A flamethrower is a ranged incendiary device designed to project a controllable jet of fire. First deployed by the Byzantine Empire in the 7th century AD, flamethrowers saw use in modern times during World War I, and more widely in World War II as a tactical weapon against fortifications.
Most military flamethrowers use liquid fuel, typically either heated oil or diesel, but commercial flamethrowers are generally blowtorches using gaseous fuels such as propane. Gases are safer in peacetime applications because their flames have less mass flow rate and dissipate faster and often are easier to extinguish.
Apart from the military applications, flamethrowers have peacetime applications where there is a need for controlled burning, such as in sugarcane harvesting and other land-management tasks. Various forms are designed for an operator to carry, while others are mounted on vehicles.
Military use
Modern flamethrowers were first used during the trench warfare conditions of World War I and their use greatly increased in World War II. They can be vehicle-mounted, as on a tank, or man-portable.
The man-portable flamethrower consists of two elements—the backpack and the gun. The backpack element usually consists of two or three cylinders. In a two-cylinder system, one cylinder holds compressed, inert propellant gas (usually nitrogen), and the other holds flammable liquid, typically some form of petrochemical. A three-cylinder system often has two outer cylinders of flammable liquid and a central cylinder of propellant gas to maintain the balance of the soldier carrying it. The gas propels the liquid fuel out of the cylinder through a flexible pipe and then into the gun element of the flamethrower system. The gun consists of a small reservoir, a spring-loaded valve, and an ignition system; depressing a trigger opens the valve, allowing pressurized flammable liquid to flow and pass over the igniter and out of the gun nozzle. The igniter can be one of several ignition systems: A simple type is an electrically heated wire coil; another used a small pilot flame, fueled with pressurized gas from the system.
Flamethrowers were primarily used against battlefield fortifications, bunkers, and other protected emplacements. A flamethrower projects a stream of flammable liquid, rather than flame, which allows bouncing the stream off walls and ceilings to project the fire into unseen spaces, such as inside bunkers or pillboxes. Typically, popular visual media depict the flamethrower as short-ranged and only effective for a few metres (due to the common use of propane gas as the fuel in flamethrowers in movies, for the safety of the actors). Contemporary flamethrowers can incinerate a target some from the operator; moreover, an unignited stream of flammable liquid can be fired and afterwards ignited, possibly by a lamp or other flame inside the bunker.
Flamethrowers pose many risks to the operator. The first disadvantage is the weapon's weight and length, which impairs the soldier's mobility. The weapon is limited to only a few seconds of burn time, since it uses fuel very quickly, requiring the operator to be precise and conservative. Flamethrowers using a fougasse-style explosive propellant system also have a limited number of shots. The weapon is very visible on the battlefield, which causes operators to become immediately singled out as prominent targets, especially for snipers and designated marksmen. Flamethrower operators were rarely taken prisoner, especially when their target survived an attack by the weapon; captured flamethrower users were in some cases summarily executed.
The flamethrower's effective range is short in comparison with that of other battlefield weapons of similar size. To be effective, flamethrower soldiers must approach their target, risking exposure to enemy fire. Vehicular flamethrowers also have this problem; they may have considerably greater range than a man-portable flamethrower, but their range is still short compared with that of alternative weapons.
The risk of a flamethrower operator being caught in the explosion of their weapon due to enemy hits on the tanks is exaggerated in films. In some cases, the pressure tanks have exploded and killed the operator when hit by bullets or grenade shrapnel. In the documentary Vietnam in HD, platoon sergeant Charles Brown tells of how one of his men was killed when his flamethrower was hit by grenade shrapnel during the battle for Hill 875.
The pressurizer is filled with a non-flammable gas that is under high pressure. If this tank ruptures, it might knock the operator forward as it was expended in the same way a pressurized aerosol can bursts outward when punctured. The fuel mixture in the containers is difficult to light, which is why magnesium-filled igniters are required when the weapon is fired. When pierced by a bullet, a metal can filled with diesel or napalm will merely leak unless the round is an incendiary type that may ignite the mixture inside.Gordon, David. Weapons of the WWII Tommy
The best way to minimize the disadvantages of flame weapons was to mount them on armoured vehicles. The Commonwealth and the United States were the most prolific users of vehicle-mounted flame weapons; the British and Canadians fielded "Wasps" (Universal Carriers fitted with flamethrowers) at infantry battalion level, beginning in mid-1944, and eventually incorporating them into infantry battalions. Early tank-mounted flamethrower vehicles included the "Badger" (a converted Ram tank) and the "Oke", used first at Dieppe.
Operation
In a propane-operated flamethrower, the gas is expelled through the gun assembly by its own pressure and is ignited at the exit of the barrel through piezo ignition.
Liquid-operated flamethrowers use a smaller tank with a pressurized gas to expel the flammable liquid fuel. The propellant gas is fed to two tubes. The first opens in the fuel tanks providing the pressure necessary for expelling the liquid. The other tube leads to an ignition chamber behind the exit of the gun assembly, where it is mixed with air and ignited through piezo ignition. This pre-ignition line is the source of the flame seen in front of the gun assembly in movies and documentaries. As the fuel passes through the flame, it is ignited and propelled towards the target.
History
Ancient Greece
The concept of projecting fire as a weapon has existed since ancient times. During the Peloponnesian War, Boeotians used some kind of a flamethrower trying to destroy the fortification walls of the Athenians during the Battle of Delium.
According to Polybius the ancient Rhodian admiral Pausistratus used a device called πυρφόρος (pyrphoros; "fire-bearer") designed to project fire onto enemy ships while keeping it safely distant from the user's own vessel. The apparatus consisted of a funnel-shaped container (scoop or basket) filled with combustible material, suspended from the end of a pole by an iron chain that projected from the prow. These poles were supported by ropes running along the inner sides of the hull, allowing the funnel to extend outward on either side of the bow. Because the funnel was angled away from the ship, fire could be discharged into an enemy vessel during a charge or while passing alongside, without risking accidental ignition of the user's own ship.Polybius, Histories, 21.7.1 - 21.7.6, Topostext.orgPausistratus' fire‐basket lexical notes to polybius 21,7,1–4, Tandfonline.com
Roman Empire
In 107 AD the Romans used a flamethrower against the Dacians; the device was similar to the one used at Delium.
Later, during the Byzantine era, sailors used rudimentary hand-pumped flamethrowers on board their naval ships. Greek fire, extensively used by the Byzantine Empire, is said to have been invented by Kallinikos of Heliopolis, probably about 673 AD. Byzantine texts described weapons, used by Byzantine land forces, which were shooting Greek fire and called cheirosiphona (χειροσίφωνα, meaning hand-held siphons, singular χειροσίφωνο). The flamethrower found its origins in a device consisting of a hand-held pump that shot bursts of Greek fire via a siphon-hose and a piston which ignited it with a match, similar to modern versions, as it was ejected.Needham, Volume 5, 77. An illustration in Poliorcetica of Hero of Byzantium display a soldier with a portable flamethrower. Byzantines also used ceramic hand grenades filled with Greek fire.Byzantine Hand Grenade with Circular Designs, Ancient-art.co.uk Greek fire, used primarily at sea, gave the Byzantines a substantial military advantage against enemies such as members of the Arab Empire (who later adopted the use of Greek fire). An 11th-century illustration of its use survives in the John Skylitzes manuscript.
China
The Pen Huo Qi ("fire spraying device") was a Chinese piston flamethrower that used a substance similar to petrol or naphtha, invented around 919 AD during the Five Dynasties and Ten Kingdoms period. The earliest reference to Greek fire in China was made in 917, written by Wu Renchen in his Spring and Autumn Annals of the Ten Kingdoms.Needham, Volume 5, 80. In 919, the siphon projector-pump was used to spread the 'fierce fire oil' that could not be doused with water, as recorded by Lin Yu (林禹) in his Wu-Yue Beishi (吳越備史), hence the first credible Chinese reference to the flamethrower employing the chemical solution of Greek fire.Needham, Volume 5, 81. Lin Yu mentioned also that the 'fierce fire oil' derived ultimately from China's contact in the 'southern seas', with Arabia (大食國 Dashiguo).Needham, Volume 5, 82. In the Battle of Langshan Jiang (Wolf Mountain River) in 919, the naval fleet of the Wenmu King of Wuyue defeated the fleet of the Kingdom of Wu because he had used 'fire oil' to burn his fleet; this signified the first Chinese use of gunpowder in warfare, since a slow-burning match fuse was required to ignite the flames.Needham, Volume 5, Part 7, 81–83. The Chinese applied the use of double-piston bellows to pump petrol out of a single cylinder (with an upstroke and a downstroke), lit at the end by a slow-burning gunpowder match to fire a continuous stream of flame (as referred to in the Wujing Zongyao manuscript of 1044). In the suppression of the Southern Tang state by 976 AD, early Song naval forces confronted them on the Yangtze River in 975. Southern Tang forces attempted to use flamethrowers against the Song navy, but were accidentally consumed by their own fire when violent winds swept in their direction.Needham, Volume 5, 89. Documented also in later Chinese publications, illustrations and descriptions of mobile flamethrowers on four-wheel push carts appear in the Wujing Zongyao, written in 1044 (its illustration redrawn in 1601 as well). Advances in military technology aided the Song dynasty in its defense against hostile neighbours to the north, including the Mongols.
Islamic World Abū ʿAbdallāh al-Khwārazmī in Mafātīḥ al-ʿUlūm (“Keys to the Sciences”) ca. 976 AD mentions the bāb al-midfa and the bāb al-mustaq which he said were parts of naphtha-throwers and projectors (al-naffātāt wa al-zarāqāt). Book of Ingenious Mechanical Device (Kitāb fī ma 'rifat al-ḥiyal al-handasiyya) of 1206 by Ibn al-Razzaz al-Jazari mentioned about ejectors of naphtha (zarāqāt al-naft).
Siege of Malta During the Great Siege of Malta the defenders used a type of flamethrower known as Trump, consisting of a tube loaded with sulphur resin and linseed oil. It produced a flame that was several yards long
Vietnam The book Hồ trường khu cơ by Dao Duy Tu describes a flamethrowing weapon called the fire tiger "The fire-thrower is also called fire-tiger, has a large bulb about one meter long, when in battle it shoots fire, the tube shoots out pine resin, if it hits something, it immediately catches fire...". "Because the fire burns fiercely, it is called fire-tiger". These weapons were later used by the Tay Son Army.
18th century