Журнал №5 / Journal #5: Статья #1

USS Pensacola
design and creation history.
On the eve of entering The First World War american designers were quite pleased by the Omaha class light cruisers. They were designed in 1916 and were ment to be best in class. "Clssmates" from other countries appeared to be much smaller in displacement and, in paper, concede to "Omaha" class in armament, speed and cruising range.However as soon as americans became familiar with characteristics of english "Howkins"class, they start to think about building cruisers with normal displacement of 10000 t and 8" weaponry

mazzeltof 13.06.14 в 11:44

USS Pensacola: Design and Construction History
On the eve of the First World War, the USN were pleased with the Omaha class light cruisers they had under construction. They were designed following the analysis of the 1915 fleet exercises, and were the best of their type on completion. However, when the details of the British "Hawkins" class became known, they tasked their designers to come up with a counter for them. The Washington Naval Treaty imposed limits of 10,000t standard displacement and 8" gun calibre on them.

Zamuchryshkin 13.06.14 в 12:41

The Planning department,which was instituted at U.S. Naval mission in London, proposed aprototype of a future scout-cruiser, armed with six 8" guns located in the center plane. This ship also would have speed of 32 knots and cruising range of 10 000 miles.A desire to have ships better, or, at least, not weaker than any foriegn analogues(e.g. "Howkins")became the main argument in favor of suchlike cruiser. Also desire of General Council to make USA dominant sea power became substantially a main driving factor for cruiser programm.

mazzeltof 13.06.14 в 13:12

The Planning department, which was instituted at the U.S. Naval mission in London, proposed a prototype of the future scout-cruiser armed with six 8" guns located in the center plane. This ship also would have speed of 32 knots and cruising range of 10 000 miles. A desire to have ships better, or, at least, not weaker than any foriegn analogues (e.g. "Howkins") became the main argument in favour of suchlike cruiser. It's necessary to take into consideration that the desire of General Council of the USA to make the country a dominant seapower became substantially the main driving factor for the cruiser programme.

Zamuchryshkin 13.06.14 в 13:19

As a subsidiary argument, they make the usefulness of a transitional (but not stronger) class of warships among existing light and battle cruisers. They also mentioned the war in the Pacific would call for bigger battle units. Despite all these reasons, the new warship was an over-indulgence comparing with the Lapanese cruisers armed with 5,5" guns only. But exactly Japan was considered to be a probable enemy. In 1920 the Planning department appreciated the demand of the USN in 73 cruisers. The head of this department offered to build 5000-tonnes cruisers armed with 6" guns (but while designing it became clear that the characteristics required couldn't be reached according to this displacement). The General Council didn't consider this to be possible to build such a number of cruisers in the nearest future, and also it predicted some problems with staffing the crew.

Zamuchryshkin 14.06.14 в 06:44

As a secondary argument, they made use of an intermediate (but not stronger) class of warships among existing light and battle cruisers. They also mentioned that the war in the Pacific would call for bigger ships. Because of this, the new American ship was overkill compared to the Japanese ships, armed only with 5.5" guns, but only because Japan was considered an enemy. In 1920, the Planning department estimated that the US Navy would need 73 cruisers. The head of this department offered to build 5000-tonnes cruisers armed with 6" guns, but during the design phase it was realized that these characteristics couldn’t be accomplished. The General Council didn't consider this to be possible to build such a number of cruisers, and it predicted that if it did, there would be problems finding enough crew to staff them.

Timroden 14.06.14 в 06:54

The Designing department began to work in two directions. The first one called the outline "A" serie assumed to decrease the displacement of Omaha with the same armament and to increase its speed a bit more at the expense of using a new engine. The second direction called the outline "B" serie provided for an arrangement of 8"/50 caliber guns supplemented with 5" guns, used for DDs destruction, saving the initial displacement.
Later on, some other directions were took up. So the "C' serie was an analogue of the British "Hawkins" and was armed with 7-8 8" guns in unarmoured settings. "D" and "F" series were armed with five 6" guns and two triple torpedo tubes gaining speed till 33,5 knots or 35,25 knots with the displacement of 5000 t or 5750 t accordingly. The last "F" serie was armed with six 8" guns and had speed of 35 knots with 6500 t displacement.

Zamuchryshkin 14.06.14 в 07:18

The Design Department began working on two sketches for the new ship. The firs, sketch A, attempted to decrease the displacement of Omaha and increase its speed through the use of a new engine, while keeping the same armaments. The second, sketch B, called for an arrangement of fifty 8" guns accompanied by 5" guns, used for DDs destruction, saving the initial displacement.

Later on, some other directions were taken up. The C series was an analogue of the British "Hawkins" and was armed with seven or eight 8" guns in unarmored settings. The D and F series were armed with five 6" guns and two triple torpedo tubes topping at speeds of 33.5 knots and 35.25 knots with displacements of 5000 t and 5750 t respectively. Finally, the F series was armed with six 8" guns and had a top speed of 35 knots with 6500 t displacement.

Timroden 14.06.14 в 07:29

The General Council took up all these sketches and acknowledged them as not corresponding to the claims of that time. So then the Council suggested to work along the sketch of a 10000 t cruiser armed with 6 8" guns, a speed of 35 knots and a range of 10000 miles. In a month, a couple of projects with the displacement from 7100 to 10000 t and armed with 5-6 8" guns in 2/3-guns turrets was offered. The most attention was paid to the largest sketch of the warship. Members of the Council noticed the insufficiency of armament for a ship with such a tonnage, so the further developments were based on a 10000 t project adding the 4th turret. As designers thought, the warship of such a scale could be defended from 6" missiles.

Zamuchryshkin 14.06.14 в 08:25

The belt armor (height - 3.05 m and thickness - 102 mm) at full length of the body together with 64 mm desk created a safety zone saving from fire of American 6"/53 gun at distance of 10-19 km. Despite it, the warship was vulnerable for 8" guns' fire at all distances. From the other side, limiting length of the belt armor and the desk till 122 m, it would be possible to increase thickness of the belt up to 1227 mm, and the desk's - up to 76 mm. That would let to secure from 8" guns' fire on distances from 14630 till 19202 m. The main characteristics were considered to be the range limit and the fire power, for the sake of which it was possible to pungle with speed and, increasingly, with armoring. In April of 1921, the General Council suggested such characteristics: eight 8" guns, four 5" AA guns, two triple torpedo tubes, 34 knot speed and 10000 mile range limit.

Zamuchryshkin 14.06.14 в 10:53

The silhouette of the warship should be like battle cruisers', and the armoring was supposed to limit by 38 mm belt armor and 25 mm desk with 38 mm slants. Exactly these groundworks influenced the USA position in the Washington conference concerning restrictions for cruisers - they easily agreed with the British to limit the displacement by 10 000 t and the main caliber by 8" guns. By the way, the guarantee of reaching 34 knot speed was developing 35 knot speed during the trials. The Planning department also suggested establishing as a standard a range limit of 15 knot pace, but not 10 knots as it was earlier.

Zamuchryshkin 14.06.14 в 10:55

Later, some disputes about the assembling of armoring and armament appeared based on the operation use. Possibilities of combats with destroyers, aircraft carriers and other cruisers were considered. So for the first ones it was preferable to use more guns of less caliber and to have the fastest speed. If it was a combat with CVs with 8" guns, it would be better to use artillery of larger caliber and the armoring saving from hitting of 8" shells. Considering all for and against, the General Council prefered to have maximum of 8" guns to the prejudice of armoring. As for the universal artillery, the opinions were divided. Ones thought it'd been necessary to install as much rapid-firing guns which gave less flares at night firing to be used against DDs.

Zamuchryshkin 14.06.14 в 11:20

Subsequently, disputes arose over the armaments and armoring based on the intended operational use. The possibility of combat with destroyers, aircraft carriers and other cruisers was considered, and it was decided to trade firepower for speed. If it was a combat with CVs with 8" guns, it would be better to use artillery of larger caliber and have armor that could withstand the impact of 8" shells. After weighing the pros and cons, the General Council opted to have 8" guns at the expense of more armor. As for the universal artillery, the opinions were divided. Some thought it necessary to install rapid-firing guns that gave less flares during night operations against DDs.

Timroden 14.06.14 в 16:12

Others thought the danger was in aviation which might carry torpedoes, so they demanded to focus on AA guns. Final sketch project of completely unarmoured ship was granted to the General council in November, 1923. According to this project, the cruiser was flush-deck with echelon disposition of engine and armament of twelve 8" guns, two 5" gun mounts for firing with illuminating shells and two triple torpedo tubes.
Taking into consideration the fact that the USN was supplied with 8 Omaha-class warships, initially the Congress refused to approve building of new 'scauts'.

Zamuchryshkin 14.06.14 в 11:59

Others saw the main threat as planes that could be carrying torpedoes, so they demanded a focus on AA guns. The final sketch of the project was a completely unarmoured ship was presented to the General council in November, 1923. According to this project, the cruiser was flush-deck with echelon disposition of engine and armament of twelve 8" guns, two 5" gun mounts for firing with illuminating shells and two triple torpedo tubes.
Taking into consideration the fact that the US Navy was supplied with 8 Omaha-class warships, Congress initially refused to approve the building of these new scouts.

Timroden 14.06.14 в 16:17

However, at the end of 1924, when it became evident that other states became or will become building new cruisers, on the 18th of December the building of eight "scauts" was accepted. Though the money was allowed for two cruisers only - CL 24 and CL 25.
In November of 1924, the developing of an alternative project began. That looked like enlarged Omaha. Changes concerned substitution of guns, increase of reserve of fuel, and the number of hydroplanes. The length of the warship was 183 m and the speed was 32.5 knots with capacity of 100 000 hp. Due to increase of displacement till 10 317 t, it happened to proceed to more balanced project armed with nine 8" guns in three triple turrets, 33 knot speed and 182 m length.

Zamuchryshkin 14.06.14 в 12:41

Owing to doubts in reliability of triple turrets, the General council commissioned to take up a version with four twin turrets and secure of DDs' fire. Sketches with a flight desk and armed with 15-20 planes or with two quadruple turrets in bow and stern were even considered. All the variants offered were divided into two categories reasoning from tasks laid on cruiser. In the first case, the speed of 27-32 knots was enough, for the second category - 32-34 knots. No variant could reach a 35 knot pace.

Zamuchryshkin 14.06.14 в 13:54

For the further development the 32 knot variant was chosen. Such a speed was enough for actions on lines of communication, and furthermore it let to use maximum armament together with anti-destroyer defence. More detailed analysis showed it was necessary to increase the number of boilers till 8 to reach the 32 knot speed (we should notice that initially in computations just seven boilers appeared, however, installation of the eighth could turn into slight increase of weight comparing to the much larger increase of capacity). In such a way, because of reserve of capacity, an opportunity to increase the armoring on 118 t, and later - another 170 t.

Zamuchryshkin 14.06.14 в 14:13

Initially, planned high poles for stretching antennas of distant radio communication were practically abolished, so instead of the mainmast a tripod with less higher topmast appeared.
5"/51 guns and 1.45" submachine guns were changed on 5"/25 caliber guns, and the upper platform of the superstructure below the stern funnel was used for directors of small caliber artillery.

Zamuchryshkin 14.06.14 в 14:42

In 1926, armour deck-cabins were decided to be installed. Hereon, forming of the outward appearance was finished, and the cruiser was laid down on the New York's shipyard.
During the very building, a strict weight discipline was obeyed to avoid an excess of displacement allowed by the agreement. Each sketch of any element of the warship prepared by the builder-company was accompanied by an evaluation of its weight. What's more interesting, the company was awarded in case of economy of weight of each tonne by 500 dollars (but not more than 50 000 dollars), and penalized in case of the displacement increase on one tonne in 500 dollars for the first 100 tonnes and in 1000 dollars for the next tonnes. At the same time, a deflection from the designed weight not more than on 100 tonnes didn't influence the price. As a result, the cruiser turned out to be on 900 t lighter and costed about 8,5 mln dollars for the state.

Zamuchryshkin 14.06.14 в 14:53

The New York Shipyard was heretofore building battleships which had practically the same length of the body but, at the least, twice more launching weight, so the stock had a corresponding little rake, but that wasn't enough. So it had to be compensated by additional actions like greasing with a special lubricant mixture. The "Pensacola" cruiser was initially called a scaut-cruiser, or a light cruiser. On the 1st of June, after the category of heavy cruisers had been accepted by the London agreement of 1930, it was reclassified into a heavy cruiser CA-24.

Zamuchryshkin 14.06.14 в 16:00

The body of "Pensacola" had mainly rivited construction, though for the reason of weight economy welding was used greatly. The designers considered the full transition to it to be premature due to insufficient experience of its use. Because of this, welding was used in those constructions which were not important for the general durability of the body, and in fitting fastening. In such a way, floorings of the fisrt and second platforms, superstructural desk, superstructures and bridges, all the conduits were restrained by welding.

Zamuchryshkin 14.06.14 в 16:42

For the improvement of hydrodynamics, bypasses in the bow part had definetely expressed bulbous look. It was considered that would be efficient, first of all, in the moderate climate on a high speed, while the bypasses without this structure of Omaha-class cruisers were in advance in a strom sea with a moderate pace of 18-20 knots. The new cruisers were given a clipper bow for the reason of anchors didn't touch the bulbous bows. As the flush-deck body for the reasons of weight economy had minimally permissible above-water board (as high as bow turrets, not covering the mediate part of the body where the height was considered as unsatisfactory), the upper desk got substantial lifting to the stem whci was to decrease space-flooding of bow on an ocean wave together with noticeable demolishing of a board.

Zamuchryshkin 14.06.14 в 16:57

As a result, if the stern freeboard height was only 4.88 m, the bow height increased to 8.73m. To reduce burying aft into the water during the longitudinal roll,
it was made wide enough, providing enough bouyancy. Besides wide stern reduced the size of propeller fencing. Also cruiser got cut deadwood tot improove mobility. Double bottom height of 0.99 m provided alongside almost all hull, while double board was only outside the engine and boiler room(EBR). The cruiser had two solid deck(main and upper) and two platforms
in the extremities outside EBR(numbered from top to bottom - the first and second). This facilitated the layout of the premises, as the tween increased only between decking of double bottom and a second platform that housed all sorts of storage, oil and gasoline tanks, but created inconvenience to
crew members.

mazzeltof 14.06.14 в 18:48

As a result, if the stern freeboard height was only 4.88 m, the bow height increased to 8.73m. To reduce burying aft into the water during the longitudinal roll, it was made wide enough providing enough bouyancy. Besides, wide stern reduced the size of propeller fencing. Cruiser also got cut deadwood tot improove mobility.

The double bottom height of 0.99 m provided alongside almost all hull, while the double board was only outside the engine- and boiler-rooms. The cruiser had two solid deck (main and upper) and two platforms
in the extremities outside the engine- and boiler-rooms (numbered from top to bottom - the first and the second). This facilitated the layout of the premises, as the tween increased only between decking of double bottom and a second platform that housed all sorts of storage, oil and gasoline tanks, but created inconvenience to the crew.

Zamuchryshkin 15.06.14 в 06:28

Internal volume of the ship's hull was divided with twelve main transverse watertight bulkheads. Five of them reached the upper deck and seven - only the main deck. As designers seriously considered a torpedo threat, cellars were positioned at the second platforminstead of the hold. This composition reduced the probabilitybility of their detonation from underwater explosion, but at the same time increased the vulnerability from artillery fire.Echeloned
location of turbine and boiler compartments was another way to increase survivability.

mazzeltof 14.06.14 в 19:26

The internal volume of the warship's hull was divided with twelve main transverse watertight bulkheads. Five of them reached the upper deck and seven - only the main deck. As designers seriously considered a torpedo threat danger, the cellars were positioned at the second platform instead of the hold. This composition reduced the probability of their detonation from underwater explosion, but at the same time increased the vulnerability from artillery fire. Echeloned location of the turbine and boiler compartments was another way to increase survivability.

Zamuchryshkin 15.06.14 в 06:32

In case of chemical warfare agents central post, compartments intercoms and switchboards on the second platform were performed gastight. Since the ship was underused by 900 tons and possess excessive stability, rolling was sharp which made cruiser unstable gun platform and led to another unpleasant consequences. \\\\\ не окончено

mazzeltof 14.06.14 в 20:54

In case of chemical warfare agents, the central post, the compartments of intercoms and switchboards on the second platform were performed gastight.
As the warships of this class was underused by 900 tons and possessed excessive stability, rolling was sharp, what made cruiser an unstable gun platform and led to other unpleasant consequences. Subsequently, designers had to take steps to decrease cruisers' crankiness including an expansion of bilgeboard and instalation of ship stabilizers in cisterns.

Zamuchryshkin 15.06.14 в 06:43

The first comings out showed the cruisers' bodies were built rather "lightly", and because of this they suffered from the stern part vibration on high speeds and experienced excessive capacity during full-salvo shooting. But the most problematic thing in respect to durability provision was the vow extremity. The rivets fastening the elements of the body set, and board edging sheets till the tenth rib were getting weaker from wave hits. Thus, during a storm, "Pensacola" got a damage of a bow part near the 12th rib and received a substantial quantity of water. This damaging was partly connected with the bulbous bow in its under-water part which caused stem burying in the fine weather. Along with messages about promlems with space-flooding of the liner "Bremen"s bow, that caused a rejection of using bulbous bows on Portland-class cruisers and sequential ones.

Zamuchryshkin 15.06.14 в 07:26

Main caliber of cruiser
consisted of ten guns 8"/55 Mk
9 Mod 2 arranged in two two-gun, and two three-gun installations, although in most official documents
the term "turret" appears to be more common.The main difference from other 8" artillery systems, mounted, for example, on aircraft carriers was
the presence of huge under-turret compartment. This was done becouse the shells were stored inside the cylindrical turret base instead of special cellar.

mazzeltof 14.06.14 в 21:16

The main caliber battery of the cruiser consisted of ten 8"/55 Mk 9 Mod 2 guns arranged in two twin and two triple arrangements, although in most of official documents the term "turret" appears to be more common. The main difference of such main caliber arrangements from the other 8" artillery systems mounted, for example, on aircraft carriers was the presence of huge under-turret compartment. This could be done because the shells were stored inside the cylindrical turret base instead of special cellars.

Zamuchryshkin 15.06.14 в 06:48

The Mk 9 Mod 2 gun was made of nickel steel and consisted of an inner tube, six fastening cylinders and a liner. The gun had a right-hand cutting with constant curvature. The barrel had a total of 64 riflings with 1.78 mm depth. Guns were placed in
joint cradle and could be dismantled through
turret loopholes. The maximum rollback length was 0.75 m. Durability of barrel was equal to 400 shots with full charge. Theoretical rate of fire- 6 rds / min., Although in practice during shooting practice it dropped to 1.5-3 rds / min, and in real combat
was about 0.5-1.2 rounds / min.

mazzeltof 14.06.14 в 21:57

The Mk 9 Mod 2 guns were made of nickel steel and consisted of an inner tube, six fastening cylinders, and a liner. The gun had a right-hand cutting with constant curvature. The barrel had a total of 64 riflings with 1.78 mm depth. Guns were placed in joint cradle and could be dismantled through the turret loopholes. The maximum rollback length was 0.75 m. Durability of a barrel was equal to 400 shots with full charge. The theoretical rate of fire was 6 rds/min. Although, during the training shooting practice, it dropped to 1.5-3 rds/min, and in real combats was about 0.5-1.2 rds/min.

Zamuchryshkin 15.06.14 в 06:54

The reason was that the ships themselves were under enemy fire, and battles took place mostly at night, whereas practical rate of fire
was measured before the war only for daytime shooting. The cruiser was armed with 2 * 3 533 mm
Mk 9 and Mk 9 mod 1 torpedo launchers. They had the firing angles of 60 degrees to either side
from the beam. Mk 11 torpedoes were stored in
quantity of 12 units. in torpedo tubes and boxes on the upper deck. They were transported to torpedo-tubes on rail carts.

mazzeltof 14.06.14 в 22:08

The reason of that was the ships themselves were under enemy fire, and battles took place mostly at night, whereas practical rate of fire was measured before the war only for a daytime shooting.
The cruiser was armed with two triple torpedo tubes Mk 9 and Mk 9 mod 1. They had the firing angles of 60 degrees to either side from the beam. Twelve torpedoes Mk 11 were stored as in torpedo tubes, as in special boxes on the upper deck. They were transported to torpedo-tubes on rail carts.

Zamuchryshkin 15.06.14 в 06:59

to launch aircraft the ship had two powder catapults, located on each side of midship. There were 50 powder charges for launch them. Crane located in front of the stern tube served to lift the aircraft. Two of them were stored directly on catapults and the other
pair - on a superstructure deck near the second
exhaust pipe. After flight a seaplane was
taken on board using towed tent planting network, which was lowered to the water at the lee
side next to the catapult. This allowed to rise the aircraft on the go.Craft ammunition included 24 45.4-kg bombs, 96 13.6-kg bombs and 48 000 rounds of 7.62 mm.

mazzeltof 15.06.14 в 09:45

To launch aircraft, the ship had two powder catapults located on each side of the midship. There were 50 powder charges for launching the planes. Crane located in front of the stern tube served to lift the aircraft. Two of four planes which were included to the cruiser's airgroup were stored directly on catapults and the other pair - on a superstructure deck near the second exhaust pipe. After flight, a seaplane was taken on board using towed tent planting network which was lowered to the water at the lee side next to the catapult. This allowed to rise the aircraft on the go. Craft ammunition included 24 45.4-kg bombs, 96 13.6-kg bombs and 48 000 rounds of 7.62 mm.

Zamuchryshkin 15.06.14 в 10:37

Originally cruiser crew consisted of 653 men (including 41 officer), but in wartime it has almost doubled - up to 1193 men. The U.S. Navy
practice to equip accommodations with
metal suspended ceiling coverings, was abandoned for the first time on this ship. In addition to weight saving, that was done to prevent rodents and insects from breeding between the ceilings and the overlaying deck. In peacetime, the cruiser took
aboard the supply of food and water for
60 days.

mazzeltof 15.06.14 в 09:53

Initially, the cruiser crew consisted of 653 men (including 41 officers), but in wartime it was almost doubled - up to 1193 men. The US Navy practice to equip accommodations with metal suspended ceiling coverings, was abandoned for the first time on this ship. In addition to weight saving, that was done to prevent rodents and insects from breeding between the ceilings and the overlaying deck. In peacetime, the cruiser took
aboard the supply of food and water for 60 days.

Zamuchryshkin 15.06.14 в 10:40

The cruiser was upgraded for several times later. Changes concerned mainly antifragmentation defense of superstructures to reduce the metacentric height, expanding keels for stabilizing and increasing the number of 127-mm guns. In 1934
the torpedo tubes were removed, being
dangerous for the ship itself. Summarizing, we can say that cruiser have had great weapons and good speed with large power reserve, but insufficient armoring, which, however, did not prevent him to become a great ship for fighting in the vast oceanic theaters.

SOURCES:
• А.А.МАЛОВ, «ТЯЖЕЛЫЕ КРЕЙСЕРА
ТИПА «ПЕНСАКОЛА». ЧАСТЬ 1
(МОРСКАЯ КОЛЛЕКЦИЯ № 4/2013»)

mazzeltof 15.06.14 в 10:27

Later, the cruiser was upgraded for several times. Changes concerned mainly antifragmentation defense of superstructures to reduce the metacentric height, expanding keels for stabilizing and increasing the number of 127-mm guns. In 1934, the torpedo tubes were removed being dangerous for the ship herself.
Summarizing, we can say that cruiser have had excellent weaponry and good speed with large range limit, but insufficient armouring which, however, did not prevent him to become a great ship for fighting in the vast oceanic theatres.

SOURCES:
• "PENSACOLA-CLASS HEAVY CRUISERS", A.A. MALOV

Zamuchryshkin 15.06.14 в 10:45