D. Boisson, M.G. Légeret, and R. Cayzac
The MECCAD code has been developed within Giat Industries to predict the heating and the cooling of a gun barrel during a burst. When the projectile moves in the barrel we calculate the convective parietal heat flux by using the Reynolds-Colburn analogy. After the projectile exit, the discharge of the propellant gas in the barrel is modelled with enough accuracy to respect the physics of the phenomena. The main difficulty is to predict the inner flow when the muzzle conditions are subsonic. The results allowed determination of the parameters of the expansion laws, which were used as the inputs of the cooling convective and radiative heat exchange laws. Thus, it is possible to calculate the initial barrel temperature just before a new firing. 120-mm gun calculations with MECCAD code were carried out for one shot with Armour Piercing Fin Stabilized Discarding Sabot (APFS-DS). The comparison with parietal temperature measurements shows a good agreement (especially near the forcing cone).
Amer Hameed, Robert D. Brown, and John G. Hetherington
There is great interest in the design and manufacture of lightweight weapon platforms that have capabilities near to existing heavy armour systems. This quest initially started with the requirement to transport field artillery guns via helicopter. With the change in the global situation, the threat has changed and new enemies have developed. This has given birth to rapid deployment forces capable of being effective in a short time. Naturally this force has to be highly mobile (fly light), with its direct-fire weapon platform being able to be delivered to the theatre of operations by C130 or A400 type aircraft. This has imposed serious limitations on the overall weight of a piece of equipment, limiting it to 17–25 tonnes. On the other hand, it is desired that the firepower of this platform matches existing systems. The aim of this paper is to look at some existing guns, having a bore sizes in the region of 105–140 mm, and their mounting on a light platform (17–25 tonnes). Work reported here concentrates on highlighting some of the important constraints that exist and possible ways of dealing with them.
P.G. Gilby, S.P. Stockley, J.A.K. Walker and C.R. Walters
UK military command and control infrastructure is undergoing significant change due to the deployment of systems such as Bowman, introducing a network-enabled capability to support command. This paper reviews how other organisations operate in a networked environment, taking two comparators, one civilian and one military. The civilian comparator was the UK-based motoring organisation, the Royal Automobile Club (RAC), which supports its emergency rescue activities with a Customer Management System, comprising a Microsoft Access database that structures each emergency call and provides an automated response, the aim being to use resources efficiently whilst minimising response time. The military organisation was that of the French Army who have developed their digitised capability incrementally over a period of 20 years. Although there are major differences between RAC and the French military in mission and role, both have incorporated into their command structure a bespoke Information and Communication System (ICS), with resultant benefits in situational awareness, and fast and effective response. The advent of the UK Defence Information Infrastructure (DII) should provide these same benefits and more when it is fully implemented.
Mubarak Al-Jaberi, Mark Richardson, John Coath, and Robin Jenkin
Laser-assisted weapons, such as laser-guided bombs, laser-guided missiles and laser-beamriding missiles pose a significant threat to military assets in the modern battlefield. Laser-beamriding missiles are particularly hard to detect because they use low-power lasers. They are even harder to defeat because current countermeasures are not designed to work against this threat [1]. The aim of this project is to examine the vulnerability of laser-warning systems to guided weapons, to build an evaluation tool for laser-warning receivers (LWRs) and seekers, and to identify suitable countermeasures for laser-beamriding missiles that use low-power lasers in their guidance systems. The project arose because of the unexpected results obtained from extensive field trials carried out on various LWRs in the United Arab Emirates desert, where severe weather conditions may be experienced. In order to approach the subject, a computer model has been developed to enable the assessment of all phases of a laser-warning receiver and missile seeker. MATLAB & SIMULINK software have been used to build the model. During this process experimentation and field trials have been carried out to verify the reliability of the model. This project enables both the evaluation and design of any generic laser-warning receiver or missile seeker and specific systems if various parameters are known. Moreover, this model will be used as a guide to the development of reliable countermeasures for laser-beamriding missiles. Part I of this series outlined the theory required to construct a computer model for a laser-beamriding missile engagement. This second part presents the implementation of the model using MATLAB and Simulink, the inputs required of the model, and the outputs generated. These results are analysed to determine the correct functionality of the model prior to its verification with laboratory-based experimental results and full-scale field trials (as presented in Part III).
D. Fraser, A.J. Lambert, and B.I. Craig
A new method for restoring images degraded by atmospheric turbulence where the resulting point spread function varies across the field of view is discussed. Such cases occur in horizontal imaging by telescope close to the ground, especially during daytime when convective turbulence is worst. Each image frame of a captured movie sequence is exposed for a time short enough to freeze the effects of the turbulence, resulting in a random wobble and blurring of the image that is position and time dependent. Registration of each frame to a reference image is achieved either by a moving region-of-interest correlation or by a gradient-based optical flow method. In this paper, we discuss a new method, replacing correlation by a moving region-of-interest Wiener filter that came from experiments visualising turbulence in jet plumes. The resulting shift information is used to dewarp each frame of the sequence before averaging to provide a result corrected for motion-blur. Further deblurring is carried out by a variety of deconvolution techniques. The shift or blur information can also be used to visualise the intervening atmospheric turbulence.
Amanda Jane Brosnan
In this paper, a variety of targeted sensitivity analysis approaches are explored for a Bayesian Belief Network (BBN) constructed as an expert tool for enemy course of action (COA) assessment at the tactical level in a conventional mid-intensity scenario. Robustness analysis is used to measure the level to which the posterior probability of the states at the root node are affected by instantiation of individual nodes in the network. Likewise, value of information analysis and gain in belief updating are used to compare how nodes of interest affect posterior probabilities at the root node, the former measuring Shannon Entropy and the latter Kullback Distance. Finally, sensor effectiveness analysis is used to measure how the reliability of reconnaissance and surveillance (R&S) assets affects updating of belief at the root node. It was found that each of the sensitivity analysis approaches could be used to optimise allocation of R&S, to identify the commander’s decision points, and to identify influential nodes for which the conditional probability tables (CPTs) should be refined. In terms of utility, it was concluded that, as in the case of the use of BBNs in the tactical COA assessment domain in general, the utility of sensitivity analysis of the BBN would be reduced in conditions of high operational tempo and myriad variables influencing tactical COA selection. Nevertheless, in a slower operational tempo environment, the benefits in refinement and utility of the BBN derived through sensitivity analysis would be significant.
