This paper introduces a novel approach for controlling the exterior ballistic properties of spin-stabilized bullets by optimizing their internal mass distributions. Specifically, the properties of interest are the bul...This paper introduces a novel approach for controlling the exterior ballistic properties of spin-stabilized bullets by optimizing their internal mass distributions. Specifically, the properties of interest are the bullets’ stability characteristics that are examined through dynamic and gyroscopic stability parameters.New analytical expressions for aerodynamic quantities are also derived to address the compressibility of air. These expressions are utilized in a bullet model that enables efficient computation of the stability parameters for a given mass distribution. The bullet model is used in the formulation of nonlinear optimization problems that provide optimal mass distributions with respect to given goals, i.e., desired stability characteristics. The bullet types investigated in this paper are a long range bullet and a limited range training bullet. In the optimization of the mass distribution of the long range bullet, the goal is that the bullet stays stable for as long as possible. The mass distribution of the training bullet is optimized such that the bullet is stable at launch but becomes unstable shortly afterwards. The global optimal solutions obtained with the new approach fulfill the desired stability characteristics better than currently used uniformly filled bullets. Overall, the optimization approach reveals a new goal focused philosophy for bullet design compared to current trial and error design practices.展开更多
A method of augmenting an airborne vehicle for short-period dynamics and stability by passive means is presented in this study.A trajectoryphase disturbance rejection capability is achieved for an unguided fin-stabili...A method of augmenting an airborne vehicle for short-period dynamics and stability by passive means is presented in this study.A trajectoryphase disturbance rejection capability is achieved for an unguided fin-stabilized vehicle by flexible mounting of the fins to the vehicle body.The deflecting fins lag the body oscillation such that the harmonic oscillation can be quickly dampened.The amount of fin deflection may be chosen by a hinge-line location;among other things,the vehicle damping behaviour is largely determined by this choice.Linear theory is applied and 6-DOF simulations are carried out to demonstrate the approach suitability for the task.展开更多
文摘This paper introduces a novel approach for controlling the exterior ballistic properties of spin-stabilized bullets by optimizing their internal mass distributions. Specifically, the properties of interest are the bullets’ stability characteristics that are examined through dynamic and gyroscopic stability parameters.New analytical expressions for aerodynamic quantities are also derived to address the compressibility of air. These expressions are utilized in a bullet model that enables efficient computation of the stability parameters for a given mass distribution. The bullet model is used in the formulation of nonlinear optimization problems that provide optimal mass distributions with respect to given goals, i.e., desired stability characteristics. The bullet types investigated in this paper are a long range bullet and a limited range training bullet. In the optimization of the mass distribution of the long range bullet, the goal is that the bullet stays stable for as long as possible. The mass distribution of the training bullet is optimized such that the bullet is stable at launch but becomes unstable shortly afterwards. The global optimal solutions obtained with the new approach fulfill the desired stability characteristics better than currently used uniformly filled bullets. Overall, the optimization approach reveals a new goal focused philosophy for bullet design compared to current trial and error design practices.
文摘A method of augmenting an airborne vehicle for short-period dynamics and stability by passive means is presented in this study.A trajectoryphase disturbance rejection capability is achieved for an unguided fin-stabilized vehicle by flexible mounting of the fins to the vehicle body.The deflecting fins lag the body oscillation such that the harmonic oscillation can be quickly dampened.The amount of fin deflection may be chosen by a hinge-line location;among other things,the vehicle damping behaviour is largely determined by this choice.Linear theory is applied and 6-DOF simulations are carried out to demonstrate the approach suitability for the task.
