US treaty battlecruiser

VC_

Post subject: US treaty battlecruiser

Posted: December 16th, 2021, 1:43 pm

Posts: 46
Joined: October 25th, 2021, 10:24 am

Hi all,

I want to share a personal design idea that has been floating around in my head in various incarnations for a while, but has only recently crystallised in this form. I wanted to make a battlecruiser using US aesthetics, and although they have plenty of interesting design studies, none really fit how I wanted her to look, so I crafted my own little back-story and gave myself a design challenge.

As we know historically, the UK received an exeption under the Washington Naval Treaty to build a class of new battleships, since they did not yet have any built or building with 16" guns while the US and Japan both did. The US Navy at this time had recently seen a vast expansion of its battlefleet, but was short of modern scouts. Though rapidly building the Omaha class and designing larger scout cruisers (that would become the Pensacola class), the US had a notable defficiency compared to the UK and Japan in lacking battlecruisers. The Lexington class under construction would naturally not be allowed under the terms of the new arms limitation treaty, but the idea that the fleet needed a battlecruiser squadron is championed nevertheless.

In this scenario, the US also receives an exception under the terms of the WNT to build new battlecruisers to fill this capability gap, in exchange for other sacrifices. Delaware, North Dakota, Utah and Florida are all to be scrapped as new ships complete. In addition, West Virginia is to be cancelled and broken up as well as Washington. This would leave the US with 75,400 tons of capital ship tonnage to use. In order to appease fears from the other nations of powerful new 16" ship construction, and to allow the US to build a squadron of three battlecruisers, an additional individual tonnage limit of 27,000 tons and minimum speed of 30 knots is agreed. Though this pushes the total slightly over the limit, it makes the ships individually equivalent to Japan's Kongo class and Britain's Renown class in size i.e. even if they do have 16" guns they would not be balanced designs to achieve the required speed and would not inherently trump existing battlecruisers.

The design presses ahead with 16" guns in order to make use of the guns and turrets already under construction for the cancelled Lexington class. However, several design departures are made to fit the tight size restrictions of the treaty, as well as evolving requirements for the ships.

- the hull is lowered at the rear to save weight, but joined via a slope to preserve structural strength, making her technically a flush-deck design (this is a feature in some historic design studies, that's where I got my inspiration). The stern is also of a newer, wider design with a flatter underside and a knuckle.
- the ship uses 12 of the same boilers as Lexington, giving her 3/4 of her power output. However, the turboelectric drive is ditched in favour of lighter and more space efficient geared turbines. The machinery follows the novel "unit" arrangement then under design for the new class of scout cruisers (Pensacola).
- the secondary armament is increased in caliber to 6" and fitted in twin enclosed mounts, piggy-backing on the assembly line for the Omaha class to save time. This heavy battery is partly to make up for the small number of main guns.
- the heavy cage masts are replaced with tripods.
- the bridge structure is revised during construction to a triangular shaped pilot house and additional shielded platforms. The trend towards this style of bridge is evident in the cruiser designs, and the 1930s refits of the older battleship classes.
- extensive aviation facilities are fitted amidships, again taking inspiration from contemporary cruiser design practice. This increases the aircraft storage and improves operability, befitting the role of these ships as fleet scouts.

The ships are fast, with powerful guns and excellent seakeeping thanks to high freeboard and a flared clipper bow. The large hull has spacious crew accommodation and they are well suited to long range patrols.

However, they have only 6 guns, limiting their firepower despite the caliber, and they are very thinly armoured as well as having bare minimum torpedo protection. Their machinery spaces are very cramped and the machinery itself is lightly built. Ammo supply for the secondary guns is also fairly limited.

I have chosen the names Ticonderoga, Bunker Hill and Valley Forge for these fictional ships

They are named after historical battles/places as the Lexington class started this pattern and take the hull numbers CC-7 through CC-9 to follow on from the cancelled 6. They are laid down in 1923 and complete in the late 1920s.

Displacement:
- 27,000 tons standard (as designed)
- 29,500 tons full load

Waterline length (LWL): 790 ft / 240.79 m
Overall length (LoA): 812.67 ft / 247.70 m
Beam: 88.00 ft / 26.82 m
Draught: 28.00 ft / 8.53 m

Armament:
- 3 x 2 16"/50
- 6 x 2 6"/53
- 8 x 1 5"/25

Armour:
- main turret - faces 11" / 28cm, sides and roof 6" / 15cm, barbettes 9" / 23cm
- belt 7" / 18cm inclined at 8 degrees
- deck 2" / 5cm
- conning tower 12" / 30.5cm

Propulsion:
- 12 boilers, 135,000 SHP
- geared steam turbines
- 4 shafts
- design speed 32 knots

Ticonderoga soon after completion:

[ img ]

Bunker Hill shown in 1940 with typical upgrades that happened during the 1930s and appropriate new camouflage measure:

[ img ]

Last edited by VC_ on December 16th, 2021, 9:06 pm, edited 2 times in total.

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US treaty battlecruiser

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