Numerical investigation of dynamic interaction with projectile and harmonic behaviour for T-finned machine gun barrels

Machine gun barrels differ from their rifle counterparts in terms of profile. To support high rates of sustained fire, machine gun barrels are made thicker in order to dissipate more heat and maintain their flexural rigidity and thus accuracy, but on other hand they also contribute in weight addition to weapon. This investigation deals with comparison between a conventional machine gun barrel and an improved innovative design having T-fins, both having same weight and chambered in 5.56 × 45 NATO ammunition, to compare their structural and harmonic characteristics which were parameterized by factors such as modal spectrum, directional deformation at muzzle ends during a single shot fire and harmonic behaviour at corresponding range of exciting frequencies. The solid models of both the barrels having same weight, were created using Solidworks. The continuous input data functions were generated by MATLAB using the field tested discreet data points. The generated velocity-distance functions were converted into time dependent functions using integration algorithms to calculate transient parameters such as time steps, excitation frequency range, angle of rotation of projectile and its angular velocity. The dynamic condition simulated the varying nature of forces due to eccentricity in projectile and this data was fed to a time step study using ANSYS transient structural work bench followed by modal and harmonic analysis. The results showed a significant reduction in muzzle end deformation which thus proved that the T-finned barrel, although had same weight as that of the conventional one, but had better structural and harmonic characteristics, and hence it would inherit better firing accuracy.     

线膛火炮烧蚀弹道解法

以烧蚀火炮的阳线磨损曲线和一种挤进压力计算方法为基础 ,建立了考虑弹带挤进过程的内弹道模型。该模型可对不同磨损程度的火炮进行内弹道计算 ,能够较好地反映火炮内弹道性能随内膛磨损程度不同而变化的特征。     

舰用火炮对抗攻击过程的模拟与仿真

海上实兵环境下的舰炮对抗攻击训练,因发射实弹易造成误伤,一直被认为是难以实现的训练科目。而我系研制的舰炮对抗攻击模拟仿真系统,有效地将多种技术综合应用,创造了接近实战的训练环境;通过采用模拟交战的方法,较好地解决了上述问题。本文就该系统的组成结构、仿真过程与技术特点等问题进行了全面的介绍,并对模拟仿真训练系统的进一步发展提出了看法。     

枪械机构故障可靠性分析方法研究

介绍枪械机构组成、机构动作和作用,利用可靠性故障分析法中常用的FMECA分析法和FTA分析法对枪械机构产生的故障进行定性分析,并通过某典型自动步枪可靠性试验数据进行统计分析,找出枪械机构动作的主要故障,设计出FMECA分析表和FTA故障树．通过以上分析,提出一些对枪械机构的设计要求．     

枪械产品可靠性建模方法研究

选择适当的建模方法, 并在分析枪械产品可靠性试验特点的基础上提出了相应的假设, 讨论了确定具体模型类型的方法及不同类型数据的参数估计和检验手段。借鉴电子产品可靠性建模方法提出了针对枪械产品可靠性模型的建立步骤, 并结合某型自动步枪寿命试验数据给出计算实例。     

BUTTER,GUNS AND ICE‐CREAM THEORY AND EVIDENCE FROM SUB‐SAHARAN AFRICA

This paper is intended to complement the existing literature on civil wars. First, it presents a simple theoretical model of conflict that defines a two‐sector economy. In a contested sector, two agents struggle to appropriate the maximum possible fraction of a contestable output. In an uncontested sector, they hold secure property rights over the production of some goods. Agents split their resource endowment between ‘butter’, ‘guns’ and ‘ice‐cream’. Following the theoretical insights the empirical analysis focuses on the relationship between civil wars and different sectors of the economy. In particular, a panel probit specification shows that the incidence of a civil war decreases in the size of manufacturing sector.     

The Tower of London and Firearms in the Reign of Edward IV

Little attention has been paid by historians to the production of firearms in the Tower of London in the fifteenth century before the reign of Henry VII. This is due to the lack of surviving records for the office of the ordnance prior to the 1490s. The discovery of the earliest surviving set of accounts by a Master of the Ordnance based at the Tower, however, means that it is now possible to examine the manufacture and refurbishment of guns at the Tower in the early 1470s. This evidence demonstrates that Edward IV was responsible for the re-establishment of the Tower as the principle facility for the production and storage of firearms in England, which laid important foundations that his Tudor successors built upon.     

大口径牵引火炮海绵轮胎改装充气轮胎稳定性研究

以某型大口径牵引火炮为例,通过机动性验证,射击稳定性试验和计算机模拟仿真,对海绵轮胎改装充气式轮胎后的火炮稳定性进行分析。结果表明,改装后,火炮能够保持良好的稳定性,大幅提高装备的机动能力,为大口径牵引火炮海绵轮胎改装充气轮胎提供参考。     

新型炮瞄火控雷达训练模拟器

雷达训练模拟器是适应现代战争条件而诞生的一种新型防空兵训练设备.从系统的角度介绍了一种新型炮瞄火控雷达训练模拟器的设计思想、结构、功能和特点,分析了模拟器的关键技术.该模拟器解决了雷达目标的实时生成、控制、搜索和显示等关键问题,新增了电子干扰与反干扰的训练内容,完整实现了战场环境下的炮瞄雷达攻防对抗训练.目前,该系统已成功应用于部队训练,获得了良好的应用效果.     

The Practice and Power of Firing Broadsides in British Men of War During the Age of Fighting Sail

The development of naval broadside tactics and practice is discussed. The technology of smooth bore ordnance is examined, with an account of naval gunfiring trials. The fundamental purpose of gunnery at sea — damage to ship structure and casualties sufficient to disable an enemy ship — is reviewed.