Difference between revisions of "Acheron Class Destroyer (1910)"

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Revision as of 11:43, 30 August 2012

Twenty-nine destroyers of the Acheron Class were completed between 1911 and 1912. Twenty were part of the 1910-1911 Programme, and an additional six (later nine) Specials were ordered.

They were the last Royal Navy destroyers to use the 12-pdr gun.

Most served in the First Destroyer Flotilla. Their 60 test runs of the 21-in Mark II torpedo in the first half of 1916 were judged 87% likely to endanger the enemy,[1] but Oak served as the dispatch vessel toIron Duke and Firedrake and Lurcher served with submarine flotillas in Harwich.[2]

In October, 1913, they were redesignated the "I" class.[3]

Performance

Turning performance was widely variable, as it had been with the Acorns. Ferret achieved 4 miles to the ton of coal at 27.5 knots. Redpole topped out at a spry 30.61 knots in rough weather! Ferret 422 yards starboard, 593 port, and Goshawk 451 yards to starboard and 470 to port. Twin-screw Hind was 669/643. Twin-screw Hornet burned 50.6 tons in an 8 hour full power test, and the nominally identical Hydra burned 61.6 tons. Triple screw consumption ranged from 54.02 tons in Jackal to 62.352 tons in Forester. Lubricating oil loss varied between 120 gallons and none at all![4]

Armament

The gun armament used here was similar to that used since the Beagle class, though the mountings improved and the 12-pdrs moved further forward than in the preceding Acorn class.

4-in Guns

Two 4-in guns were mounted forward and aft. They were 4-in BL Mark VIII guns on P V mountings with 36 common and 84 lyddite rounds each (plus 14 practice rounds per gun per quarter).[5][6]

The mounting could elevate to 20 degrees and depress to 10 degrees, but the sight could elevate 15 degrees (9,300 yards full charge).

The sight was lightweight, non-FTP cam-worked design with range dials provided for 2150 fps, 1-in aiming rifle and .303-in aiming rifle. MV could be corrected by a moving scale plate to +/- 150 fps.

The deflection gearing constant was 43.76 with 1 knot equal to 3.05 arc minutes, corresponding to 2275 fps at 2000 yards. Drift was corrected by inclining the sight backet 2 degrees.

Sight lines were 16.5 inches above the bore, and 15 inches left for the layer and 17.46 inches above and 12.5 inches right for the trainer. There were open sights on both sides and temperature correctors were provided.

During the war, some of the ships had their aft 4-in gun landed to accommodate depth charges.[7]

12-pdr Guns

Two 12-pdr guns were mounted just after the break of the forecastle deck, port and starboard.[8]

They were 12-pdr 12 cwt QF guns on P VI mountings with 30 common and 70 lyddite rounds per gun (plus 10 practice rounds per gun per quarter),[9] the same weapon as since the "Tribal" group. The mountings could elevate to 20 degrees and depress to 10.

The sights were gear-worked with a range gearing constant of 30.857, and range dials for 2200 fps, 2175 fps, 1-in and .303-in aiming rifles. They could elevate to 11.5 degrees, or 6,075 yards full charge). There was no means of correcting for muzzle velocity. It was a simple design compared to that used in the Acorn class.

Deflection gearing constant was 45.707, with 1 knot equalling 3.76 arc minutes, corresponding to 2200 fps at 2000 yards.

Drift was corrected by inclining guides to the sight carrier 2 degrees. Sighting lines for the layer were 11.558 inches above the bore and 10.106 inches left. The trainer's sighting lines were 12.270 inches above the bore and 10.881 inches right. Open sights and head rests were provided on both sides. There was no temperature corrector.

Gun trials showed that the sightsetter (probably for the 12-pdr guns)[Inference] was in danger of falling overboard when firing at some bearings.[10]

Torpedoes

Two single 21-in tubes on the centre line

Other Weapons

Depth charges were added during the war to many of the ships, requiring some to surrender their aft 4-in gun.[11]

Fire Control

By 1915, at least, these ships also had fixed voice pipes installed between decks with the last lengths being flexible (one voice pipe for gunnery, one for torpedoes) fitted between bridge and guns, torpedo tubes, and searchlights. A third voicepipe, entirely flexible, ran from bridge to the forward gun.[12]

Instruments

By 1920, the ships in Acorn to Laforey classes had Wise Pressure Telegraphy Systems in place to support fire control.[13]


Alterations

By November 1918, Ferret and Sandfly were fitted to carry 38 mines, as they were operating with the Twentieth Destroyer Flotilla which was uniformly capable in this regard. The torpedo tubes and guns removed when the mines were shipped could be placed back aboard with enough notice.[14]

See Also

Footnotes

  1. Annual Report of the Torpedo School, 1916, p. 87.
  2. March, p. 122.
  3. Conway's All the World's Fighting Ships, 1906-1921, p. 75.
  4. March. p. 119.
  5. March, p. 116.
  6. The Sight Manual, 1916, pp. 4, 85, 108, Plate 38.
  7. Technical History and Index Vol. 4, Part 34, p. 14.
  8. The Sight Manual, 1916, pp. 4, 96, 108, Plate 45.
  9. March, p. 116.
  10. March. pp. 118.
  11. Technical History and Index Vol. 4, Part 34, p. 14.
  12. Manual of Gunnery, Vol. III., 1915., p. 150.
  13. Technical History and Index Vol. 4, Part 34, pp. 15-16.
  14. Admiralty. Annual Report of the Torpedo School Mining Appendix, 1917-1918, p. 11. Plate 7.

Bibliography

Template:Acheron Class (1910)