Figure 25. T28 Thruster.
experience with previous systems, but the testing phase
workhorse model is fabricated and tested.
The
is the major determinant. Systems are tested on
procedure then becomes one of modification and retest
breadboard mockups and on rocket sleds at various
until the design specifications are satisfied with the most
speeds to determine the overall operation of each
efficient arrangement of components.
device in conjunction with every other device.
g. A portion of the design and testing phases may
be eliminated by using computers. An analog computer
c. The operation of devices in a system may be
has been used for analyzing a catapult's performance
sequenced by mechanical means such as gear trains or
theoretically under various acceleration loads and
static lines; however, the most common method is
friction forces.
through pyrotechnic delays and bypass fittings on the
ends of propellant actuated devices. Many pyrotechnic
36. Systems. a. Multi-component PAD systems
delays have been standardized, but their metal parts
generally are designed by the air-frame or missile
often are modified to insure the proper fit in the various
manufacturer under the direction of the cognizant
cartridge cases. The tubing, hose, and gas fittings used
agency. However, in the design of propellant actuated
in these systems are also standardized. Various fittings
devices, systems can be improved by eliminating
and types of hose or tubing have been studied, but
devices or combining several operations into one device
standardization has not reached the point of determining
to improve reliability and guarantee proper operating
equivalent lengths of hose for fittings, as is done in the
sequence of the system.
hydraulics industry.
b. The sequencing of operations is determined by
Section V. COMPONENT DESIGN
sealed in position by crimping the
37. Cartridge. a. General.
cartridge case.
(1) The cartridge (fig. 26) is a metal can
which contains the propellant, igniter, and
(2) Most cartridges contain percussion
primer. It is designed to burst open from
primers,
although
electric
ignition
the pressure of the propellant gases. The
elements have been used in place of
can (case) is hermetically sealed to keep
percussion primers in cartridges for
out moisture (moisture interferes seriously
missile applications.
An electrically
with performance). The hardware portion
initiated cartridge is similar except for the
of the cartridge consists of a drawn
primer. The percussion primer is fired by
aluminum case and a head. The head is
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