The GTE drives the propulsor assembly by means
well as the drive pads for the lube oil supply and
of the power train assembly. We have already talked
scavenge pumps. Eight thermocouples, one in each
about the LM2500 GTE that provides the power for the
main bearing, monitor bearing temperatures.
foilborne propulsion system. Now, let's take a look at
Flexible Coupling and Shaft Assemblies
the propulsor assembly for this system.
A double-diaphragm flexible coupling connects the
PROPULSOR ASSEMBLY
low-speed and high-speed pinion shafts. Each coaxial
output shaft consists of an inner high-speed quill shaft
The foilborne propulsor consists of a two-stage
and an outer low-speed quill shaft. Splines in the
Aerojet Liquid Rocket waterjet pump, a bearing, and a
high-speed and low-speed output gears drive the output
seal assembly. The Aerojet pump forces seawater up
shafts.
through the two ducts in the two aft foil struts into a
single foilborne water jet nozzle that exhausts the
FOILBORNE CONTROL SYSTEMS AND
seawater through a transom at the hullborne waterline.
OPERATING STATIONS
(See figs. 7-19 and 7-20.) The frost stage of the waterjet
pump operates at a lower speed for good suction
The foilborne control systems include all the
performance. The second stage runs at a higher speed to
systems that allow a PHM in the foilborne mode to
increase pressure and velocity. The propulsor assembly
respond to control commands. These systems include
is driven by the GTE through the gearbox assembly or
the ACS, foilborne engine control system (FECS),
power train, which we will discuss next.
foilborne propulsor control system (FPCS), and the
bulkhead-mounted electronics enclosure (BMEE). The
POWER TRAIN ASSEMBLY
foilborne control systems also include the foilborne
equipment and systems found in the foilborne control
The power train assembly consists of the gearbox,
stations, such as the EOS and the pilothouse.
flexible coupling, and shaft assemblies. The GTE drives
the gearbox through a high-speed flexible coupling
Pilothouse
shaft. This shaft is designed to accommodate any axial
or radial movement between the GTE and gearbox that
Foilborne operation is primarily controlled from the
results from dynamic loads and thermal expansion.
pilothouse. The pilothouse control console, which is
Because the GTE is directly coupled to the propulsor
shown in figure 7-21, is designed for a two-man
t h r o u g h the gearbox, there is no disengagement
operation under normal conditions. The helmsman is
capability. This means that whenever the GTE is
seated on the right with the primary maneuvering
operating, the propulsor is being driven.
controls and displays arranged on the console within his
or her reach. The displays necessary for conning and
Gearbox Assembly
monitoring the ship are grouped on the left in front of
the OOD seat. Overhead panels, which can be reached
The gearbox assembly is a Western Gear
from either seat, contain the controls and indicator lights
lightweight, reduction transmission unit that sends
f o r critical ship's systems and the windshield
power from the GTE to the foilborne propulsor through
washer/wiper controls.
the bearing and seal assembly. The gearbox is split
vertically into a high-speed assembly and a low-speed
Engineer Operating Station
assembly and consists of main drive pinions that drive
two coaxial output shafts through two sets of double
The EOS is located on the port side of the platform
helical reduction gears. This design allows it to provide
deck adjacent to the gas turbine machinery room and
speed reduction and power split to the two propulsor
turbine inner intake plenum. Although a seat is available
impellers. It does this by reducing the input speed from
for a second operator or for training purposes, the EOS
the GTE and providing separate output shafts to the
is basically arranged for a one-man operation.
propulsor first-stage inducer and the second-stage
impeller, allowing these two sections to operate at
The EOS control panel arrangement is shown in
different speeds. An access hole in the high-speed
figure 7-22. The power plant controls are on the main
assembly and one in the low-speed assembly provide a
console. The electrical and fuel controls are on the
means for inspection. The gearbox assembly also
i n b o a r d cabinet. The hydraulic panel is placed
provides four hydraulic pump accessory drive pads as
diagonally at the corner. A more detailed view of a
7-23
