Schwalbe-class cruiser

Through the 1870s and early 1880s, Germany built two types of cruising vessels: small, fast avisos suitable for service as fleet scouts and larger, long-ranged screw corvettes capable of patrolling the German colonial empire. A pair of new cruisers was authorized under the 1886–1887 fiscal year, intended for the latter purpose.^[1] In the early 1880s, the fleet's colonial cruisers consisted of a motley collection of older sailing ships that were suitable only for training purposes. General Leo von Caprivi, the Chief of the Kaiserliche Marine (Imperial Navy), sought new cruisers that would have strong fighting capabilities in addition to traditional overseas cruiser characteristics.^[2] At that time, the navy largely relied on gunboats to patrol the colonies, supported by a flying squadron of cruisers as necessary. As the overseas empire grew in size, it became increasingly untenable to rely on this structure to enforce German claims on its colonies. The two new cruisers were intended to support the colonial gunboats on a permanent basis.^[3]

The design was prepared in 1886–1887,^[4] and competing operational requirements defined their characteristics. The need to operate close to shore necessitated a relatively shallow draft. Commerce protection duties mandated an auxiliary sailing rig, while the need to conduct police actions in the colonies required a crew large enough that a landing party could be spared. The Schwalbe class was the first unprotected cruiser design built in Germany, and along with several other small warships, they permitted Caprivi to retire five old sailing frigates and modernized the German cruiser force. They were well-received by the German Navy, and they also provided the basis for the even more successful Bussard-class cruisers.^[2][5]

The ships of the Schwalbe class were 62.59 meters (205 ft 4 in) long at the waterline and 66.90 m (219 ft 6 in) long overall. They had a beam of 9.36 m (30 ft 9 in), though over the sponsons for the main guns, the beam increased to 10.10 m (33 ft 2 in). The ships had a draft of 4.4 m (14 ft 5 in) forward and 4.72 m (15 ft 6 in) aft. They displaced 1,111 metric tons (1,093 long tons) as designed and up to 1,359 t (1,338 long tons) at full load. The ships' hulls were constructed with a transverse framing composed of steel, and were covered with a layer of wood and copper sheathing to protect them from marine biofouling on extended voyages overseas. Their stem and stern were made of wood, and a bronze ram was mounted at the bow. The hull was divided into eleven watertight compartments.^[6]

Steering was controlled by a single rudder. The two cruisers were good sea boats, and were very maneuverable. They suffered from severe weather helm, and tended to roll badly in a beam sea; their metacentric height was .665 m (2 ft 2.2 in). They lost little speed in a head sea. Schwalbe and Sperber each had a crew of 9 officers and 108 enlisted men. They carried a number of small boats, including one picket boat, one cutter, one yawl, and one dinghy.^[7]

Their propulsion system consisted of two horizontal 2-cylinder double-expansion steam engines, with steam provided by four coal-fired cylindrical fire-tube boilers trunked into a single funnel. The engines drove a pair of 3-bladed screw propellers that were 2.8 m (9 ft 2 in) wide in diameter. The ships' engines provided a design speed of 13.5 knots (25.0 km/h; 15.5 mph) from 1,500 metric horsepower (1,500 ihp). They had a range of approximately 3,290 nautical miles (6,090 km; 3,790 mi) at a speed of 10 knots (19 km/h; 12 mph). On trials, both ships exceeded their rated speeds, with Schwalbe reaching 14.1 knots (26.1 km/h; 16.2 mph) and Sperber making 14.3 knots (26.5 km/h; 16.5 mph), from 1,558 and 1,595 metric horsepower (1,537 and 1,573 ihp), respectively. At these speeds, the cruising radius fell to 1,630 nmi (3,020 km; 1,880 mi). To supplement the steam engines, the ships were fitted with a barquentine rig. Schwalbe was fitted with one electricity generator rated at 5 kilowatts (6.7 hp) at 67 volts during her modernization in 1903.^[6][8]

Since Caprivi sought overseas cruisers that would still have significant combat power, the ships were armed with a relatively heavy main battery—for ships of their size—of eight 10.5 cm (4.1 in) K L/35 guns in single pedestal mounts. Four were placed in sponsons fore and aft to give a measure of end-on fire, and the remaining four amidships on the main deck. Four guns could fire on either broadside. They were supplied with 765 rounds of ammunition in total. They had a range of 8,200 m (9,000 yd). Four of the guns were mounted in sponsons, with two side by side forward and aft. The remaining four guns were placed amidships in gun ports. Four guns were mounted on each broadside. The gun armament was rounded out by five 3.7 cm (1.5 in) Hotchkiss revolver cannon for defense against torpedo boats.^[6][8] The ships also carried a single torpedo tube that was carried amidships on a trainable mount, which could be fired to either side at a fixed angle.^[9]