Flare

For other uses, see Flare (disambiguation). "Signal flare" redirects here. For the character, see Signal Flare (Transformers).

Oh, joy. Another meticulously documented account of humanity's ingenious methods for creating bright, ephemeral light. One might think, given the vastness of the universe and the brevity of existence, that our species would find more compelling uses for its collective effort than illuminating the void with chemical reactions. But here we are.

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!Illumination flares being used during military training exercises Illumination flares being used during military training exercises. Because nothing says "strategically advantageous" like setting things on fire.

!Flares being fired from a ship during a fleet review Flares being fired from a ship during a fleet review. An expensive way to make a point, or simply to announce one's presence with extreme prejudice.

A flare, which is also sometimes rather quaintly referred to as a fusée, fusee, or bengala, [1] [2] and occasionally bengalo [3] in various European countries—because why have one name when you can have several that mean essentially the same thing?—is, at its core, a particular type of pyrotechnic. Its primary function is to produce a conspicuously bright light or, in certain applications, an intense burst of heat, all without the dramatic, concussive force of an [explosion]. It's a controlled burst of chemical reaction, precisely engineered to demand attention. Flares are deployed across a spectrum of scenarios, from desperate distress signaling and battlefield illumination to sophisticated defensive [countermeasures] in both the civilian and military spheres. These devices manifest in several forms: they can be ground-based pyrotechnics, ignited and left stationary; they can be projectile pyrotechnics, launched into the air; or they can be suspended by a parachute, designed to drift slowly and provide maximum illumination time over a broad area. Projectile variants are incredibly versatile, capable of being deployed from aircraft, fired with considerable velocity from rockets or [artillery] pieces, or even launched with more localized precision by [flare guns] or robust, handheld percussive tubes. A truly multifaceted way to say, "Look at me!" or "Leave me alone!" depending on the context.

Origin

Oh, the endless human fascination with making things go "boom" or "flash." Long before the intricate chemical formulations we see today, the seeds of pyrotechnic signaling were sown.

See also: History of gunpowder and Fireworks

The earliest verifiable instance of gunpowder being repurposed for signaling purposes, rather than immediate destructive intent, was documented during the Chinese Song Dynasty (960–1279 CE). This rudimentary but effective device was known as the 'signal bomb.' It found its moment of historical significance when the Mongol-led Yuan Dynasty (1271–1368 CE) laid siege to the city of Yangzhou in 1276. These 'bombs,' unlike their more lethal counterparts, were designed with a soft casing and were timed to detonate high in the midair. Their purpose was not to inflict damage, but to transmit messages across considerable distances to detached units of troops, a primitive but undeniably effective form of long-range communication. Another, equally telling, mention of these 'signal bombs' surfaces in a text from 1293, which rather prosaically requests their collection from existing stores in [Zhejiang]. [4] Clearly, even back then, inventory management was a concern. By the year 1600, a more advanced 'signal gun' had made its appearance in Korea. Further evidence of this progression is found in the Wu I Thu Phu Thung Chih, or Illustrated Military Encyclopedia, an extensive work compiled in 1791, which includes an explicit illustration depicting a signal gun. [5] It seems the desire to get someone's attention from afar is a timeless human impulse.

Transition

The intricate art and science of Chinese fireworks, along with other seminal pyrotechnic technologies, inevitably traversed the vast distances, accompanying the gradual, inexorable spread of gunpowder into European countries. Nations such as Italy and Germany, ever eager to embrace new forms of both artistic expression and scientific inquiry, enthusiastically adopted fireworks. This adoption spurred significant chemical and technological advancements, transforming mere explosive power into dazzling displays. However, the early European pyrotechnicians, often grandly titled "fire masters" [6], rather conspicuously failed to develop truly effective, reliable signal flares. Their efforts were hampered by an over-reliance on a relatively unsophisticated mixture, primarily composed of gunpowder, saltpeter, and various colorant metals. While this concoction certainly caused rapid combustion, the resulting 'blue lights'—as they were rather optimistically nicknamed—were largely ineffective. Despite emitting a bright white light, the crucial element of distinct, decipherable colors proved elusive, rendering them utterly unreliable for the complex communication purposes they were intended for. This was the closest Europe came to a functional signal flare for a considerable period, a testament to the fact that enthusiasm alone does not guarantee innovation.

It wasn't until the pivotal year of 1859 that American inventor Martha Jane Coston stepped into the spotlight. Following the tragic demise of her husband, Benjamin Franklin Coston, she painstakingly continued his nascent work, ultimately developing and patenting her groundbreaking "Pyrotechnic Night Signal." This invention was a monumental leap forward, utilizing a far more sophisticated and stable chemical composition involving oxidizers, fuel, and precisely selected colorants (as we'll discuss in the Chemistry section) to produce flares that were not only intensely bright but also remarkably long-lasting. [7] Coston, a woman clearly ahead of her time, didn't stop at the invention itself. Recognizing the critical need for practical application, she simultaneously developed a comprehensive code system [8] specifically designed for maritime use. This dual innovation—a reliable signal and a standardized method for interpreting it—created an unparalleled, effective communication method for vessels navigating the vast, often treacherous expanses of the sea. Her profound advancements in both the chemical formulation and the technical deployment of signal flares fundamentally reshaped safety protocols. These innovations were swiftly adopted and applied to roadside [9], rail, military, and maritime safety devices, establishing the enduring standard for modern flares across virtually all applications that persist to this very day. A singular mind, cutting through the noise and delivering something truly useful. It happens, occasionally.

Civilian use

Ah, the civilian world, where the stakes are often merely inconvenient rather than existentially dire. Even here, the flare finds its purpose, primarily as a desperate plea for attention or a simple warning.

A conventional flare pistol. This particular model uses 26.5-millimeter (1.04 in) flares (manufactured by Patel Ballistics).

In the civilian sphere, flares are most commonly employed as signals. These signals can be initiated in several ways: they may be ignited directly on the ground, creating a stationary beacon; they can be launched as an aerial signal, typically fired from a pistol-like [flare gun], sending a projectile skyward; or, for simpler deployment, they can be launched from a self-contained tube, a more compact and less specialized method. Given their critical role in emergencies, flares are a ubiquitous and essential component commonly found within marine [survival kits], a testament to their enduring reliability when all else fails.

Maritime distress signal

The concept of distress rockets, often referred to as "rocket-propelled parachute flares" [10], has been firmly entrenched in the modern era of civilian maritime emergencies since at least the mid-19th century, with records dating back to 1856. The venerable U.S. Nautical Magazine of that year, a publication that no doubt chronicled many a maritime woe, explicitly mentions the strategic use of "rocket stations" specifically for ship-related emergencies. [11] Initially, only white rockets were utilized for distress signaling, a rather bland and potentially confusing choice, given that white lights could signify many things on the open sea. This monochromatic approach persisted until 1873, when Commander John Yorke of the venerable Royal Navy astutely observed the glaring need for rockets designated for distress to possess a distinctly identifiable color. His insightful request was driven by the very practical desire to mitigate confusion between genuinely distressed vessels and the rockets routinely employed by [pilot ships]—vessels that guided larger ships into harbor and often used signals themselves. [12]

By 1875, the UK Board of Trade had responded to this critical need, issuing comprehensive regulations for ship captains concerning night signals. These new directives stipulated that rockets containing a minimum of 16 ounces of [composition] were to be exclusively reserved as a definitive sign of a ship in dire distress. Furthermore, passenger ships of the era were mandated to carry a specific complement of 12 such rockets, ensuring they were adequately equipped for emergencies. [13] The Merchant Shipping Act 1894 further codified these protocols, explicitly stating that these distress rockets were to be fired one at a time, at short, deliberate intervals of approximately one minute apart, to maximize visibility and avoid ambiguity. [14] This practice of using distinctively colored distress rockets continued, as tragically exemplified by the infamous sinking of the RMS Titanic. It was a known fact at the time that various shipping companies maintained "a particular kind of distress rocket (that differed by color)." Each vessel was also furnished with a detailed guide outlining the specific colors to be deployed depending on the nature of the signal intended to be sent. [14] [15] A system, it seems, that was perhaps too nuanced for the chaos of a true emergency.

The use of modern red distress signals gained official recognition much later. The United States Bureau of Mines noted their importance as early as 1959, specifying that "12 handheld rocket-propelled parachute red flare distress signals" were to be carried by ocean-going vessels. [16] The color red was ultimately integrated into the United States' "Universal color language" on 17 December 1979, solidifying its unambiguous meaning. [10] Consequently, red distress rockets and/or flares are now universally recognized international symbols, unequivocally indicating a ship in distress, a plea for aid understood across all maritime boundaries. [17] [18] The International Convention for the Safety of Life at Sea (SOLAS), the authoritative body governing maritime safety, has established rigorous standards for visual signals, encompassing both handheld and aerial flares. Handheld flares, for instance, are required to burn for a minimum duration of one minute, maintaining an average [luminosity] of 15,000 [candelas]. Aerial flares, designed for greater visibility over distance, must burn for at least 40 seconds, emitting a more potent 30,000-candela average luminosity. [19]

While these pyrotechnic rockets and flares undeniably remain a viable option for signaling distress, they have, with the relentless march of technological progress, been largely superseded by more advanced and efficient methods. Distress signals can now be transmitted with remarkable precision and reliability using automated radio signals originating from a [search and rescue transponder]. Other internationally acknowledged methods include the iconic radio message [SOS], a desperate plea famously employed during the 1912 sinking of the [Titanic], and the universally understood emergency procedure word "[Mayday]," a term that has been in use since the 1920s. [17] [20] [21] It seems even the most dramatic of signals eventually yields to the silent efficiency of digital transmission.

Roadside and rail

Three road flares burning. A surprisingly poetic sight for such mundane circumstances.

Another common application for flares, specifically the variety known as the fusee, is in terrestrial signaling. These particular flares are designed to burn with a distinctive, bright red light [22] and typically fall into two primary categories, each tailored for specific environments: roadways and [rail transportation]. The first type, often encountered on asphalt, are fusees intended for roadways, colloquially known as highway flares or road flares. [23] [24] These are routinely deployed to mark obstacles or to advise caution on roadways, particularly during the low visibility of night, and are considered an essential component of most roadside emergency kits. [25] Law enforcement agencies also frequently utilize these flares, either propped up on a biped stand for elevated visibility or simply laid flat on the ground, to signal traffic hazards or to indicate that a road segment is blocked. They often serve as a more conspicuous and immediate alternative to traditional traffic cones, especially in dynamic situations. [26] [27] [28] In the United States, law enforcement typically favors magnesium-based flares, which provide a consistent burn time ranging from 15 to 30 minutes, a relatively brief but effective window for managing traffic. [28]

The second distinct category comprises fusees specifically designed for rail applications, aptly termed railroad flares. These are commonly employed by railroad personnel for a dual purpose: performing critical hand signals, particularly in low-light conditions, and serving as temporary torches in various [rail transport] scenarios. [22] [29] Railroad flares are engineered for a longer burn duration, lasting at least 10 minutes, and unlike some other signaling devices, they are not fastened to train cars. Instead, they are handheld by railroad personnel, providing a portable and immediate means of protection and communication during night operations. [22] During an Appeals case, it was compellingly argued that railroad flares possess significantly greater visibility than traditional [lanterns], underscoring their effectiveness in critical safety applications. [22] As a general rule, trains encountering a lit railroad flare are under strict orders to stop their movement until the flare has completely burned out, a testament to the imperative nature of this signal. [30] To distinguish them from their highway counterparts, fusees manufactured specifically for railroad use are equipped with a sharp steel spike at one end, a practical feature designed to allow the fusee to be firmly embedded upright into a wooden [railroad tie], ensuring stability and optimal visibility.

Forestry and firefighting

In the demanding and often perilous fields of forestry and firefighting, fusees—these humble, bright-burning sticks—find a surprisingly strategic application, particularly in the intricate dance of [wildfire suppression] and the deliberate ignition of [controlled burns]. They are not merely for show; these flares are a tool of precision and controlled chaos. They possess a relatively low ignition temperature, igniting reliably at 191 °C (376 °F), making them easy to deploy. Once ignited, however, they burn with an astonishing intensity, reaching temperatures as high as 1,600 °C (2,910 °F). [31] This extreme heat allows them to rapidly ignite fuel, creating firebreaks or backburns with efficiency, turning fire against fire in a calculated, if still dangerous, manner. A stark reminder that even destruction can be a tool.

Protests

Flares, it seems, are also a favored accessory in the theater of human dissent and control.

!Antifa protestors using flares Antifa protestors using flares. Because nothing says "peaceful demonstration" like a bright, burning chemical reaction.

Unsurprisingly, flares are not exclusively for emergencies or controlled burns. They are also deployed by law enforcement agencies, such as the United States National Guard and various police forces, as a calculated component of [riot control]. [32] This practice, a subtle form of psychological warfare and crowd management, dates back to at least the 1940s, where they are mentioned in military texts as being "useful in night operations." [32] The bright, disorienting light can be used to break up formations, signal movements, or simply to create a sense of unease. Conversely, handheld flares are also co-opted and utilized by protestors themselves during [demonstrations]. [33] Whether for visibility, dramatic effect, or as a symbolic act of defiance, the human desire to be seen and heard—or to prevent others from being so—manifests in predictable, fiery ways.

Military use

Where the stakes are, by definition, always dire.

Maritime signal flare

As mentioned previously, a testament to her enduring impact, in 1859, Martha Coston successfully patented the Coston flare. This pivotal invention was the culmination of the foundational work initially undertaken by her late husband, Benjamin Franklin Coston. [34] Her contribution to maritime safety and military communication was truly foundational.

Illumination

Further information: Battlefield illumination

The military's need for illumination extends beyond mere signaling; sometimes, you simply need to see what's lurking in the shadows. In 1922, a device known as a "landing flare" was already in use. This ingenious contraption consisted of an aerial candle, robustly attached to a parachute, and its primary purpose was to facilitate the hazardous endeavor of landing an airplane in the profound darkness of night. The flare, though brilliant, had a rather limited operational lifespan, burning for less than four minutes, but it compensated with an impressive [candlepower] of approximately 40,000 [lumens]. [35] During the tumultuous period of [World War II], the U.S. Navy, ever innovative in its pursuit of tactical advantage, even experimented with underwater flares. These specialized flares were designed for the crucial task of detecting submerged [submarines], attempting to pierce the murky depths with light to expose hidden threats. [36] The lengths to which humanity will go to illuminate its targets, even beneath the waves, is truly something.

Countermeasure

Main article: Flare (countermeasure)

Perhaps the most technologically sophisticated application of flares lies in their use as defensive [countermeasures] in military aircraft. These are not your average roadside beacons. This specialized variety of flares is specifically engineered to protect against the insidious threat of heat-seeking missiles. These flares are typically discharged either individually or in rapid salvos by the pilot, often in conjunction with vigorous evasive maneuvering, or automatically by sophisticated tail-warning devices that detect incoming threats. Their purpose is to create a more attractive infrared signature than the aircraft itself, thereby diverting the missile. Since their entire raison d'être is to deceive infrared missiles, these flares burn at extraordinarily high temperatures, often reaching thousands of degrees Celsius. This intense heat causes them to [incandesce] not only in the infrared spectrum, but also quite vividly in the visible spectrum, creating a blinding flash that adds to the confusion for any pursuing weapon system. It's a fleeting, fiery distraction, but sometimes, a fleeting moment is all you need to survive.

Tripflares

Main article: Tripflare

In the less glamorous, but equally critical, realm of perimeter security, flares are ingeniously integrated into devices known as [tripwires]. These unassuming devices are strategically deployed to guard an area against unauthorized infiltration. The mechanism is elegantly simple: when the [tripwire] is triggered by an unsuspecting intruder, it initiates the flare. The immediate result is a sudden burst of light and, often, an accompanying sound, serving a dual purpose: providing both an unmistakable alarm to alert defenders and instant illumination of the area, revealing the presence and position of the intruder. It's a rather blunt but undeniably effective way to say, "You've gone too far."

Regulation

Even the creation of bright, fiery signals cannot escape the long arm of bureaucracy and environmental concern.

Under the UN hazard number system, the various forms of pyrotechnic flares are universally designated as class 1.4 explosives. [37] This classification, of course, comes with a host of regulations concerning their manufacture, storage, and transport, ensuring that the very tools meant to signal safety don't inadvertently cause a catastrophe themselves.

In a more localized, yet increasingly significant, development, several U.S. states, notably California and Massachusetts, have begun to implement stringent regulations concerning the permissible levels of potassium perchlorate in various products. This compound, while effective in pyrotechnic formulations, can pose serious health risks if present at certain concentrations in drinking water supplies. Contaminated drinking water can lead to a range of alarming symptoms, including gastric irritation, persistent nausea, vomiting, fever, troublesome skin rashes, and in severe, tragic cases, even fatal [aplastic anemia]—a devastating reduction in all types of blood cells. [38] It seems even the most dazzling displays can leave a toxic residue.

Chemistry

Ah, the intricate dance of elements that brings forth such brilliant, ephemeral light. It's all rather straightforward, if you understand the fundamental principles of combustion.

Flares produce their characteristic light through the carefully controlled [combustion] of a precisely engineered [pyrotechnic composition]. The specific ingredients vary considerably depending on the desired effect, but they are frequently based on core oxidizers such as [strontium nitrate] (often used for red colors), [potassium nitrate] (a classic oxidizer), or [potassium perchlorate] (a powerful, though increasingly regulated, oxidizer). These oxidizers are meticulously mixed with a suitable fuel. Common fuels include finely powdered [charcoal], elemental [sulfur], [sawdust] (a rather rustic choice, but effective), powdered [aluminium], elemental [magnesium] (known for its intense white light), or a suitable [polymeric resin] that provides a consistent burn. [39] To achieve the vibrant, distinct colors so crucial for signaling, flares are further enhanced by the precise inclusion of specific [pyrotechnic colorants]—metal salts that emit light at particular wavelengths when heated to incandescence. For specialized applications, such as underwater illumination, [calcium] flares are employed. These are specifically designed to burn effectively in a submerged environment, providing light where traditional flames would be extinguished, illuminating the murky depths for various purposes.

Perchlorate flare health issues

Humanity's drive for efficiency often comes with unforeseen ecological and health consequences. The pervasive use of perchlorate in pyrotechnics is a prime example.

Many of the colored signal flares and the spectrally balanced [decoy flares] currently in service, particularly in older stockpiles, contain [perchlorate] [oxidizers]. Perchlorate, a type of [salt] in its solid, crystalline form, exhibits a rather unfortunate characteristic: it readily dissolves in water and moves with alarming speed through both groundwater and surface water systems. The insidious nature of perchlorate lies in its biological effect; even at low concentrations in drinking water supplies, this compound is known to inhibit the crucial uptake of [iodine] by the [thyroid gland]. This interference can have significant health ramifications, as the thyroid plays a vital role in regulating metabolism. While, perhaps surprisingly, there are currently no US federal [drinking water standards] specifically for perchlorate, a growing number of states have taken proactive measures. Some have established public health goals or action levels, while others are in the arduous process of establishing state-specific maximum contaminant levels. For instance, the [US Environmental Protection Agency] has dedicated considerable resources to studying the multifaceted impacts of perchlorate on both the environment and, critically, on drinking water sources. [40] California, ever at the forefront of environmental regulation, has also issued comprehensive guidance regarding perchlorate use within its borders. [41]

The legal system, a slow but often inevitable arbiter of consequence, has also taken action concerning the widespread use of perchlorate in the manufacturing of pyrotechnic devices like flares. A significant precedent was set in 2003 when a federal district court in California ruled that the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) applied to perchlorate. The court's reasoning was that perchlorate is inherently ignitable and therefore constitutes a "characteristic" [hazardous waste] under US law. [42] This ruling has had tangible effects: flares currently manufactured in the United States have, as a direct result, undergone significant reformulation. They no longer utilize [potassium perchlorate] as an oxidizer and have also eliminated the inclusion of [aluminium] or [magnesium] in their compositions, seeking to mitigate the environmental and health risks associated with these legacy ingredients. [43] A small step, perhaps, but one that acknowledges the long-term cost of short-term brilliance.