No description available.

An experimental investigation into the effects of shock/wake and shock/flame interaction on the base pressure of axisymmetric bodies at Mach 2 has been carried out. This investigation has determined the effects of various forms of shock generator (axisymmetric cowls, twodimensional wedges and 'delta' wings) on the base pressure. Shock waves generated by over-expanding the airflow in an open-jet wind tunnel have been used to determine the effect of shock strength on the base pressure of an axisymmetric fuel injector. Both peripheral bleed and axial bleed of hydrogen fuel have been examined and the effect of shock compression on the resulting flame has been determined. In the axial bleed case nitrogen and hydrogen bleed without combustion has also been examined. The effect of varying the airflow stagnation temperature has also beeninvestigated. It is demonstrated herein that there is a distinct shock/wake interaction position that maximises the base pressure, that with interaction at this optimal position the static pressure rise across the shock wave can be communicated in full to the base of the centrebody, and that favourable aerodynamic interference between the wake and a cowl of 50 convergent-divergent internal section can give rise to a net drag reduction. The shock/wake and shock/flame experiments demonstrate that a significant base thrust can be generated, however, the fuel efficiency decreases with increasing shock strength. It is shown that the fuel specific impulse is a function of shock strength, interaction position and bleed mode (peripheral or axial). The onset of boundary layer separation due to the adverse pressure gradient encountered when the base pressure is high appears to limit the useful addition of wake combustion. Finally, it is demonstrated that the base pressure, with and without combustion, is only a weak function of airflow stagnation temperature.

No description available.

No description available.

No description available.

In the design of new, more sophisticated missile systems, simulations need to be realistic and fast. Realistic target models are just as important as realistic models of the missile, but have often been overlooked in the past. Existing methods for creating realistic target models require considerable computational resources. This thesis addresses the problem of using limited resources to create realistic target models for simulating engagements with radar guided homing missiles. A multiple genetic algorithm approach is presented for converting inverse synthetic aperture radar images of targets into scatterer models. The models produced are high fidelity and fast to process. Results are given that demonstrate the generation of a model from real data using a desktop computer. Realistic models are used to investigate the effects of target fidelity on the missile performance. The results of the investigation allow the model complexity to be traded against the fidelity of the representation to optimise simulation speed. Finally, a realistic target model is used in a feasibility study to investigate the potential use of glint for target manoeuvre detection. Target glint is considered as noise in conventional missile systems and filtered to reduce its effects on the tracking performance- The use of glint for target manoeuvre detection would provide a cheap and novel alternative to the optical techniques currently being developed. The feasibility study has shown that target manoeuvre detection using glint may be as fast as optical techniques and very reliable.

The main aim of the study is to document the development of US Fleet Ballistic Missile technology from its mid-1950s beginnings through to Trident II D5. This historical documentation is framed by a perspective which seeks to understand how technology evolves and what the relationship is between, to put it simply, technology and strategy, or technology and politics. Of particular interest in this case study is the relationship between technology and nuclear strategy. It is a commonplace assertion that technology is a dominant, determining factor in the arms race, that indeed there is a technological imperative. In particular there are many who argue that improvements in missile accuracies have driven changes in nuclear strategy away from counter-city retaliatory deterrence to war-fighting counter-force postures. Tracing the history of FBM development from Polaris, considered by many the archetypal counter-city deterrent, to Trident II, with hard-target kill capability comparable to MX, helps our understanding of this issue. In considering this central theme, the development of FBM technology is analysed in the social constructionist terms of the 'new' sociology of technology. This approach argues that technical change must be explained impartially and symmetrically, and that the success of a particular technology is not sufficient explanation in itself, but is rather exactly what needs to be explained. Technology is considered to be underdetermined by the physical world, and thus to be fundamentally shaped by the social world. The extreme characterizations of the relationship between technology and politics - either that technology is simply the tool of political will or that technology is out-of-control (as in the view that accuracy improvements have driven strategy) - are found to be inadequate in this study. Instead it is found that the 'bureaucratic politics' approach captures much of the rich complexity of the process of technological change. Yet even this approach fails fully to capture the complex inter-relatedness of 'technology' and 'politics', nor does it take into account the importance of the physical production of technology.

When considering advances in “smart” weapons it is clear that air-launched systems have adopted an integrated approach to meet rigorous requirements, whereas air-defence systems have not. The demands on sensors, state observation, missile guidance, and simulation for air-defence is the subject of this research. Historical reviews for each topic, justification of favoured techniques and algorithms are provided, using a nomenclature developed to unify these disciplines. Sensors selected for their enduring impact on future systems are described and simulation models provided. Complex internal systems are reduced to simpler models capable of replicating dominant features, particularly those that adversely effect state observers. Of the state observer architectures considered, a distributed system comprising ground based target and own-missile tracking, data up-link, and on-board missile measurement and track fusion is the natural choice for air-defence. An IMM is used to process radar measurements, combining the estimates from filters with different target dynamics. The remote missile state observer combines up-linked target tracks and missile plots with IMU and seeker data to provide optimal guidance information. The performance of traditional PN and CLOS missile guidance is the basis against which on-line trajectory optimisation is judged. Enhanced guidance laws are presented that demand more from the state observers, stressing the importance of time-to-go and transport delays in strap-down systems employing staring array technology. Algorithms for solving the guidance twopoint boundary value problems created from the missile state observer output using gradient projection in function space are presented. A simulation integrating these aspects was developed whose infrastructure, capable of supporting any dynamical model, is described in the air-defence context. MBDA have extended this work creating the Aircraft and Missile Integration Simulation (AMIS) for integrating different launchers and missiles. The maturity of the AMIS makes it a tool for developing pre-launch algorithms for modern air-launched missiles from modern military aircraft.