Dimitrios N. Gkritzapis, Elias E. Panagiotopoulos, Dionissios P. Margaris, and Dimitrios G. Papanikas
This study investigates the effect of the aerodynamic jump phenomenon on the flat-fire free flight trajectory motion of projectiles launched horizontally at various angles from low-speed helicopters. The ammunition used was the 30-mm-diameter XM788 projectile type fired from M230 machine automatic cannon. Modified linear 6-DOF flight simulation modelling was applied to the free-trajectory prediction of spin-stabilized projectiles. This analysis includes variable coefficients of the most significant aerodynamic forces, moments, and Magnus effects, which have been taken from official tabulated database, in addition to gravity acceleration. During the entire atmospheric flight the coupled epicyclic pitching and yawing motion analysis is taken into account.
Nathan A. Minami and Donna H. Rhodes
The current revolution in military affairs is centred largely on the integration of new information technologies into traditional military command and control (C2) structures. While many military leaders report that new information “tools” such as the U.S. Army’s Battle Command System (ABCS) give them an unprecedented level of situational awareness, others assert that the integration of this new digital technology comes with some unintended consequences that in some cases actually slows information flow. We studied the brigade combat team (BCT) with specific emphasis on the brigade’s ability to disseminate and process information within and between command posts, using system dynamics as a modelling tool to help to understand better the impact of various policy decisions. Our study concluded with five heuristics that could potentially have profound implications for future C2 architectures.
M.P. Fewell, J.M. Thredgold, and D.J. Kershaw
This paper presents an initial quantitative analysis of the extent to which networking multiple-monostatic active sonar systems can improve performance in detecting submarines. The improvement mechanism explored is the sharing of data on detections, with tracking being performed centrally. Our analysis indicates the conditions under which the improvement should be present and provides an estimate of its magnitude. This is achieved by focusing on the step of centralised track initiation, using sonar coverage area as the metric. We identify situations where coverage area at the 95% level can be more than a factor of 10 larger with centralised tracking compared with tracking by individual sonars. This is achieved solely by sharing detections, without any other modifications to the submarine kill chain. The results show that a 30% detection probability (P ) can be tactically useful provided that there are other sonars with a similar P for the target of interest that share information on detections. This result may provide a practical way around the great and continuing difficulty of obtaining acceptably high P values at tactically significant
Peter Dobias
This paper presents several possible complexity-based measures of effectiveness (MOE) that address some of the limitations imposed by the use of attrition as a primary MOE in evaluating results of combat models. The considered measures are Shannon entropy (especially spatial entropy), fractal dimension, symmetropy, and the Hurst coefficient. Some of these measures have been used before (entropy, fractal dimension), others have not (symmetropy, Hurst coefficient). The suitability of the measures for the assessment of crowd confrontation operations (CCO) is discussed. CCOs are a prime example of a case in which attrition provides inadequate information. At the same time, crowds, due to their inherent complexity are an excellent test bed for the proposed measures. It is demonstrated that the complexity-based MOEs are effective in capturing the temporal dynamics of CCOs. Furthermore, the use of these MOEs allows for identification of emergent behaviours and patterns in the system dynamics. It is suggested that the changes in crowd dynamics due to the interaction with the law enforcement are consistent with phase transitions in critical systems, namely with a self-organized criticality.
Alan C. McLucas
Highly reliable software is critical to the operation of weapons systems and communications and information systems (CIS). In weapons systems, software enables the real-time calculation of the relative position of a weapon to its target and adjusts the trim of control surfaces in missiles. In CIS, software controls frequency synthesizers, electronic protection (EP) devices, antenna tuners and, as radios become more like computers, virtually any form of modulation can be synthesized through software. Military applications software needs to be highly reliable, and this brings specific demands for engineering of software systems and managing software development projects. Despite the growing body of knowledge in software engineering and project management, projects involving software development or integration frequently overrun cost and schedule estimates by factors typically of at least two. This is highly undesirable and results in severe criticism of acquisition managers and systems engineers alike. This paper examines what differentiates software development and integration from other complex projects. It is argued that much of what is taken for granted in terms of estimating activity durations is fundamentally flawed because many activities involve rework but they are not recognized as such. Rather, conventional planning and duration estimating consider these as being linear-sequential activities. The need for rework impacts upon almost every aspect of software projects. This demands that an alternative approach, one which recognizes many project activities as involving rework, is necessary to improve likelihood of successful project delivery, particularly as far as cost and schedule is concerned. Levels of rework required can be affected by the need to: build trust between those involved in the project, work iteratively through requirements development and effectiveness in identifying defects in early phases of the project. The need for seemingly indeterminate amounts of rework is examined.
