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|Preceded by:||Colossus class|
|Succeeded by:||King George V class|
|Length:||581 ft (177.1 m)|
|Beam:||88 ft (26.8 m)|
|Draught:||24 ft (7.3 m)|
|Propulsion:||Direct-drive steam turbines, 18 boilers, 4 shafts: 27,000 hp (20 MW)|
|Speed:||21 knots (38.9 km/h)|
|Range:||6,730 nm at 10 knots (12,450 km at 18.5 km/h)|
The Orion-class battleships were four super-dreadnought battleships—the first ships of that type—of the Royal Navy. The lead ship, Orion, was launched in 1910. They were the first Royal Navy dreadnoughts to have all their main guns in the centreline; the U.S. Navy's first dreadnoughts, the South Carolina class, had pioneered this advanced feature. The Orions were quite distinct from the later classes of 13.5-inch gun super-dreadnoughts (the King George Vs and Iron Dukes) in that the foremast was placed behind the forefunnel. This arrangement was common in early Royal Navy dreadnoughts but created major problems for the gunnery direction team in the spotting top.
Design and development
Previous British dreadnoughts had been built very much with an eye on cost. By 1909, the escalating Anglo-German naval arms race had released greatly increased resources from the British treasury. These ships were much bigger than the preceding Colossus class and cost almost £1.9 million each to construct.
The move to the 13.5-inch (343 mm) gun came out of necessity. The final iteration of the 12-inch (305 mm), the high velocity 50 calibre long Mark XI,[page needed] had been unsuccessful. It lost some of its accuracy and was subject to considerable bore erosion that limited its useful life to about 80 discharges. A lower velocity weapon was indicated, and this was realized in the 13.5-inch, 45 calibres long, and with a much heavier projectile. The projectile used was 1,250 lb (567 kg) or 1,400 lb (635 kg) against 850 lb (386 kg). The shorter range of the low-velocity gun was compensated by increasing the maximum elevation from 15 to 20 degrees. The 13.5-inch was considered a successful design, although its effectiveness was compromised by poor shell design until availability of the "Green Boy" shells in 1918.[note 1]
The adoption of the all-centreline armament was also born of necessity. The previous Colossus and Neptune classes had already adopted a superfiring pair of turrets aft in an effort to save deck space, and competing designs in the U.S. and elsewhere had led the way in the all-centreline arrangement. From a combat efficiency standpoint the staggered turret configuration of the Colossuses and Neptunes complicated internal arrangements and was generally not considered a success. Unfortunately, the retention of outdated sighting hoods meant the Orions were not able to fire the superimposed turrets over the deck turrets for fear that the blast would injure crews in the lower turrets. Also, the design's relatively high centre of gravity gave the Orions a pronounced roll in rough seas. Both these defects were eventually cured and the improvements included in subsequent classes of British dreadnoughts.
The armour belt was increased to 12 inches (305 mm) in view of the general increase in gun calibre of potential adversaries. It is typical of British designs where armour thickness lagged behind their carried gun size, this being the opposite design driver of German ships in which armour thickness was usually greater than the calibre of the guns they carried. It is also of interest to note adequacy of ship armour was still being judged by belt thickness, while deck thickness was a secondary consideration. This became more critical as battle ranges extended beyond approximately 12,000 yards (11 km) and the trajectory of the incoming shells became increasingly steep.
All four were present at the Battle of Jutland of 1916 in World War I, but took no damage. They had a relatively short career, all being decommissioned in 1921, due to the Washington Naval Treaty. Orion and Conqueror were scrapped in 1922. Monarch served as a target, surviving a full day of shelling and bombing on 20 January 1925 before being sunk by fire from HMS Revenge. Thunderer served longest, acting as a training ship from 1922 until she, too, was sold for scrap in December 1926.
|Orion||HM Dockyard, Portsmouth||29 November 1909||20 August 1910||2 January 1912||Broken up at Upnor, 1923|
(ex-King George V)
|Armstrong Whitworth, Elswick||1 April 1910||30 March 1911||27 April 1912||Sunk as target, 21 January 1925|
|Conqueror||William Beardmore, Dalmuir||5 April 1910||1 May 1911||1 December 1912||Broken up, 1923|
|Thunderer||Thames Ironworks, London||13 April 1910||1 February 1911||15 June 1912||Broken up at Blyth, 1926|
- Fitzsimons, Bernard, editor. The Twentieth Century Weapons and Warfare (London: Phoebus, 1979), Volume 19, p.2048, "Orion".
- Fitzsimons, Bernard, editor. The Twentieth Century Weapons and Warfare (London: Phoebus, 1979), Volume 19. The 12 inch had been RN's standard weapon since 1893.
- Parkes, Oscar (1956). British Battleships : Warrior to Vanguard 1860-1950 - A History of Design, Construction and Armament.
- Burt, Ray (1986) (2012). British Battleships of World War One, Seaforth Publishing, ISBN 978 1 84832 147 2
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