R. Meyer J. Köhler A. Homburg Explosives

157 Gurney energy
which these powders are utilized. Such powders are known as “cold
propellants”.
Further research for gunbarrel-saving propellants led to the development
of nitroguanidine powders, in which W Nitroguanidine (picrite) is
the third energy-containing component, beside nitroglycerine (or diglycol
dinitrate or triglycol dinitrate) and nitrocellulose. Powders containing
more than 40% nitroguanidine can be made only with the aid of
solvents.
Another special processing method is used for the manufacture of
W Ball Powder. Floating spheres of concentrated nitrocellulose solutions
are cautiously suspended in warm water; the solvent evaporates
gradually and the floating spheres solidify. Finally, an intensive surface
treatment is needed to reach the desired ballistic behavior. The ballistic
properties of a powder are affected not only by its chemical
composition, but also by its shape. Thus, in conventional weapons, it
ought to bring about progressive burning, or at least ensure that the
surface area of the grain remains constant during combustion.
The following geometric forms of powder grains are manufactured:
perforated long tubes perforated tubes, cut short
multi perforated tubes flakes
strips ball powder
cubes rods, cut short
rings
Finer-grained powders are used for portable firearms; tubular powder
is mostly employed for guns; powders in the form of flakes and short
tubes are employed for mortars, howitzers, and other high-angle firearms.
Finer-grained powders can be improved in their ballistic behavior by
W Surface Treatment. Phlegmatizers are infiltrated in the outer layer of
the powder grains; the burning rate in the weapon chamber begins
slowly and turns progressive.
Gurney energy
The energy EG per unit mass available for the acceleration of fragments
of detonating explosives. It consists of the kinetic energies of
the moving accelerated fragments and fumes.
Gurney velocity
The velocity of fragments of explosives extrapolated to zero mass.
vG = öäää 2 EG