Time-Accurate Calculations of Free-Flight Aerodynamics of Maneuvering Projectiles
Time-Accurate Calculations of Free-Flight Aerodynamics of Maneuvering Projectiles

Author:

Publisher:

Published: 2007

Total Pages: 6

ISBN-13:

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This paper describes a multidisciplinary computational study undertaken to model the flight trajectories and the free-flight aerodynamics of finned projectiles both with and without control maneuvers. Advanced computational capabilities both in computational fluid dynamics (CFD) and rigid body dynamics (RBD) have been successfully fully coupled on high performance computing (HPC) platforms for "Virtual Fly-Outs" of munitions similar to actual free flight tests in the aerodynamic experimental facilities. Time-accurate Navier-Stokes computations have been performed to compute the unsteady aerodynamics associated with the free flight of a finned projectile at a supersonic speed using an advanced scalable unstructured flow solver on a highly parallel Linux Cluster. Some results relating to the portability and the performance of the flow solver on the Linux clusters are also addressed Computed positions and orientations of the projectile along the flight trajectory have been compared with actual data measured from free flight tests and are found to be generally in good agreement. Computed results obtained for another complex finned configuration with canard-control pitch-up maneuver in a virtual fly-out show the potential of these techniques for providing the actual time-dependent response of the flight vehicle and the resulting unsteady aerodynamics for maneuvering projectiles.

Design for Control of Projectile Flight Characteristics
Design for Control of Projectile Flight Characteristics

Author: United States. Army Materiel Command

Publisher:

Published: 1966

Total Pages: 290

ISBN-13:

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This handbook presents a general survey of the principal factors affecting the flight of projectiles, and describes the methods commonly used for predicting and influencing the flight performance. The coefficients which characterize the aerodynamic forces and moments of a moving body are identified, methods for determining the coefficients applicable to a projectile having a given shape and center of gravity location are described, and the coefficients of a number of projectiles and projectile shapes are given. The use of aerodynamic coefficients in predicting stability, range and accuracy is described. The effects of variations in projectile shape and center of gravity location on range, accuracy and lethality are discussed. Some material on prototype testing and the effects of round-to-round variations in production lots is presented.

Time-accurate Numerical Prediction of Free Flight Aerodynamics of a Finned Projectile
Time-accurate Numerical Prediction of Free Flight Aerodynamics of a Finned Projectile

Author:

Publisher:

Published: 2005

Total Pages: 18

ISBN-13:

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This report describes a new multi-disciplinary computational study undertaken to compute the flight trajectories and to simultaneously predict the unsteady free flight aerodynamics of a finned projectile configuration. Actual flight trajectories are computed by an advanced coupled computational fluid dynamics (CFD)-rigid body dynamics technique. An advanced time-accurate Navier-Stokes computational technique has been used in CFD to compute the unsteady aerodynamics associated with the free flight of the finned projectile at supersonic speeds. Computed positions and orientations of the projectile have been compared with actual data measured from free flight tests and are found to be generally in good agreement. Predicted aerodynamics forces and moments also compare well with the forces and moments used in the six-degree-of freedom fits of the results of the same tests. Unsteady numerical results obtained from the coupled method show the aerodynamic forces and moments and the flight path of the projectile.

Time-Accurate Numerical Prediction of Free Flight Aerodynamics of a Finned Projectile
Time-Accurate Numerical Prediction of Free Flight Aerodynamics of a Finned Projectile

Author:

Publisher:

Published: 2005

Total Pages: 26

ISBN-13:

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This report describes a new multi-disciplinary computational study undertaken to compute the flight trajectories and to simultaneously predict the unsteady free flight aerodynamics of a finned projectile configuration. Actual flight trajectories are computed by an advanced coupled computational fluid dynamics (CFD)-rigid body dynamics technique. An advanced time-accurate Navier-Stokes computational technique has been used in CFD to compute the unsteady aerodynamics associated with the free flight of the finned projectile at supersonic speeds. Computed positions and orientations of the projectile have been compared with actual data measured from free flight tests and are found to be generally in good agreement. Predicted aerodynamics forces and moments also compare well with the forces and moments used in the six-degree-of freedom fits of the results of the same tests. Unsteady numerical results obtained from the coupled method show the aerodynamic forces and moments and the flight path of the projectile.

Physics-Based Virtual Fly-Outs of Projectiles on Supercomputers
Physics-Based Virtual Fly-Outs of Projectiles on Supercomputers

Author:

Publisher:

Published: 2006

Total Pages: 44

ISBN-13:

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This paper describes the development and application of a new multidisciplinary computational capability to compute the flight trajectories and the free flight aerodynamics of projectiles. Advanced computational capabilities both in computational fluid dynamics (CFD) and rigid body dynamics (RBD) have been successfully fully coupled on high performance computing (HPC) platforms for Virtual Fly-Outs of guided munitions identical to actual free flight tests in the aerodynamic experimental facilities. For the first time, this integrated capability now allows time-accurate truly coupled CFD/RBD computations to simultaneously predict the free flight aerodynamics and compute the actual flight trajectories of both spin and fin stabilized projectiles and missiles with and without flight control maneuvers using microjets or control surfaces such as canards. Computed positions and orientations of the projectiles have been compared with actual data measured from free flight tests and are found to be generally in good agreement. Unsteady numerical results obtained from the coupled method show the flow field, the aerodynamic forces and moments, and the flight trajectories of the projectiles. Computed results obtained for a complex configuration with canard-control pitch-up maneuver in a virtual fly-out show the potential of these techniques for providing the actual timedependent response of the flight vehicle and entire flight trajectory of a complex guided projectile system. It can lead to accurate determination of aerodynamics.

Parallel Computational Fluid Dynamics 2007
Parallel Computational Fluid Dynamics 2007

Author: Ismail H. Tuncer

Publisher: Springer Science & Business Media

Published: 2009-04-21

Total Pages: 489

ISBN-13: 3540927441

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At the 19th Annual Conference on Parallel Computational Fluid Dynamics held in Antalya, Turkey, in May 2007, the most recent developments and implementations of large-scale and grid computing were presented. This book, comprised of the invited and selected papers of this conference, details those advances, which are of particular interest to CFD and CFD-related communities. It also offers the results related to applications of various scientific and engineering problems involving flows and flow-related topics. Intended for CFD researchers and graduate students, this book is a state-of-the-art presentation of the relevant methodology and implementation techniques of large-scale computing.

Modern Exterior Ballistics
Modern Exterior Ballistics

Author: Robert L. McCoy

Publisher: Schiffer Military History

Published: 2012

Total Pages: 0

ISBN-13: 9780764338250

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Modern Exterior Ballistics is a comprehensive text covering the basic free flight dynamics of symmetric projectiles. The book provides a historical perspective of early developments in the 19th century, the technology leading to World War I and that through World War II into the modern post-war era. Historical topics include the first ballistic firing tables, early wind tunnel experiments, the development of free flight spark ranges and the first supercomputer, ENIAC, which was designed to compute artillery trajectories for the U.S. Army Ballistic Research Laboratory. The level of the text requires an undergraduate education in mathematics, physics, and mechanical or aerospace engineering. The basic principles of ballistic science are developed from a comprehensive definition of the aerodynamic forces that control the flight dynamics of symmetric projectiles. The author carefully starts with the basic vacuum point mass trajectory, adds the effects of drag, discusses the action of winds, simple flat fire approximations, Coriolis effects and concludes with the classic modified point mass trajectories. Included in the discussion are analytical methods, change of variables from time to distance, numerical solutions and a chapter on the Siacci Method. The Siacci Method provides a historical perspective for computing flat fire trajectories by simple quadrature and is used in the sporting arms industy. The final six chapters of the book present an extensive physical and mathematical analysis of the motion of symmetric projectiles. The linearized equations of angular and swerving motion are derived in detail. The effects of mass asymmetry, in-bore yaw, cross wind and launch in a slipstream are discussed. Special consideration is given to the derivation and explanation of aerodynamic jump. These subjects are then expanded to include a complete chapter on nonlinear aerodynamic forces and moments. The final chapter in the book presents an overview of experimental methods for measuring the flight dynamics of projectiles. The great forte of Modern Exterior Ballistics is the author's effort to provide many fine specific examples of projectile motion illustrating key flight behaviors. The extensive collection of data on projectiles from small arms to artillery used to substantiate calculations and examples is alone a valuable reference. The ultimate joy of the book is the incomparable comprehensive set of flow field shadow graphs illustrating the entire spectrum of projectile flight from subsonic, through transonic and supersonic. The volume is a necessary addition to any undergraduate or graduate course in flight dynamics.

Aerodynamics of the 120-mm M831A1 Projectile: Analysis of Free Flight Experimental Data
Aerodynamics of the 120-mm M831A1 Projectile: Analysis of Free Flight Experimental Data

Author:

Publisher:

Published: 2000

Total Pages: 0

ISBN-13:

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The 120-mm M831A1 projectile is a low-cost training projectile used by U.S. armor troops. For the last several years, program managers have received feedback from the users that in some cases, M831A1 impact performance did not appear consistent with the current M831A1 computer correction factor. Based on this information, a low-scale but in-depth experimental analysis of the projectile was conducted to assess its aero-ballistic qualities and hopefully identify any potential issues that could affect accuracy performance. The work was conducted by the U.S. Army Research Laboratory at the Transonic Experimental Facility. Although the projectile has undergone fairly extensive target impact dispersion (TID), radar, and wind tunnel testing, this study presents the first spark range data and detailed free-flight aero-ballistic analysis for the M831A1. Roll data were measured via roll pins for the computation of roll-related coefficients. All rounds exhibited very little roll over the measured trajectory, mostly because of a very small roll moment. Yaw magnitudes displayed variability, and several shots had at least moderate levels. The source of the yaw levels imparted to the projectiles was the launch dynamics, and a detailed study of in-bore dynamics is in progress. Most shots exhibited a 'stepping', motion in plots of total yaw versus range. This phenomenon is the result of trim, which is believed to be caused by an aerodynamic asymmetry. A source of the trim has not been isolated. Accurate free-flight drag and pitching moment coefficients were computed on the basis of the measured trajectories. Pitch-damping characteristics were marginal. Although the M831A1 currently performs within acceptable TID standards, further experimental work is recommended, as well as a study of possible stabilizer design modifications.