Stability and Control Investigations in Early Stages of Aircraft Design

Hasan, Yasim Julian; Flink, Jan; Freund, Sebastian; Klimmek, Thomas; Kuchar, Richard; Liersch, Carsten M.; Looye, Gertjan; Moerland, Erwin; Pfeiffer, Till; Schrader, Mario; Zenkner, Sebastian

doi:10.2514/6.2018-2996

Cited by 6 publications

(7 citation statements)

References 28 publications

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“…15 Setup of design environment and interaction between DLR and AIRBUS surface model. An exemplary application of such a multi-fidelity process on the MULDICON Baseline configuration was already performed within Mephisto and is briefly presented in [50] (Section B.4, pp. 11-14).…”

Section: Discussionmentioning

confidence: 99%

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Design studies and multi-disciplinary assessment of agile and highly swept flying wing configurations

Liersch¹,

Schütte²,

Siggel

et al. 2020

CEAS Aeronaut J

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This article belongs to a series of publications on the design and assessment of the MULDICON UCAV configuration. MULDICON is a 53° swept flying wing combat aircraft concept, investigated in a common effort between the DLR research project Mephisto and the NATO STO Research Task Group AVT-251. This article focuses on the development of the overall concept starting from its predecessor, the SACCON configuration, and the requirements which had been defined for the MULDICON design task. A second focus is placed on the investigation of the vortex-dominated flow topology arising around such a configuration and its sensitivity to specific geometric changes. Furthermore, the article briefly introduces the DLR conceptual aircraft design system and the extensions which have been developed for improving its capabilities for UCAV assessment. Finally, an industrial view on the MULDICON design task is provided, as well as a conclusion of the Mephisto results and an outlook upon further work.

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Section: Discussionmentioning

confidence: 99%

“…As it was not clear at this point, how much yawing moment coefficient would be required, a target maximum value of 0.015 was chosen based on experience. To validate this value, an investigation with varying yaw control efficiency was performed by Hasan et al [50] (Fig. 25, p. 27).…”

Section: Muldicon Designmentioning

confidence: 99%

Design studies and multi-disciplinary assessment of agile and highly swept flying wing configurations

Liersch¹,

Schütte²,

Siggel

et al. 2020

CEAS Aeronaut J

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“…The parameters of the model reference NDI control law are designed according to the desired dynamic characteristics and do not need to be adjusted according to changes in the configuration parameters [25]. As a result, the FCL achieves the desired closed-loop flying qualities of the varying aircraft configuration and eliminates the disturbance attributable to variation in the control system.…”

Section: Aircraft Modeling Selection Of Flight Conditions and Evaluation Criteria 41 Aircraft Modellingmentioning

confidence: 99%

“…Inverse model-based control techniques, e.g., nonlinear dynamic inversion (NDI) as well as incremental nonlinear dynamic inversion (INDI), offer a great advantage to continuously changing plants [23,24]. The studies of DLR (German Aerospace Center) and others [25,26] show that the flight control law based on the NDI method can effectively adapt to changing aircraft configurations. Therefore, this paper proposes an aircraft configuration parameter boundaries design method based on closed-loop flying qualities requirements.…”

Section: Introductionmentioning

confidence: 99%

Aircraft Configuration Parameter Boundaries Based on Closed-Loop Flying Qualities Requirements

et al. 2021

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For aircraft employing the fly-by-wire technique, the closed-loop dynamic characteristics are determined by both the configuration design and the flight control system. As the capacity of the control system has certain limitations, the configuration parameters are also constrained by the requirements of the closed-loop flying qualities. This paper presents an aircraft configuration parameter boundaries determination method based on closed-loop flying qualities requirements independent of the actual flight control law design, mainly aiming at the parameters that affect the stability and control characteristics. First, a nonlinear dynamic inversion-based flight control law is adopted to decouple the control law gains from the configuration parameters and to study the relationship between the configuration parameters and closed-loop flying qualities. Second, a flying qualities evaluation scheme is established by selecting the most severe flight conditions and the evaluation criteria that are most sensitive to changes in the parameters. Finally, the parameter boundaries according to the requirements of Level 1 flying qualities are determined by searching for the critical values that lead to degradation of the flying qualities. The proposed method is verified by an application example of the design ranges of a sample aircraft’s wing position, horizontal tail area, center of gravity, vertical tail area and vertical tail position.

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“…High sweep angle and leading edge shape in aircraft with lambda wings cause complex unsteady aerodynamic and nonlinear flow that lead to weak aerodynamic stability and control because of flow separation and large vortex breakdown (Allen et al, 2018;Da Ronch et al, 2018;Hasan et al, 2018). Flight and wind tunnel tests are necessary for better comprehension of aerodynamic and stability behaviour of these wings (Cummings et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

The effects of flow separation on a lambda wing aerodynamics

Dadkhah

Masdari

Vaziri

et al. 2019

AEAT

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Purpose In this paper, experimental and numerical results of a lambda wing have been compared. The purpose of this paper is to study the behaviour of lambda wings using a CFD tool and to consider different numerical models to obtain the most accurate results. As far as the consideration of numerical methods is concerned, the main focus is on the evaluation of computational methods for an accurate prediction of contingent leading edge vortices’ path and the flow separation occurring because of the burst of these vortices on the wing. Design/methodology/approach Experimental tests are performed in a closed-circuit wind tunnel at the Reynolds number of 6 × 105 and angles of attack (AOA) ranging from 0 to 10 degrees. Investigated turbulence models in this study are Reynolds Averaged Navior–Stokes (RANS) models in a steady state. To compare the accuracy of the turbulence models with respect to experimental results, sensitivity study of these models has been plotted in bar charts. Findings The results illustrate that the leading edge vortex on this lambda wing is unstable and disappears soon. The effect of this disappearance is obvious by an increase in local drag coefficient in the junction of inner and outer wings. Streamlines on the upper surface of the wing show that at AOA higher than 8 degrees, the absence of an intense leading edge vortex leads to a local flow separation on the outer wing and a reverse in the flow. Research limitations/implications Results obtained from the behaviour study of transition (TSS) turbulence model are more compatible with experimental findings. This model predicts the drag coefficient of the wing with the highest accuracy. Of all considered turbulence models, the Spalart model was not able to accurately predict the non-linearity of drag and pitching moment coefficients. Except for the TSS turbulence model, all other models are unable to predict the aerodynamic coefficients corresponding to AOA higher than 10 degrees. Practical implications The presented results in this paper include lift, drag and pitching moment coefficients in various AOA and also the distribution of aerodynamic coefficients along the span. Originality/value The presented results include lift, drag and pitching moment coefficients in various AOA and also aerodynamic coefficients distribution along the span.

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Stability and Control Investigations in Early Stages of Aircraft Design

Cited by 6 publications

References 28 publications

Design studies and multi-disciplinary assessment of agile and highly swept flying wing configurations

Design studies and multi-disciplinary assessment of agile and highly swept flying wing configurations

Aircraft Configuration Parameter Boundaries Based on Closed-Loop Flying Qualities Requirements

The effects of flow separation on a lambda wing aerodynamics

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