A key design factor impacting the use of electrical power to drive aircraft systems and subsystems is energy efficiency. With the design of an all-electric, hybrid ice protection system, energy consumption can be reduced to a large extent. The hybridization is achieved through an intentional partitioning of the ice at the stagnation line by melting via surface heating and ice shedding in the unheated regions of the airfoil surface via an electromechanical deicing system based on piezoelectric multilayer actuators. To further reduce energy consumption, the adhesion forces between the ice and the airfoil surface can be reduced using an ultrasmooth, nanostructured surface with water- and ice-repellent properties that encourages ice shedding. Experimental investigations, performed in a laboratory-scale icing wind tunnel for a small-scale configuration, reveal that the hybrid approach for ice protection reliably sheds the ice accreted on the airfoil surface. Compared with an all-thermoelectric system for ice protection investigated in the same icing wind tunnel facility using identical test conditions, the hybrid approach was demonstrated to reduce power consumption up to 91%. Beyond the laboratory tests, numerical simulations of the hybrid strategy analogous to the one used for the experiments are performed. The time history of the residual ice shapes aft of the heated region is simulated using the ice accretion prediction software LEWICE2D for a wet-running anti-icing subsystem. Finite element analyses of the effects of the piezoelectric actuators are then performed using Abaqus to investigate the ice-shedding capability in the unheated regions of the airfoil surface. The numerical results show that the variation in the different ice shapes affects the stiffness of the model. It becomes obvious that the critical threshold for ice shedding, that is, the stiffness that determines whether residual ice delaminates from the airfoil surface, is affected to a minor extent by the interfacial area and predominantly by the thickness of the ice layer. Further, the simulation results correlate well with experimental results obtained in the icing wind tunnel. It can be concluded that reliable operation of the hybrid system for ice shedding can be guaranteed when using a harmonic sweep excitation able to excite the structure at its resonance.

During early phases of aircraft development, overall systems design is performed to estimate relevant system design parameters such as mass, power consumption, and compliance with architectural requirements (redundancy). The GeneSys software framework has been developed for parametric modeling of aircraft on-board systems for overall systems design. To this end, model-based architecture definition, topology generation (components positioning and connections routing), and system sizing are conducted. The topology generation is currently performed using design templates containing knowledge-based heuristics derived from systems topologies of existing aircraft. However, using such design templates limits their generic application to novel aircraft models because exceptions for geometric differences between these models need to be implemented. This especially applies to the topology generation of power supply systems (electric, hydraulic) due to their high number of interfaces to consumer systems. To overcome these limitations, an automated routing method is presented in this paper as a generic approach for topology generation. With this method, the system topology is generated based on a defined routing network, which comprises areas of the aircraft for allowed components positioning and connections routing. Using Dijkstra’s algorithm, the shortest path connections are found within the established routing network. Furthermore, boundary conditions for routing, for instance adding a cost function for power segregation, can be defined. An assessment of the automated routing method applied on the electric power supply system is performed using qualitative parameters such as the capability to adapt the routing network. Quantitative parameters like cable length and system mass are assessed as well.

This paper presents the nonlinear system identification of a slightly flexible 25 kg fixed-wing UAV in the time-domain using a computationally efficient distributed aerodynamics model and a linear structural dynamics representation. The equations of motion are formed by making use of the free vibration modes of the structure and the mean axes formulation. The structural modes and mode shapes are determined from ground vibration tests. The distributed aerodynamics, accounting for elastic deformations, are modeled using a quasi-steady stability and control derivative approach and by applying strip theory. Initial distributions for the derivatives are obtained from vortex-lattice-method calculations. For matching the model response to the measured response, parameters for scaling the initial derivative distributions are introduced. The flexible model is subsequently identified based on flight test data using the output error method in the time-domain and maximum-likelihood estimation. A good overall identification result is achieved with a close match of the fast aircraft dynamics. Finally, an evaluation is given on the suitability of the identified model for real-time simulation, loads’ estimation, and active load control law design.

Integrated Modular Avionics (IMA) is a promising resource sharing concept in the avionics domain. It reduces weight and cost of current aircraft. Saving potentials rise with the evolution of IMA, e.g. distributed IMA (DIMA). However, the inherently rising number of functions and the technological degrees of freedom make the selection of the optimal DIMA architecture a complex task. Complexity can be reduced by supporting the IMA designer with solving subtasks of the design process as mathematical optimization problems. Important subtasks are the software and hardware mapping, i.e. for a given aircraft structure finding the optimal distribution of DIMA devices, and for a given hardware topology finding the optimal distribution of aircraft system functions. It is shown how to solve these problems as multi-objective mathematical programming problems for mass and cost objectives, whereby optimizer input is automatically derived from a DIMA architecture domain model. The proposed methods are demonstrated on a reference DIMA architecture consisting of several aircraft systems and a state-of-the-art DIMA platform, which has been constructed and optimized manually. Optimization results reveal major optimization potentials, all possible trade-offs, as well as correlations between objectives. In summary, a valuable support of the DIMA design process by multi-criteria optimization with a practical example is presented.

The aircraft design process is a complex task that requires the collaboration of disciplinary experts from various fields. In practice, this complexity requires a large investment in setting up communication interfaces for the exchange of disciplinary data, and serious misinterpretations are not uncommon. To increase the efficiency and robustness of data exchange, a common language is essential. As such, the Common Parametric Aircraft Configuration Schema (CPACS) serves as a central data model, which currently includes detailed parametrizations of aircraft geometry and analysis results from traditional disciplines (e.g., aerodynamics, structure, etc.). However, with the recent interest in alternative propulsion and complex on-board system architectures, CPACS is proving to be too limited to meet the needs of the various disciplinary system experts. The particular challenge here is to enable different views on the same systems, i.e., a functional/logical as well as a geometric/physical representation, without violating the principle of unambiguous data. Therefore, this paper proposes an extension of CPACS which introduces an explicit system definition covering both representations. Its potential is demonstrated by two use cases from disciplinary experts in the field of on-board system design at the Hamburg University of Technology (TUHH), based on data provided by aircraft design experts. Through validation against the experts’ needs, the proposed system definition proves to bridge the gap between preliminary aircraft design and on-board system design, enabling a holistic, robust and efficient aircraft design process.