Can a blade's static moment establish its rotational inertia?

The short answer

No. Static mass moment and rotational inertia describe different distributions. The first weights each mass by distance; the second weights it by distance squared. Equal blade static moments can therefore coexist with different inertias, which matters when reviewing rotor acceleration or a dynamic model.

Use a deliberately simple counterexample

Consider two hypothetical point-mass arrangements about the same axis. One has 2 kg at 1 m; the other has 1 kg at 2 m. Both have first moment 2 kg m, but their inertias are 2 and 4 kg m squared respectively. The example does not represent complete blades, and point masses omit each component’s own distributed inertia. It demonstrates why the first moment cannot determine the second.

Identify the dynamic quantity being requested

A rotor inertia used in acceleration calculations must be referenced to the actual rotation axis. A blade inertia about its own root is not automatically the same quantity. Hub offset, orientation and other rotating parts enter the assembly calculation. A static balancing result may address eccentricity without establishing the inertia needed for braking-energy or torsional-response assessment. Relabelling kg m as kg m squared would conceal that missing information.

Keep both data needs visible

For an OEM rotor review, request mass properties that name the axes, origins, attachment boundary and calculation or measurement method. If only a static moment is available, retain inertia as an unresolved model input instead of deriving an unjustified value. NASA centre-of-gravity material supports first-moment interpretation; the squared-distance comparison is elementary illustrative mechanics. MARSTON rotor inertia remains configuration-specific, and no acceleration, stop time or energy-storage performance follows from an unverified blade-set static moment. An inertia request should identify whether the value is a scalar about one shaft axis or a full mass-inertia tensor. Those deliverables answer different model needs and cannot be substituted merely because both mention inertia.