Smokeless Powder - Flashless Propellant

Flashless Propellant

Muzzle flash is the light emitted in the vicinity of the muzzle by the hot propellant gases and the chemical reactions that follow as the gases mix with the surrounding air. Before projectiles exit a slight pre-flash may occur from gases leaking past the projectiles. Following muzzle exit the heat of gases is usually sufficient to emit visible radiation – the primary flash. The gases expand but as they pass through the Mach disc they are re-compressed to produce an intermediate flash. Hot combustible gases (e.g. hydrogen and carbon-monoxide) may follow when they mix with oxygen in the surrounding air to produce the secondary flash, the brightest. The secondary flash does not usually occur with small-arms.

Nitrocellulose contains insufficient oxygen to completely oxidize its carbon and hydrogen. The oxygen deficit is increased by addition of graphite and organic stabilizers. Products of combustion within the gun barrel include flammable gasses like hydrogen and carbon monoxide. At high temperature, these flammable gasses will ignite when turbulently mixed with atmospheric oxygen beyond the muzzle of the gun. During night engagements the flash produced by ignition can reveal the location of the gun to enemy forces and cause temporary night-blindness among the gun crew by photo-bleaching visual purple.

Flash suppressors are commonly used on small arms to reduce the flash signature, but this approach is not practical for artillery. Artillery muzzle flash up to 150 feet (46 m) from the muzzle has been observed, and can be reflected off clouds and be visible for distances up to 30 miles (48 km). For artillery the most effective method is a propellant that produces a large proportion of inert nitrogen at relatively low temperatures that dilutes the combustible gases. Triple based propellants are used for this because of the nitrogen in the nitroguandine.

Before the use of triple based propellants the usual method of flash reduction was to add inorganic salts like potassium chloride so their specific heat capacity might reduce the temperature of combustion gasses and their finely divided particulate smoke might block visible wavelengths of radiant energy of combustion.