Modelling and simulation of projectile flight is at the core of ballistic computer software and is essential to the study of performance of rifles and projectiles in various engagement conditions.An effective and repr...Modelling and simulation of projectile flight is at the core of ballistic computer software and is essential to the study of performance of rifles and projectiles in various engagement conditions.An effective and representative numerical model of projectile flight requires a relatively good approximation of the aerodynamics.The aerodynamic coefficients of the projectile model should be described as a series of piecewise polynomial functions of the Mach number that ideally meet the following conditions:they are continuous,differentiable at least once,and have a relatively low degree.The paper provides the steps needed to generate such piecewise polynomial functions using readily available tools,and then compares Piecewise Cubic Hermite Interpolating Polynomial(PCHIP),cubic splines,and piecewise linear functions,and their variant,as potential curve fitting methods to approximate the aerodynamics of a generic small arms projectile.A key contribution of the paper is the application of PCHIP to the approximation of projectile aerodynamics,and its evaluation against a set of criteria.Finally,the paper provides a baseline assessment of the impact of the polynomial functions on flight trajectory predictions obtained with 6-degree-of-freedom simulations of a generic projectile.展开更多
As part of a research program, an extensive study on the dispersion characteristics of eight different7.62 ? 51 mm ammunition types was conducted. The paper presents the main steps in the experimental and analytical p...As part of a research program, an extensive study on the dispersion characteristics of eight different7.62 ? 51 mm ammunition types was conducted. The paper presents the main steps in the experimental and analytical process carried out to evaluate, namely to measure and compare, the dispersion characteristics of the ammunitions; namely,(1) identify the number of rounds to fire in the trials,(2) establish a test plan and the setup for the precision trials,(3) fire the rounds, following an established protocol for the experiments,(4) collect the impact points, and measure the performance through statistical measures,(5) perform a statistical analysis of dispersion applied to the results obtained in the trials, and(6)conclude on the ammunition characteristics. In particular, the paper proposes a statistical method to evaluate the precision of ammunitions fired with precision(Mann) barrels. The practical method relies on comparison of confidence intervals and hypothesis testing on the standard deviation of samples,namely the impact points. An algorithm is proposed to compare the variances of two or more populations of ammunitions.展开更多
Sources of dispersions that contribute to delivery error and reduce the soldier performance in terms of hit probability are numerous.In order to improve the warfighter performance,the source of the errors contributing...Sources of dispersions that contribute to delivery error and reduce the soldier performance in terms of hit probability are numerous.In order to improve the warfighter performance,the source of the errors contributing to the inaccuracy and dispersion of the weapon systems must be understood.They include ammunition dispersion error,gun dispersion,aerodynamic jump and the aiming error.The aiming error or gun pointing error is defined as the angle between the gun muzzle at the instant the trigger is pulled and the line of fire that corresponds to the intendent aim point.This is a round-to-round error.In weapons systems that include the rifle,the ammunition,a sight and a gunner,the aiming error was shown to be the single most important source of dispersion for the regular infantryman.In other words,for the general purpose rifle weapon system,the weak link is often the human.In order to verify and quantify this assertion,an experimental investigation was carried out to determine the aiming error associated with general purpose rifle fired by infantryman.The aiming error was evaluated for various firing positions and scenarios using infantryman for ranges varying between 100 m and 500 m.The results show that the aiming error is the main contributor to dispersion for the general purpose rifle fired by a non-specialized infantryman.The aiming error induced dispersion for unstressed and rested gunners is shown to be at best equivalent to that of the weapon fired from a bench rest by a marksman.Crown Copyright(?) 2019 Production and hosting by Elsevier B.V.on behalf of China Ordnance Society.展开更多
文摘Modelling and simulation of projectile flight is at the core of ballistic computer software and is essential to the study of performance of rifles and projectiles in various engagement conditions.An effective and representative numerical model of projectile flight requires a relatively good approximation of the aerodynamics.The aerodynamic coefficients of the projectile model should be described as a series of piecewise polynomial functions of the Mach number that ideally meet the following conditions:they are continuous,differentiable at least once,and have a relatively low degree.The paper provides the steps needed to generate such piecewise polynomial functions using readily available tools,and then compares Piecewise Cubic Hermite Interpolating Polynomial(PCHIP),cubic splines,and piecewise linear functions,and their variant,as potential curve fitting methods to approximate the aerodynamics of a generic small arms projectile.A key contribution of the paper is the application of PCHIP to the approximation of projectile aerodynamics,and its evaluation against a set of criteria.Finally,the paper provides a baseline assessment of the impact of the polynomial functions on flight trajectory predictions obtained with 6-degree-of-freedom simulations of a generic projectile.
文摘As part of a research program, an extensive study on the dispersion characteristics of eight different7.62 ? 51 mm ammunition types was conducted. The paper presents the main steps in the experimental and analytical process carried out to evaluate, namely to measure and compare, the dispersion characteristics of the ammunitions; namely,(1) identify the number of rounds to fire in the trials,(2) establish a test plan and the setup for the precision trials,(3) fire the rounds, following an established protocol for the experiments,(4) collect the impact points, and measure the performance through statistical measures,(5) perform a statistical analysis of dispersion applied to the results obtained in the trials, and(6)conclude on the ammunition characteristics. In particular, the paper proposes a statistical method to evaluate the precision of ammunitions fired with precision(Mann) barrels. The practical method relies on comparison of confidence intervals and hypothesis testing on the standard deviation of samples,namely the impact points. An algorithm is proposed to compare the variances of two or more populations of ammunitions.
文摘Sources of dispersions that contribute to delivery error and reduce the soldier performance in terms of hit probability are numerous.In order to improve the warfighter performance,the source of the errors contributing to the inaccuracy and dispersion of the weapon systems must be understood.They include ammunition dispersion error,gun dispersion,aerodynamic jump and the aiming error.The aiming error or gun pointing error is defined as the angle between the gun muzzle at the instant the trigger is pulled and the line of fire that corresponds to the intendent aim point.This is a round-to-round error.In weapons systems that include the rifle,the ammunition,a sight and a gunner,the aiming error was shown to be the single most important source of dispersion for the regular infantryman.In other words,for the general purpose rifle weapon system,the weak link is often the human.In order to verify and quantify this assertion,an experimental investigation was carried out to determine the aiming error associated with general purpose rifle fired by infantryman.The aiming error was evaluated for various firing positions and scenarios using infantryman for ranges varying between 100 m and 500 m.The results show that the aiming error is the main contributor to dispersion for the general purpose rifle fired by a non-specialized infantryman.The aiming error induced dispersion for unstressed and rested gunners is shown to be at best equivalent to that of the weapon fired from a bench rest by a marksman.Crown Copyright(?) 2019 Production and hosting by Elsevier B.V.on behalf of China Ordnance Society.
