Topic
Lift-induced drag
About: Lift-induced drag is a research topic. Over the lifetime, 2861 publications have been published within this topic receiving 41094 citations.
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01 Oct 2020
TL;DR: A novel control allocation method by which full three-axis control authority can be achieved by the use of conventional lift effectors only, which reduces system complexity and control deflection required to achieve a given yawing moment.
Abstract: Tailless aircraft without vertical stabilisers typically use drag effectors in the form of spoilers or split flaps to generate control moments in yaw. This paper introduces a novel control allocation method by which full three-axis control authority can be achieved by the use of conventional lift effectors only, which reduces system complexity and control deflection required to achieve a given yawing moment. The proposed method is based on synthesis of control allocation modes that generate asymmetric profile and lift induced drag whilst maintaining the lift, pitching moment and rolling moment at the trim state. The method uses low order models for aerodynamic behaviour characterisation based on thin aerofoil theory, lifting surface methodology and ESDU datasheets and is applied to trapezoidal wings of varying sweep and taper. Control allocation modes are derived using the zero-sets of surrogate models for the characterised aerodynamic behaviours. Results are presented in the form of control allocations for a range of trimmed sideslip angles up to 10 degrees optimised for either maximum aerodynamic efficiency (minimum drag for a specific yawing moment) or minimum aggregate control deflection (as a surrogate observability metric). Outcomes for the two optimisation objectives are correlated in that minimum deflection solutions are always consistent with efficient ones. A configuration with conventional drag effector is used as a reference baseline. It is shown that, through appropriate allocation of lift based control effectors, a given yawing moment can be produced with up to a factor of eight less aggregate control deflection and up to 30% less overall drag compared to use of a conventional drag effector.
11 citations
TL;DR: In this paper, advanced drag prediction methods based on the momentum conservation theorem were applied to CFD computational results, which can decompose total drag into drag components such as wave, viscous and induced drag as well as spurious drag attributed to numerical computations.
Abstract: In this paper, advanced drag prediction methods based on the momentum conservation theorem were applied to CFD computational results. These methods can decompose total drag into drag components such as wave, viscous and induced drag as well as spurious drag attributed to numerical computations. Hence the more accurate drag prediction is possible by the elimination of the spurious drag term. The computational results showed that the advanced methods had the good capability of drag prediction and meaningful drag decomposition with accuracy. It was also found that the predicted physical drag values were weakly dependent on the mesh quality.
11 citations
TL;DR: In this article, the flow field is determined by solving two-dimensional incompressible Navier-Stokes equations while the effects of turbulence are accounted for by the k-ϵ model.
11 citations
TL;DR: In this article, the aerodynamic characteristics of an airfoil might be substantially improved by imposing certain limitations upon the air flow about its tips, such as mounting thin plates, in planes perpendicular to the span, at the wing tips.
Abstract: Tests have recently been made at Langley Memorial Aeronautical Laboratory to ascertain whether the aerodynamic characteristics of an airfoil might be substantially improved by imposing certain limitations upon the air flow about its tips. All of the modified forms were slightly inferior to the plain airfoil at small lift coefficients: however, by mounting thin plates, in planes perpendicular to the span, at the wing tips, the characteristics were improved throughout the range above three-tenths of the maximum lift coefficient. With this form of limitation the detrimental effect was slight; at the higher lift coefficients there resulted a considerable reduction of induced drag and consequently, of power required for sustentation. The slope of the curve of lift versus angle of attack was increased.
11 citations
TL;DR: In this article, the effects of wingtip connection on decreasing energy consumption and increasing flight endurance for solar aircraft were explored, and a flight endurance margin model was proposed to evaluate the advantages of wing tip connection quantitatively.
11 citations