Date of Award

Spring 1999

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Aerospace Engineering

Committee Director

Donald L. Kunz

Committee Member

Raymond G. Kvaternik

Committee Member

Mark W. Nixon

Committee Member

Jeng-Jong Ro

Call Number for Print

Special Collections; LD4331.E535 P563

Abstract

The performance of a higher harmonic control system called the Multipoint Adaptive Vibration Suppression System (MA VSS) at reducing 3/rev wing vibratory loads and fuselage vibrations on a dynamically-scaled tiltrotor model is presented. Previous wind tunnel tests on a semispan aeroelastic tiltrotor model have demonstrated the effectiveness of MAVSS for reducing wing vibratory loads using both an active flaperon and swashplate. The primary goal, however, of such a vibration suppression system is to reduce tiltrotor fuselage vibrations in order to improve passenger comfort. The present study addresses the reduction of both wing and fuselage vibrations using MA VSS active flaperons on a 1/10-scale dynamic tiltrotor model designed to be representative of a tiltrotor configuration. Also, this study attempts to identify possible problems that may impede the application of MA VSS flaperon control forces for the purpose of tiltrotor vibration reduction in the presence of full-span symmetric and antisymmetric wing modes of vibration. Electromagnetic shakers applied simulated 3/rev vibratory hub loads and higher harmonic control forces, simulating active flaperons, to the tiltrotor model. MAVSS is shown to be effective at reducing individual and combined 3/rev vibratory wing loads in the semispan configuration. For the more complex full-span configuration, MAVSS flaperon control forces are shown to be effective at reducing wing vibratory loads or fuselage vertical accelerations, but not as effective at reducing wing loads and fuselage vibrations simultaneously. Vibration reduction trends are shown to be a function of the simulated rotor speed for both the semispan and full-span configurations. These results suggest that the application of MA VSS-controlled flaperons to a tiltrotor configuration may prove to be difficult due to elevated wing vibratory loads during reduction of fuselage vibrations and because wing vibratory loads and fuselage vibrations cannot be reduced simultaneously.

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DOI

10.25777/9v8h-xf44

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