and, consequently, reducing the pressure of the gas
gas-actuated device is critical: the pins must withstand
remaining in the chamber.
the shock of the drop test and yet shear when the firing
pin is subjected to a specific gas pressure. The concept
b. In transferring hot gas from one chamber to
of shear pins is presented in chapter 4.
another, as with initiators, teflon-lined hose is used
16. Heat Loss. a. A highly theoretical discussion of
primarily because it absorbs less heat than stainless
heat loss is unnecessary in the design of propellant
steel tubing and introduces less friction loss than rubber
actuated devices. It is important, however, that several
hose.
factors be understood. To minimize heat loss, the metal
c. In preliminary designs of propellant actuated
surface in contact with the hot propellant gas should be
devices, it is common to assume the devices to be 8 to
kept to a minimum, consistent with the chamber volume
10 percent efficient. No attempt is made to calculate
required. Heat loss has a great effect on devices which
the actual losses due to heat and friction, but rather, the
retain or produce hot propellant gas for a long period of
above efficiency is assumed and adjustments in energy
time (gas generators) ; the chamber walls absorb heat,
requirements are made during testing.
thus lowering the temperature of the gas in the chamber
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