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Development of a System for Improved Helicopter Blade Tracking.

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Final rept. Sep 92-Mar 95,

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This report presents the results of the Phase II experimental verification portion of a research program in support of the development of a quality control system for obtaining improved helicopter rotor blade tracking. The specific objective of the system is the accurate concurrent measurement of both the first and second mass moments i.e., the static mass moment and the mass moment of inertia. The results of the Phase I study showed that, subject to the strict maintenance of linearity, the eventual system should be capable of making these measurements with accuracies to within 0.02 of nominal values. This degree of accuracy should result in blade-tracking characteristics superior to what are presently measurable and, hence, obtainable. The planned system would involve a horizontally supported blade configuration using a trapeze-like cradle suspension system. The technical basis of the measurement process involves two operations first, the accurate measurement of the eigenvalues of the essentially rigid-body dynamic system using appropriate transient time histories, and second, the extraction of the mass moments using the measured eigenvalues, together with other known mechanical properties of the system. The experimental results of this study were twofold 1 A series of tests were performed on a prismatic aluminum bar having length and mass characteristics of the same scale as those of a UH-6O Blackhawk helicopter rotor blade, but of as simple enough construction to enable analytical prediction of the mass characteristics, and 2 a second series of tests were similarly performed on a population of actual Blackhawk rotor blades to assess variability in properties and correlation with onerev vibration characteristics.

Subject Categories:

  • Helicopters

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