The U-52 class was a class

Ship class

A ship class is a group of ships of a similar design. This is distinct from a ship-type, which might reflect a similarity of tonnage or intended use. For example, the is a nuclear aircraft carrier of the Nimitz class....

 of four ocean-going submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s or U-boats planned for the Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

  during World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. The submarine design was based on the A 6 proposal submitted by Stabilimento Tecnico Triestino

Stabilimento Tecnico Triestino

Stabilimento Tecnico Triestino was a private shipbuilding company based in Trieste from the mid-19th to early 20th century, and the most important naval shipbuilding firm of the Austro-Hungarian Empire....

 (STT) as part of a Navy design competition. STT, under its wartime name of Austriawerft, began construction on the first two boats in 1916, but neither boat was launched or completed before the end of the war. Both incomplete submarines were scrapped after the war ended. Neither of the third and fourth submarines was ever laid down.

Design

Austria-Hungary

Austria-Hungary

Austria-Hungary , more formally known as the Kingdoms and Lands Represented in the Imperial Council and the Lands of the Holy Hungarian Crown of Saint Stephen, was a constitutional monarchic union between the crowns of the Austrian Empire and the Kingdom of Hungary in...

's U-boat fleet was largely obsolete at the outbreak of World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, and over the first two years of the war the Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

 focused its efforts on building a U-boat fleet for local defense within the Adriatic. With boats to fill that need either under construction or purchased from Germany, efforts were focused on building ocean-going submarines for operation in the wider Mediterranean, outside the Adriatic.

To that end, the Austro-Hungarian Navy selected the Stabilimento Tecnico Triestino

Stabilimento Tecnico Triestino

Stabilimento Tecnico Triestino was a private shipbuilding company based in Trieste from the mid-19th to early 20th century, and the most important naval shipbuilding firm of the Austro-Hungarian Empire....

 (STT) A 6 design as the winner of a design competition for a new ocean-going submarine. The plans called for a boat that displaced

Displacement (ship)

A ship's displacement is its weight at any given time, generally expressed in metric tons or long tons. The term is often used to mean the ship's weight when it is loaded to its maximum capacity. A number of synonymous terms exist for this maximum weight, such as loaded displacement, full load...

 849 t (935.9 ST) surfaced and 1200 t (1,322.8 ST) submerged. The boats were to be 249 in 3 in (75.97 m) long with a beam

Beam (nautical)

The beam of a ship is its width at the widest point. Generally speaking, the wider the beam of a ship , the more initial stability it has, at expense of reserve stability in the event of a capsize, where more energy is required to right the vessel from its inverted position...

 of 22 in 10 in (6.96 m) and a draft

Draft (hull)

The draft of a ship's hull is the vertical distance between the waterline and the bottom of the hull , with the thickness of the hull included; in the case of not being included the draft outline would be obtained...

 of 11 in 6 in (3.51 m). For propulsion, the design featured two shafts, with twin diesel engine

Diesel engine

A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

s of 2400 bhp (total) for surface running at up to 15.75 knots, and twin electric motor

Electric motor

An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

s of 1480 shp (total) for submerged travel at up to 9 knots. The U-52 class boats were designed for a crew of 40 men.

The U-52 design called for six 45 cm (17.7 in) torpedo tubes—four bow tubes and two stern tubes—and a complement of nine torpedoes. The original design specified two 10 cm/35 (3.9 in) deck gun

Deck gun

A deck gun is a type of artillery cannon mounted on the deck of a ship or submarine.The deck gun was used as a defensive weapon against smaller boats or ships and in certain cases where torpedo use was limited. Typically a crew of three; gunner, loader, and layer, operated the gun, while others...

s, which were superseded by two 12 cm/35 (4.7 in) deck guns in plans for the third and fourth boats.

Construction

By 1916, Austriawerft, the new, more-"patriotic" wartime name for STT, had begun construction on U-52 and U-53, the first two boats of the class. Austriawerft remained headquartered at Trieste, but sources do not specifically say where the two U-52 submarines were laid down. These first two boats, which comprised one-third of the six ocean-going submarines under construction in 1916,The other four boats were U-48 and U-49 of the and U-50 and U-51 of the . See: Gardiner, p. 341. were followed by orders for U-54 and U-55 in December 1917.

Shortages of skilled shipyard workers as well as material slowed construction of all of the ocean-going boats. As a result, neither of the first two boats was ever launched, much less completed, and the second pair was cancelled before either was laid down. U-52 was 25% complete at war's end, while U-53 was only 10% complete. Both boats were scrapped in 1919.