A flare gun works in the same way as any traditional fi rearm with one key diff erence: it must ignite its projectile and propel it high into the sky. Generally credited to Edward Very, the fi rst gun that could fi re a flare was tested by the American Navy back in 1882. When the trigger of a fl are gun is pulled, a chain of events begins. First, the fl are’s propellant is ignited as the gun’s hammer strikes the detonator cap. The signal is then pushed out of the gun’s barrel through defl agration, which is a subsonic combustion process where an intense burning of gases in a small space generates pressure. The short time it takes to ignite the propellant is enough for the fl are to also be lit. These objects burn so brightly because they contain magnesium, an element also used in fireworks. Other chemical additives can produce varying colours. In some cases, the flare will also have an in-built parachute (most commonly for military use) that prolongs its fall to Earth and extends the average 40-second period that a fl are will typically burn brightly for.
