to difficulties when rotating during take-off and to higher stall speeds.
Rear center of gravity position: If the COG is too far back, the aircraft becomes tail heavy. This can lead to pitch instability and problems with recovery after a stall.
Dependencies of the COG area
Aircraft type and configuration
The COG range can vary depending on the aircraft type and configuration, e.g. between passenger and cargo aircraft.
Fuel position and consumption sequence
The position of the fuel and the order in which it is consumed can influence the COG.
Payload distribution and loading processes
The distribution of the payload and the way in which the aircraft is loaded are decisive for compliance with the COG range.
Use of the COG range
Load planning
The COG range is used when creating load plans to ensure that the aircraft is loaded within the permitted limits.
Flight testing and certification
During flight testing and certification, the COG area is checked to ensure that the aircraft can be operated safely under various conditions.
Compliance with the COG range is therefore a key aspect of flight safety and efficiency.
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