Design Report Guided Missile Submarine SSG(X) - AOE - Virginia ...

SSG(X) Design – VT Team 3 Page 89
4.8.5 Final External Arrangements
The locations of the vertical launch system (VLS) and hydrogen storage tanks are the two important criteria in
developing the external arrangements see section 4.3. Figure 89 and Figure 90 show the location of the combat and
mission systems. The combat system is comprised of the VLS located at amidships, torpedo and sonar systems
located in the bow, and the sail and masts located forward of the VLS. The command, control, and communications
space is located directly below the sail in the pressure hull. The ballast tanks, hydrogen fuel tanks, compensating
fuel tank, shrouded propeller, sail and stern plans are also shown in Figure 89 and Figure 90.
4.9 Final Weights, Loading and Equilibrium
Figure 89 - External Arrangements
Figure 90 - External Arrangements - Profile View
4.9.1 Summary of Concept Development Equilibrium Changes
The first step in balancing SSG(X) was to calculate its longitudinal center of buoyancy (LCB). To do this, the
LCBs of each displacing volume were compiled into an Excel spreadsheet. The LCBs were estimated using the
ship’s arrangements drawings. The LCB and TCB of the ship were determined by summing the LCBs of the
displacing volumes. The next step in balancing SSG(X) was to calculate its longitudinal center of gravity (LCG).
Ship weights are grouped by SWBS. The components list was obtained from the Model Center optimization. The
weight for each component was compiled into the spreadsheet. In addition to the weights, their centers of gravity
(vertical and longitudinal) were entered. These centers of gravity were estimated using the ship’s arrangements
drawings. The weights and centers of gravity (CGs) were used to find the lightship load and the LCG of SSG(X).
To make sure that SSG(X) was balanced, the LCG needed to be as close to the LCB as possible. In order to
facilitate this need, the CG of every component was taken with reference to the LCB of the submarine. The variable
ballast tank volumes and CGs were then added to the spreadsheet. The variable ballast tanks were used to create the
boundary of the equilibrium polygon. The equilibrium polygon serves as the boundary of the operational envelope
for ballast and trim for SSG(X). The submarine design is feasible if all of its loading conditions lie within the
equilibrium polygon. The arrangements drawings, weights spreadsheet, and the variable loads are used in creating
the extreme loading conditions in the different water densities that the submarine will encounter. The loading
conditions used are the Normal Condition, Light #1, Heavy #1, Heavy #2 (mines), Heavy Forward #1, Heavy
Forward #2, and Heavy Aft. Table 39 illustrates each of the loading conditions and the water density used for each
loading condition. Figure 91 shows the initial equilibrium polygon with the initial loading conditions.