Adrian Dica and Derek F. Allsop
An analysis of the forces acting on the SA80 assault rifle during firing was undertaken to investigate barrel rotation whilst the bullet was travelling in the barrel. Bullet displacement and velocity from initial movement to the point when the bullet left the barrel were first calculated. Two separate numerical methods were used to calculate barrel angular displacement and angular velocity against time caused by the propellant pressure acting on the breech face and the angular acceleration of the bullet. The two different methods gave good agreement, giving a barrel angular displacement of 0.066rad and an angular velocity of 3.75 x 10-4 rad/s respectively.
David J. Purdy
Improvements in the Stabilisation Ratio (SR) of current Main Battle Tanks (MBTs) are due to the use of hull disturbance feedforward. For the predicted im1provements to be realised, it is shown that the effects of non-linear friction must be compensated for. Simulations of a linear and non-linear Weapon Control System (WCS) are used to show the benefits of hull disturbance feedforward and the necessity to cancel out the effects of real friction in the non-linear case.
Amer Hameed, Robert D. Brown, and John G. Hetherington
This paper compares the external expansion of a thick-walled test cylinder manufactured from EN1A free-cutting, mild steel, when subjected to an internal pressure with that of a simulated autofrettaged thick-walled cylinder cross-section, using finite element (FE) analysis. The results produced by FE are also compared with the conventional approach used for evaluating external strain in a thick-walled cylinder. This paper assumes kinematic material hardening (bilinear and multilinear) characteristics with Bauschinger effect. Comparison of results shows that those results produced by FE analysis are in good agreement with experimental results. The paper also highlights the appearance of Luder's band (stretch marks) on a thick-walled cylinder, due to plastic yielding.
Harald Naunheimer
The drive system in tracked vehicles has to accomplish tasks which go far beyond the usual requirement of wheeled vehicles. Besides forward and backward propulsion and other tasks, it also assumes the safety-related functions of braking and steering. New studies investigating electrical transmission systems were started a few years ago [1]. One result of this work was the development of the RENK Electro-Mechanical Transmission (EMT). This transmission belongs to the category of electric drives and offers specific advantages. Because of its few mechanical parts the EMT provides significant reductions in the power requirements of the electric motors and corresponding power electronics compared with 'purely' electric sprocket drive systems. This paper describes the basic ideas and the technology of the electro-mechanical transmission RENK EMT for future tracked vehicles.
David J. Swann
Emerging defence systems need to be able to exploit terrain in the form of digital geographic information. The component of defence systems that will perform this critical role is the geographic information system (GIS). The implementation of GIS poses many challenges for system developers and this paper aims to expose some of the most important issues that must be addressed. Three issues are raised as typifying the complexities of GIS. The need for compromise between speed, functionality and openness in a GIS implementation is identified. The need for, and complexities of, geographic data management are discussed and finally the need for organisational change is proposed. The paper concludes by briefly examining the reasons why some defence systems continue to be planned without GIS services despite all the arguments that this is not a sensible approach.
Bruce McClure and Iain Macleod
Ready information flow is critical to the success of military operations — commanders need up-to-date information to make sound plans, which must be communicated without delay to relevant forces. Adequate communications bandwidth for these functions is normally available within and between fixed headquarters, but future deployable headquarters will have to operate using a variety of communications channels ranging from HF radio to satellite links. Such channels are characterised by widely varying latencies, error rates and bandwidths, with lack of available bandwidth the most prevalent constraint. Any problems here are compounded by a need to exchange information across levels of command and to operate in a hostile environment. Current C3I systems, their constituent COTS products and supporting communications infrastructures have a very limited ability to adapt co-operatively to changing network conditions. We propose an approach that integrates application, system and network policy expressions with the aim of facilitating the best outcome in terms of military objectives given orders of magnitude variation in network Quality of Service.
Merfyn A. Lloyd
This paper attempts from first principles to establish some of the information flows and processes within the battlegroup. As a start point, it takes the current iteration of British Military Doctrine with its manoeuverist approach to warfighting and the consequent need for Mission Command. Using a Soft Systems approach to the analysis, a Root Definition of the battlegroup is derived which serves as the basis for discussion. It treats the battlegroup as a system, sitting within a wider system and itself made up of a number of similar and easily defined sub-systems. The flows between these can be related to the Areas of Interest, Operation and Influence and show that knowing the Origin, Location and Time of the information can be used to identify its relevance to a particular system.
John Kearney
System dynamics (SD) modelling has been successfully applied in many commercial scenarios. This brief paper reports on recent successful applications of SD in strategic planning and management of defence weapon systems and in particular combat radios. The application of SD has generated shared understanding and allowed tailored logistics to be provided more cost effectively. Case studies illustrate the application of SD in defence.
