An Examination of In-Bore Projectile Motion from an EM Railgun

An Examination of In-Bore Projectile Motion from an EM Railgun
Author: Larry Burton
Publisher:
Total Pages: 20
Release: 1993
Genre:
ISBN:

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An investigation was undertaken to examine electromagnetic (EM) gun barrel/projectile interaction. The RASCAL code was used in this study because of its ability to easily manipulate relevant parameters such as gun tube centerline, projectile/bore contact stiffness, and projectile design geometry. This work centers around a comparison of projectile performance in the 9-MJ EM railgun at the University of Texas Center for Electromechanics (UTCEM) and a double-travel conventional gun. This comparison was made by varying the parameters listed above for two different projectile designs, one projectile being the M829 tank round, the other, a preliminary EM design. It was hoped that adoption of this format would identify specific areas of the EM gun/projectile system that excite transverse loading, with the results of the analysis presented here.

A Comparison of In-Bore Projectile Motion from an Electromagnetic Railgun Versus that of a Conventional Cannon Barrel

A Comparison of In-Bore Projectile Motion from an Electromagnetic Railgun Versus that of a Conventional Cannon Barrel
Author: Lawrence W. Burton
Publisher:
Total Pages: 44
Release: 1993
Genre:
ISBN:

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An investigation was undertaken to examine electromagnetic (EM) gun- barrel projectile interaction. the RASCAL code was used in this study because of its ability to easily manipulate relevant parameters such as gun tube centerline, projectile contact stiffness, and projectile design geometry. This work compares the projectile performance in the 9-MJ EM railgun at the University of Texas Center for Electromechanics (UTCEM) to that in a double- travel conventional gun. This comparison was made by varying the parameters listed above for two projectile designs, one projectile being the M829 Link round, the other, a preliminary EM design. It was believed that adoption of this format would identify specific areas of the EM gun-projectile system that excite transverse loading, with the results of this analysis presented here. RASCAL, Transverse acceleration, EM Railgun, In-bore projectile dynamics, Velocity, Electromagnetic guns.

An Approximate Analysis of Balloting Motion of Railgun Projectiles

An Approximate Analysis of Balloting Motion of Railgun Projectiles
Author:
Publisher:
Total Pages: 26
Release: 1991
Genre:
ISBN:

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This is the final of three reports dealing with the in-bore balloting motion of a projectile fired from an electromagnetic railgun. Knowledge of projectile in-bore motion is important to its design and the design of the railgun. It is a complicated problem since many parameters are involved and it is not easy to determine the interacting relationships between them. To make the problem easier to understand it was analyzed on several levels. Beginning from the basic simple model which computed only the axial motion, more complicated models were introduced in upper levels that included the more significant lateral forces and gun tube vibration effects. This report deals with the approximate analysis of balloting motion. This model considers the effects of the propulsion force, the friction force of the projectile package (projectile and armature), air resistance, gravity, the elastic forces, and the projectile/ barrel clearance. To simplify the modeling, a plane motion configuration is assumed. Though the projectile is moving with a varying yaw angle, the axes of the barrel and the projectile package, and the projectile center of gravity are always considered in a plane containing the centerlines of the rails. Equations of motion are derived and solved. A sample computation is performed and the results plotted to give a clearer understanding of projectile in-bore motion.

Basic Simple Modeling of Balloting Motion of Railgun Projectiles

Basic Simple Modeling of Balloting Motion of Railgun Projectiles
Author:
Publisher:
Total Pages: 23
Release: 1991
Genre:
ISBN:

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This is the second of three basic reports dealing with the in-bore balloting motion of a projectile launched in an electromagnetic railgun. The first report addressed axial projectile motion without cocking and was titled 'A Basic Single Model of In-bore Motion of Railgun Projectiles.' Understanding the inbore motion of a projectile is important to its design and its ability to hit a target with some effectiveness. Analysis of in-bore motion is a complicated problem since many parameters are involved and the interacting relationships between them must be determined. To make the problem easier to understand, it was analyzed on several levels beginning with the basic simple model which computed only the axial motion and followed by more complicated models in the upper analysis levels that included as many lateral forces and gun tube vibration effects as possible. This report deals with the second basic or zero level of balloting analysis. A basic simple model considering only the effect of the propulsion force, the friction force of the armature, and the clearance between the projectile and the barrel is presented. The computation of the axial projectile motion with a certain cocking angle is the goal of this analysis. Equations of motion are derived and solved. A sample computation with available data is performed and the results plotted to give a clearer understanding of balloting action.

Basic Simple Modeling of In-Bore Motion of Railgun Projectiles

Basic Simple Modeling of In-Bore Motion of Railgun Projectiles
Author:
Publisher:
Total Pages: 17
Release: 1991
Genre:
ISBN:

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In an electromagnetic railgun a projectile encounters a complex force environment during launch. A thorough understanding of these forces is critical to projectile and gun tube design. There are many parameters involved and interacting relationships which must be determined. To better understand and establish the in-bore force models, we begin with a basic simple model which computes only the axial motion. More complicated models will be introduced in subsequent reports which will include lateral forces and gun tube vibration effects. This report deals with a very simple axial motion model. Only the effects of the propulsion force, projectile package mass, air resistance, and the friction forces are presented. Equations of motion are derived and solved. A sample computation with available data is performed and curves plotted to give clearer understanding of the results.

Acceleration of an Initially Moving Projectile

Acceleration of an Initially Moving Projectile
Author: Miguel Del GÃ1⁄4ercio
Publisher:
Total Pages: 28
Release: 2009-07-31
Genre:
ISBN: 9781463562427

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In the early 1980s, the principal mission for railguns required launch velocities in excess of 3 km/s. The focus of the research was centered on railguns employing plasma armatures. Significant efforts were expended on understanding the fundamentals of plasma armatures and their interaction with the bore. The temperatures associated with plasma armatures in railguns typically exceed 2 eV and, as a result, cause significant degradation in the bore materials leading to degradation of railgun performance. One parameter that seemed to ameliorate the effect of long dwell time was the use of a projectile injected into the breech of the railgun. This technique was often used with inert gas as the propulsive media. However, propellants were evaluated (1) and used to inject propellant-accelerated projectiles into the breech of a railgun (2). The burning propellant gases were insufficiently conductive to break down and form a plasma arc with 6000 V applied across the breech of the railgun. While no deleterious interactions were noted between the combustion products and plasma electrodynamics, the research was plagued with large variability in the injection velocity, obturation in the squarebore railgun, and reliable initiation of the plasma. All challenges were eventually solved. More recently, the mission for railguns has found utility using velocities

In-bore Dynamic Response Analysis of a SLEKE I Projectile Fired from the Single Shot Gun (SSG) Railgun

In-bore Dynamic Response Analysis of a SLEKE I Projectile Fired from the Single Shot Gun (SSG) Railgun
Author: Lawrence W. Burton
Publisher:
Total Pages: 28
Release: 1994
Genre:
ISBN:

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Recently, Kaman Sciences Inc. experienced an in-bore failure of its Rodman cone projectile design in the single shot gun (SSG) railgun at Maxwell Laboratories as part of the SLEKE projectiles program. This projectile design had been successfully launched from a conventional powder gun at axial acceleration levels exceeding those encountered during the electromagnetic (EM) launch which resulted in the failure. As part of the investigation into this failure, an in-bore dynamics code, RASCAL, was utilized to determine the magnitude of the lateral loads encountered. While RASCAL is capable of computing bending and shear responses, it cannot provide detailed stress and strain data through the projectile. What the analysis did show was that for the EM case, the lateral loads were ten times greater than those typical of conventional gun systems and certainly contributed to the cause of failure. A kink in the rail centerline profile was found to initiate large transverse and pitching accelerations of the projectile. Details of the analysis and the ramifications of bore non-straightness on the Rodman cone projectile design are presented in this report.

A RASCAL In-Bore Dynamic Analysis of the Task B and Task C Electromagnetic Railguns

A RASCAL In-Bore Dynamic Analysis of the Task B and Task C Electromagnetic Railguns
Author:
Publisher:
Total Pages: 88
Release: 1995
Genre:
ISBN:

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Previous RASCAL in-bore gun dynamics analyses 90-mm railguns have shown high transverse accelerations can be expected because of anomalies in the bore straightness. A request was made for similar analyses to be made for the Task B and Task C 90-mm railguns, with the Sabot Launched Electromagnetic Gun KE (SLEKE) II projectile design. Results of the RASCAL analyses showed the importance of matching the contact stiffness of the rear and front bore riders of the SLEKE II designs. Numerous cases were run to show the effects of variations in contact stiffness. Mismatched contact stiffness resulted in elevated transverse accelerations at the less stiff of the two bore riding contacts. Comparisons of the results of this work are made against previous RASCAL analyses. These results verify the effect a kink in the bore centerline profile has on the projectile's in-bore response.

Examination of a High-Explosive Round for a High-Aspect Ratio Railgun Bore

Examination of a High-Explosive Round for a High-Aspect Ratio Railgun Bore
Author:
Publisher:
Total Pages: 30
Release: 2001
Genre:
ISBN:

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A railgun bore with a rectangular cross section is advantageous for launching a hypervelocity kinetic energy penetrator. An analysis is presented that supports the operation of a mass-stablized round with a high-explosive (HE) payload from the same bore. The design criteria and two bounding cases are provided to illustrate the effectiveness. Modifications to the bore insulators, ranging from 0 to 15 mm, can provide space for the projectile base diameter. The resultant HE round provides an increased capability, compared to conventionally launched HE rounds in velocity, armor penetration, and payload capacity.