HMS Leonidas was a Laforey class

Laforey class destroyer (1913)

The Laforey class was a class of 22 torpedo boat destroyers of the Royal Navy, twenty of which were built under the Naval Programme of 1912 - 1913 and a further two under the War Emergency Programme of 1914. As such they were the last pre-war British destroyer design. All served during World War I...

 torpedo boat

Torpedo boat

A torpedo boat is a relatively small and fast naval vessel designed to carry torpedoes into battle. The first designs rammed enemy ships with explosive spar torpedoes, and later designs launched self-propelled Whitehead torpedoes. They were created to counter battleships and other large, slow and...

 destroyer

Destroyer

In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

 of the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. She was launched on 30 October 1913. She served in 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...

 with the 3rd Destroyer Flotilla and as a convoy escort in World War I and was broken up in 1922. The ship was originally named Rob Roy but the name was changed after a new naming scheme was introduced to give all ships of the same class names beginning with the same letter. Overall cost of the ship was £100,000

Technical innovations

Leonidas, together with Lucifer, was one of two experimental destroyers ordered in 1912 from Parsons to be fitted with fully geared turbines. Gearing meant that the turbine itself could run at higher speeds than the propeller, which improved efficiency. Two previous experimental destroyers, Badger and Beaver

HMS Beaver (1911)

HMS Beaver was an Acheron-class destroyer of the Royal Navy that served during the First World War and was sold for breaking in 1921. She was the ninth Royal Navy ship to be named Beaver, after the mammal of the same name.-Construction:...

 had been ordered in 1911 which used gearing for the high pressure (HP) turbines but not for the low pressure (LP) ones. Sufficiently robust gearboxes were at that time experimental and were only just being produced by Parsons who had developed innovative gear cutting equipment. Ships propellers rotated at a maximum speed of 380 rpm, while the LP turbines ran at 1800 rpm and the HP at 3000 rpm. It was anticipated that the additional gearing would produce an overall 10% increase in efficiency, ranging from 9% at full power to 26% at low power, since turbines are more efficient at higher speeds and performance particularly suffered when the engines were running slowly. Comparative tests indicated the savings equated to the ships being able to remain on patrol at cruising speeds for an extra two days as compared to a ship using partially geared turbines. Cost of the ships increased because of providing gearboxes, but this was partly offset against a reduction in the total necessary power from the turbine to achieve a given speed, meaning that smaller and cheaper turbines could be used. Other ships of the class built without LP gearing required 24,500 shp compared to 22,500 shp for this design.

Two designs were produced for the ships propellers because of disagreement between the admiralty and Parsons on the better design. For the same overall dimensions, Parsons used a blade area of 54 square feet (5 m²) while the admiralty preferred 42.5 sq ft (3.9 m²). The introduction of gearing meant that bearings holding the shafts were now subject to large lateral forces where the gears pushed against each other. This was a significant difficulty in gearbox design but was overcome by the introduction of the new Michell

Anthony Michell

Anthony George Maldon Michell FRS was an Australian mechanical engineer of the early 20th century.-Early life:...

 tilting-pad fluid bearing

Fluid bearing

Fluid bearings are bearings which support the bearing's loads solely on a thin layer of liquid or gas.They can be broadly classified as fluid dynamic bearings or hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and...

. This was first employed in 1913 on a cross channell steamer, Paris built by Denny

William Denny and Brothers

William Denny and Brothers Limited, and often referred to simply as Denny, were a Scottish shipbuilding company.-History:The Company was founded by Peter Denny in 1840 and based in Dumbarton, on the River Clyde. Although the Denny yard was situated near the junction of the River Clyde and the River...

 of Dunbarton which also used geared turbines, and then on Leonidas and Lucifer. Traditional bearings were found unable to support the forces in turbine gearboxes but also had higher friction in more traditional application with reciprocating engines. It was estimated that the reduced frictional losses on new bearings introduced throughout the fleet saved the admiralty £500,000 in reduced fuel consumption in 1918.

Career

Leonidas took part in a battle off Noorhinder Bank

Battle off Noordhinder Bank

The Battle off Noordhinder Bank on 1 May 1915 was a naval action between a squadron of four British naval trawlers supported by a flotilla of four British destroyers, and a pair of German torpedo boats from the Flanders Flotilla. The battle began when the two torpedo boats were sent on a search and...

 on 1 May 1915 when together with three other destroyers, Laforey

HMS Laforey (1913)

HMS Laforey was the lead ship of the her class of destroyer built for the Royal Navy. Launched a year before the First World War began, she was attached to the Dover Patrol. Laforey saw action in several engagements with German torpedo boats, including the Battle off Noordhinder Bank and the Action...

, Lawford and Lark, she was dispatched to go to the aid of four British armed trawlers which had engaged two German Topedo boats, A2 and A6. One of the trawlers had been sunk, but sufficient damage had been caused to A6 that the Germans chose to withdraw. The four destroyers pursued the torpedo boats, eventually catching and sinking them.