Fire is one of the most useful natural phenomena in the
world. When early humans first captured fire from naturally
burning areas, and later generated flames themselves, their
lives changed dramatically. With this understanding of nature,
they could have light and
heat after nightfall, and they could cook their food.
fire is also one of the most dangerous phenomena in the world,
and this fact wasn't lost on early humans. Archeological
evidence suggests early hunters used fire to flush out their
prey, and some groups may have used it to fight other humans.
Throughout history, fire has proven to be an extremely
effective, devastating weapon.
One of the most interesting developments in fire weaponry
was the flamethrower. The modern flamethrower came
about in the early 20th century, but the original idea is
actually thousands of years old. In this edition of HowStuffWorks,
we'll look at these early pyrotechnic weapons, as well as
their modern counterparts, to understand what they do and how
they do it.
Feel the Burn Fire is caused by a chemical
reaction between two or more substances, typically oxygen in
the air and some sort of fuel (gasoline, wood, or coal
for example). This reaction is triggered by extreme heat,
often caused by another flame or a spark. The fire's own heat
is sufficient to keep the chemical reaction going as long as
there is fuel to burn.
The basic idea of a flamethrower is to spread fire by
launching burning fuel. The earliest flamethrowers,
dating roughly from the 5th century B.C., were long tubes
filled with burning solid material (such as sulfur or coal).
These weapons worked in the same way as a blow-gun -- warriors
just blew into one end of the tube, propelling the burning
matter toward their enemies.
A more sophisticated sort of flamethrower came into
widespread use in the 7th Century. In this era, the Byzantine
Empire added "Greek fire" to its arsenal. Greek fire
was probably a mixture of liquid petroleum, sulfur, quicklime
and other elements. In any case, it was a highly-flammable,
Early use of "Greek fire," as shown in a 10th
In combat, Byzantine forces would pump this substance from
a large reservoir, through narrow brass tubes. These tubes
concentrated the pressurized liquid into a powerful stream,
the same way a hose and nozzle concentrate water into a narrow
jet. The soldiers lit a fuse at the end of the brass tubes to
ignite the fluid stream as it shot out. The fluid stream
carried fire dozens of feet through the air.
The Byzantines mounted these weapons along the walls of
Constantinople, as well as the bows of their ships. Since the
flammable substance was oil-based, it would still burn even
when it hit the water, making it a particularly effective
weapon in naval battles.
Initially, the Byzantines' enemies were mystified by this
horrific weapon, but before long, others were copying the
technology. The Chinese applied their advanced technology to
take the idea to the next level. The Byzantines used a very
basic pump, like the sort used to drive water out of an
underground well. This kind of pump only pushes out fluid on
the downstroke, so the Byzantine flamethrower could only shoot
fire in short bursts. The Chinese had developed a more
advanced pump, the double-acting bellows. Double-acting
bellows consist of a pivoting pedal that drives two pumping
chambers. When the pedal is pushing down on one chamber (the
downstroke), it's lifting up on the other (the upstroke). In
this way, the pump is constantly pushing out fluid, allowing a
continuous stream of fuel (and therefore a constant blast of
Soon after this sort of weaponry came into use, it was
eclipsed by another pyrotechnic technology: gunpowder.
Over the next thousand years, gunpowder revolutionized the
world of warfare, and flamethrowers more or less fell by the
But as we'll see in the next section, flamethrowers were
eventually reintroduced into the world's combat arsenal, in a
Fight Fire With Fire In World War I, the
German army rediscovered the flamethrower and added it to
their arsenal (in a new and improved form). By World War II,
forces on both sides used a range of flamethrower weapons on
Photo courtesy NARA French soldiers make a gas and flame attack
on German trenches in Flanders, Belgium, during WWI.
The most impressive innovation was the handheld
flamethrower. This long, gun-type weapon has an attached
fuel tank that soldiers can carry on their back.
Photo courtesy NARA A
U.S. flamethrower operator in Vietnam during Operation
New Castle -- the weight and size of the fuel tanks made
the soldier extremely vulnerable to enemy fire, and
troops had to be assigned to protect
The diagram below shows how a typical handheld unit works.
The backpack contains three cylinder tanks. The two
outside tanks hold a flammable, oil-based liquid fuel, similar
to the material used to make Greek fire. The tanks have
screw-on caps, so they can be refilled easily. The middle tank
holds a flammable, compressed gas (such as butane). This tank
feeds gas through a pressure regulator to two connected tubes.
One tube leads to the ignition system in the gun, which
we'll discuss later on. The other tube leads to the two side
fuel tanks, letting the compressed gas into the open area
above the flammable liquid. The compressed gas applies a great
deal of downward pressure on the fuel, driving it out of the
tanks, through a connected hose, into a reservoir in the gun.
The gun housing has a long rod running through it,
with a valve plug on the end. A spring at the back of the gun
pushes the rod forward, pressing the plug into a valve seat.
This keeps the fuel from flowing out through the gun nozzle
when the trigger lever is released. When the operator squeezes
the trigger lever, it pulls the rod (and the attached plug)
backward. With the valve open, the pressurized fuel can flow
through the nozzle. A flamethrower like this one can shoot a
fuel stream as far as 50 yards (46 meters).
As it exits the nozzle, the fuel flows past the ignition
system. Over the years, there have been a variety of
ignition systems used in flamethrowers. One of the simpler
systems was a coil of high-resistance wire. When electrical
current passed through these wires, they released a lot of
heat, warming the fuel to the combustion point. The gun in the
above diagram has a slightly more elaborate system.
When the ignition valve is open, compressed
flammable gas from the middle cylinder tank on the backpack
flows through a long length of hose to the end of the gun.
Here it is mixed with air and released through several small
holes into the chamber in front of the nozzle. The gun also
has two spark plugs positioned in front of the nozzle, which
are powered by a portable battery.
To prepare the gun, the operator opens the ignition valve and
presses a button that activates the spark plug. This creates a
small flame in front of the nozzle, which ignites the flowing
fuel, creating the fire stream.
Photo courtesy U.S. Department of
Defense A U.S. Navy "Zippo"
flamethrower is tested from a patrol boat. The
unreliability of electronic ignition systems meant that
operators sometimes had to use a Zippo lighter to ignite
the fuel as it left the
In World Wars I and II, as well as in the Vietnam war,
similar flamethrower designs were mounted on tanks.
Photo courtesy NARA Flame tanks of the 1st Tank Battalion attack
No-name Village, in the Quang Ngai province of Vietnam,
Typically, the fuel in these weapons was driven by rotary
or piston pumps, powered directly by the tank engine. With
greater pumping power, tank-mounted flamethrowers had better
range, and with more fuel tank space, they had a larger
Civilians with Fire Military forces continue
to use these sorts of weapons today, but the technology is
more commonly used for nonviolent civilian purposes.
Most notably, foresters use flamethrowers in prescribed
burning, and farmers use it to clear fields. Some car
enthusiasts install low-range flame throwers at the back of
their cars, to release an impressive ball of fire when they
take off. Rock stars and other entertainers often include
flamethrowers as part of elaborate pyrotechnic displays.
One of the most widely known flamethrower technologies
today is actually the simplest. "Fire breathers" turn
their own bodies into flamethrowers by pouring fuel (typically
kerosene) into their mouth and holding an ignition system
(typically a torch) in front of them. When they spit out the
kerosene, the torch ignites it, creating a dazzling stream of
fire (only professionals should attempt this -- it is
extremely dangerous). The technique is definitely low-tech,
but the operating principle is exactly the same as in the most
expensive military flamethrowers!
For more information on flamethrowers and related topics,
check out the links on the next page!