Muzzle flash

Muzzle blast is the term used to describe the release of high temperature, high pressure gas

Gas

Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...

es expelled from the muzzle

Muzzle (firearm)

The muzzle of a firearm is the end of the barrel from which the projectile will exit.Precise machining of the muzzle is crucial to accuracy, because it is the last point of contact between the barrel and the projectile...

of a firearm

Firearm

A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...

when it is discharged. Muzzle flash is the term used to describe the visible light

Visible spectrum

The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...

of the muzzle blast. The blast and flash are caused by the combustion products of the gunpowder

Gunpowder

Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...

, and any remaining unburned powder, mixing with the ambient air. The size and shape of the muzzle flash is dependent on the type of ammunition

Ammunition

Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...

being used and the individual characteristics of firearm and any devices attached to the muzzle (such as a muzzle brake

Muzzle brake

Muzzle brakes and recoil compensators are devices that are fitted to the muzzle of a firearm or cannon to redirect propellant gases with the effect of countering both recoil of the gun and unwanted rising of the barrel during rapid fire...

or flash suppressor

Flash suppressor

A flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a device attached to the muzzle of a rifle or other gun that reduces the visible signature of the burning gases that exit the muzzle. This reduces the chances that the shooter will be blinded in dark...

Muzzle blast

The muzzle flash is often broken down into two components, an auditory component and a non-auditory component. The auditory component, the sound of the muzzle blast, is important because it can cause hearing loss or give away the gun's position, while the non-auditory component, the overpressure wave, can cause damage to items near the blast.

Sound

The sound of a gunshot may have two sources; the muzzle blast itself, and any sound produced by a transonic

Transonic

Transonic speed is an aeronautics term referring to the condition of flight in which a range of velocities of airflow exist surrounding and flowing past an air vehicle or an airfoil that are concurrently below, at, and above the speed of sound in the range of Mach 0.8 to 1.2, i.e. 600–900 mph...

or supersonic

Supersonic

Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...

projectile. Suppressor

Suppressor

A suppressor, sound suppressor, sound moderator, or silencer, is a device attached to or part of the barrel of a firearm which reduces the amount of noise and flash generated by firing the weapon....

s help to reduce the level of sound of a firearm, by providing a large area for the propellant gas to expand and cool before release.

Overpressure wave

The overpressure

Overpressure

The term Overpressure is applied to a pressure difference, relative to a "normal" or "ambient" pressure, in various circumstances:* In engineering: the pressure difference over the wall thickness of a pressure vessel...

wave from the muzzle blast of a firearm can contain a significant amount of energy because it travels at an extremely high velocity. Residual pressures at the muzzle can be a significant fraction of the peak chamber pressure, especially when slow burning powders or short barrels are used. This energy can also be harnessed by a muzzle brake

Muzzle brake

to reduce the recoil of the firearm, or by a muzzle booster

Muzzle booster

A muzzle booster or recoil booster is a device affixed to the muzzle of a firearm, intended to harness the energy of the escaping propellant to augment the force of recoil on portions of the firearm. Muzzle boosters are usually used to improve the reliability of a recoil operated firearm...

to provide energy to operate the action.

Problems caused by muzzle blast

Muzzle blasts can reach levels of 140 decibel

Decibel

The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...

s, which can cause permanent hearing loss even with brief and infrequent exposure. With big guns such as artillery, that danger can extend outwards a significant distance from the muzzle.

The force of the muzzle blast can cause damage to items near the muzzle, and with artillery, the energy is sufficiently large to cause severe damage to surrounding structures and vehicles.

The muzzle flash refers to the light emitted by the muzzle blast, both visible light and infrared

Infrared

Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

. Both heat and pressure can result in light being emitted.

Muzzle flash characteristics

Muzzle flash can be broken down into five distinct components.

Muzzle glow is a reddish glow that is visible before the bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...

leaves the barrel
Gun barrel
A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....

. Muzzle glow is created by superheated gases that have leaked past the projectile and have exited the barrel.
The primary flash is caused by propellant gases exiting the firearm behind the bullet. Although amongst the brightest of the flashes, the heat of the primary flash dissipates quickly and thus is no longer visible.
The intermediate flash is caused by shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...

s created by the high speeds of the escaping gases and projectile, and appears as a reddish disc shape in front of the muzzle.
The secondary flash appears farthest from the muzzle as a large white or yellow flame. Secondary flash is caused by the mixture of fuel-rich gases and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

in the atmosphere surrounding the muzzle.
Following the dissipation of the muzzle flash, partially unburnt powder or other heated materials can be ejected from the muzzle and appear as sparks
Ember
Embers are the glowing, hot coals made of greatly heated wood, coal, or other carbon-based material that remain after, or sometimes precede a fire. Embers can glow very hot, sometimes as hot as the fire which created them...

.

Suppression of muzzle flash

Muzzle flash, particularly the long duration secondary flash, is an inherent problem in most firearms. Due to its brightness

Brightness

Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target...

, muzzle flash can temporarily blind the shooter, or give away the shooter's location, especially at night. Ingestion of the muzzle flash from aircraft mounted guns has also been implicated in compressor stall

Compressor stall

A compressor stall is a situation of abnormal airflow resulting from a stall of the aerofoils within the compressor of a jet engine. Stall is found in dynamic compressors, particularly axial compressors, as used in jet engines and turbochargers for reciprocating engines.Compressor stalls result in...

and flameout

Flameout

A flameout refers to the failure of a jet engine caused by the extinction of the flame in the combustion chamber. It can be caused by a number of factors, including fuel exhaustion; compressor stall; insufficient oxygen supply; foreign object damage ; severe inclement weather; and mechanical...

, causing loss of aircraft.

Flash suppressor

Flash suppressor

s attempt to suppress the flash mechanically, by interfering with the shock wave using either a cone or a series of slots at the muzzle of the firearm. However, since the primary cause of the secondary flash is combustion of hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

and carbon monoxide

Carbon monoxide

Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

, chemical approaches are also used. In World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, bags of sodium chloride

Sodium chloride

Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

(table salt) were placed in front of the propellant charges of artillery to suppress the flash. Addition of a few percent of alkali

Alkali

In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...

salt

Salt

In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

s to the powder for flash suppression is common, typically salts of potassium

Potassium

Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

such as potassium chloride

Potassium chloride

The chemical compound potassium chloride is a metal halide salt composed of potassium and chlorine. In its pure state, it is odorless and has a white or colorless vitreous crystal appearance, with a crystal structure that cleaves easily in three directions. Potassium chloride crystals are...

, potassium sulfate

Potassium sulfate

Potassium sulfate is a non-flammable white crystalline salt which is soluble in water...

, potassium carbonate

Potassium carbonate

Potassium carbonate is a white salt, soluble in water , which forms a strongly alkaline solution. It can be made as the product of potassium hydroxide's absorbent reaction with carbon dioxide. It is deliquescent, often appearing a damp or wet solid...

, and potassium bicarbonate

Potassium bicarbonate

Potassium bicarbonate , is a colorless, odorless, slightly basic, salty substance...

. In both cases, the salts act as catalysts, and interfere with the hydrogen-oxygen combustion to reduce the muzzle flash. The side effects of the alkali salts is a reduction in power, an increase in smoke, and fouling and corrosion of the firearm and nearby equipment (a significant concern with aircraft guns). Ammonium chloride

Ammonium chloride

Ammonium chloride NH4Cl is an inorganic compound with the formula NH4Cl. It is a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of natural, mineralogical form of ammonium chloride...

and ammonium nitrate salts have also been tried with success.

Detection of muzzle blast and flash

Systems to detect muzzle blast with microphones and triangulate the location where the shots were fired are commercially available, and have been installed in many high crime areas of large cities. These gunshot location system

Gunshot Location System

A gunfire locator is a system that detects and conveys the location of gunfire or other weapon fire using acoustic, optical, potentially other types of sensors, as well as a combination of such sensors. These systems are used by law enforcement, security, military and businesses to identify the...

s provide a fairly precise location of the source of a shot fired outdoors—99% to within 33 feet (10m) or better—and can provide it to police within seconds of the shot being fired.

Muzzle flashes create distinct signatures that can be located using infrared

Infrared

imaging technology. In fact, technology is being developed to detect enemy muzzle flashes before the projectile reaches its target.

External links

High speed photographs of shotgun muzzle blasts
Tutorial on how to add muzzle flares to a gun

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.