Tuesday 31 May 2011

MORTAR AND BOMBS

A mortar is an indirect fire weapon that fires shells at low velocities, short ranges, and high-arcing ballistic trajectories. It is typically muzzle-loading and has a barrel length less than 15 times its caliber.

A mortar is relatively simple and easy to operate. A modern mortar consists of a tube into which gunners drop a shell, which is usually referred to as a bomb. The shell contains a quantity of propellant. When it reaches the base of the tube it hits a firing pin, which detonates the propellant and fires the shell. Some larger caliber mortars have a string operated firing pin instead of a fixed one. The tube is generally set at between 45 and 85 degrees angle to the ground, with the higher angle giving shorter firing distances.

From the 18th to the early 20th century very heavy, relatively immobile siege mortars were used, of up to one metre calibre, often made of cast iron and with outside barrel diameter many times that of the bore diameter. Smaller and more portable designs were introduced during the First World War, primarily for trench warfare, which took place at relatively close ranges. Mortars continue to be in use to the present day.

Light and medium mortars are portable, and usually used by infantry units. The chief advantage a mortar section has over an artillery battery is the flexibility of small numbers, mobility and the ability to engage targets in the defilade with plunging fires. Mortars are able to fire from the protection of a trench or defilade. In these aspects the mortar is an excellent infantry support weapon, as it can be transported over any terrain and is not burdened by the logistical support needed for artillery.

Heavy mortars are typically between 120- and 300-mm caliber. These weapons are usually towed or vehicle-mounted, sometimes breech-loaded, and normally employed by infantry units attached to battalion through division level. Even at this size, mortars are simpler and less expensive than comparable howitzers or field guns.

A mortar can be carried by one or more men (larger mortars can usually be broken down into components), or transported in a vehicle. An infantry mortar can usually also be mounted and fired from a mortar-carrier, a purpose-built or modified armoured vehicle with a large roof hatch. A mortar can also be a launcher for fireworks, a hand-held or vehicle-mounted projector for smoke shells or flares, or a large grenade launcher. Heavy mortars can be mounted on a towed carriage, or permanently vehicle-mounted as a self-propelled mortar.
Improvised, mortars have been used by insurgent groups, usually to attack fortified military installations. As each tube fired only one round, mortars were usually deployed as a battery of four or six welded onto a steel frame. This was often concealed inside a van such as a Ford Transit. The idea was that the improvised propellant fuses could be set once the mortar carrier was aimed roughly at the target and the mortars would automatically fire after a delay – this allowed the mortar gunner time to escape before the rounds were fired. After firing, a timer-operated incendiary device could set the vehicle on fire in order to destroy any forensic evidence it contained.

TRINITROTOLUENE (TNT) EXPLOSIVE

Trinitrotoluene (TNT), is a yellow colored solid chemical compound sometimes used as a reagent in chemical synthesis, but it is best known as a useful explosive material with convenient handling properties. The explosive yield of TNT is considered to be the standard measure of strength of bombs and other explosives. In chemistry, TNT is used to generate charge transfer salts.
The formula of TNT is C6H2(NO2)3CH3.


 Preparation

Industrially, TNT is synthesized in a three-step process. First, toluene is nitrated with a mixture of sulfuric and nitric acid to produce mono-nitrotoluene or MNT. The MNT is separated and then renitrated to dinitrotoluene or DNT. In the final step, the DNT is nitrated to trinitrotoluene or TNT using an anhydrous mixture of nitric acid and oleum. Nitric acid is consumed by the manufacturing process, but the diluted sulfuric acid can be reconcentrated and reused. Subsequent to nitration, TNT is stabilized by a process called sulphitation, where the crude TNT is treated with aqueous sodium sulfite solution in order to remove less stable isomers of TNT and other undesired reaction products. The rinse water from sulphitation is known as red water and is a significant pollutant and waste product of TNT manufacture.

Control of nitrogen oxides in feed nitric acid is very important because free nitrogen dioxide can result in oxidation of the methyl group of toluene. This reaction is highly exothermic and carries with it the risk of runaway reaction and explosion.

In the laboratory, 2,4,6-trinitrotoluene is produced by a two step process. A nitrating mixture of concentrated nitric and sulfuric acids is used to nitrate toluene to a mixture of mono- and di-nitrotoluene isomers, with cooling to maintain careful temperature control. The nitrated toluenes are separated, washed with dilute sodium bicarbonate to remove oxides of nitrogen, and then carefully nitrated with a mixture of fuming nitric acid and sulfuric acid. Towards the end of the nitration, the mixture is heated on a steam bath. The trinitrotoluene is separated, washed with a dilute solution of sodium sulfite and then recrystallized from alcohol.

GUN POWDER USED FOR FIREARMS


         Gunpowder, also known as black powder, is a mixture of sulfur, charcoal, and potassium nitrate. Gunpowder can be made just using potassium nitrate and charcoal (or alternatively without charcoal), but without the sulfur (or coal), the powder is not as strong. It burns rapidly, producing a volume of hot gas made up of carbon dioxide, water, and nitrogen, and a solid residue of potassium sulfide. Because of its burning properties and the amount of heat and gas volume that it generates, gunpowder has been widely used as a propellant in firearms and as a pyrotechnic composition in fireworks. The term gunpowder also refers broadly to any propellant powder. Modern firearms do not use the traditional gunpowder (black powder) but instead use smokeless powder. Antique firearms or replicas of antique firearms are often used with black powder substitute.

         Gunpowder is classified as a low explosive because of its relatively slow decomposition rate and consequently low brisance. Low explosives deflagrate at subsonic speeds. High explosives detonate, producing a supersonic wave. Ignition of the powder packed behind a bullet must generate enough pressure to force it from the muzzle at high speed, but not enough to rupture the gun barrel. Gunpowder is thus less suitable for shattering rock or fortifications, where high explosives such as TNT are preferred.

         Gunpowder was, according to prevailing academic consensus, discovered in the 9th century by Chinese alchemists. This discovery led to the invention of fireworks and the earliest gunpowder weapons in China. In the centuries following the Chinese discovery, gunpowder weapons began appearing in the Arab world, Europe, and India. The consensus is that this was spread from China, through the Middle East, and then into Europe, although there remains some dispute over the amount of Chinese influence on later advancements in gunpowder technology.

Saturday 28 May 2011

INTRODUCTION AND FUNCTION OF RIFLE

A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the bullet, imparting spin around an axis corresponding to the orientation of the weapon. When the bullet leaves the barrel, the spin averages out curve from imperfections improving accuracy and prevents tumbling which improves range, in the same way that a properly thrown American football or rugby ball behaves. The word "rifle" originally referred to the grooving, and a rifle was called a "rifled gun." Rifles are used in warfare, hunting and shooting sports.

Typically, a bullet is propelled by the contained deflagration of an explosive compound (originally black powder, later cordite, and now nitrocellulose), although other means such as compressed air are used in air rifles, which are popular for vermin control, hunting small game, formal target shooting and casual shooting ("plinking").
Formerly, rifles only fired a single bullet with each squeeze of the trigger. Modern assault rifles are capable of firing more than one round per trigger squeeze; some fire in a fully automatic mode and others are limited to bursts of three to five rounds per squeeze. Thus, modern assault rifles overlap somewhat with machine guns. Generally, the difference between an automatic rifle and a machine gun comes down to weight and feed system; rifles, with their relatively light components (which overheat quickly) and small magazines, are incapable of sustained automatic fire in the way that machine guns are. While machine guns may require more than one operator, the rifle is an individual weapon.


MACHINE GUNS AND ITS FUNCTION

A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute.

In United States gun law, machine gun is a term of art for any fully automatic firearm, and also for any component or part that will modify an existing firearm such that it functions as a fully automatic firearm.

 
 
Machine guns are generally categorized as sub-machine guns, machine guns, or autocannons. Sub-machine guns are designed to be portable automatic weapons for personal defense or short range combat, and are intended to be fired while being hand held. Submachine guns use small pistol caliber rounds. A proper machine gun is often portable to a certain degree, but is generally used when mounted on a stand or fired from the ground on a bipod. Light machine guns can be fired hand held like a rifle, but the gun is more effective when fired from a prone position. Proper machine guns use larger caliber rifle rounds. The difference between machine guns and autocannons is based on caliber, with autocannons using calibers larger than 16 mm.

 
Another factor is whether the gun fires conventional rounds or explosive rounds. Guns firing large-caliber explosive rounds are generally considered either autocannons or automatic grenade launchers ("grenade machine guns"). By contrast with the other two categories (sub-machine guns and autocannons), machine guns (like rifles) tend to share the characteristic of a very high ratio of barrel length to caliber (a long barrel for a small caliber); indeed, a true machine gun is essentially a fully automatic rifle, and the boundaries between the two are often blurred. Often, the criterion for a machine gun as opposed to an automatic rifle is considered to be the presence of a quick change barrel or other cooling system.

TYPES OF PISTOLS

Single shot

These types of handgun were mainly seen during the era of flintlock and musket weaponry where the pistol was loaded with a lead ball and fired by a percussion cap. However, as technology improved, so did the single shot pistol. New operating mechanisms were created, and due to this, they are still made today. They are often used to hunt game.

Multi-barreled

These were common during the same time as single shot pistols. As designers looked for ways to increase fire rates, multiple barrels were added to all guns including pistols. Some examples of multi-barreled pistols are Derringers and Duck's foot pistols.

Revolving Cylinder

The evolution of handguns between the rotating-barrel and the semi-automatic is defined as a revolver,with a rotating cylinder most often seen with 5 or 6 round capacities. These pistols are very common to be seen in "Old Western" movies and are well known for being extremely accurate despite being one of the lesser accurate types.
Single-action - a type of revolver requiring the "hammer" to be drawn back manually each time
Double-action -a type of revolver that can be used as if a single action,but also as a semi-automatic (with the pulling of the trigger pulling the hammer,rotating the cylinder,and releasing the hammer into the firing pin or plate)

Semi-automatic

This was next development of the pistol. Instead of using multiple barrels which all needed to be reloaded individually, semi-automatic pistols could deliver greater fire rate and only require a few seconds to reload depending on the skill of the shooter. They work by the fired cartridge generating enough kinetic energy to force the bolt back to allow the magazine spring to push another round into the chamber. This also includes certain types of revolvers.

Machine pistol

A Machine Pistol is a fully automatic pistol. It utilises the same functions as a semi automatic pistol, similar gas reaction pushed the hammer back continously until the magazine is emptied. This usually requires the fitting of a longer magazine or drum magazine.

Thursday 26 May 2011

ANCIENT AND CLASSIC WEAPONS

 Ancient weapons were evolutionary improvements of late neolithic implements, but then significant improvements in materials and crafting techniques created a series of revolutions in military technology:
The development of metal tools, beginning with copper during the Copper Age (about 3,300 BC) and followed shortly by bronze led to the Bronze Age sword and similar weapons.
The first defensive structures and fortifications appeared in the Bronze Age, indicating an increased need for security. Weapons designed to breach fortifications followed soon after, for example the battering ram was in use by 2500 BC.
Although early Iron Age swords were not superior to their bronze predecessors, once iron-working developed - around 1200 BC in Sub-Saharan Africa, iron began to be used widely in weapon production because iron ore was much more readily available than the copper and tin required to create bronze.
Cavalry developed once horses were bred to support the weight of a man . The horse extended the range and increased the speed of attack, but was not a weapon as much as it provided an enhanced capability.
Domestication of the horse and widespread use of spoked wheels by ca. 2000 BC, led to the light, horse-drawn chariot. The mobility provided by chariots were important during this era. Spoke-wheeled chariot usage peaked around 1300 BC and then declined, ceasing to be militarily relevant by the 4th century BC.
Ships built as weapons or warships such as the Triremes were in use by the 7th century BC. These ships were eventually replaced by larger ships by the 4th century BC.

OLD WEAPONS

Very simple weapon use has been observed among chimpanzees, leading to speculation that early hominids began their first use of weapons as early as five million years ago. These would have been wooden clubs, spears, and unshaped stones—none of which would leave an unambiguous record.
Some of the earliest unambiguous weapons were throwing sticks and spears dated to around 400,000 years ago. The Schöninger Speere, eight wooden throwing spears from the Lower Paleolithic era, are thought to be the earliest known example of weapons used by the genus Homo. 

INTRODUCTION



       A weapon is a tool used with the aim of causing damage or harm (either physical or mental) to living beings. In human society weapons are used to increase the efficacy and efficiency of tasks such as hunting, fighting, the committing of criminal acts, the preserving of law and order, and the waging of war. Weapons are employed individually or collectively. A weapon can be either expressly designed as such or an item re-purposed through use (for example, hitting someone with a hammer), their form can range from simple implements such as clubs through to complicated modern implementations such as intercontinental ballistic missiles and biological weapons. Weapon development has progressed from early wood or stone clubs through revolutions in metalworking (swords, maces, etc.) and gunpowder (guns, cannon), electronics and nuclear technology. In a broader context, weapons may be construed to include anything used to gain a strategic, material or mental advantage over an adversary on land, sea, air, or even outer space.