CHAPTER 4
STEAM-POWERED CATAPULTS
Steam is the principal source of energy and is
supplied to the catapults by the ship's boilers. The
steam is drawn from the ship's boilers to the catapult
wet steam accumulator, where it is stored at the desired
pressure. From the wet accumulator, it is directed to the
launch valve, and provides the energy to launch aircraft.
The most significant differences between the various
types of steam catapults are the length and capacity. See
table 4-1 for the differences.
Each steam catapult consists of eight major systems:
Steam System
Launching Engine System
Lubrication System
Bridle Tensioning System
Hydraulic System
Retraction Engine System
Drive System
Catapult Control System
STEAM SYSTEM
LEARNING OBJECTIVES: Describe the
components of the steam system. Describe the
function of the steam system.
The catapult steam system (fig. 4-1) consists of the
steam wet accumulator, accumulator fill and blowdown
valves, trough warm-up system, steam smothering
system and the associated valves and piping. The seam
system
is
under
the
technical
cognizance
of
NAVSEASYSCOM and is operated and maintained by
engineering department personnel. An explanation of
the steam system major components will provide a
better understanding of catapult operations. Figure 4-2
is a simplified schematic of a typical catapult steam
piping arrangement. The schematic only shows the
piping and valves associated with a single catapult
when lined up with the steam plant that normally
supplies that catapult. Valves and piping that allow
cross connecting of catapults with all steam plants are
not shown. Cross connecting provides the capability of
operating any catapult from any power plant.
WET ACCUMULATOR WARM-UP
The accumulator warm-up procedure allows valves
and piping between the steam plant and the catapult to
initially
slowly
warm
up
to
bring
the
metal
temperatures to operating level. Hot feed water is
admitted into the steam accumulator to approximate the
low operating level. The launch valve is opened to
purge air from the accumulator and steam is slowly
admitted into the accumulator feed water to raise the
water temperature. When the water temperature
reaches approximately 225 degrees, the launch valve is
closed and accumulator heating continues. Steam
pressure is increased in increments allowing enough
time at each increment for the water temperature to
increase to a predetermined temperature. This slow
increase in temperature and pressure will ensure a
thermally
stable
accumulator
when
operating
parameters are reached.
TROUGH WARM -UP
The trough warm-up procedure allows valves and
piping between the steam plant and the catapult to
slowly warm -up to bring the metal temperatures to
operating level. When steam is directed to a catapult for
4-1
Item
C-13-0
C-13-1
C-13-2
Power stroke (in feet)
249-10"
309-8 3/4"
306-9"
blTrack length (in feet)
264-10"
324-10"
324-10"
Weight of shuttle and pistons (in pounds)
6,350
6,350
6,350
Cylinder bore (in inches)
18
18
21
Power stroke displacement (in cubic feet)
910
1,148
1,527
Table 4-1.—Steam Catapult Data
