Parametric analysis for structural design and weight estimation of cantilever and strut-braced wing-boxes

Abstract

Computationally cheap and accurate enough weight estimation tools are needed for the multidisciplinary design optimization and the design exploration studies of novel aircraft at the conceptual design stage. In this study, a new wing-box structural design and weight estimation method for conceptual or early preliminary design of novel aircraft configurations is introduced. The wing-box weight estimation is achieved through structural sizing using standard structural theoretical procedures. To achieve this, a new wing geometric description with a new wing-box idealization model is introduced. Realistic symmetric maneuver, rolling, and combined loading cases are generated following CS.25 requirements. The structure is sized considering bending, shear, and buckling constraints, and the total weight is estimated from the sized components. The tool is validated against data from nine cantilever and one strut-braced aircraft with aluminum and composite wing- boxes, and a standard error of 1.7% and an average error of -0.2% are achieved. The effect of the strut addition on the total wing-box weight of high aspect-ratio wings is studied. It was shown that the strut helped reduce the wing-box weight of aluminum and composite wing-boxes by 11.9% and 16.2%, respectively. The capabilities and sensitivity of the new wing-box weight estimation method are also successfully presented through an in-depth parametric study. The effects of fourteen aircraft design parameters on the total wing-box weight of moderate and high aspect-ratio cantilever and strut-braced wings are investigated. It was shown that some design parameters have a significant effect on the wing-box weight of cantilever and SBW aircraft, and any wing-box weight estimation model not covering these effects is likely to have limited accuracy or sensitivity.