Kerstin Claudie Huber

UCAV model design and static experimental investigations to estimate control device effectiveness and S&C capabilities

The experimental investigations of two generic UCAV configurations with control surfaces are presented. The current paper is covering the design of the model, layout of the control surfaces as well as the static wind tunnel tests. The low speed static wind tunnel tests have been undertaken to evaluate the effectiveness of different control surfaces and control surface settings. Finally, the experimental results are used to establish a common CFD test matrix for the NATO STO Task Group AVT-201 for computer code validation and to assess the capability to predict the complex vortical flow and aerodynamic Stability and Control (S&C) characteristics of configurations with highly swept leading edges and vortex dominated flow field.

Conceptual Design and Aerodynamic Analyses of a Generic UCAV Configuration

Applying DLR’s conceptual aircraft design system to military flying wing configurations, the design of a generic UCAV configuration is presented. For its outer shape, the SACCON geometry specified by NATO STO/AVT-161 Task Group was taken. For mission analysis and structural sizing, aerodynamic data from fast and robust conceptual design methods (i.e. potential flow theory) were used. In order to assess the validity of these simple methods for such configurations, a comparison with results from RANS aerodynamics and wind tunnel measurements was performed. The results of this design task were included into the stability and control investigations performed within the AVT-201 task group.

Low-speed Dynamic Wind Tunnel Test Analysis of a Generic 53° Swept UCAV Configuration

Several static and dynamic forced-motion wind tunnel tests have been conducted on a generic unmanned combat air vehicle (UCAV) configuration with a 53° swept leading edge. These tests are part of an international research effort to assess and advance the state-of-art of computational fluid dynamics (CFD) methods to predict the static and dynamic stability and control characteristics for this type of configuration. This paper describes the dynamic forced motion data collected from two different models of this UCAV configuration as well as analysis of the control surface deflections on the dynamic forces and moments.

Static and dynamic numerical simulations of a generic UCAV configuration with and without control devices

A contribution for the assessment of the static and dynamic aerodynamic behavior of a generic UCAV configuration with control devices using CFD methods is given. For the CFD simulations the unstructured grid based DLR TAU-Code and the structured grid based NLR solver ENSOLV are used. The numerical methods are verified by experimental wind tunnel data. The current investigations should provide a contribution to assess the prediction capability of control device effectiveness using CFD methods. The presented computational results for the assessment will be validated by dedicated experimental data. Furthermore, it should support the understanding of the flow physics around the trailing edge control devices of highly swept configurations with a vortex dominated flow field. Design requirements should be able draw by analyzing the interaction between the vortical flow and the control devices. The present work is part of the NATO STO/AVT Task Group AVT-201 on Stability and Control prediction methods

Numerical Investigation of the Aerodynamic Properties of a Flying Wing Configuration

The main objective of this study is to contribute towards a more comprehensive understanding of the vortex dominated flow over the DLR-F17E configuration with varying leading edge radii as part of the DLR UCAV2010 project. The vortical flow over sharp edges delta wings is mainly understood though the need has arisen to further extend the knowledge about the vortex system behaviour over blunt edged delta wings. This work aims to determine the effect of Reynolds number and Mach number variation over the DLR-F17E configuration. For the numerical investigation the DLR flow solver TAU, solving for the compressible, three-dimensional, time-accurate Reynolds-Averaged Navier-Stokes equations, is used. The configuration was meshed using the unstructured-hybrid grid generator Centaur. Experimental data on the SACCON in the NWB Braunschweig, gathered prior to this work, serves as comparative data for the numerical outcomes. For low Mach numbers at low angles of attack the numerical outcomes matched the experiment data quite well. However for higher angles of attack the flow solver failed to give a near real world representation of the vortex systems as observed during the experiment. With increasing angle of attack the tip vortex moves towards the apex and at high angles of attack a large high suction region over the entire wing is observed. Further it was found that with increasing Mach number the apex vortex gains in strength and the tip vortex moves towards the apex. The tip vortex develops to a huge outer vortex which introduces a high suction area initializing a nose down pitching moment of the configuration at M=0.4 up to M=0.6. The Reynolds number effect on the configuration was found to be minor. Though, it was possible to determine that the tip vortex gains in strength with increasing Reynolds number. Also the tip vortex slightly increased its size towards the trailing edge with increasing Reynolds number. Experimental investigations on the DLR-F17E model are currently being planned in order to compare these here conducted numerical results, as part of the FaUSST project. Furthermore numerical investigations using the cell-centered approach are being conducted.

Aerodynamics and Conceptual Design Studies on an Unmanned Combat Aerial Vehicle Configuration

The ability to accurately predict both static and dynamic stability characteristics of air vehicles using computational fluid dynamics methods could revolutionize the air vehicle design process, especially for military air vehicles. A validated computational fluid dynamics capability would significantly reduce the number of ground tests required to verify vehicle concepts and, in general, could eliminate costly vehicle “repair” campaigns required to fix performance anomalies that are not adequately predicted before full-scale vehicle development. This paper outlines the extended integrated experimental and numerical approach to assess the stability and control prediction method capabilities, as well as the design and estimation of the control device effectiveness, for highly swept low observable unmanned combat aerial vehicle configurations. The aim of the AVT-201 Task Group is to provide an assessment of the computational fluid dynamics capabilities using model-scale experiments and transfer this knowled...

The NATO STO AVT-201 Task Group on ExtendedAssessment of Stability and Control PredictionMethods for NATO Air Vehicles: Summary, Conclusions and Lessons Learned

This article presents cross-comparisons of the results obtained within the NATO STO AVT-201 Extended Assessment of Reliable Stability & Control Prediction Method for NATO Air and Sea Vehicles Task Group. The results of five participating organizations and six different CFD solvers are compared to the available wind tunnel data from the DNW-NWB wind tunnel obtained at low Mach number, for both static and dynamic cases. The comparisons help to find commonalities and disparities in the CFD predictions of the aerodynamics of a generic UCAV, SACCON, and point to areas where CFD is challenged by non-linear aerodynamics ow prediction. These comparisons help to show where the modeling and simulation of novel aircraft platforms in the earliest stages of design development can contribute to a more successful design process by determining diffcult non-linear aerodynamics and helping to change the design prior to the later stages of the design process.

Stability and Control Investigations of Generic 53 Degree Swept Wing with Control Surfaces

A contribution for the assessment of the static and dynamic aerodynamic behavior of a generic unmanned combat air vehicle configuration with control devices using computational fluid dynamics methods is given. For the study, various computational approaches have been used to predict stability and control parameters for aircraft undergoing nonlinear flight conditions. For the computational fluid dynamics simulations, three different computational fluid dynamics solvers are used: the unstructured grid-based solvers DLR TAU code and USM3D from NASA, as well as the structured grid-based National Aerospace Laboratory/NLR solver ENSOLV. The numerical methods are verified by experimental wind-tunnel data. The correlations with experimental data are made for static longitudinal/lateral sweeps and at varying frequencies of prescribed roll/pitch/yaw sinusoidal motions for the vehicle operating with and without control surface deflections. Furthermore, the investigations should support the understanding of the flow physics around the trailing-edge control devices of highly swept configurations with a vortex-dominated flowfield. Design requirements should be drawn by analyzing the interaction between the vortical flow and the control devices. The present work is part of the North Atlantic Treaty Organization’s Science and Technology Organization/ Applied Vehicle Technology Task Group AVT-201 on stability and control prediction methods´.

Extended Assessment of Stability and Control Prediction Methods for NATO Air Vehicles: Summary

This paper presents cross comparisons and assessments of the aerodynamic results obtained within the North Atlantic Treaty Organization’s Science and Technology Organisation Applied Vehicle Technology-201 Task Group. The results of five participating organizations and six different computational fluid dynamics solvers are compared to the available wind-tunnel data from the German–Dutch Wind Tunnels, and the results were obtained at low subsonic speeds for both static and dynamic cases. The comparisons help to find commonalities and disparities in the computational fluid dynamics predictions of the aerodynamics of a generic unmanned combat aerial vehicle (the stability and control configuration) and point to areas where computational fluid dynamics is challenged by nonlinear aerodynamics flow prediction. These comparisons help to show where the modeling and simulation of novel aircraft platforms in the earliest stages of design development can contribute to a more successful design process by determining difficult nonlinear aerodynamics and helping to change the design before the later stages of the design process.

Experimental and Numerical Investigation of Dynamic Derivatives of an UCAV Configuration

Within the AVT-161 Task Group ,,Assessment of Stability and Control Predictions for NATO Air and Sea Vehicles“ a generic UCAV configuration with rounded leading edges was examined. This configuration is also considered in the DLR internal project UCAV-2010 and is still a challenge in the successor DLR project FaUSST. This paper will give an overview of the main objectives and responsibilities of these projects. Focus is the ability to accurately predict both static and dynamic stability characteristics of UCAV configurations using experimental and computational fluid dynamics (CFD) methods. In order to create a S&C databases for such a configuration it is also necessary to have information about the deflection of control surfaces and its impact on the flight dynamic behaviour. Therefore different wind tunnel models for several wind tunnels and flight conditions are considered and should also be part of the future RTO/AVT-201 activities. In case of slender configurations, incorporating vortical flow and high angles of attack, linear mathematical models for the data evaluation may be insufficient to describe the effects properly and non-linear mathematical models should be employed. Preliminary investigations are done to asses the accuracy of the linear models and the range of application.