Gran Princesa de los Cielos-class cruiser

60,000 shp (44,760 kW)

4 x 50 cm torpedo tubes

120 x mines, 2 stern rails

Turrets: 60–20 mm (2.5–1 in)

Barbettes: 40–20 mm (1.5–1 in)

Conning tower: 80 mm (3 in)

Torpedo bulkhead: 20 mm (1 in)

The ***Gran Princesa de los Cielos*-class cruisers** were a group of two scout cruisers (Spanish: *crucero explorador*; German: *spähkreuzer*) ordered by the Spanish Navy (Spanish: *Armada Española*) from the AG Vulcan Stettin shipyard in Germany. The ships were one of several foreign designs pursued concurrently under the **Crucero de Flota 1914** requirement, part of a general initiative to modernize and expand the Spanish blue-water fleet. The German designers interpreted this specification as effectively calling for a small battlecruiser (German: *kleiner großer kreuzer*) instead of a conventional light cruiser, and draft plans to that effect were produced and approved by early 1914. Two ships were laid down that year - *Gran Princesa de los Cielos* and *Ángel de la Guarda*. However, with the outbreak of World War I the incomplete hulls were seized by the German government, and both would eventually be commissioned into the Imperial German Navy (German: *Kaiserliche Marine*), as SMS *Lauenburg* and SMS *Bütow*.

## Background

Description of the RFP requirements and naval situation of the country in question goes here.

## Design

Design process for the individual ship and judging results go here.

## Description

Ordered and laid down in Germany as "**Großer Flottenkreuzer A**" and "**Großer Flottenkreuzer B**", the *Gran Princessa de los Cielos*-class cruisers are generally classified by modern sources as light cruisers or scout cruisers, although their design has several features that distinguish them from other contemporary warships of these types. The general form broadly resembled the concurrently-built **1913 Program Flottenkreuzer** (*Königsberg* class) constructed for the Imperial German Navy. Measuring 150 meters (492.13 feet) between perpendiculars, the hull was roughly the same length as that of the *Königsberg* class. However, it was somewhat wider at 15 meters (49.21 feet) and sat deeper in the water at 7.04 meters (23.11 feet) full draught; *Königsberg* had a beam of 14.2 meters (46.59 feet) and a draught at full load of 6.32 meters (20.73 feet).

As designed, the hull would displace 7,800 long tons at normal load, which was significantly higher than most other scout cruisers of the era. The profile was characterized by a relatively high freeboard which made the ships comfortable seaboats at speed or in inclement weather, a two-level interrupted break deck similar to other German-built cruisers, a nearly vertical "cleaver" bow and a sharply raked stern terminating in a small transom. At full load, the ships were reportedly somewhat bow-heavy.

### Propulsion

The large displacement and high speed requirement for the *Gran Princessa de los Cielos* class resulted in a propulsion arrangement similar to contemporary German battlecruiser designs and radically different from previous light cruiser types. The steam plant consisted of 10 Wagner "Marine type" oil fired double-ended boilers divided between two engine rooms. These powered two sets of Parsons turbines; each set consisted of a high-pressure outboard turbine which exhausted into a low-pressure inboard turbine. One turbine set drove each of the two 3.8 meter (12.47 feet) diameter three-bladed propellers through a Bergmann Föttinger-Transformator hydraulic transmission. The use of hydraulic coupling had been demonstrated in an experimental installation on the cruiser SMS *Wiesbaden* as an economical alternative to expensive and difficult-to-manufacture reduction gearing sets for high-speed turbines, although at this time it was still considered unproven technology.

The engines were designed to produce 60,000 shaft horsepower (44,760 kW) for a projected top speed of 30.45 knots. Using forced draft on trials, SMS *Lauenburg* reached 88,839 shaft horsepower (66,273 kW) and a top speed of 30.9 knots (57.2 km/h; 35.6 mph). SMS *Bütow*'s trial figures are not recorded. The trials were conducted in shallow water due to the war; in deep water, the ships were calculated to be capable of reaching speeds in excess of 33.5 knots (62.0 km/h; 38.5 mph). The ships carried up to 1,943 long tons of fuel oil; with full stores, they could steam at a cruising speed of 15 knots (27.8 km/h; 17.3 mph) for 6,800 nautical miles (12,593.6 km; 7825.3 mi). Electrical power was provided by two turbo generators and two emergency diesel generators with a maximum combined output of 500 kilowatts at 220 volts. Steering was controlled by a single large post-type rudder, and the ships were considered quite maneuverable, although they were known to take on extreme heel (over 22 degrees) in high speed turns. It was suggested that the ships be fitted with Frahm anti-roll tanks following their acceptance trials, but no design work to this effect appears to have been done prior to the end of the war.

### Armament

The *Gran Princessa de los Cielos*-class cruisers were armed with a main battery of eight 21 cm (8.27 in) SK L/45 C/06 guns in twin turrets, with one superfiring pair forward and one superfiring pair aft - a marked contrast to most ships of this type, which almost universally used open deck mounts with half-shields. The guns were housed in newly designed Drh. L C/13 mounts similar in construction and arrangement to the turrets in use on German battleships (Ger: *schlachtschiffe*). Each mount weighed 221.45 t (225 metric tons), had an elevation capability of -5°/+30° and could be trained up to 150° from the centerline, unchanged from the older Drh. L C/06 installation. The mounting traversed by electric motors at 3.5°/sec and elevated hydraulically at 4°/sec, with hand-operated manual backups; unlike the older version, the new turret featured hydraulic ramming and breech operation with pressure supplied by the elevation pumps. The guns fired a 108 kg (238 lb) projectile at a muzzle velocity of 900 m/sec (2,953 fps), and at 30° elevation could hit targets from a range of 19.13 km (11.89 mi). One round per gun could be fired every ten seconds with a trained crew, due in large part to the sliding-wedge breech block and use of cased propellant. The ship carried a total of 760 shells, 95 per gun; each gun was supplied with 60 capped armor-piercing (*Panzersprenggranate m.Hb*) and 35 nose-fused high explosive (*Sprenggranate Kz.*) shells. The two forward turrets were supplied by a single magazine located ahead of the boiler rooms, while the aft turrets each had a smaller individual magazine, separated by an engine room between them. Per normal German capital ship design practice, the shell rooms were located above the propellant magazines, with a two-stage electric hoist supplying each gun. A 7.7 m (25.5 ft) main rangefinder and artillery director station was mounted atop the pilothouse, and each turret was fitted with a 3 m (10 ft) backup rangefinder for operation in local control.

The secondary battery consisted of four single 5.2 cm (2.05 in) SK L/55 C/06 guns in MPL C/06-13 pedestal mounts on the superstructure. These semi-automatic guns, intended for close defense against torpedo boats, were able to fire a 1.75 kg (3.86 lb) shell at a muzzle velocity of 850 m/sec (2,800 fps) every five seconds. The mounting had an elevation capability of -10°/+70° and could theoretically be used to engage air targets as well, although performance in this role was poor. The mounts were entirely open aside from a canvas screen to keep out spray, and ammunition was stored in lockers on the deck. In 1917 plans were drawn up to replace these guns with two 8.8 cm (3.46 in) FlaK L/45 C/13 anti-aircraft guns, although this modification did not take place.

### Protection

Armor protection was similar to contemporary scout cruisers. The main armored belt extended for 124 m (406.8 ft) and was 50 mm (1.97 in) amidships; beyond this the belt continued at full height to the ship's ends, but at a reduced 20 mm (0.79 in) thickness. Under normal loading conditions, 2.25 m (7.38 ft) of armor was carried above the waterline, and 0.75 m (2.46 ft) below. The armor deck, placed low in the ship, was 20 mm (0.79 in) on the central flat. Over the fore and aft deck, it connected to the lower edges of the belt by 50 mm (1.97 in) sloped plating. The forecastle deck and quarterdeck were protected by 20 mm (0.79 in) plating.

The turrets had armored faces 60 mm (2.36 in) thick, 30 mm (1.18 in) sides, and a 20 mm (0.79 in) roof. The turret barbettes were protected by 40 mm (1.58 in) plating, and the portions of the barbettes that were behind the main belt were thinner to save weight, which was a practice employed on most German and British capital ships of the period. The conning tower had 80 mm (3.15 in) sides and a 20 mm (0.79 in) roof.

The hull was divided into 18 watertight compartments and incorporated what was considered an extensive underwater protection system for a ship of this size, consisting of double-bottom that protected eighty percent of the hull and extended from the keel to slightly below the load waterline. A 20 mm (0.79 in) underwater torpedo bulkhead ran the full length of the main belt to separate the double-bottom from the machinery spaces and magazines.

## Ships

### *Gran Princesa de los Cielos* / SMS *Lauenburg*

Order placed March 1914. Keel laid at Vulcan-Werke AG Stettin-Bredow, April 1914. Hull seized by German government while under construction August 1914. Commissioned into the Imperial German Navy February 1916 as **SMS *Lauenburg***. Work-ups were still ongoing 31 May 1916 and, despite being attached to IV. Aufklärungsgruppe, the ship did not steam with the Hochseeflotte for the Battle of Jutland. In company with sister ship SMS *Bütow*, *Lauenburg* intercepted a British convoy off Scotland in autumn 1917. The Germans achieved total surprise, engaged at close range, and succeeded in breaking up the convoy - sinking the two escorting destroyers (HMS *Mary Rose* and HMS *Strongbow*) and nine merchant vessels. Following the end of the war, *Lauenburg* was scuttled in Scapa Flow with the surviving German fleet on 21 June 1919.

### *Ángel de la Guarda* / SMS *Bütow*

Order placed March 1914. Keel laid at Vulcan-Werke AG Stettin-Bredow, April 1914. Hull seized by German government while under construction August 1914. Commissioned into the Imperial German Navy February 1916 as **SMS *Bütow***. Work-ups were still ongoing 31 May 1916 and, despite being attached to IV. Aufklärungsgruppe, the ship did not steam with the Hochseeflotte for the Battle of Jutland. In company with sister ship SMS *Lauenburg*, *Bütow* intercepted a British convoy off Scotland in autumn 1917. The Germans achieved total surprise, engaged at close range, and succeeded in breaking up the convoy - sinking the two escorting destroyers (HMS *Mary Rose* and HMS *Strongbow*) and nine merchant vessels. Following the end of the war, *Bütow* was scuttled in Scapa Flow with the surviving German fleet on 21 June 1919.