Torpedo Deflection Sight Mark V

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T.D.S. Mark V[1]

The Torpedo Deflection Sight Mark V Types were British torpedo deflection sights. Unlike most of the others, these had only a single torpedo setting graduated on their deflection ring.

Mark V

The Mark V had just a single deflection ring, bearing the letter designation of a C in a circle, etched for the 26.75-27.25 knot setting of the 18-in Mark IV torpedo and the 14-in Mark X* torpedo.

By mid 1919, the 14-in torpedo tubes had been removed from the "P" class patrol boats, and so the T.D.S. Mark V was removed from them, leaving them only on the subset of the "S" class destroyers that carried 18-in tubes. Shortly thereafter, those ships would also lose their 18-in (Mark VI?)[2] torpedoes, leaving no vessels carrying the Mark V.[3]

It was considered that the freed-up Mark V sights could be used as primary control and night firing sights on the bridges of capital ships, replacing Pattern 2391A directors that had been modified for use as deflection sights and which were not fully satisfactory. It was thought that a sufficient plan for night firings was to use a fixed sight angle of 26 degrees, corresponding to an enemy at 17 knots and inclination 70 or 110 degrees and gyro angling such that forward flat torpedoes ran at 90 degrees and aft flat torpedoes ran 20 degrees abaft the beam. This would require the sight to have fixed stops at 64, 84, 116 and 136 degrees from right ahead and remove the need to agree on gyro angles before dark. The Mark V was thought splendid for this application, and it was considered that the deflection strip should be marked in director angle on one side and for the 35 knot setting on the other.[4]

Mark V*

T.D.S. Mark V*[5]
T.D.S. Mark V* Pedestal[6]

In 1920, however, it was desired to have sights graduated no in torpedo deflection but simply in director angle. The disused Mark V devices were an easy alteration to this purpose and so became the T.D.S. Mark V*.[7]

These were supplied, two each, to four of the Queen Elizabeth class (Queen Elizabeth already possessed sights altered to this standard), the Revenge class, the Iron Duke class, and H.M.S. King George V, replacing torpedo directors Pattern 2391 and Pattern 2392. Two Mark V* sights also went to Vernon, two to serve as spares, and one each to Actæon and Defiance. Ships' artificers were to alter the sight pedestals to receive the new sights.[8]

1921 alteration for night gyro settings[9]

Initially, these were provided with fixed night director angle settings of 26 degrees, and torpedoes were to leave forward tubes at 90 degrees relative, and from aft tubes at 110 degrees relative. Accordingly, the sights had stops at 64, 84, 116 and 136 degrees, with the two inside stops being fixed. Around 1921, it was decided to reduce the fixed director angle to 16 degrees, and it was realised that the director design should also admit the possibility that the torpedoes' gyro angle settings might in future be altered, and so it was deemed fit to adjust the design so that such stops could be made adjustable within limits. The new kits were adopted and their allocation authorised.[10]

See Also

Footnotes

  1. Annual Report of the Torpedo School, 1917. Plate 53.
  2. Annual Report of the Torpedo School, 1919. p. 103.
  3. Annual Report of the Torpedo School, 1918. p. 159.
  4. Annual Report of the Torpedo School, 1919. p. 111.
  5. Annual Report of the Torpedo School, 1920. Plate 27.
  6. Annual Report of the Torpedo School, 1920. Plate 28.
  7. Annual Report of the Torpedo School, 1920. p. 77.
  8. Annual Report of the Torpedo School, 1920. p. 78, Plate 28.
  9. Annual Report of the Torpedo School, 1921. Plate 43.
  10. Annual Report of the Torpedo School, 1921. pp. 137-8.

Bibliography

  • H.M.S. Vernon. Annual Report of the Torpedo School, 1918. C.B. 1527. Copy 20 at The National Archives. ADM 189/38.
  • H.M.S. Vernon. Annual Report of the Torpedo School, 1919. C.B. 1569. Copy 103 at The National Archives. ADM 189/39.
  • H.M.S. Vernon. Annual Report of the Torpedo School, 1920. C.B. 1584. Copy 126 at The National Archives. ADM 189/40.