Готовый перевод Журнал №5 / Journal #5: Статья #1

On the eve of entering 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.

The Planning department, based in the US Naval mission in London proposed a scout-cruiser armed with six 8" guns mounted on the centre line. The ship would have a top speed of 32 knots and a cruising range of 10,000 miles. It was desirable for the new ship to be better, or at least even, with comparative foreign designs, such as the British "Hawkins" class, and these foreign designs became the main argument in favour of such a cruiser. It is important to remember that at this time the US Navy were trying to become equal with the British Royal Navy as the foremost naval power, which was one of the main driving force behind the cruiser building programme.

As a lesser argument, the transitional class of warships between existing light and battle cruisers would be useful. It was also mentioned that a Pacific war would call for larger battle units. However, despite these advantages, the new ship was an over-indulgence compare to the Japanese cruisers armed with 5.5" guns only, and Japan was considered to be a probable enemy. In 1920 the Planning department saw that the USN would need 73 cruisers for all duties. The head of the department offered a 5,000t cruiser armed with 6" guns, but it became clear in the design stage that the other requirements could not be met on 5,000t. The General Council didn't think it would be possible to build such a large number of cruisers in the near future, and also predicted problems with crewing those vessels.

The Design department began to work along two sketches. The first, designated as "A", worked around a smaller version of Omaha with the same armament, but with an increase in speed due to the use of new machinery. The second, known as "B", used a main battery of 8"/50 calibre guns with a secondary battery of 5" guns to be used against destroyers, which saved displacement.
Later, other designs were developed. The "C" series was analogous to the British "Hawkins" and was armed with seven or eight 8" in unarmoured mounts. "D" and "E" were armed with five 6" guns and two triple torpedo tubes, with speeds of 33.5 knots and 35.25 knots on 5,000t and 5,750t respectively. The last design in this series was "F", which was armed with six 8" guns on 6,500t displacement and a maximum speed of 35 knots.

The General Council regarded the sketches, and accepted that they didn't fit the requirements set out. They then suggested to work to a 10,000t displacement, 6" gun, 35 knot speed and 10,000 mile range limit. To this end, a number of sketches with displacement between 7,100t and 10,000t and five to six 6" guns in twin or triple turrets were tendered. Several members of the council noted how under-gunned the ship was for its tonnage, so a 10,000t design was further developed with the addition of a fourth turret. The design was to be protected from 6" shells.

The belt armour (3.05m high and 4" thick) went the full length of the hull, along with a 64mm deck, which gave the ship an immunity zone of between 10km and 19km against its own guns. However, the ship was vulnerable to 8" fire at all ranges. Alternatively, by limiting the length of the belt and deck armour to 122m the designers were able to increase the thickness of the belt to 5" and the deck to 3". This gave protection against 8" fire between 14.6km and 19.2km. The most important characteristics were believed to be the range of operation and the armament, with speed and protection being sacrificed to meet to desired values for range and armament. In April 1921, the General Council suggested the following characteristics: eight 8" guns, four 5"/25 guns, two triple torpedo tubes, a 34 knot speed and a 10,000 mile operational range.

The silhouette of the cruiser was to resemble that of the planned battle cruiser's, and the armouring was limited to 38mm belt armour and 25mm deck armour, with 38mm on the slopes. These ground-works for the new cruiser influenced the US position at the Washington conference in regards to the restrictions for cruisers: they easily agreed to with the British limit of 10,000t displacement and 8" main guns. In addition, the guarantee of reaching the 34 knot speed was confirmed when 35 knots were achieved during trials. The Planning department also suggested increasing the cruising speed from the current 10 knots to 15 knots.

Later, there were debates about the armour and armament scheme considering their operational use. Combat scenarios with destroyers, aircraft carriers and other cruisers were considered. For the first scenario, guns of a smaller calibre with short reload cycles were best. For the second scenario, larger guns were preferred due to their greater hitting power, and have sufficient armour to stop 8" shells. Considering the pros and cons, the General Council preferred to have 8" guns in preference to armour. For universal artillery, there were split opinions. Some believed it necessary to install a large number of rapid firing guns with smaller muzzle flash which would be good against DDs at night.

Others thought that the danger was to be found in the form of torpedo planes, so they argued for a focus on AA guns. In November 1923 the General Council were supplied with a sketch for a completely unarmoured ship. According to this sketch the cruiser was of flush-deck design with the engines mounted en echelon. Armament was twelve 8" guns, two 5" guns for firing star shells and two sets of triple torpedo tubes. Baring in mind that the USN had eight "Omaha" class cruisers in service, Congress initially refused to approve the construction of the new scouts.

However at the end of 1924, when it became evident that other countries were or were going to be building new cruisers, the approval was given to the building of eight scout cruisers, the date being the 18th December. However only enough money for two cruisers, CL-24 and CL-25 was authorised at that point. In November 1924, an alternative project was developed. It looked like an enlarged Omaha. The main modifications concerned the change of guns, increase of fuel capacity and hull's hydroplanes. The length of the ship was 183m, and had a 32.5 knot speed with 100,000hp. Due to the increase of displacement to 10,317t, it was modified to a more balanced design armed with nine 8" guns in three triple turrets, a 33 knot speed and a 182m length.

Due to doubts about the reliability of triple turrets, the General Council asked for a version with four twin turrets and protection from destroyer fire. Sketches with a flight deck and 15-20 planes or with one quadruple turret fore and aft only were considered. All the variants offered fell into two categories divided between the tasks asked of a cruiser. In the first category a speed of 27-32 knots was enough, for the second category 32-34 knots. None of the studies could reach a 35 knot speed.

A 32 knot design was chosen for further development. This speed was larger enough for service along lines of communication, and it also allowed for maximum armament along with anti-destroyer defence. More detailed analysis showed that it was necessary to increase the number of boilers to eight to reach the 32 knot speed (It should be noted that the initial calculations had just seven boilers, but the addition of an eighth would cause only a slight increase in weight for a much larger increase in engine capability). The opportunity was also taken to increase the armour by 118t, and later by another 170t.

Initially, plans for high pole masts for the radio aerials were scrapped, so instead of a mainmast a tripod mast topped with a topmast, of lower overall height, was planned. 5"/51 and 37mm auto-cannons were replaced with 5"/25 guns, and the upper deck of the superstructure below the stern funnel was used for secondary armament directors.

In 1926 it was decided to fit deck armour. Hereon, the outward appearance of the ship was finished, and the cruiser was laid down in the New York Shipyard. During construction the weight was kept down to maintain within the limits set by the Washington Naval Treaty. Each and every element of the ship prepared by the builder was accompanied by an evaluation of its weight. What is more interest is the that the company was awarded $500 for each tonne saved (but no more than $50,000) and penalised $500 for each one tonne increase for the first 100 tonnes and by $1000 for each tonne after that. At the same time, deflection from the design that weighed no more than 100 tonnes did not influence the price. As a result, the cruiser turned out to be 900t lighter, and cost the state $8.5 million.

The New York Shipyard was building battleships up to this point, and they had practically the same length, but at least twice the launching weight, so correspondingly the stock had little rake, but it wasn't enough. This meant that there was compensation in the form of a special lubricant mixture being used. The "Pensacola" cruiser was initially classified as a scout cruiser, or light cruiser. On the 1st June, after the category of heavy cruisers had been accepted by the London Treaty of 1930, it was reclassified as a heavy cruiser, CA-24.

The body of the "Pensacola" had mainly riveted construction, though for the reason of weight economy welding was used greatly. The designers considered a full transition to welding to be premature due to insufficient experience of its use. Because of this, welding was used in parts whose construction was not vital to the integrity of the ship, and in fastening fittings. As such, the flooring of the first and second deck, the superstructure decks, the superstructure and the bridge, all were fixed in place by welding.

For the improvement of hydrodynamics, the hull shape had a distinctly bulbous look. It was considered that would be efficient, first of all, in a moderate climate at a high speed, whilst the less bulbous Omaha class were wet even in a mild sea at 18-20 knots. The new cruisers were given a clipper bow because the anchors didn't touch the bulbous bow. As the flush-deck body had, for the purpose of saving weight, a minimal water board (as high as the fore turrets, not covering the centre section of the hull where the height was considered unsatisfactory), and the upper deck was substantially higher than the deck at the stern, which was to decrease wetness of the bow on an ocean wave together with a noticeable lowering the board.

As a result, the stern freeboard height was only 4.88m, and the bow height increased to 8.73m. To reduce the aft burying into the water during longitudinal roll, it was made wide enough to provide enough buoyancy. Besides, the wide stern reduced the size of propeller fencing, Also the cruiser cut deadweight to improve mobility. The double bottom, of 0.99m height, ran almost the entire length, whilst the double side was only outside the outer engine rooms and boiler rooms. The cruiser had two armoured decks (main and upper) and two separate sections above the engine and boiler rooms (numbered top to bottom as first and second). This facilitated the layout of the rooms, the area between the double bottom and the second deck housed all sorts of storage, oil and gasoline tanks, but it caused inconvenience for the crew.

The internal volume of the ship's hull was divided with twelve main transverse watertight bulkheads. Five of them reached the upper deck and the other seven only reached the main deck. As the designers considered the threat of torpedoes, the cellars were positioned on the second deck rather than the hold. This position reduced the probability of their detonation from an underwater explosion, but increased their vulnerability to artillery fire at the same time. The echeloned location of the turbine and boiler compartments was another way to increase survivability.

In case of chemical warfare, the bridge, the intercom and switchboard rooms on the second deck of the superstructure were airtight. As the ships were underweight by 900t, and possessed excessive stability, rolling was sharp, which made the cruiser an unstable gun platform, and lead to other unpleasant consequences. Subsequently, designers had to take steps to decrease these problems, which included the expansion of the bulges and the installation of stabilisers in the ships cisterns.

The initial service showed that the cruisers' bodies were rather lightly build, and because of this they suffered from heavy vibrations at the stern at high speeds, and experienced excessive roll during full-salvo shooting. But the most problematic thing in respect to durability provision was the bow extremity. The rivets fastening the parts of the hull, and the eading sheets up to the tenth rib were getting weaker from wave hits. This, during a storm, "Pensacola" suffered damage in the bow near the 12th rib and took on a substantial volume of water. This damage was partly connected to the submerged bulbous bow section which caused the stern to bury itself in fine weather. Along with messages about problems with the flooding of the liner "Bremen"'s bow, this caused the rejection of using bulbous bows on the Portland class cruisers, and the sequential ones.

The main battery of the cruiser consisted of ten 8"/55 Mk 9 Mod 2 guns situated in two twin and two triple arrangements, although in most official documents the term "turret" appears to be more common. The main difference of such mountings from other 8" mountings, such as those on aircraft carriers, was the presence of a huge under-turret compartment. This could be done because the shells were stored inside the barbette instead of a shell room.

The Mk 9 Mod 2 guns were made of nickel steel, and consisted of an innder tube, six fastening cylinders and a liner. The gun had right-hand grooves of a constant curvature. The barrel had 64 riflings in total, each with 1.78mm depth. The guns were placed in a joint cradle and could be dismantled though the turret loopholes. The maximum recoil was 0.75m. Durability was 400 rounds with full charges. The theoretical rate of fire was 6 rpm. Although, during the shooting practice it dropped to 1.5-3rpm, and in real combat it was about 0.5-1.2prm.

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

To launch aircraft, the ship had two powder catapults located amidships, one on either beam. There were 50 powder charges for launching the planes. A crane located nearby served to lift the aircraft. Two of the four planes carried were stored directly on the catapults, whilst the other pair were on the superstructure deck near the second funnel. After flight, a seaplane was taken on board using a towed tent planting network which was lowered to the water at the lee side next to the catapult. This allowed the aircraft to be picked up whilst the ship was moving. Plane ammunition included 24 45.3kg bombs, 96 13.6kg bombs and 48,000 rounds of 7.62 ammunition.

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

Later, the cruiser was upgraded a number of times. Changes mainly concerned the shrapnel defence of the superstructure to reduce metacentric height, expanding the keels to stabilising the ship and increasing the number of 5" guns. In 1934, the torpedo tubes were removed as they were viewed as being dangerous for the ship itself.
Summarising, we can say that the cruiser had excellent weaponry and a good speed with a large range, but insufficient armouring which, however, did not prevent the class being great ships for fighting in the vast oceanic theatres.

Sources:
- "Pensacola class heavy cruisers", A.A.Malov

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