Flare (pyrotechnic)
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- This article is about pyrotechnic flares. For other uses, see flare (disambiguation).
A flare is a type of pyrotechnic that produces a brilliant light or intense heat without an explosion. Flares are used for signaling, illumination, or defensive countermeasures in civilian and military applications.
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[edit] Delivery and composition
Flares generally produce their light through the combustion of magnesium metal, sometimes colored by the inclusion of other metals. Calcium flares are used underwater for illumination.
Flares may be ground pyrotechnics, projectile pyrotechnics, or parachute-suspended to provide maximum illumination time over a large area. Projectile pyrotechnics may be dropped from aircraft, fired from rocket or artillery, or deployed by handheld percussive tubes. Flares may also be dropped in the water to illuminate submerged objects.
[edit] Civilian use
In the civilian world, flares are commonly used as distress signals, and may be ignited on the ground or fired as an aerial signal from a pistol-like flare gun. Flare guns are commonly found in marine survival kits.
Another type of flare is the fusee, which burns for 15-60 minutes with a bright red light. Fusees are commonly used to indicate obstacles or advise caution on roadways at night; in this usage they are also called highway flares or ground flares. They are commonly found in roadside emergency kits.
In forestry and firefighting, fusees are sometimes used in wildland fire suppression and in the ignition of controlled burns. They are especially effective in igniting burnouts or backburns in very dry conditions, but not so effective when fuel conditions are moist. Since controlled burns are often done during relatively high humidity levels (on the grounds that they could not be safely contained during periods of very low humidity), the driptorch is more effective and more often used. Fusees are also commonly carried by wildland firefighters for emergency use, to ignite an escape fire in surrounding fuels in case of being overrun by a fire if no other escape routes are available.
Fusees are also known as railroad flares and are used to perform hand signals in rail transport applications. Since they can be used only once, fusees are intended for emergency use (as opposed to the incandescent lanterns typically used during normal operating conditions).
Incendiary flares have been shown to leach perchlorate in water since 2002 [citation needed]. One groundwater aquifer system in San Martín, CA has been impacted, affecting neighboring cities with widespread low level concentrations of perchlorate from incendiary flare operations of former flare manufacturer.
Flares are commonly used by spectators of sporting matches.
[edit] Military use
[edit] Land
Ground military forces in need of a large-area illumination for artilleries or for an attack, often request the delivery of parachute-flares. Ground forces may also deploy hand-held flares for aerial or ground signaling to indicate the correct area for releasing ordnance, deploying paratroopers, or landing an aircraft. In World War II, clusters of coloured flares were deployed by reconnaissance aircraft or pathfinders to mark targets for bomber missions and supply drops.
[edit] Sea
Naval flares may be employed by naval forces to illuminate undersea targets such as submarines at depth. Naval flares are also launched from anti-submarine aircraft from fixed, multi-barrel, ejectors on the sides of the fuselage.
[edit] Air
A special variety of flare is used in military aircraft as a defensive countermeasure against heat-seeking missiles. These flares are usually discharged individually or in salvoes by the pilot or automatically by tail-warning devices, and are accompanied by vigorous evasive maneuvering. Since they are intended to deceive infrared missiles, these flares burn at temperatures of thousands of degrees, incandescing in the visible spectrum as well. Soids are floating flares that are effective only in the terminal phase of missiles with infrared signature seeker heads.
[edit] See also
- Very flare (WWI)
