This instrument is a gravity-driven pendulum system for moment-of inertia-measurement of control surfaces up to 500 lb / 225 kg. Moment of Inertia test equipment is important to measure the MOI of an aircraft control surface to ensure that the maximum MOI about the hinge line does not exceed pre-established limits. This is to better predict and reduce the likelihood of flutter and divergence characteristics.
Space Electronics Control Surface MOI Instrument suspends the test article in a horizontal orientation to create a gravity-driven pendulum. The pendulum oscillation is initiated manually. The frequency of oscillation and damping coefficient are measured, and forces are recorded using a high-accuracy force transducer to measure control surface Center of Gravity. Inertia is derived from the oscillation period, the mass of the control surface, and CG offset distance. Measured MOI is accurate to ±3%.