Aerodynamic Considerations in the Design of Truss-Braced-Wing Aircraft

Gur, Ohad; Schetz, Joseph A.; Mason, William H.

doi:10.2514/1.c031171

Cited by 41 publications

(25 citation statements)

References 22 publications

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“…Elements of multidisciplinary analysis and optimization have thus been incorporated in recent studies [45][46][47][48][49][50]. Although some of these studies involve CFD, none involve CFD-based ASO.…”

Section: Braced Wingmentioning

confidence: 99%

Euler-Equation-Based Drag Minimization of Unconventional Aircraft Configurations

Gagnon

Zingg

2016

Journal of Aircraft

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This study investigates the potential of unconventional aircraft transports through numerical optimization. Three distinct configurations are investigated: a box wing, a C-tip blended wing-body, and a braced wing. Each transport is sized for the same regional mission and is subjected to the same optimization strategy based on the Euler equations. The figure of merit is inviscid pressure drag at transonic speed; the nonlinear constraints are lift, pitching moment, and internal volume. The design variables include the section shape and twist distribution of the main lifting surfaces. It is found that the box-wing, C-tip blended-wing-body, and braced-wing configurations investigated here are, respectively, 34.1, 36.2, and 40.3% more efficient than a similarly optimized conventional tube-and-wing configuration. Each optimization revealed, in one way or another, the importance of accounting for flow nonlinearity during the early stages of unconventional aircraft design. For the blended wing-body, the C tip does not appear to provide a drag benefit over a purely vertical winglet, presumably as a result of the compressibility effects prevalent in the C opening. For the braced wing, compressibility effects also lead to a curious result, where the supporting strut finds itself carrying negative lift at the optimum. Nomenclature= span efficiency L = lift, N n = normal force (section), m q ∞ = freestream dynamic pressure, N∕m 2 W = weight, N x, y, z = chordwise, spanwise, and vertical coordinates, m α = angle of attack, deg

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Section: Braced Wingmentioning

confidence: 99%

Euler-Equation-Based Drag Minimization of Unconventional Aircraft Configurations

Gagnon

Zingg

2016

Journal of Aircraft

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“…The potential for significant improvement in lift-to-drag ratio (L/D) for the TBW configuration has been borne out through prodigious research performed in the past decade [3,4,5,6,7,8,9,10,11,12]. The motivation for adopting a TBW configuration is based on the well-known relationship between induced drag and wing aspect ratio.…”

Section: Sugar Tbw Configuration and Design Requirementsmentioning

confidence: 99%

Multidisciplinary Design Optimization of a Truss Braced Wing Concept

Nam

Chakraborty

Groß

et al. 2014

14th AIAA Aviation Technology, Integration, and Operations Conference

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Over the last few decades, the design of subsonic civil transport aircraft has largely focused on making improvements to well-understood, well-established designs in the interest of minimizing risk. This has resulted in comparatively little consideration for designs that achieve major improvements through more radical changes in the overall configuration. This is beginning to change however, as environmental concerns and airline economics create a strong incentive to produce designs capable of major reductions in fuel consumption, emissions, noise, and direct operating cost. Presented here is a study of an aircraft featuring a truss-braced wing configuration that has been optimized for minimum fuel consumption using multi-disciplinary design optimization. The investigation proceeds following Phase I of the Boeing SUGAR N+3 study, which selected the truss-braced wing concept as the most promising of several N+3 concept vehicles. This comes from the fact that a significantly higher aspect ratio wing could achieve substantial reductions in induced drag, but requires major structural changes to support such a large span. This problem was explored through the use of a multi-disciplinary design and analysis environment implemented in ModelCenter. Optimization was performed using ModelCenter's Design Explorer and Darwin genetic algorithm optimizers. Using the multi-disciplinary environment, a large multi-dimensional design space was explored featuring design variables spread across the major aircraft design disciplines. Configurations featuring a strut-braced wing, and truss-braced wings with one and two juries were evaluated with different boundary conditions for the strut anchor points, which were connected with either a ball joint or a pinned joint. When these three configurations were evaluated with the same wingspan constraint, it was found that adding a single jury to a strut-braced wing configuration resulted in a lower wing weight. However, the wing weight reduction from the addition of a second jury was only marginal due to the associated drag penalty. For each configuration, relaxation of the span constraint resulted in higher fuel efficiency due to higher aspect ratios, but diminishing returns were obtained for spans exceeding 170 ft. The single-jury configuration with 170 ft span was down-selected and used as the baseline for comparing the effect of natural laminar flow over the wing upper surface and over both upper and lower surfaces relative to fully turbulent flow. It was found that natural laminar flow over only the wing upper surface could provide the same fuel burn benefits as that over both upper and lower surfaces provided a certain maximum lift coefficient was available with takeoff flap setting. The multi-disciplinary optimization used for this investigation was able to produce candidate designs with the desired attributes and performance improvements, while satisfying all relevant geometric and performance constraints.

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“…1. Following Pfenninger's ideas, the concept of strut-braced wing (SBW) and TBW configurations for long and medium-range civilian transport aircraft has been investigated using multidisciplinary design optimization (MDO) approach [4][5][6][7][8][9][10] . These studies clearly established the potential benefits of such configurations in reducing take-off gross weight (TOGW) and/or fuel consumption.…”

Section: Introductionmentioning

confidence: 99%

Multidisciplinary Design Optimization of Subsonic Strut-Braced Wing Aircraft

Gupta

Mallik

Kapania

et al. 2014

52nd Aerospace Sciences Meeting

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In this study, a multidisciplinary design optimization technique has been used to investigate the potential benefits of truss-braced wing configurations in the design of medium-range subsonic military cargo aircraft. Previous studies of truss braced wing aircraft (both strut-braced wings) and truss-braced wing) at Virginia Tech for both Boeing-777 and Boeing-737 type of missions have shown that such advanced configurations provide both structural and aerodynamic benefits. The objective of this study was to explore the potential benefits of truss-braced wings in minimizing fuel consumption when applied to a subsonic Lockheed Martin C-130J like aircraft with a cruise Mach number of 0.60, 1800 NM range and a maximum payload of 40,000 lbs. The results show a 10.7% reduction in fuel weight with just a 5%increase in TOGW of the aircraft, a 27% increase in lift to drag ratio and 25% increase in wingspan for strutbraced wing aircraft. This study highlights the benefits of the truss-braced wing configurations for cargo aircraft and provides a comparison amongst various trussbraced wing configurations. For this class of aircraft, the strut-braced wing proves more attractive than a truss-braced wing (strut plus one jury) configuration.

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Aerodynamic Considerations in the Design of Truss-Braced-Wing Aircraft

Cited by 41 publications

References 22 publications

Euler-Equation-Based Drag Minimization of Unconventional Aircraft Configurations

Euler-Equation-Based Drag Minimization of Unconventional Aircraft Configurations

Multidisciplinary Design Optimization of a Truss Braced Wing Concept

Multidisciplinary Design Optimization of Subsonic Strut-Braced Wing Aircraft

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