Ballistics external and internal: concept, definition, basics of study, goals, objectives and the need for study

Science 2023

Table of contents:

Ballistics external and internal: concept, definition, basics of study, goals, objectives and the need for study
Ballistics external and internal: concept, definition, basics of study, goals, objectives and the need for study
Anonim

Ballistics is the science of movement, flight and the effects of projectiles. It is divided into several disciplines. Internal and external ballistics deal with the movement and flight of projectiles. The transition between these two modes is called intermediate ballistics. Terminal ballistics refers to the impact of projectiles, a separate category covers the degree of damage to the target. What does internal and external ballistics study?

external ballistics studies

Guns and missiles

Cannon and rocket engines are types of heat engine, in part converting chemical energy into apropellant (the kinetic energy of a projectile). Propellants differ from conventional fuels in that their combustion does not require atmospheric oxygen. To a limited extent, the production of hot gases with combustible fuel causes an increase in pressure. The pressure propels the projectile and increases the burning rate. Hot gases tend to erode the gun barrel or throatrockets. The internal and external ballistics of small arms studies the movement, flight and impact that the projectile has.

When the propellant charge in the gun chamber is ignited, the combustion gases are held back by the shot, so the pressure builds up. The projectile begins to move when the pressure on it overcomes its resistance to movement. The pressure continues to rise for a while and then drops as the shot accelerates to high speed. Fast combustible rocket fuel is soon exhausted, and over time, the shot is ejected from the muzzle: a shot speed of up to 15 kilometers per second has been achieved. Folding cannons release gas through the back of the chamber to counteract recoil forces.

A ballistic missile is a missile that is guided during a relatively short initial active phase of flight, whose trajectory is subsequently governed by the laws of classical mechanics, unlike, for example, cruise missiles, which are aerodynamically guided in flight with the engine running.

weapon ballistics external and internal

Shot trajectory

In external and internal ballistics, trajectory is the path of a shot subject to gravity. Under the sole influence of gravity, the trajectory is parabolic. Dragging slows down the path. Below the speed of sound, drag is roughly proportional to the square of the speed; shottail rationalization is only effective at these speeds. At high speeds, a conical shock wave comes from the nose of the shot. The traction force, whichlargely dependent on the shape of the nose, being the smallest for fine point strokes. Dragging can be reduced by venting burner gases into the tail.

Tail ribs can be used to stabilize projectiles. Rear stabilization provided by threading induces gyroscopic oscillation in response to aerodynamic drum forces. Not enough spin allows you to fall and too much prevents the nose from sinking as it travels along the trajectory. Shot drift is due to lift, meteorological conditions and the rotation of the Earth.

internal and external ballistics briefly

Impulse response

Rockets move in response to an impulse of outflow of gas. The engine is designed in such a way that the pressures generated are almost constant during combustion. Radially stabilized rockets are sensitive to crosswinds, two or more engine jets tilted away from the flight line can provide spin stabilization. Targets are usually hard and are called thick or thin depending on whether the impact of the shot affects the underlying material.

Penetration occurs when impact stress intensities exceed the yield strength of the target; it causes ductile and brittle failure in thin targets and hydrodynamic material flow in thick targets. On impact, failure may occur. Penetration completely through the target is called perforation. Advanced armor traps either detonate a compressed explosive against a target or explosively focus a jet of metal onto it.surface.

internal ballistics

Degree of local damage

The internal and external ballistics of a shot are mainly related to the mechanisms and medical consequences of injury caused by bullets and explosive fragments. Upon penetration, the impulse transmitted to the surrounding tissues generates a large temporary cavity. The degree of local damage is related to the size of this transition cavity. Evidence suggests that physical injury is proportional to the projectile's cube speed, mass, and cross-sectional area. Body armor research aims to prevent projectile penetration and minimize injury.

Ballistics external and internal - is the field of mechanics that deals with the launch, flight, behavior and effects of projectiles, especially bullets, unguided bombs, rockets and the like. it is a kind of science or even art of designing and accelerating projectiles to achieve the desired performance. A ballistic body is a body with momentum that can move freely, subject to forces such as gas pressure in a gun, rifling in a barrel, gravity, or aerodynamic drag.

external ballistics

History and background

The earliest known ballistic projectiles were sticks, stones and spears. The oldest evidence for stone-tipped projectiles, which may or may not be loaded with a bow, dates back 64,000 years.ago, which were found in the Sibudu Cave, in South Africa. The oldest evidence for the use of bows for shooting dates back to about 10,000 years ago.

Pine arrows were found in the Ahrensburg valley north of Hamburg. They had shallow furrows on their underside, indicating that they were shot from a bow. The oldest bow still being restored is around 8,000 years old and was found in the Holmegard swamp in Denmark. Archery seems to have arrived in the Americas with the arctic small tool tradition about 4,500 years ago. The first devices identified as tools appeared in China around 1000 AD. BC, and by the 12th century the technology had spread throughout Asia and into Europe by the 13th century.

After a millennium of empirical development, the discipline of ballistics, external and internal, was originally studied and developed by the Italian mathematician Niccolo Tartaglia in 1531. Galileo established the principle of compound motion in 1638. The general knowledge of external and internal ballistics was put on a solid scientific and mathematical foundation by Isaac Newton with the publication of Philosophia Naturalis Principia Mathematica in 1687. This gave the mathematical laws of motion and gravity, which for the first time made it possible to successfully predict trajectories. The word "ballistics" comes from the Greek, which means "to throw".

information from internal and external ballistics

Projectiles and launchers

Projectile - any object projected into space (empty or not) whenapplication of force. Although any object in motion in space (such as a thrown ball) is a projectile, the term most often refers to a ranged weapon. Mathematical equations of motion are used to analyze the projectile's trajectory. Examples of projectiles include balls, arrows, bullets, artillery shells, rockets, and so on.

Throw is the manual launch of a projectile. Humans are unusually good at throwing due to their high agility, this is a highly developed trait. Evidence of human throwing dates back 2 million years. The throwing speed of 145 km per hour found in many athletes far exceeds the speed at which chimpanzees can throw objects, which is about 32 km per hour. This ability reflects the ability of human shoulder muscles and tendons to remain elastic until needed to propel an object.

internal and external ballistics of the shot

Internal and external ballistics: weapons in brief

One of the most ancient launchers were ordinary slingshots, bow and arrows, catapult. Over time, guns, pistols, rockets appeared. Information from internal and external ballistics includes information about various types of weapons.

  • Spling is a weapon commonly used to eject blunt projectiles such as stone, clay, or a lead "bullet". The sling has a small cradle (bag) in the middle of the connected two lengths of cord. The stone is placed in a bag. The middle finger or thumb is placed through the loop at the end of one cord, and the tab at the end of the other cord is placed between the thumb andindex fingers. The sling swings in an arc, and the tab is released at a certain moment. This frees the projectile to fly towards the target.
  • Bow and arrows. A bow is a flexible piece of material that fires aerodynamic projectiles. The string connects the two ends, and when it is pulled back, the ends of the stick are bent. When the string is released, the potential energy of the bent stick is converted into the speed of the arrow. Archery is the art or sport of archery.
  • A catapult is a device used to launch a projectile at a great distance without the aid of explosive devices - especially various types of ancient and medieval siege engines. The catapult has been used since ancient times as it proved to be one of the most efficient mechanisms during war. The word "catapult" comes from the Latin, which, in turn, comes from the Greek καταπέλτης, which means "throw, hurl". Catapults were invented by the ancient Greeks.
  • A pistol is a conventional tubular weapon or other device designed to release projectiles or other material. The projectile may be solid, liquid, gaseous, or energetic, and may be loose, as with bullets and artillery shells, or with clamps, as with probes and whaling harpoons. The projection medium varies according to the design, but is usually carried out by the action of gas pressure generated by the rapid combustion of the propellant, or compressed and stored by mechanical means operating inside the open-ended tube inpiston type. The condensed gas accelerates the moving projectile along the length of the tube, imparting sufficient velocity to keep the projectile moving when the gas stops at the end of the tube. Alternatively, you can use acceleration by generating an electromagnetic field, in which case you can discard the tube and replace the guide.
  • A rocket is a rocket, spacecraft, aircraft or other vehicle that is hit by a rocket engine. The exhaust of a rocket engine is completely formed from the propellants carried in the rocket before use. Rocket engines work by action and reaction. Rocket engines push rockets forward by simply throwing their exhausts back very quickly. Although they are comparatively inefficient for low speed use, rockets are relatively light and powerful, capable of generating high accelerations and reaching extremely high speeds with reasonable efficiency. Rockets are independent of the atmosphere and work great in space. Chemical rockets are the most common type of high performance rocket, and they typically create their exhaust gases when the rocket fuel is burned. Chemical rockets store large amounts of energy in an easily released form and can be very dangerous. However, careful design, testing, construction and use will minimize risks.
fundamentals of internal ballistics

Fundamentals of external and internal ballistics: main categories

Ballistics can be studied using high-speed photography orhigh speed cameras. A photograph of a shot taken with an ultra-high speed air gap flash helps to view the bullet without blurring the image. Ballistics is often broken down into the following four categories:

  • Internal ballistics - the study of processes that initially accelerate projectiles.
  • Transitional ballistics - the study of projectiles during the transition to cashless flight.
  • External ballistics - the study of the passage of a projectile (trajectory) in flight.
  • Terminal ballistics - the study of a projectile and its effects as it completes

Internal ballistics is the study of movement in the form of a projectile. In guns, it covers the time from propellant ignition until the projectile exits the gun barrel. This is what internal ballistics studies. This is important for designers and users of firearms of all types, from rifles and pistols to high-tech artillery. Information from internal ballistics for rocket projectiles covers the period during which the rocket engine provides thrust.

Transient ballistics, also known as intermediate ballistics, is the study of the behavior of a projectile from the moment it exits the muzzle until the pressure behind the projectile is balanced, so it falls between internal and external ballistics.

External ballistics is the study of atmospheric pressure dynamics around a bullet and is part of the science of ballistics, which deals with the behavior of a projectile without power in flight. This category is often associated with firearms andis related to the unoccupied free-flight phase of the bullet after it exits the gun barrel and before it hits the target, so it sits between transition ballistics and terminal ballistics. However, external ballistics also concerns the free flight of missiles and other projectiles such as balls, arrows, and so on.

Terminal ballistics is the study of the behavior and effects of a projectile as it hits its target. This category is relevant for both small caliber projectiles and large caliber projectiles (artillery firing). The study of extremely high velocity effects is still very new and is currently applied mainly to spacecraft design.

internal ballistics studies

Forensic Ballistics

Forensic ballistics involves the analysis of bullets and bullet impacts to determine information about use in a court or other part of the legal system. Separate from ballistics information, the Firearms and Tool Mark (“Ballistic Fingerprint”) exams involve reviewing evidence of firearms, ammunition, and tools to determine if any firearm or tool was used in the commission of a crime.

Astrodynamics: orbital mechanics

Astrodynamics is the application of weapon ballistics, external and internal, and orbital mechanics to the practical problems of propulsion of rockets and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion.and the law of gravity. It is the core discipline in space mission design and control.

external and internal ballistics pm

Projectile travel in flight

The basics of external and internal ballistics deal with the travel of a projectile in flight. The path of a bullet includes: down the barrel, through the air, and through the target. The basics of internal ballistics (or original, inside a cannon) vary according to the type of weapon. Bullets fired from a rifle will have more energy than similar bullets fired from a pistol. More powder can also be used in gun cartridges because the bullet chambers can be designed to withstand more pressure.

Higher pressures require a larger gun with more recoil, which loads more slowly and generates more heat, resulting in more metal wear. In practice, it is difficult to measure the forces inside the gun barrel, but one easily measured parameter is the speed at which the bullet exits the barrel (muzzle velocity). The controlled expansion of gases from burning gunpowder creates pressure (force/area). This is where the bullet base (equivalent to barrel diameter) is located and is constant. Therefore, the energy transferred to the bullet (with a given mass) will depend on the mass time multiplied by the time interval over which the force is applied.

The last of these factors is a function of barrel length. Bullet movement through a machine gun device is characterized by an increase in acceleration when the expanding gasespress it, but reduce the pressure in the barrel as the gas expands. Up to the point of decreasing pressure, the longer the barrel, the greater the acceleration of the bullet. As the bullet travels down the barrel of a gun, there is a slight deformation. This is due to minor (rarely major) imperfections or variations in the rifling or marks in the barrel. The main task of internal ballistics is to create favorable conditions for avoiding such situations. The effect on the subsequent trajectory of the bullet is usually negligible.

information from internal ballistics

From gun to target

External ballistics can be briefly called the journey from gun to target. Bullets usually do not travel in a straight line to the target. There are rotational forces that keep the bullet from a straight axis of flight. The basics of external ballistics include the concept of precession, which refers to the rotation of a bullet around its center of mass. Nutation is a small circular motion at the tip of a bullet. Acceleration and precession decrease as the bullet's distance from the barrel increases.

One of the tasks of external ballistics is to create the perfect bullet. To reduce air resistance, the ideal bullet would be a long, heavy needle, but such a projectile would go straight through the target without dissipating most of its energy. The spheres will lag behind and release more energy, but may not even hit the target. A good aerodynamic compromise bullet shape is a parabolic curve with a low frontal area and branching shape.

The best bullet composition is lead, which has a highdensity and cheap to obtain. Its disadvantages are that it tends to soften at > 1000fps, which causes it to lubricate the barrel and reduce accuracy, and lead tends to melt completely. Alloying the lead (Pb) with a small amount of antimony (Sb) helps, but the real answer is to bond the lead bullet to a hard steel barrel through another metal soft enough to seal the bullet in the barrel, but with a high melting point. Copper (Cu) is best for this material as a jacket for lead.

Terminal ballistics (target hitting)

The short, high-velocity bullet begins to growl, twist, and even spin violently as it enters tissue. This causes more tissue to be displaced, increasing drag and imparting most of the target's kinetic energy. A longer, heavier bullet may have more energy over a wider range when it hits the target, but it can penetrate so well that it exits the target with most of its energy. Even a bullet with low kinetics can cause significant tissue damage. Bullets produce tissue damage in three ways:

  1. Destruction and crushing. Tissue crush injury diameter is the diameter of the bullet or fragment, up to the length of the axis.
  2. Cavitation - a “permanent” cavity is caused by the trajectory (track) of the bullet itself with tissue fragmentation, while a “temporary” cavity is formed by radial tension around the bullet track from the continuous acceleration of the medium (air or tissue) inas a result of the bullet, causing the wound cavity to stretch outward. For projectiles moving at low speed, the permanent and temporary cavities are almost the same, but at high speed and with bullet yaw, the temporary cavity becomes larger.
  3. Shock waves. The shock waves compress the medium and move ahead of the bullet as well as to the sides, but these waves last only a few microseconds and do not cause deep damage at low speed. At high speed, the generated shock waves can reach up to 200 atmospheres of pressure. However, bone fracture due to cavitation is an extremely rare event. The ballistic pressure wave from a long-range bullet impact can cause a concussion in a person, which causes acute neurological symptoms.

Experimental methods to demonstrate tissue damage used materials with characteristics similar to human soft tissue and skin.

internal and external ballistics of small arms

Bullet design

Bullet design is important in injury potential. The 1899 Hague Convention (and subsequently the Geneva Convention) prohibited the use of expanding, deformable bullets in wartime. This is why military bullets have a metal jacket around the lead core. Of course, the treaty had less to do with compliance than the fact that modern military assault rifles fire projectiles at high velocities and bullets must be copper-jacketed as lead begins to melt due to the heat generated at > 2000 frames per second.

The external and internal ballistics of the PM (Makarov pistol) differs from the ballistics of the so-called "destructible" bullets, designed to break when hitting a hard surface. Such bullets are usually made from a metal other than lead, such as copper powder, compacted into a bullet. Target distance from the muzzle plays a large role in wounding ability, as most bullets fired from handguns have lost significant kinetic energy (KE) at 100 yards, while high velocity military guns still have significant KE even at 500 yards. Thus, the external and internal ballistics of the PM and military and hunting rifles designed to deliver bullets with a large number of CE over a longer distance will differ.

Designing a bullet to efficiently transfer energy to a particular target is not easy because the targets are different. The concept of internal and external ballistics also includes projectile design. To penetrate the thick hide and tough bone of an elephant, the bullet must be small in diameter and strong enough to resist disintegration. However, such a bullet penetrates most tissues like a spear, dealing slightly more damage than a knife wound. A bullet designed to damage human tissue will require certain "brakes" to ensure that all CE are transmitted to the target.

It is easier to design features that help slow down a large, slow moving bullet in tissue than a small, high speed bullet. Such measures include shape modifications such as round, flattened ordomed. Round nose bullets provide the least drag, are usually sheathed, and are useful primarily in low-velocity pistols. The flattened design provides the most form-only drag, is not sheathed, and is used in low-velocity pistols (often for target practice). The dome design is intermediate between a round tool and a cutting tool and is useful at medium speed.

The bullet's hollow point design makes it easier to turn the bullet "inside out" and line up the front, referred to as "expansion". Expansion only reliably occurs at speeds in excess of 1200 fps, so it is only suitable for guns with maximum speed. A destructible powder bullet designed to disintegrate on impact, delivering all of the CE but without significant penetration, the size of the fragments should decrease as the impact velocity increases.

Potential for injury

The type of tissue affects the potential for injury as well as the depth of penetration. Specific gravity (density) and elasticity are the main tissue factors. The higher the specific gravity, the greater the damage. The more elasticity, the less damage. Thus, light tissue with low density and high elasticity is damaged less muscle with higher density, but with some elasticity.

The liver, spleen and brain do not have elasticity and are easily injured, as is adipose tissue. Fluid-filled organs (bladder, heart, large vessels, intestines) can burst due to the pressure waves created. Bullet hittingbone, can result in bone fragmentation and/or multiple secondary missiles, each causing an additional wound.

Pistol ballistics

This weapon is easy to hide, but difficult to aim accurately, especially at crime scenes. Most small arms fires occur at less than 7 yards, but even so, most bullets miss their intended target (only 11% of attackers' rounds and 25% of police-fired bullets hit their intended target in one study). Usually low caliber weapons are used in crime because they are cheaper and easier to carry and easier to control while shooting.

Tissue destruction can be increased by any caliber using an expanding hollow point bullet. The two main variables in handgun ballistics are the bullet diameter and the amount of powder in the cartridge case. Older design cartridges were limited by the pressures they could handle, but advances in metallurgy have allowed the maximum pressure to be doubled and tripled so that more kinetic energy can be generated.

Popular topic