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Aetna-class ironclad floating battery
French floating battery Lave
Lave, one of the Aetna class's French half-sisters.
Class overview
Name: Aetna
Operators: Naval Ensign of the United Kingdom.svg Royal Navy
Succeeded by: Erebus-class ironclad floating battery
Built: 1854-56
In service: 1855-73
Building: 6
Planned: 5
Completed: 5
Lost: 2
Retired: 4
General characteristics
Class & type: Aetna class floating battery
Tonnage: 1,469 BOM
1,535 BOM broad beam
1,588 BOM lengthened Aetna[1]
Length: Overall
172 ft 6 in (52.58 m)
186 ft 0 in (56.69 m) lengthened Aetna
Keel
146 ft 0 in (44.50 m)
157 ft 9 in (48.08 m) lengthened Aetna[1]
Beam: 43 ft 11 in (13.39 m)
45 ft 2.5 in (13.780 m) broad beam
43 ft 11 in (13.39 m) lengthened Aetna
For tonnage
43 ft 6 in (13.26 m)
44 ft 9.5 in (13.653 m) broad beam
43 ft 6 in (13.26 m) lengthened Aetna[1]
Draught: 8 ft 8 in (2.64 m)
6 ft 0 in (1.83 m) lengthened Aetna[1]
Propulsion: single screw, two cylinder horizontal single expansion 150 nhp engines[1] generating 530 ihp (400 kW) on Meteor's trials.[2]
(200 nhp for lengthened Aetna)[1]
Sail plan: Three masts 885 m2 (9,530 sq ft) sail[3][4]
Speed: 4.5–5.5 kn (8.3–10.2 km/h)
4 knots (7.4 km/h) lengthened Aetna[1]
Complement: 200 men[1]
Armament: 14 x 68 pdr 95 cwt smoothbores
16 x 68 pdr 95 cwt smoothbores lengthened Aetna[1]
Armour: 3.5-4 inch (90-100 mm) wrought iron
4 inch (100 mm) wrought iron lengthened Aetna[1][2]

The Aetna-class ironclad floating batteries were built during the Crimean War for the attack of Russian coastal fortifications.

Britain and France each laid down five of these coastal attack vessels in 1854. The French used three of their batteries in 1855 against the defences at Kinburn on the Black Sea, where they were effective against Russian shore defences. The British plan to use theirs in the Baltic Sea against Kronstadt in 1856 was influential in causing the Russians to sue for peace.[5] The development of such iron-armoured batteries was step towards the development of ironclad warships. "These armoured batteries were among the most revolutionary ships ever built and provided British and French designers with the germ of the battleship."[2]

One of the British batteries, the Trusty, was used for trials in 1861 with a prototype rotating turret, based on Captain Cowper Phipps Coles designs.

GenesisEdit

Emperor Napoleon III initiated the design of armoured steam-powered batteries for the French Navy. The original idea was to protect the sides with boxes of cannon balls, but the British engineer Thomas Lloyddisambiguation needed suggested using thick wrought iron plates instead. Trials at Vincennes showed that Lloyd's idea was more effective, so it was adopted.[2]

Napoleon wanted ten floating batteries built in time for the 1855 campaign, but as French industry could only build five in time, France's British allies were asked to build the other five.[2] Unfortunately the First Lord, Sir James Graham confused this concept with the unsuccessful iron-hulled frigates built in the late 1840s, and asked for further trials,[6] so the British armoured batteries were not ordered until 4 October 1854.[2]

DesignEdit

These vessels were copies of the French Dévastation-class batteries. The French batteries carried 16 guns, but had 24 gun ports. The British Aetna class were also intended to carry 16 guns, but the first four completed only carried 14 guns to reduce draught to 8 ft 8 in (2.64 m).[1][2] The Admiralty design drawing showed them with 32 gunports.[1] These ports were very large 34 in (0.86 m) x 40 in (1.0 m).[2]

The Aetna class had "wooden hulls, straight vertical sides and a flat bottom with a very bluff bow and stern. Their armour plates, nominally 4in [100mm] but in many cases rolled 0.25-0.5in under thickness, were locked together with tongue and groove joints."[2] The iron armour was supported by 20 in (510 mm) thick oak sides.[7] The wooden upper deck was 9 in (230 mm) thick.[2] There were two conning towers protected by 58 in (16 mm) wrought iron plate.[2]

In October 1858, experimental firing trials were undertaken against the Meteor and one of the follow-on class of iron-hulled armoured batteries, the Erebus. These demonstrated the importance of wooden backing for the armour, as the Meteor put up far better resistance than Erebus, where the frames were displaced by concussion.[7]

MachineryEdit

The first four completed had two-cylinder 25.5 in (0.65 m) diameter 24 in (0.61 m) stroke horizontal single expansion engines of 150 nhp, which operated at 62 psi (430 kPa).[1] Although they were completed as single screw vessels, the Meteor was altered to triple screw with wing-shafts;[1] her trials with triple screw were 12 days after her trials with single screw.[2] The most likely method of driving the wing shafts was a belt arrangement, which was common practice at the time.[2] It is unclear whether any of the others were also altered to triple-screw.[1]

On trials with a single 6 ft (1.8 m) diameter, 12 ft 6 in (3.81 m) pitch screw, Meteor reached 5.7 knots (10.6 km/h) at 139 rpm with the safety valve set at 60 psi, and engine power was recorded as 530 ihp (400 kW).[2] On her trials fitted as triple screw, the Meteor reached 5.25 knots (9.72 km/h) at 139 rpm. Engine power was recorded as 498 ihp (371 kW).[2] The two wing screws on this trial were 6 ft (1.8 m) diameter, 7 ft 6 in (2.29 m) pitch.[2]

Aetna (ii) had two-cylinder 27 in (0.69 m) diameter 30 in (0.76 m) stroke horizontal single expansion engines of 200 nhp. Her boilers were salvaged from Aetna (i).[1]

Building programmeEdit

Ship (a) Hull builder
(b) Main machinery manufacturers
Ordered Laid Down Launched Completed Initial cost Total
Initial
Cost
Hull Machinery to
complete
for sea
Aetna class
Aetna (i) (a) J Scott Russell, Millwall
(b) J Scott Russell
4 Oct 1854 9 Oct 1854 3 May 1855 Never Never delivered, caught fire during construction
Meteor (a) CJ Mare & Co, Limehouse
(b) Maudslay, Sons & Field
4 Oct 1854 9 Oct 1854 17 Apr 1855 4 Jul 1855 £43,799 £10,123 £7,468 £61,390
Thunder (a) CJ Mare & Co, Limehouse
(b) Miller, Ravenshill & Co
4 Oct 1854 9 Oct 1854 17 Apr 1855 21 Jul 1855 £43,784 £10,343 £8,210 £62,337
Broad beam Aetna class
Glatton (a) R & H Green, Limehouse (no 314)
(b) Miller, Ravenshill & Co
4 Oct 1854 9 Oct 1854 18 Apr 1855 3 Aug 1855 £43,479 £11,244 £5,858 £60,581
Trusty (a) R & H Green, Limehouse (no 315)
(b) Miller, Ravenshill & Co
4 Oct 1854 9 Oct 1854 3 May 1855 13 Jun 1855 £43,491 £10,446 £10,004 £63,941
Lengthened Aetna class
Aetna (ii) (a) Chatham Dockyard
(b) Maudslay, Sons & Field
16 Nov 1855 25 Nov 1855 5 Apr 1856 1866
Harbour service
£38,357 £11,000 £495 £49,852
Source: Lyon & Winfield, pages 240-2[1]

Note that whilst Admiralty records for Meteor, Thunder, Glatton and Trusty state that both the Mare and the Green yards were at Limehouse, other vessels built by Mare and by Green were built at Blackwall. It is possible that there is an error in the records, and they were really built at Blackwall.[1]

FatesEdit

  • Aetna (i) was to have been launched on 5 May 1855, but caught fire on the building slip, and launched herself two days early. Her remains were broken up on the river-bank.[1]
  • Meteor was ready in 1855 but reached the Black Sea too late for action. She was laid up in theatre for the winter, and in the Spring, when peace was signed, returned home for the great review of April 1856.[2] The Meteor was used in experimental firing trials in October 1858.[7] She was broken up in 1861.[1]
  • Thunder took part in the great review in April 1856 after the end of the Crimean War.[2] She was broken up at Chatham in June 1874.[1]
  • Glatton was ready in 1855 but reached the Black Sea too late for action. She was laid up in theatre for the winter, and in the Spring, when peace was signed, returned home for the great review of April 1856.[2] She was broken up in 1864.[1]
  • Trusty took part in the great review in April 1856 after the end of the Crimean War.[2] She was used in trials of the new Armstrong 40-pdr BL in January 1859 and the 100-pdr BL in September 1859; contrary to expectations, hits on her armour from the 40-pdr and 100-pdr had no serious effect.[7] She was used in trials with a prototype Coles turret in 1861 and in so doing became the first warship to be fitted with a turret.[1] She was broken up by Castle at Charlton in 1864.[1]
  • Aetna (ii) was too late for the Crimean War, and was fitted for harbour service in 1866. She burnt out at Sheerness in 1873 and was broken up in 1874.[1]

FootnotesEdit

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 Lyon, David & Winfield, Rif The Sail and Steam Navy List, all the ships of the Royal Navy 1815-1889, pub Chatham, 2004, ISBN 1-86176-032-9 pages 240-2.
    Note that there is a typographical error on page 241, where it says that the Aetna was launched on 3 May 1854, which should read 3 May 1855.
    Lyon & Winfield state that the armour thickness was 3.5-4.5 inches for the Aetna class, and 4.5 inches for Aetna (ii). The other sources referenced give the maximum hull thickness as 4 in. The details in Lyon & Winfield are within the 0.5 inch tolerance for rolled armour of the period.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 Brown, David K Before the Ironclad, development of ship design, propulsion and armament in the Royal Navy, 1815-60, pub Conway, 1990, ISBN 0-85177-532-2 pages 156-8.
  3. Assumed to be the same as the French Lave. Lyon & Winfield do not mention the sail plan of these vessels.
  4. Brown, David K Before the Ironclad, development of ship design, propulsion and armament in the Royal Navy, 1815-60, pub Conway, 1990, ISBN 0-85177-532-2 page 5 has a drawing of the Thunderer at sea with three masts and sails.
  5. Lambert A. "Iron Hulls and Armour Plate"; Gardiner Steam, Steel and Shellfire p. 47-55
  6. Brown says that these trials were in September 1856 - Before the Ironclad page 156. This date seems wrong - September 1854 would be more plausible. This needs checking.
  7. 7.0 7.1 7.2 7.3 Parkes, Oscar British Battleships, first published Seeley Service & Co, 1957, published United States Naval Institute Press, 1990. ISBN 1-55750-075-4 page 12-4.

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