Pennsylvania-class battleship

The Pennsylvania-class battleship is an American battleship. Only two are known to have existed.

Characteristics
The Pennsylvania-class ships were significantly larger than their predecessors, the Nevada class. They had a waterline length of 600 feet (182.9 m), an overall length of 608 feet (185.3 m), a beam of 97 feet (29.6 m) (at the waterline), and a draft of 29 feet 3 inches (8.9 m) at deep load. This was 25 feet (7.6 m) longer than the older ships. Its designed standard and full load displacements were 31,400 long tons (31,900 t) and 32,440 long tons (32,960 t), respectively, but they actually displaced 29,158 long tons (29,626 t) standard and 31,917 long tons (32,429 t) at full load, over 4,000 long tons (4,060 t) more than the older ships. The class had a metacentric height of 7.82 feet (2.4 m) at full load.

The ships had four direct drive Parsons steam turbine sets with geared cruising turbines, each of which drove a propeller 12 feet 1.5 inches (3.7 m) in diameter. They were powered by twelve Babcock & Wilcox water-tube boilers. The turbines were designed to produce a total of 31,500 shaft horsepower (23,500 kW), but only achieved 29,366 shp (21,898 kW) during Pennsylvania's sea trials, when it slightly exceeded its designed speed of 21 knots (39 km/h; 24 mph). Pennsylvania reached 21.75 knots (40.28 km/h; 25.03 mph) during full-power trials in 1916, and Arizona reached 21.5 knots (39.8 km/h; 24.7 mph) in September 1924. The class was designed to normally carry 1,548 long tons (1,573 t) of fuel oil, but had a maximum capacity of 2,305 long tons (2,342 t). At full capacity, they could steam at a speed of 12 knots (22 km/h; 14 mph) for an estimated 6,070 nautical miles (11,240 km; 6,990 mi); this could be extended to 7,585 nautical miles (14,050 km; 8,730 mi) with a clean bottom. They had four 300-kilowatt (402 hp) turbo generators.

The Pennsylvania class carried twelve 14-inch/45 caliber guns in triple gun turrets. The guns could not elevate independently and were limited to a maximum elevation of +15° which gave them a maximum range of 21,000 yards (19,000 m). The ships carried 100 shells for each gun. Defense against torpedo boats was provided by twenty-two 5-inch/51 caliber guns mounted in individual casemates in the sides of the hull; these proved vulnerable to sea spray and could not be worked in heavy seas. At an elevation of 15°, they had a maximum range of 14,050 yards (12,850 m). Each gun was provided with 230 rounds of ammunition. The ships mounted four 3-inch (76 mm)/50 caliber anti-aircraft (AA) guns, although only two were fitted when completed. The other pair were added shortly afterward on top of Turret III. The class also mounted two submerged 21-inch (533 mm) torpedo tubes and carried 24 Bliss-Leavitt Mark 3 torpedoes for them.

The Pennsylvania-class design continued the all-or-nothing principle of armoring only the most important areas of the battleships, which began in the preceding Nevada class. The waterline armor belt of Krupp armor measured 13.5 inches thick and only covered the class' machinery spaces and magazines. It had a total height of 17 feet 6 inches (5.3 m), of which 8 feet 9.75 inches (2.7 m) was below the waterline; beginning 2 feet 4 inches (0.7 m) below the waterline, the belt tapered to its minimum thickness of 8 inches. The transverse bulkheads at each end of the ships ranged from 13 to 8 inches in thickness. The faces of the gun turrets were 18 inches (457 mm) thick while the sides were 9–10 inches (230–250 mm) thick and the turret roofs were protected by 5 inches of armor. The armor of the barbettes was 13 to 4.5 inches (330 to 114 mm) thick. The conning tower was protected by 16 inches (406 mm) of armor and had a roof eight inches thick.

The main armor deck was three plates thick with a total thickness of 3 inches; over the steering gear the armor increased to 6.25 inches (159 mm) in two plates. Beneath it was the splinter deck that ranged from 1.5 to 2 inches (38 to 51 mm) in thickness. The boiler uptakes were protected by a conical mantlet that ranged from 9 to 15 inches (230 to 380 mm) in thickness. A 3-inch torpedo bulkhead was placed 9 feet 6 inches (2.9 m) inboard from the side, and the class was provided with a complete double bottom. Testing in mid-1914 revealed that this system could withstand 300 pounds (140 kg) of TNT.

History
While both members of this ship-class were present at Pearl Harbor during its attack, only USS Arizona is known to have appeared onscreen. Most notably, it was the ship that suffered a one-hit K.O. when an Aichi D3A bomb reached the ship's ammunition-storage area.

Sometime after, it was said that several men were trapped inside the sunken Arizona, though unlike the Oklahoma, no rescue efforts were shown happening at the ship.

Trivia

 * The Arizona is the only ship in Pearl Harbor that was never salvaged.