A Parabolised Navier-Stokes (PNS) flow solver is used to predict the aerodynamic heating on the surface of a hypersonic vehicle. This case study highlights some of the main heat flux sensitivies to various conditions for a full-scale vehicle and illustrates the use of different complimentary methods in assessing the heat load for a realistic application. Different flight phases of the vehicle are considered, with freestream conditions from Mach 4 to Mach 8 across a range of altitudes. Both laminar and turbulent flows are studied, together with the effect of the isothermal wall temperature, boundary-layer transition location and body incidence. The effect of the Spalart-Allmaras and Baldwin-Lomax turbulent models on the heat transfer distributions is assessed. A rigorous assessment of the computations is conducted through both iterative and grid convergence studies and a supporting experimental investigation is performed on a 1/20th scale model of the vehicle’s forebody for the validation of the numerical results. Good agreement is found between the PNS predictions, measurements and empirical methods for the vehicle forebody. The present PNS approach is shown to provide useful predictions of the heat transfer over the axisymmetric vehicle body. A highly complex flow field is predicted in the fin-body-fin region at the rear of the vehicle characterised by strong interference effects which limit the predictions over this region to a predominately qualitative level.

This paper presents the design and implementation of a vision-based automatic guidance system on a fixed-wing unmanned aerial vehicle (UAV). The system utilises a low-cost ordinary video camera and simple but efficient image processing techniques widely used in computer-vision technology. The paper focuses on the identification and extraction of geographical tracks such as rivers, coastlines, and roads from real-time aerial images. The image processing algorithm primarily uses colour properties to isolate the geographical track of interest from its background. Hough transform is eventually used to curve-fit the profile of the track which yields a reference line on the image plane. A guidance algorithm is then derived based on this information. In order to test the vision-based automatic guidance system in the laboratory without actually flying the UAV, a hardware-in-the-loop simulation system is developed. Description regarding the system and significant simulation result are presented in the paper. Finally, an actual test flight where the UAV successfully follows a stretch of a river under automatic vision-based guidance is also presented and discussed.

Free-form deformation (FFD) is a method first introduced within the graphics industry to enable flexible deformation of geometric models. FFD uses an R3 to R3 mapping of a deformable space to the global Cartesian space to produce the geometry deformation. This method has been extensively used within the design optimisation field as a shape parameterisation technique. Typically it has been used to parameterise analysis meshes, where new design geometries are produced by deforming the original mesh. This method allows a concise set of design variables to be used while maintaining a flexible shape representation. However, if a computer aided design (CAD) model of the resulting geometry is required, reverse engineering techniques would need to be utilised to recreate the model from the deformed mesh. This paper extends the use of FFD within an optimisation routine by using FFD to directly parameterise a CAD geometry. Two methods of linking the FFD methods with the CATIA V5 CAD package are presented. Each CAD integration technique is then critiqued with respect to shape optimisation. Finally the set-up and initialisation of a case study is illustrated. The case study chosen is the aerodynamic optimisation of the wing-fuselage junction of a typical passenger aircraft.

Aero engine designs can have a life time of over 45 years, which is long enough for the understanding of environmental problems to change significantly. This places the aero engine designer in a position of uncertainty, as unforeseen environmental problems could affect the viability of a design. ‘Risk’ is used to describe future uncertainties that can lead to undesirable consequences. This paper presents a framework for environmental risk management that allows the designer to answer the question: what is the risk to a design from its environmental impacts over the life cycle? The framework provides a process for turning complex environmental business hazards into a form that can be used to develop mitigating actions within the design process. The paper demonstrates the framework through two examples and discusses findings, leading to conclusions on what is required to implement the framework into a business.

A method to predict the effects of rotor icing on the flight characteristics of a UH-60A helicopter is presented. By considering both natural ice shedding and different types of ice accretion due to local temperature variations on the blade surface, an improved rotor icing model was developed. Next, the effects of icing on rotor force, torque and flapping were incorporated in a nonlinear helicopter dynamic model. Based upon icing design envelopes in cumuliform clouds, trim and stability characteristics were studied. Further development of the helicopter state-space model allowed control and handling qualities characteristics to be investigated with variation of the three icing-related cloud variables (atmospheric temperature, liquid water content, and median volumetric diameter). Results indicated that this method of evaluating rotorcraft icing is both feasible and useful.