In this paper, in-flight remote sensing technologies are considered for two applications: active load alleviation of gust and turbulence and wake impact alleviation. The paper outlines the strong commonalities in terms of sensors and measurement post-processing algorithms and presents also the few differences and their consequences in terms of postprocessing. The way the post-processing is being made is detailed before showing results for both applications based on a complete and coupled simulation (aircraft reaction due to disturbances and control inputs during the simulation is influencing the sensor measurements). The performances in terms of wind reconstruction quality for the gust/turbulence case and in terms of wake impact alleviation performance for the wake vortex case are shown based on simulations and are very promising.

A flying wing configuration with highly swept leading edges and low aspect ratio such as the generic UCAV configuration DLR-F19 is very attractive for military applications due to its very favorable stealth capabilities as well as its high agility. To assure good flying qualities, however, is a critical aspect for such a configuration. It should thus be considered early in the design process. This paper presents an innovative way to derive a flight dynamics model from wind tunnel experiments by applying a system identification approach, normally employed for flight tests. This allows the modelling of nonlinear aerodynamic effects and provides a model which can be integrated directly into flight dynamics simulations. New wind tunnel maneuvers are applied, which significantly reduce the time of the wind tunnel experiments and improve the quality of the aerodynamic dataset generation. The aerodynamic model is then integrated into a 6-degreesof-freedom simulation environment in order to perform a flight dynamics analysis of the UCAV configuration. The purpose of this analysis is to compare the flying qualities as derived from wind tunnel data with the numerical results determined on the basis of potential flow methods used in preliminary aircraft design. Keywords system identification, parameter estimation, flying qualities analysis, wind tunnel experiment, aerodynamic modelling, UCAV LIST OF SYMBOLS α angle of attack, [°] α* angle of attack where half of airflow is detached, [°] β angle of sideslip, [°] Δα angle of attack difference between current and next breakpoint, [°] ΔC i j delta coefficient of the force or moment i, whose strongest influence is parameter j, [-] Δti equivalent time delay of parameter i, [s] Φ bank angle, [°] Φt critical bank angle for roll performance, [°] ω0 natural frequency, [rad/s] a1 reduction in slope of the lift curve, [-] Bp breakpoint, [-] Ci coefficient of force or moment i, [-] Ci0 basic coefficient of force or moment i, [-] Cij non-dimensional derivative of force or moment i with respect to j, [-] Cijα angle-of-attack-dependent non-dimensional derivative of force or moment i with respect to parameter j, [-] CDX, CmX hysteresis influence factor on drag and pitching moment, [-] D damping ratio, [-] FvD vortex drag factor, [-] f0 model oscillation frequency, [Hz] fs sampling frequency, [Hz] g gravity constant, [m/s²] Ixx,Iyy,Izz moment of inertia in x/y/z-axis, [kg m²] L, D, Y aerodynamic lift, drag and side force [N] L β , N β dimensional roll moment derivative with respect to sideslip angle, [1/s²] LIB left inboard control surface, [°] LOB left outboard control surface, [°] l, m, n aerodynamic moments, [N m] N r dimensional yaw moment derivative with respect to roll rate, [1/s] nz vertical load factor, [-] p, q, r roll rate, pitch rate, yaw rate, [rad/s] V velocity [m/s] RIB right inboard control surface, [°] ROB right outboard control surface, [°] SP20 split flap with 20 % chord depth, [°] SP25 split flap with 25 % chord depth, [°] T2 time to double amplitude, [s] t time, [s] X non...

Wake vortices are an inevitable result of lift generation and can pose a threat to any aircraft, which accidentally encounters the wake of another aircraft. However, wake vortices can also be used in a beneficial way. Due to its rotational direction, the air flows upwards outside of the vortex pair, giving additional energy to any aircraft located in these regions. This method to save energy is used by migratory birds, resulting in these birds flying in the typical V-formations. This study deals with the question, whether it is possible with a standard autopilot (without a dedicated formation flight mode) to keep the aircraft's position accurately at a desired position in the wake flow field without accidentally encountering those areas of the wake where steady-state-flight is impossible, even in the presence of atmospheric disturbances (e.g. turbulence) and fluctuating vortex core positions. For this purpose, simulations were performed applying threedimensional flowfields generated with large eddy simulations (LES). Here, even with young vortices the target _____________________________________________

Flight training simulators have a limited capability to replicate aircraft motion cues because the space envelope of current motion systems impedes a better fidelity and urges the user to make sometimes painful compromises. Therefore, it is all the more important to use the given space envelope as well as possible. But this trivial consideration yields an answer to the question what "good" means and therefore what strategy shall to be pursued by a control algorithm. For the Apparent Vertical Filter (AVF) this means that the amount and direction of the force combined with the corresponding rotational velocity shall be met as long as the given space envelope allows that approach. If this is not possible anymore the direction of the specific force shall be reproduced correctly. Only if both, the rotational and the translational cueing cannot be achieved a decision must be made. This is the case e.g. for the side force during a taxi turn on ground. During such maneuvers a compromise needs to be found between a correct specific force and a limited rotational velocity of the simulator. Within this paper the working principle of the Apparent Vertical Filter will be discussed for a taxi turn on ground maneuver. Furthermore, it will give a general overview of the AVF response to lateral maneuvers in general. Finally, it presents the results for the lateral tests of the Objective Motion Cueing Test (OMCT) showing that, in general, the AVF is able to meet the requirements of the test.

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