Heat Loss

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