What does "static balance" mean in relation to control surfaces?

Static balance in relation to control surfaces refers to the condition where the control surface is balanced around its hinge line when it is at rest, without the influence of external forces such as airflow or gravitational forces acting on it. This means that the center of mass of the control surface is aligned with the hinge point, ensuring that the surface does not require any additional force to maintain its position. This balance is crucial for the effective functioning of the control surface, as it allows for smooth and predictable movement when it is actuated.

The other options do not accurately describe static balance. For instance, defining static balance as balance achieved without reference to any forces overlooks the essential role of the hinge line in the balance of a control surface. The term "dynamic flight conditions" implies motion and external forces, which are not relevant to the concept of static balance. Therefore, the correct understanding of static balance is that it pertains specifically to the intrinsic balance about the hinge point when no other forces are acting on the surface.