P-class cruiser
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The P class was a planned group of twelve
heavy cruiser The heavy cruiser was a type of cruiser, a naval warship designed for long range and high speed, armed generally with naval guns of roughly 203 mm (8 inches) in caliber, whose design parameters were dictated by the Washington Naval T ...
s of Nazi Germany's '' Kriegsmarine''; they were the successor to the s. Design work began in 1937 and continued until 1939; at least twenty designs were submitted with nine of them being considered. There were three designs that were selected as the final contenders. One design was armed with six 283mm main guns in one triple turret forward and one more turret aft. It had two 150mm double secondary gun turrets as secondary armament with one being positioned above and just fore of the aft of the main 283mm main turret, and the other being in front and lower of the front main gun turret. This design had more beam than the other 2 designs. It also mounted 2 seaplanes on its fantail instead of the mid ship area. The final design was armed with six quick-firing guns in two triple turrets, as in the preceding ''Deutschland'' class. The ships were designated as ''Panzerschiff'' (armored ship), and given the preliminary names P1–P12. They were an improved design over the preceding planned D-class cruisers, which had been canceled in 1934. Although the ships were already assigned to shipyards, construction never began on the P-class ships after the design superseded them.


Design

In the early 1930s,
Adolf Hitler Adolf Hitler (; 20 April 188930 April 1945) was an Austrian-born German politician who was dictator of Nazi Germany, Germany from 1933 until Death of Adolf Hitler, his death in 1945. Adolf Hitler's rise to power, He rose to power as the le ...
began a rearmament program in Germany. He signed the
Anglo-German Naval Agreement The Anglo-German Naval Agreement (AGNA) of 18 June 1935 was a naval agreement between the United Kingdom and Germany regulating the size of the '' Kriegsmarine'' in relation to the Royal Navy. The Anglo-German Naval Agreement fixed a ratio whe ...
in 1935, which allowed Germany to build up its navy to 35 percent of the strength of the British
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and effectively repudiated the restrictions of the
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on the German fleet. This led to a decision in 1937 to build ships to an improved design, which were at that time classified as "" (armored ship). Design work on the new class of armored ships began that year. After more than twenty designs were evaluated to meet the navy's specifications, one was chosen; it was designated as cruiser "P". It called for a ship that displaced , which had a maximum speed of , and was armed with a
main battery A main battery is the primary weapon or group of weapons around which a warship is designed. As such, a main battery was historically a gun or group of guns, as in the broadsides of cannon on a ship of the line. Later, this came to be turreted ...
of six guns in two triple turrets. By 1938, it became clear to Admiral
Erich Raeder Erich Johann Albert Raeder (24 April 1876 – 6 November 1960) was a German admiral who played a major role in the naval history of World War II. Raeder attained the highest possible naval rank, that of grand admiral, in 1939, becoming the f ...
that Hitler's aggressive foreign policy would bring conflict with Britain. He therefore decided that a significantly larger force of armored ships would be necessary to execute an effective commerce raiding campaign against the British. Raeder's intention to fight a commerce war against Britain was the basis for
Plan Z Plan Z was the name given to the planned re-equipment and expansion of the ''Kriegsmarine'' (German navy) ordered by Adolf Hitler in early 1939. The fleet was meant to challenge the naval power of the United Kingdom, and was to be completed by 194 ...
, which included twelve ships of the P-class design. The design work on the new ships proceeded in parallel with work on the design. Experiments were conducted on at least nine different design proposals between March 1938 and December 1939. The designs varied somewhat in terms of dimensions as well as armament; some of the designs featured three 28 cm triple turrets. Many problems were encountered with designing the ships, the most prevalent being armor. The required maximum speed of meant that the minimum length had to grow from the original to . It also meant that the
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could be a minimum of —unless
diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-ca ...
s, like those used in the ''Deutschland''s, were desired; they would increase the beam by . Unfortunately for the designers, the widened beam meant that an even longer hull was needed to maintain hydrodynamic efficiency. All of this complicated the armor arrangements, as more armor was needed to cover the hull as it grew in size. Eventually it was deemed that it was impossible to include diesel power on a 20,000-metric-ton displacement. The displacement limit was therefore increased to accommodate diesel engines. Initially, twelve ships were ordered based on the P-class design. The ships were ordered under the provisional names P1 through P12; the contracts were awarded to a number of German shipyards, including
Deutsche Werke Deutsche Werke was a German shipbuilding company that was founded in 1925 when Kaiserliche Werft Kiel and other shipyards were merged. It came as a result of the Treaty of Versailles after World War I that forced the German defense industry to shri ...
in
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, Blohm & Voss in
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, and the in
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. However, Plan Z was reduced in size, and the number of armored ships was pared down to only eight vessels. This caused several of the contracts to be shifted around amongst the various shipbuilding companies. The first keel was set to be laid on 1 Feb 1940. The revised version of Plan Z, approved on 27 July 1939, removed the P-class ships from the construction queue. Instead, the decision was made to build the O-class battlecruisers only. And the outbreak of
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
in September meant that not even those vessels would be built.


General characteristics and machinery

The P-class ships were to have been long at the waterline, and overall. The ships would have had a beam of and a designed
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of ; the maximum draft was to be . The design featured a very long
forecastle The forecastle ( ; contracted as fo'c'sle or fo'c's'le) is the upper deck of a sailing ship forward of the foremast, or, historically, the forward part of a ship with the sailors' living quarters. Related to the latter meaning is the phrase " be ...
deck that extended for most of the length of the hull, terminating just forward of the aft main battery turret. They were to have incorporated longitudinal frame stringer steel construction, and would have been primarily
welded Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as braz ...
to save weight. The ships would have had thirteen
watertight compartment A compartment is a portion of the space within a ship defined vertically between decks and horizontally between bulkheads. It is analogous to a room within a building, and may provide watertight subdivision of the ship's hull important in retaini ...
s and a
transom stern The stern is the back or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite the bow, the foremost part of a ship. Or ...
. The forward superstructure consisted of a large, armored conning tower with a heavy tower mast; a smaller secondary conning tower with a pole mast was located further aft. The ships were to have been equipped with two catapults on the quarterdeck, arranged side-by-side, perpendicular to the
centerline Center line, centre line or centerline may refer to: Sports * Center line, marked in red on an ice hockey rink * Centre line (football), a set of positions on an Australian rules football field * Centerline, a line that separates the service cou ...
. Each catapult carried an
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. The ships were designed to be equipped with twelve MAN 9-cylinder V-configuration double acting two-stroke diesel engines, which were arranged in four sets of three, each of which drove one of four shafts. The shafts each turned a
screw A screw and a bolt (see '' Differentiation between bolt and screw'' below) are similar types of fastener typically made of metal and characterized by a helical ridge, called a ''male thread'' (external thread). Screws and bolts are used to f ...
that was in diameter. Smoke from the diesels would have been vented through a pair of large funnels
amidships This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water (mostly though not necessarily on the sea). Some remain current, while many date from the 17th ...
. The propulsion system was rated to produce a top speed of from . The ships were designed to carry of fuel oil, but were capable of storing up to . At a cruising speed of , this enabled a maximum range of ; at , the range was reduced to .


Armament and armor

The ships were armed with a main battery of six quick-firing guns mounted in two triple turrets, one fore and one aft on the centerline. It is not known if these were to have been the same 28 cm SK C/28 guns as the preceding ''Deutschland''-class cruisers, or the 28 cm SK C/34 guns used by the ''Scharnhorst''-class battleships. The ships were also armed with a
secondary battery A rechargeable battery, storage battery, or secondary cell (formally a type of energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or pri ...
of four /L55 guns in two twin turrets, also mounted on the centerline, fore and aft. The fore 28 cm turret would have been superfiring over the fore 15 cm turret; the layout was reversed for the aft pair of turrets. The 15 cm twin turrets were Drh L. C/34 mounts—the same type as those fitted to the - and s, as well as a number of other designs. The turrets allowed depression to −10 degrees and elevation to 40 degrees, which enabled a maximum range of . The 15 cm guns had a rate of fire of between 6 and 8 rounds per minute, at a muzzle velocity of 875 meters per second (2,871 ft/s). The guns used two propellant charges: a RPC/38 fore charge and a main charge in a brass cartridge. The P-class ships were to have mounted a fairly small anti-aircraft battery: four /L65 high-angle guns and four Flak guns. The 10.5 cm guns were carried in four twin turrets, one pair abreast the forward conning tower and the other on either side of the rear funnel. These guns fired two types of projectiles: a
high explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An ...
shell and a incendiary round. Both types of ammunition used a single propellant charge: the RPC/32 charge. The guns could elevate to 80 degrees, and could hit targets away. The ships were also armed with six submerged
torpedo tube A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboa ...
s. The armor layout was to have used Krupp cemented steel, but the design was not complete; only broad requirements are known. The main armored deck was thick on the flat, with –thick plate on sides, where it sloped downward to connect to the bottom of the armor belt. The upper deck was thick. The two main-battery barbettes had armor protection that ranged between and 100 mm thick, and had a depth of . The
armored belt Belt armor is a layer of heavy metal vehicle armor, armor plated onto or within the outer hulls of warships, typically on battleships, battlecruisers and cruisers, and aircraft carriers. The belt armor is designed to prevent projectiles from p ...
was thick over the vital areas of the ship, and tapered down to in less critical areas.


Footnotes


References

* * * * * {{Good article Plan Z Cruisers of the Kriegsmarine Proposed ships of Germany