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Aircraft Control Surface for MOI Testing

Product Details

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%.

The Aircraft Control Surface MOI measurement instrument is a cantilevered design, allowing for a smaller footprint, unobstructed mounting of long parts, and a stiffer system.

The Control Surface MOI Instrument relies on absolute rather than relative measurements. Unlike the relative measurement method, which requires a mass model for system calibration and then compares the measurements of production units to mass model measurements, the absolute method measures MOI directly.

And by measuring the decay of the amplitude of oscillation, we are able to correct for the effects of entrained air in the wake of the oscillating control surface, a significant source of measurement error.

Design Advantages of the Control Surface MOI Instrument

  • Out-of-level error tolerance inconsequential up to 5 degrees
  • Ease of handling and loading interface locations are independent of ground support handling requirements
  • Ceiling height parts are measured in the shortest, most ergonomically efficient configuration

The absolute measurement method also allows for quick measurements of prototypes or major block revisions. It is also insensitive to the effects of altitude, temperature, and humidity.

Technical Specifications

MOI Accuracy ±3%
Payload Weight Capacity 50 to 500 lb
Hinge Point Spacing 48 to 112 in
Test Article Length (Span) (typ.) 54 to 288 in
Test Article Width (Chord) Up to 72 in

Custom sizes available

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