Showing papers on "Trajectory of a projectile published in 1988"

The aerodynamics of tennis balls-The topspin lob

Abstract: A general description is presented of the calculation of the ballistic trajectory of a flying spinning ball acted on, in addition to the forces of gravity and drag, by the so‐called Magnus force By applying the regression analysis to results of wind‐tunnel measurement of the drag and lift coefficients of a spinning ball, a calculation of the nonlinear differential equation of the hodograph was carried out by means of the Runge–Kutta method The theoretical results that can be used to calculate the ballistic trajectories for any ball game were applied to one of the most difficult and most interesting tennis strokes, ie, to the topspin lob Practical results obtained for various distances are presented in a table as well as in graphical form UFAJP

Weapon aiming device

Abstract: The invention relates to an aiming device for weapons whose targets are disposed at changing distances and whose fired projectiles follow a curved trajectory. The aiming device calculates the distance from the weapon to the target. The calculated distance is used as a basis for correcting the point of aim with allowance for the ballistical trajectory, the latter being dependent upon the particular weapon and particular ammunition used. To correct the point of aim, a storage medium storing the ballistic trajectory correlates the range-finding data with the ballistic trajectory data. The resulting signal actuates a row of diodes which are reflected into the beam path of the optical system. Depending upon the range and the trajectory, a particular diode of the row lights up and is brought into registration with the target.

Guided artillery projectile with trajectory regulator

Abstract: A guided artillery projectile with a flight attitude or trajectory regulator in the autopilot of the projectile for the guidance of a transition into a gliding trajectory at the assumption of a predetermined pitch angle after the passage through the apogee of the ballistic firing trajectory.

Techniques for the Measurement of Tank Cannon Jump

Abstract: : To attain the goal of producing tank gun systems possessing enhanced accuracy, an experimental methodology examining the disturbances acting upon a projectile during the launch process and initial stages of free flight has been developed. The disturbances are characterized by the angular deviation of the projectile trajectory from an anticipated line of flight extending between the gun muzzle and the aim point prior to firing the cannon. Gun motion during the projectile in-bore time, including both rotation of the tube about the trunnions and vibrations of the cannon, is determined using a combination of strain gauges and proximity probes. This information provides the orientation of the muzzle relative to the line of fire and gun velocity perpendicular to the projectile line of flight at the instant the bullet leaves the cannon. A technique employing multiple orthogonal x-rays is used to measure both the linear c.g. and angular motion of the projectile during the transitional ballistic flight phase. Radiographs taken in the immediate vicinity of the muzzle provide the initial flight dynamics, indicating the relative motion of the projectile with respect to the muzzle caused by in-bore balloting, gun/projectile decoupling, initial sabot discard and muzzle blast disturbances. Comparison of these measurements with those obtained from radiographs obtained after sabot separation yield a quantitative measure of the disturbances due to asymmetric sabot discard. The measurements also provide the initial conditions for the free flight trajectory of the projectile.

Effect of sidespin and wind on projectile trajectory, with particular application to golf

Abstract: This article describes the computer simulation of the three‐dimensional projectile motion of a spinning golf ball subjected to aerodynamic effects. Linear lift and drag forces are employed in the mathematical model and shown to be physically valid for launch conditions typical of a drive with a 1‐wood. The effects of sidespin and wind are also included in the model, and an analytical solution of the dynamic equations of motion is obtained. This solution has been encoded in a fortran‐77 program to provide rapid computation of trajectories, and graphical plots are presented that clearly illustrate the resulting ‘‘slicing’’ or ‘‘hooking’’ motion. Finally, the effects of various combinations of sidespin and crosswind on the final ball position are presented. Specifically, it is shown that a ball hit with sidespin into a crosswind can fly farther than it could in conditions of no wind.

Method and arrangement for determining passage through an apogee

Abstract: A method for the on board determination for the passage through an apogee by a ballistically launched projectile through the receipt and comparison of a sequence of measured values vacillating or fluctuating specifically relative to the trajectory. Also disclosed is an arrangement for the on board determination of the point in time of an apogee of a projectile which is launched in a ballistic trajectory, through the receipt and comparison of a sequence of measured values vacillating specific to the trajectory.

Method and arrangement for the autonomous determination of an inertial positional reference on board a guided projectile

Abstract: A method for the autonomous determination of an inertial positional reference on board a guided projectile through the ascertaining and evaluating of pressure values in the surroundings of the projectile during the movement thereof along a ballistic trajectory. Moreover, also disclosed is an arrangement for the autonomous determination of an inertial positional reference on board a guided projectile which is launched in a ballistic trajectory through measuring of the pressure in the surroundings about the projectile. In an aerodynamically stable condition of flight of the projectile, there is measured the dynamic atmospheric pressure of the surrounding medium onflowing relative to the projectile, and for the measured value of the atmospheric pressure as the characteristics curve parameter for the momentarily given elevator or stabilizer position of the momentarily absolute pitch position angle of the projectile, is read out from a field of characteristics curves, which as its content, provides from model observations or model investigations, the pitch position angle in dependence upon the projectile elevator position pursuant to the aerodynamic trim equations for the assumed condition of flight.

System for guiding a flying object towards a target

Abstract: The invention relates to a system for guiding of a projectile towards a target and a projectile for carrying out the system. The projectile has means for guiding the projectile towards a desired target, e.g. by means of control signal from a target seeker. In a given point of the projectile trajectory blades or wings are swung-out from the projectile body, which blades in swung-out position are shaped as a propeller so that they are driven by the stream of air passing the projectile. In order to guide the projectile towards the target in the final phase of the trajectory the said blades are then adjusted in dependence upon the control signal from the target seeker. In one embodiment, in which the blades are rotatably journalled on the projectile body, the rotational axis of the blades is set in a given angle relative to the length axis of the projectile. This oblique setting between the rotational axis and length axis then will produce a desired force in lateral direction on the projectile. In other embodiments the blade angle, i.e. the angle between the length axis of each individual blade and the rotational axis, or the angle of incidence, i.e. the angular setting of each individual blade around its own length axis, is varied periodically in rhythm with the rotation of the blades in space.

A method for guiding a flying object, as a projectile, towards a target and a projectile for carrying out the method

Abstract: of EP0283094A method for guiding a flying object, as a projectile, towards a target and a projectile for carrying out the method. The invention relates to a method for guiding of a projectile towards a target and a projectile for carrying out the method. The projectile has means for guiding the projectile toward a desired target, e.g. by means of control signal for a target seeker. In a given point of the projectile trajectory blades or wings are swung-out from the projectile body, which blades in swung-out positions are shaped as a propeller so that they are driven by the stream of air passing the projectile. In order to guide the projectile towards the target in the final phase of the trajectory the said blades are then adjusted in dependence upon the control signal from the target seeker. In one embodiment, in which the blades are rotatably journalled on the projectile body, the rotational axis of the blades is set in a given angle relative to the length axis of the projectile. This oblique setting between the rotational axis and length axis then will produce a desired force in lateral direction on the projectile. In other embodiments the blade angle, i.e. the angle between the length axis of each individual blade and the rotational axis, or the angle of incidence, i.e. the angular setting of each individual blade around its own length axis, is varied periodically in rhythm with the rotation of the blades in space.