What is the default type of sheaf and its parameters in fire missions?

The correct choice identifies the default type of sheaf used in fire missions as a circular sheaf with a radius of 100 meters. This default setting is crucial for various types of indirect fire missions, allowing for effective dispersion and coverage of the target area.

A circular sheaf is typically the favored default because it provides a uniform distribution of firepower around a designated target point. This helps to minimize the risk of collateral damage while ensuring maximum effectiveness against enemy positions or assets. The standard radius of 100 meters is often prescribed, as it strikes a balance between effective target engagement and safety for friendly forces.

In contrast, the other types of sheafs mentioned either do not serve as the default or are measured differently. A linear sheaf, for example, focuses on a specific line of engagement but lacks the broad area coverage of a circular sheaf. Similarly, a rectangular sheaf has its own applications but is not the standard for general fire missions. The converged sheaf is also utilized in specific scenarios but does not align with the default parameters in most fire mission contexts. Thus, the circular sheaf with a radius of 100 meters is the most versatile and commonly used default configuration for fire missions.