Magnetoelastic Generator Type Transducer

The Evaluation of Piezoelectric Contact Target Sensor Taking Account the Wave Processes

A semiempirical mathematical model of motion of the center of mass of a spinning projectile in the atmosphere is proposed This model takes into account the effects of the derivation and change in the frontal resistance due to variation in the angle of attack These effects are accounted for without a detailed description of spinning in our model, which allows using a large integration step and provides the capability of real-time computation of ballistic corrections The selection procedure of the model parameters for real weapon systems is described in detail

A Mathematical Model of the Motion of a Spinning Projectile

When calculating projectile flight trajectories, an urgent issue is the definition and representation of aerodynamic forces (moments) and parameters of the atmosphere, which are significantly non-linear in nature, in the system of mathematical models - differential equations of spatial motion of projectiles. A significant component of the error in determining the aerodynamic force is introduced by the operation of numerical differentiation of tabular values of aerodynamic coefficients, which are included as components in systems of differential equations. In this direction, a scientific approach based on the approximation of the data of aerodynamic coefficients and parameters of the atmosphere by analytical functions is promising, the requirement for which is the possibility of obtaining a single and continuous function within the entire range of changes in the flight parameters of the projectile and ensuring their best approximation to tabular data. A unified approach to the possibility of approximating qualitatively different aerodynamic coefficients and parameters of the atmosphere found further development; as approximating functions, it is proposed to use an analytical function as the sum of a reference function (error function) and a set of basic functions (Gaussian functions), which allows to obtain a continuous-differentiated approximating function on the segment of the change of the projectile flight parameter, which can be represented by a single analytical expression. The obtained values of the single continuous-differentiated on the segment of the change of the projectile flight parameter approximating the function of the aerodynamic coefficients and the parameters of the atmosphere, which are given by a single analytical expression, can be used to solve the problems of calculating Firing tables and preparing data using ballistic integrating algorithms for firing artillery systems.
Keywords: aerodynamic forces (moments), parameters of the atmosphere, projectile, approximation, differentiation, analytical expression, error function, Gaussian function.

Аналітичні функції нелінійних параметрів польоту снаряда

The structure of modern fuzes includes micro-electromechanical systems (MEMS), which have such advanced devices as micro-accelerometers and micro-switches, being triggered at a specified level of setback. Independent power source (PS), as an inherent part of the MEMSfuze, charges an energy storage unit during the shot and triggers the fuze firing circuit when the shell encounters the target. Operating level of the control signal should be achieved within the time of remote arming, determined by the type of ammunition. The paper considers a possibility to develop PS as a thermoelectric generator (TEG) with aerodynamic heating of hot junctions due to friction of the projectile body on the incoming airflow. The initial temperature is determined by the driving band cutting into the rifling and friction during the movement of projectile through the tube bore. The paper presents a technique for calculating the temperature field along the body of the projectile from the critical point, located at the top of the shell head. The solution of the equation of heat balance reveals the temporal development of the projectile body temperature. The proposed mathematical model of the TEG describes the process of converting heat into electrical output signal (thermo-EMF). An example of calculation for a specific artillery system – 57-mm anti-aircraft gun S-60 is given. Calculation of the TEG output signal was limited by the time, which is necessary to reach the top of the projectile trajectory. It is shown that at high altitude the temperature difference may drop to zero, thus cutting off the TEG output signal. Selection of capacitive storage parameters can be based on the reliability test conditions of the fuze firing circuit actuators, taking into account the partial storage discharge on the trajectory before the projectile encounters the target.

Albert Efremov

Papers

Approximation of the air resistance law of 1943

Magnetoelastic Generator Type Transducer

Some features of calculating the response of contact target sensors of fuses

The Evaluation of Piezoelectric Contact Target Sensor Taking Account the Wave Processes

Oxidation of benzyl alcohol in the copper-doped ZIF-8 metal-organic framework with encapsulated nitroxyl radical