designed to pass 0.5 ampere without firing
c. Releases.
and to fire when the current was 1.0
(1) Releases have been developed that
ampere. This early series of ignition
disconnect the parachute from a crash-
elements used the body of the element for
locator beacon, suspend and release
a ground.
A later series of ignition
single lug bombs, release external stores
elements was designed with 4 internal
front aircraft, and pull safety pins from
pins, insulated from the body of the
other propellant actuated devices.
device (fig.
Two pins are
(2) The release designed to pull the safety
interconnected and provide a testing
pin of another propellant actuated device
circuit separate from the firing circuit.
is shown in figure 9. It consists of a
The other two pins are connected to the
cylinder (body), piston with integral pin,
firing circuit. This device is designed with
and locking mechanism. The release pin
a 1.5 ampere no-fire and a 3.5 ampere
replaces the safety pin in the firing
all-fire qualification.
mechanism of a propellant actuated
(2) The two pins in the firing circuit are
device. The device does not contain a
connected to a wire filament in the
cartridge. Propellant gas supplied to the
element. This wire is coated with an
release unlocks the piston and causes it to
ignition bead which is ignited when the
retract and withdraw its pin from the firing
filament is heated by passing the required
mechanism of the device assembled to it,
current through it. Ignition of the bead
thereby arming the device.
sets off the main charge of the element.
(3) The type of release shown in figure 9 is
(3) To improve the reliability of electrically
commonly used in aircraft escape
initiated systems, auxiliary firing sources,
systems to unlock the firing mechanisms
such
as
electromagnetic
impulse
of initiators used to fire catapults. In
generators, have been developed.
these systems, the release is actuated
Electromagnetic
impulse
generators
automatically at the end of the pre-
contain several bar magnets and a coil.
ejection cycle. This prevents personnel
Movement of the handle or trigger on the
ejection prior to performing such
generator changes the reluctance in the
operations as seat positioning and canopy
magnetic circuit, generating a current in
removal.
the coil. These units have indefinite life,
d. Ignition Elements.
are
unaffected
by
environmental
(1) The electric ignition element is a device
extremes, and present a fixed impedance
designed to replace the firing pins and
for circuit checking.
percussion primers used with gas or
10. Systems. a. Aircraft Escape Systems.
mechanically fired propellant actuated
(1) Seat escape systems.
devices. Ignition elements have been
(a) Initially, relatively simple systems
developed that are capable of being fired
for canopy removal and seat
by an electrical power source such as an
ejection provided for the escape of
aircraft 28-volt dc supply.
The first
ignition
elements
developed
were
Figure 9. Release.
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