R. Meyer J. Köhler A. Homburg Explosives

Specific Impulse
f = pV = nRT
where p is the pressure, V is the volume, n is the number of moles of
the explosion gases per kg (also Volume of Explosive Gases), R is the
ideal gas constant, and T is the absolute temperature of the explosion.
If we put the volume equal to unity, i.e., if the loading density is unity,
the specific energy becomes
f = p
i.e., is equal to the pressure which would be exerted by the compressed
explosion gases in their confinement, if the latter were indestructible.
This is why the term “specific pressure” is also frequently
used, and why the magnitude f is often quoted in atmospheres.
Nevertheless, strictly speaking, f is an energy per unit mass and for
this reason is reported in meter-tons per kg. The value of T will have
this dimension if R is taken as 0.8479·10 –3 mt·K·mol.
In accordance with recent standardisation regulations, the energy data
are also reported in joules. For more details on the calculation W Thermodynamic
Calculation of Decomposition Reactions; also W Strength.
Specific Impulse
spezifischer Impuls; impulse spécifique
The specific impulse of a propellant or a pair of reacting liquids in
rocket motors is the most important characteristics of the performance.
It is the W ThrustVtime (i.e., the impulse) per unit weight of
propellant:
F ·t
Is =
W
Is specific impulse
F: thrust
T: time
W: weight of propellant
It is measured in kilopond-seconds (or Newton-seconds) per kilogram
of propellant*). It can be evaluated by the equation
Is = öäääääää 2J (Hc–He) N s/kg
J: mechanical heat equivalent
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* Since the numerical values of kp and kg are the same, the apparent dimension
of the specific impulse is simply the second. For this reason, all impulse data
can be directly compared with each other, even if other unit systems are
employed.