Commercial applications of flying wing aircraft, as the Flying-V here considered, can contribute to reducing carbon and nitrogen emissions produced by the aviation sector. However, because of the lack of a tail, all flying wing aircraft have reduced controllability. For this reason, the placement and sizing of the control surfaces along the wing is a non-trivial problem. The paper focuses on solving this problem using offline handling quality simulations based on certification requirements. In different flight conditions, the aircraft must be able to perform a certain set of maneuvers as defined by the certifying authorities. First, offline simulations calculate the minimum control authority required from the elevator, aileron, and rudder to perform each maneuver. Then, based on the global minimum for all maneuvers, the control surfaces are sized and placed along the wings. The aerodynamic model employed uses a combination of Reynolds-averaged Navier-Stokes (RANS) and vortex lattice method (VLM) simulations. The control authority of the control surfaces is estimated with VLM and VLM calibrated with RANS simulations, showing significant differences between the two.@en

The Flying-V is a novel flying wing aircraft design that aims to improve aerodynamic efficiency and fuel consumption. In recent years, there has been an increased effort to evaluate the handling qualities (HQs) of the Flying-V, and to develop new flight control strategies. One of the latest flight control designs for the Flying-V uses Incremental Nonlinear Dynamic Inversion (INDI) with a Flight Envelope Protection system. The purpose of this research is to validate this FCS design and its conclusions on handling qualities by conducting piloted experiments. To facilitate a sound comparison, the aerodynamic model, flight control structure, and airframe characteristics are taken as is from the existing study. For the experiment, numerous maneuvers are designed and carried out. The experiment is performed on the SIMONA Research Simulator of the Delft University of Technology, with three real-life test pilots as participants. The results show a significant correlation with offline findings and demonstrate the improvement in HQs provided by the flight control system.@en

The Flying-V emerges as a unique flying wing type commercial aircraft design, distinguished by its V-shaped configuration. For such unconventional airframes, flight control systems are vital for ensuring safety and enhancing flight performance. Current Flying-V control systems primarily use incremental nonlinear dynamic inversion (INDI), a sensor-based feedback linearization method requiring an onboard control effectiveness model. Although INDI handles model uncertainties, significant mismatches between actual and onboard models caused by damages or faults degrade performance and compromise flight safety. This study proposes an adaptive strategy for incremental nonlinear dynamic inversion, employing an online two-step method to estimate changes in the aircraft’s control effectiveness. Estimates are used to update the onboard control effectiveness model to minimize the mismatch between the actual and onboard representation of control effectiveness.@en

This research describes a near-optimal feedback guidance, based on nonlinear orbit control, for low-thrust Earth orbit transfers. Lyapunov stability theory leads to proving that although several equilibria exist, only the desired operational conditions are associated with a stable equilibrium. This ensures quasi-global asymptotic convergence toward the desired final orbit. The dynamical model includes the effect of eclipsing on the available thrust, as well as all the relevant orbit perturbations, such as several harmonics of the geopotential, solar radiation pressure, aerodynamic drag, and gravitational attraction due to the Sun and the Moon. Near-optimality of the feedback guidance comes from careful selection of the control gains. They are identified in two steps. Step (a) is an extensive table search in which the gains are changed in a large interval. Step (b) uses a numerical optimization algorithm that refines the gains found in (a), while minimizing the time of flight. For the numerical simulations, two scenarios are defined: (i) nominal conditions and (ii) nonnominal conditions, which arise from orbit injection errors and stochastic failures of the propulsion system. For case (i), gain optimization leads to obtaining numerical results very close to those corresponding to a known optimal orbit transfer with eclipse arcs. Moreover, for case (ii), extensive Monte Carlo simulations demonstrate that the nonlinear feedback guidance at hand is effective in driving a spacecraft from a low Earth orbit to a geostationary orbit, also in the presence of nonnominal flight conditions.@en

This research proposes a near-optimal feedback guidance based on nonlinear control for low-thrust Earth orbit transfers. For the numerical simulations, two flight conditions are defined: (i) nominal conditions and (ii) nonnominal conditions that account for the orbit injection errors and the stochastic failures of the propulsion system. Condition (ii) is studied through an extensive Monte Carlo Analysis, to demonstrate the nonlinear feedback guidance’s numerical stability andconvergence properties. To illustrate the performance under both conditions, an orbit transfer from low Earth orbit to geostationary orbit is considered. Near-optimality of the feedback guidance comes from carefully selecting the nonlinear control gains. Comparison of the transfer with an existing study that uses optimal control reveals that orbit transfers based on feedback orbit control are very close to the optimal solution.@en