Spanload optimization for strength designed lifting surfaces

Craig, Anthony P; Mclean, J. D.

doi:10.2514/6.1988-2512

Cited by 16 publications

(10 citation statements)

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“…This is because the structural deformation is normally compensated for (jig-shape correction) by changing the geometric twist from optimal geometric twist of the rigid wing Eq. (6). That is, the elastic wing twist is equal to the optimal geometric twist from step 1 Eq.…”

Section: Step 3: Change Of Deformation Twist As a Function Of The mentioning

confidence: 99%

“…In other words, although the twist for an elliptic spanload is more effective than the twist of a straight line wrapped surface, the latter seemed to be less sensitive to changes due to structural deformation and may be preferred if tailoring the structure for the off-design conditions is not an option. Table 9: Effect of constant angle of attack adjustment on drag optimum swept-tapered wing of Twist B for 6 . 0…”

Section: Non-optimal Wingsmentioning

confidence: 99%

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Tailoring Wing Structures for Reduced Drag Penalty in Off-Design Flight Conditions

Papila¹,

Haftka²,

Mason³

et al. 2004

10th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference

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The induced drag penalty associated with off-design flight conditions is investigated. The investigation is limited to off-design flight conditions at a lower lift coefficient than the design lift coefficient. Two types of total angle of incidence distribution obtained at the design condition are studied. One is the distribution for elliptic spanloads and the other is the spanload distribution for straight-line wrapped surfaces. It is shown that the penalty may be significant as the structural deformation changes the total angle of incidence distribution and the spanload. The penalty is higher for the wing with the near optimal elliptic spanload at the design flight condition. The wing with straight-line wrapped surfaces does not have the minimum induced drag at the design condition. However, it is found to be insensitive to the structural deformation. = Geometric twist distribution as built into wing

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Section: Step 3: Change Of Deformation Twist As a Function Of The mentioning

confidence: 99%

Section: Non-optimal Wingsmentioning

confidence: 99%

Tailoring Wing Structures for Reduced Drag Penalty in Off-Design Flight Conditions

Papila¹,

Haftka²,

Mason³

et al. 2004

10th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference

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“…For a fixed wing weight and parasite drag, McGeer [13] used an iterative scheme to find the optimum span load for minimum drag. Craig and McLean [14] introduced fuselage interactions and aeroelastic effects while performing trade studies on wing weight and total drag, including profile drag. The MDO study conducted by Wakayama and Kroo [15] combined the aerodynamics and structures subspaces; however, the span load optimization step was not explicitly addressed.…”

mentioning

confidence: 99%

Preliminary Aerostructural Optimization of a Large Business Jet

Piperni

Abdo

Kafyeke

et al. 2007

Journal of Aircraft

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An overview of an industrial approach to the aerostructural optimization of a large business jet is presented herein. The optimization methodology is based on the integration of aerodynamic and structural analysis codes that combine computational, analytical, and semi-empirical methods, validated in an aircraft design environment. The aerodynamics subspace is analyzed with a three-dimensional transonic small disturbance code capable of predicting the drag of a complete, trimmed aircraft within engineering accuracy. The design of the wing structure is accomplished using a quasi-analytical method that defines the layout of the ribs and geometry of the spar webs, spar caps, and skin-stringer panels, and predicts the wing flexural properties and weight distribution. In addition, the prediction of operating economics as well as the integrated en route performance is coupled into the scheme by way of fractional change functional transformations. To illustrate the automated design system capabilities, the methodology is applied to the optimization of a large business jet comprising winglets, rear-mounted engines, and a T-tail configuration. The aircraft-level design optimization goal in this instance is to minimize a cost function for a fixed range mission assuming a constant maximum takeoff weight.Nomenclature A sk = cross-sectional area of skin, in: 2 A st = cross-sectional area of stiffener, in: 2 AR = aspect ratio C crew = hourly cost of the flight (and cabin) crew, CU=h C D = total drag coefficient C fees = landing fee charge based on maximum landing weight, CU=lb C fuel = price of fuel, CU=lb C L = operating lift coefficient C mnt = time-dependent airframe and engine maintenance cost, CU=h C mnt cyc = cyclic airframe maintenance cost, CU C mnt eng = cyclic engine maintenance component that is assumed to have a functional dependency with the engine derate level, CU E = relative or absolute error f = function; substitution parameter in modified integrated range model formulation g = acceleration due to gravity, ft=s 2 H = fuel calorific value, Btu=lb k aero = control factor used to regulate the extent of coupling (congruity or otherwise) between high-speed and intermediate-speed aerodynamic efficiency k clb = constant of proportionality required to predict all-up weight at top of climb k M = empirically derived coefficient used to establish a simplified relationship between overall power plant efficiency and Mach number k res = constant of proportionality establishing linear relationship between fractional change in total reserve fuel and fractional change in zero-fuel weight L=D = lift-to-drag ratio M = Mach number R = range, nm t = time, as in block or flight time, h V = forward speed [(knots, calibrated airspeed (KCAS) or knots, indicated airspeed (KIAS)] W= weight of a given component or assembly, all-up weight, lb x, y = arbitrary independent parameters or design variables z = arbitrary dependent parameters or objective functions = exponent, flight profile correction coefficient when useful load varies but payl...

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“…Craig and McLean [13] developed a computer program along similar lines. The analysis includes the effects of aeroelastic twist and viscous section drag.…”

mentioning

confidence: 99%

“…Accordingly, Refs. [13][14][15]17] specify a maneuver condition separately from the reference cruise condition. McGeer [14] points out that minimizing drag at the maximum load condition can produce "extraordinarily high drag at cruise C L 's," and this behavior is demonstrated theoretically in [8,10].…”

mentioning

confidence: 99%

Lift Distributions for Minimum Induced Drag with Generalized Bending Moment Constraints

Pate

German

2013

Journal of Aircraft

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The previous works of Prandtl, Jones, and Klein and Viswanathan addressed the problem of determining the lift distribution that minimizes induced drag for a given lift and specified bending moment. In these formulations, bending moment is considered to be a surrogate for wing weight. These classical methods require the bending constraints to be imposed at the same lift coefficient at which drag is minimized. In practice, however, it is commonly desired to minimize drag at a representative cruise lift coefficient while imposing the bending constraints at a limiting structural load condition, such as a maneuver lift coefficient. This paper presents an approach to extend the classical methods by allowing the bending constraints to be imposed at different lift coefficients than that at which induced drag is minimized. An example for a wing planform similar to that of a Boeing 737 shows that the penalty for optimizing induced drag at the maneuver lift coefficient as implied in the classical methods results in between a 1-10% increase in drag at cruise compared to the results from this new approach. It is expected that the new approach will enable the classical methods to be extended to practical applications in multidisciplinary wing design.

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Spanload optimization for strength designed lifting surfaces

Cited by 16 publications

References 0 publications

Tailoring Wing Structures for Reduced Drag Penalty in Off-Design Flight Conditions

Tailoring Wing Structures for Reduced Drag Penalty in Off-Design Flight Conditions

Preliminary Aerostructural Optimization of a Large Business Jet

Lift Distributions for Minimum Induced Drag with Generalized Bending Moment Constraints

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