GLOSSARY
Adiabatic-Occurring without gain or loss of heat.
Adiabatic flame temperature-The temperature attained by the gaseous products of the combustion of a propellant if no
heat is lost to the surrounding medium.
Ballistic cycle-The elapsed time between the ignition of propellant actuated device and the completed function of the
device.
Buffer-(See Damper.)
Burning rate, linear-The rate of regression of a burning propellant surface measured normal to the surface. Generally
expressed in inches per second.
Burning rate, mass-The rate of consumption of a propellant charge, generally expressed in pounds (or grams) per
second.
Cartridge actuated device (CAD)-(See Propellant actuated device.)
Catapult-A propellant actuated device designed to propel an ejection seat with personnel from the aircraft.
Conditioning temperature-The temperature at which a propellant actuated device is "soaked" before test firing.
Cutter-A propellant actuated device designed to sever cables or parachute shroud lines.
Damper-A hydraulic or pneumatic device incorporated in or attached to a propellant actuated device to limit the velocity
of the stroking member.
Double-base propellant-A propellant which contains two explosive ingredients, commonly nitrocellulose and nitroglycerin.
Efficiency, piezometric (ballistic)-The ratio of the mean ballistic cycle pressure to peak pressure in a propellant actuated
device during the ballistic cycle.
Efficiency, thermal-The ratio of the mechanical energy of an accelerated mass to the energy resulting from propellant
Ejector-A stroking-type propellant actuated device designed to eject small masses.
Expansion ratio-The ratio of the final to the initial volume available to the propellant gases in a stroking type device.
Form function-The property of a propellant which describes the amount of gases produced with the burning of a given
fraction of the propellant web.
Function time-In a stroking-type propellant actuated device, it is the interval of time from the initiation of operation to the
completion of the stroke.
Granulation, propellant-The geometry of propellant grain, e.g., solid cylinder, single-perforated, and multi-perforated
cylinders.
Head space-The distance between the cartridge head and the breech face. Propellant actuated devices are designed
with "zero" head space.
Ignition delay-The interval between the actuation of the firing mechanism and the beginning of sustained pressure in the
propellant chamber.
Impetus-The energy released by the burning propellant per unit weight of propellant, generally expressed in foot-pounds
per pound.
Initiator-A propellant actuated device designed to supply gas pressure to initiated propellant actuated devices.
Inverse of molecular weight-The number of moles in a unit weight of propellant.
Isochoric adiabatic flame temperature-Adiabatic flame temperature attained in a constant volume system.
Key-A small mechanical component in a locking mechanism which acts to restrain the motion of a stroking member.
Latch-(See Key.)
Neutral burning-(See Neutral granulation.)
Neutral granulation-Propellant granulation in which the surface area of a grain remains constant during the burning.
The burning of a propellant with neutral granulation is termed "neutral burning."
Nonplateau-A propellant whose burning rate varies with pressure over the full pressure range.
Pin, safety-A manual locking member used on a propellant actuated device to prevent accidental operation.
Pin, shear-A pin used as a locking member which is released by shearing.
Plateau propellant-A propellant whose burning rate is almost constant over a range of pressures.
Pressure-time curve-A curve of the internal pressure of a propellant actuated device plotted as a function of time.
Primer blow back-The escape of propellant gas through the primer cup in the cartridge head.
Progressive burning-(See progressive granulation.)
Progressive granulation-With progressive granulation, the surface area of a grain increases during the burning. The
burning of a propellant with progressive granulation is termed "progressive burning".
Propellant actuated device (PAD)-A device that employs the energy supplied by gases produced by propellants to
accomplish or initiate a mechanical action, other than expelling a projectile. Propellant actuated devices were
formerly referred to as cartridge actuated devices.
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