development of the first series of thrusters, designated
limitations of the human body in the various flight suits
M1, M2, M3, and M5. Since that time many new and
which have been developed. Table I summarizes the
varied applications for propellant actuated devices have
present limitations outlined in the military specification
been found in the escape system and other weapons
covering the design of propellant actuated devices.
systems for various services.
Table I. Physiological Limitations for Personnel
i. Propellant actuated devices are commonly
Ejection
supplied by the Air Force as Government Furnished
Equipment (GFE).
Current development and
Maximum
Maximum
manufacture is accomplished primarily by the Munitions
Direction of ejection
rate of change
Command at Frankford Arsenal. Approximately 175
(g)
of acceleration
propellant actuated devices and cartridges are
(g/sec)
fabricated and over one-half have been standardized
Upward ................................
20
250
and are available off the shelf.
Downward............................
12
125
5. Uses. a. Although propellant actuated devices were
Rearward (seat positioning) .
6
60
developed originally for emergency escape from
aircraft, they have been used for many other short-
duration, high-force applications, such as ejecting radio
f. The first ejection seat catapult was standardized
beacons in the event of a crash, supplying gas pressure
in 1947 and designated the M1 Personnel Catapult. The
to operate hydraulic pumps in missiles, releasing bombs
design and development of the M1 and M2 canopy
or jettisoning stores from aircraft, and ramming
removers followed in quick succession. These early
projectiles into the breech of a howitzer. Propellant
devices were mechanically initiated; i.e., cocked firing
actuated devices are useful in these applications
pins were released by rotating or withdrawing a sear.
because of their reliability, simplicity, light weight, small
The "choke coil," bell-crank rod, and cable-actuated
size, and ability to withstand long periods of storage
system left much to be desired from a reliability,
under extremes of environment without impairment of
simplicity, and maintenance standpoint.
reliability.
g. In 1949, Frankford Arsenal developed a
b. Propellant actuated devices have been
propellant gas pressure source which was designated an
proposed for parachute and cargo separation, reduction
initiator.
Concurrently, the Arsenal redesigned the
of landing shock, landing gear extenders, Gatling gun
existing devices to incorporate a pressure-operated
and missile rotators, and life raft inflators. Applications
firing mechanism. The propellant gas was transmitted
in the form of rotational motors for augmenting or
by hydraulic hose assemblies from the initiators to the
starting standard engines and operation of a varied
firing mechanisms.
family of such devices in space, where weight and bulk
h. With the advent of the B-52 airplane and its
are at a premium, is also practicable. In addition, gas
requirements for multi-crew, multi-functional, integrated
servo mechanisms would eliminate some of the
escape system, it was realized that a new form of
common problems inherent in hydraulic systems by
propellant actuated device (PAD) could furnish thrust to
substitution of gas which is more suitable to applications
position ejection seats, unlock hatches, stow control
involving high temperatures and radiation. All such
columns, etc. In 1951, with the enthusiastic support of
devices are capable of full output on command and may
the airframe contractors and Wright Air Development
be time phased after triggering as desired.
Center, Frankford Arsenal commenced the design and
2
