Ballistics influence many areas of study, ranging from the analysis of the baseball’s trajectory curve to the development of the Army’s missile guidance systems. [2]
In this article, let’s learn about ballistics and its fields of study.
Article contents:
Ballistics
It is the science that studies the motion and effect of projectiles. It is divided into several disciplines, namely, internal and external ballistics, and they examine the propulsion and flight of projectiles. The transition between these two systems is called intermediate ballistics. The final ballistics, studies the effect of projectiles on target objects.
A “projectile” is an object that has been launched or dropped, and which continues to move because of its inertia. Its trajectory is determined by its initial velocity, direction, gravitational forces, and air resistance. For example, for objects ejected near the ground and with negligible air resistance, the path takes the form of a parabola. [1]، [2]
push the missiles
A gun and a rocket engine, for example, are two types of heat engines that partially convert the chemical energy of the propellant into the kinetic energy of the projectile. The propellants differ from conventional fuels in that their combustion does not require atmospheric oxygen. The production of hot gases by the burning fuel increases the pressure that drives the projectile and increases the rate of combustion. Hot gases also corrode the barrel of the gun.
When the propellant charge ignites in the chamber of the gun, the combustion gases are trapped by the shot; The pressure rises. The bullet begins to move when the pressure overcomes its resistance to movement. The pressure continues to rise for some time and then decreases, as the bullet accelerates to a high velocity. The burning propellant quickly runs out, and in time the shot exits the muzzle. It has recorded speeds of up to 15 kilometers (9 miles) per second. Recoil guns vent gas through the rear of the chamber to counteract recoil forces.
The primary explosion occurs that precedes the exit of the shot, and then is followed by the main explosion, as compressed gases are released behind the shot. The fast gas flow skips the shot for a short time and therefore you may experience severe oscillation. The blast shock wave, which travels outward at faster than the speed of sound, is heard as gunshots. The heat generated near the nozzle causes the large guns to flash with flames. Devices can also be installed on the nozzle to suppress the blast and flash by dispersing shock waves, and can reduce recoil by dispersing the flow. [1]
An intermediate or transition ballistic is defined as a transitional state between the inner and outer ballistic near the crater. The emission of gas from the barrel in front of the projectile and the discharge of propellant gases behind it indicate these transitional changes. In this regard, the effect on the projectile leaving the cannon and the use of the momentum of the propellant gases are of particular importance. [3]
Objects free fall
To understand the motion of projectiles, it is first necessary to understand the “free fall” motion of objects, which are objects that we simply drop from a certain height above the ground. In the simplest case, when the air resistance is negligible and when the objects are close to the surface of the Earth, the Italian astronomer and physicist “Galileo Galilei” (1564-1642) showed that two objects fall at the same distance and in the same period of time, regardless of their weight. The velocity of a falling body increases in equal increments in equal intervals of time. For example, a ball falling from the top of a building will start to rest, increase to 32 feet (9.8 meters) per second after one second, then to 64 feet (19.6 meters) per second after two seconds, and then to 96 feet (29.4 meters) meters) per second after three seconds, and so on. So we find that the change in velocity is always 32 feet per second. The change in velocity for each period of time is known as acceleration and is constant. This acceleration is equal to 1 g, where g is the acceleration due to the force of gravity.
The gravitational acceleration g becomes smaller as the distance from the Earth increases. But for most terrestrial applications we can set the g-value to be constant (it only changes by 0.5% as the altitude changes by 10 miles [16 كم]). On the other hand, the “air resistance” can vary greatly depending on the altitude, wind, characteristics and velocity of the projectile itself. It is known that paratroopers can change their height relative to other paratroopers simply by changing the shape of their bodies. It is also known that a boulder will fall more quickly than a feather. When researching ballistics issues, it is necessary to separate the effects of gravity, which are very simple, and the effects of air resistance, which are more complex. [2]
Sources
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