Results of an Aeroelastic Tailoring Study for a Composite Tiltrotor Wing

Author: Popelka David   Lindsay David   Parham Tom   Berry Victor   Baker Donald J.  

Publisher: AHS International

ISSN: 2161-6027

Source: Journal of the American Helicopter Society, Vol.42, Iss.2, 1997-04, pp. : 126-136

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Abstract

The feasibility of a composite tailored wing for a high-speed civil tiltrotor is addressed using existing analytical methods. Composite tailoring is utilized to increase the proprotor aeroelastic stability margins for a thin wing (18% t/c) designed to improve high speed performance and productivity. Structural tailoring concepts are applied to the wing alone to improve the stability of the symmetric wing beamwise bending mode and the symmetric wing chordwise bending mode, which are the two most critical modes of instability. Skin laminate tailoring is shown to favorably influence the wing pitch/bending coupling and improve the stability of the wing beamwise mode. The wing chordwise mode stability is reduced by skin laminate tailoring due to a decrease in wing stiffness, but by tailoring the distribution of stringer and spar cap areas, the wing chord mode stability can be recovered. Parametric studies show that the overall stability gains from composite tailoring can be limited because of conflicting structural design requirements imposed by the two critical modes of instability, and the necessity to balance the stability boundaries for both modes. The parametric studies are used to define an 18% t/c tailored wing configuration that meets the stability goals with a minimum weight penalty.