Handling qualities are expressed as requirements at the interface of the pilot and the machine. In this way, the key functionality questions facing the design engineer are seen from the perspective of the interaction of the human pilot with the aircraft system and the environment in which it operates. In this paper, the author takes a ‘virtual engineering’ approach to handling qualities, emphasising the importance of conducting ‘requirements capture’ and preliminary design as an iterative process. When stretched capabilities are required, this approach minimises the risk to finding appropriate technology solutions, through developing explicit relationships between capability and design parameters, thus facilitating fully informed trade studies and predictions. Case studies from the development of a civil tiltrotor aircraft are presented that show how the difficult challenges facing the designer first need to be structured in terms of HQ predictions and assignments. This then provides the basis on which handling qualities improvements can be constructed within the multidisciplinary context of rotorcraft engineering.

This paper shows the advantages of applying exergy-based analysis and optimisation methods to the synthesis/design and operation of aircraft systems. In particular, an Advanced Aircraft Fighter (AAF) with three subsystems: a Propulsion Subsystem (PS), an Environmental Control Subsystem (ECS), and an Airframe Subsystem – Aerodynamics (AFS-A) is used to illustrate these advantages. Thermodynamic (both energy and exergy based), aerodynamic, geometric, and physical models of the components comprising the subsystems are developed and their interactions defined. Off-design performance is considered as well and is used in the analysis and optimisation of system synthesis/design and operation as the aircraft is flown over an entire mission.

An exergy-based parametric study of the PS and its components is first presented in order to show the type of detailed information on internal system losses which an exergy analysis can provide and an energy analysis by its very nature is unable to provide. This is followed by a series of constrained, system synthesis/design optimisations based on five different objective functions, which define energy-based and exergy-based measures of performance. The former involve minimising the gross takeoff weight or maximising the thrust efficiency while the latter involve minimising the rates of exergy destruction plus the rate of exergy fuel loss (with and without AFS-A losses) or maximising the thermodynamic effectiveness.

A first set of optimisations involving four of the objectives (two energy-based and two exergy-based) are performed with only PS and ECS degrees of freedom. Losses for the AFS-A are not incorporated into the two exergy-based objectives. The results show that as expected all four objectives globally produce the same optimum vehicle. A second set of optimisations is then performed with AFS-A degrees of freedom and again with two energy- and exergy-based objectives. However, this time one of the exergy-based objectives incorporates AFS-A losses directly into the objective. The results are that with this latter objective, a significantly better optimum vehicle is produced. Thus, an exergy-based approach is not only able to pinpoint where the greatest inefficiencies in the system occur but appears at least in this case to produce a superior optimum vehicle as well by accounting for irreversibility losses in subsystems (e.g., the AFS-A) only indirectly tied to fuel usage.

The objective of this work is to make an overview of opportunities and issues related to the aeronautical application of solid oxide fuel cell hybrid systems. The great interest on fuel cells comes from their capacity of producing electric energy with high efficiency at low pollutant production. The application of these systems as full-time auxiliary power units is an interesting alternative in a future scenario, which is supposed to include a More Electric Aircraft and more restrictive environmental standards. A review of the technological aspects of this application is presented. The physical models found in literature were investigated and the results were compared and discussed.

A recently developed transitional model for boundary-layer flows has been examined on a flat plate and the well-known S809 wind turbine blade. Proposed numerical model tries to simulate streamwise fluctuations, induced by freestream turbulence, in pre-transitional boundary-layer flows by introducing an additional transport equation for laminar kinetic energy term. This new approach can be used for modeling of transitional flows which are exposed to both the freestream turbulence intensity and streamwise pressure gradient, which are known as the most dominant factors in occurrence of transition. Computational method of this model is based on the solution of the Reynolds averaged Navier-Stokes (RANS) equations and the eddy-viscosity concept. The model includes three transport equations of laminar kinetic energy, turbulent kinetic energy and dissipation rate frequency. The present model is capable of predicting either natural or bypass transitional mechanisms, which may occur in attached boundary-layer flows. In addition, the model can simulate transition in the separated free shear layers and the subsequent turbulent re-attachment to form a laminar separation bubble. Flat plate was exposed to different freestream turbulence intensities and streamwise pressure gradients. Wind turbine blade was examined under two different Reynolds numbers, with one of them suitable for the occurrence of laminar separation bubbles on its surfaces. To evaluate the performance of this new model in resolving transitional boundary-layer flows, final results have been compared to those obtained through application of conventional turbulence models. Comparison of final results for the flat plate and the S809 aerofoil with available experimental data show very close agreements.

Current and future Air Force weapons systems lack the necessary power and cooling capacity to provide full systems level capability as a result of energy and thermal management limitations. Cooling capacity of fuel is already fully utilised leaving little room for additional cooling needs. Additionally, increasing speed, power, and miniaturisation of future systems continue to stress any thermal management capability that we can now deliver. Thus, the focus of this paper is a conceptual assessment of the key energy and thermal management technologies to meet the future energy challenges. It presents an overview of the current state of the art and also possible future research.

Trailing edge blowing over a Coanda surface has been utilised as a circulation control mechanism for increasing the lift of an aircraft wing. Typically, high energy air is blown from a narrow spanwise slot over the rounded trailing edge of a wing and the air supply is modulated to effect a degree of lift control on the wing. This configuration produces an aerodynamic force in a uni-directional sense only. An alternative novel flow control actuator is described which utilises a simple variable geometry Coanda surface with upper and lower spanwise blowing slots to achieve fully proportional bi-directional control in the manner of a conventional flap. A prototype device has been wind-tunnel tested and is shown to have substantially linear response characteristics and to be as efficient as an equivalent flap surface. The performance of a flow control actuator suitable for small UAV applications is described.