Which method is used to balance a narrow rotor compared to diameter and center hung?

The single-plane method is the appropriate choice for balancing a narrow rotor that is center hung. This method focuses on adjusting the rotor's mass distribution in a single plane to minimize unbalance. When dealing with narrow rotors, this technique is effective because it allows for the removal or addition of weight at one specific plane, directly addressing the unbalance without complicating factors that could arise from multi-plane adjustments.

This method is particularly advantageous in practical applications, as it simplifies the balancing process and makes it easier to achieve desired performance outcomes. In essence, the single-plane method is efficient for rotors where the design and operational parameters support balancing in a single dimension, enhancing reliability and reducing wear on associated components.

Other methods mentioned may involve more complexity than necessary for a narrow rotor application or may even require multiple adjustments across different planes. In this context, the single-plane method stands out as the most effective choice for achieving balance in the described scenario.