Torpedo Director

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A Torpedo Director is merely a sight for torpedo fire, more similar to a settable gunsight than to a gunnery director.

Nature and Function

The Director Angle is the proper angle between the line of sight to the target and the path of the torpedo. Helping the torpedo officer judge and discern this angle from data available to him by direct observation or external sources is the fundamental purpose of any torpedo director. Additionally, a good torpedo director design should offer its user a quick means of judging whether the target is near enough that the torpedo will be able to reach it.

It should be noted that the proper director angle is dependent upon a proper estimation of enemy heading and speed (expressed in one of several ways), and upon the assumption that his motion while the torpedo is underway will, on average, continue about this mean heading. It is easy to see aiming a torpedo which generally takes longer to reach its target than does a shell requires more cooperation on the part of the target!

By 1916, the Royal Navy was clearly not happy with its directors. They were seen as flimsy, mechanically loose, and not very easy or quick to set.[1]

Director Triangle

The Royal Navy began the 20th century with a series of sights that characterized the torpedo firing problem according to the Director Triangle formed by the path of the torpedo, the line of sight to the target at the moment of firing, and the path of the target between firing and impact.[2] It delivered a number of sights which embodied this geometry, including the Pattern 2006 Torpedo Director.

Deflection Triangle

In 1915,[3] the Royal Navy started to migrate toward a different geometric model called the Deflection Triangle, formed by the path of the torpedo, the line of sight, and that component of the target's speed-across attributable to its movement alone (i.e., the Dumaresq Deflection as if our ship were not moving.[4][5]

Common Accoutrements

A Radiomir Fore Sight is one with a small glass tube containing radium for use in night work.

A Compass Ring was conceived in 1911 for 2006 and 2391/2392 ... an outer ring marked in Quadrant bearings that could be attached to the base of the director and set to own ship's course. The enemy bar would be clamped to this ring. and it was thought that this ring could be adjusted manually if own ship changed course by reference to a compass near at hand or perhaps by automatic adjustment via a gyrocompass repeater.[6] It sounds like a snafu.

A Inclination Disc (or Robinson Disc[7] ) is a disc that rides the sighting arm and is marked 0 to 180 degrees left and right so that target Inclination is directly readable.[8]

A Longmore Disc was a disc that showed the inclination of the enemy to the torpedo bar (rather than the sight bar). It was used on the 2380, but in 1915 or thereafter, it was to be replaced by a Robinson Disc.

A Gyro Angle Base or "angled stand" was proposed for some directors in 1911[9] to support the proposed general introduction of torpedoes with angled gyros. It consisted of a pair of discs that could rotate up to 40 degrees either side of zero against each other and lock every 10 degrees (initially) or 5 degrees (from 1916 or so) by use of a conical spring permitted them to be clicked to the same heading a torpedo set to the same gyro angle would take upon being fired.[10]

A Tangent Bar was a small armature which could be added to a torpedo director to offset its rear sight a short distance to make its sighting angle converge with the track of the torpedo when the director could not be located on or near the firing tube. The idea was an example of the Royal Navy over-thinking the problem, and the service soon great disenchanted with the fragility and complexity they bestowed upon the directors. Some time during the production of directors Pattern 2391a and 2392a, some were being sent out without tangent bars and directors of Pattern 2006 and later that were brought in for repair were sent back without their tangent bars.[11] The conclusion finally reached was that the lateral errors that would remain untreated without the tangent bars were apt to be vastly smaller than the other sources of error inherent in accurate torpedo fire except in very short range attacks. These scenarios were to be treated by choosing a suitably offset aim point on the target.[12]

A Central Bearing Disc "similar to those fitted in Patts. 2391-2" was considered in 1911 for the 2006 directors.[13]


Royal Navy Torpedo Directors

Pattern 1192/1192a

A large, semicircular director, presumably of the director triangle principle, not used in any modern ships as of 1912.[14] If a 1192a existed, it was similar, but made stronger in its pivots and sighting bar.[15] As of 1916, it was noted as being in use in the H.M.S. Pelorus class, and its semicircular nature related to its employment as a "broadside director".[16] Some were fitted with tangent bars and regraduated to 2/3rd scale for use from TBD fore bridges and heater torpedoes.[17]

Pattern 1193/1193a

Had a 60 degree arc, used in early torpedo craft. If a 1193a existed, it was similar, but made stronger in its pivots and sighting bar.[18] Likely available in 1903, with a graduated sighting arm.[19] It was sometimes called the "Right Ahead" director.[20]

Pattern 1895/1895a

Very similar to the 1193, the 1895 had a 60 degree arc and was used in early torpedo craft. If a 1895a existed, it was similar, but made stronger in its pivots and sighting bar.[21] It lacked graduations on its sighting arm.[22] In 1909, those used with heater torpedoes had their scales regraduated at 2/3rds scale to allow for the faster torpedoes.[23]

Pattern 2006/2006a

Thirty of these compact, circular directors were ordered for trial at 'Vernon and at sea in 1904. Its torpedo arm was not pivoted, and the square knob for the enemy speed pinion was geared such that each flat of the square knob was a knot of enemy speed (4 knots per turn). The sights were fine wires in sighting arches. The distance from the fore sight to the pivot of the sight bar was fixed at 17 inches.[24]

Probably ready for service some time in 1905[25]m it was used in conning towers and director towers of "earlier ships" (as judged by 1912[26]) with a tangent bar, and perhaps also at times directly on tubes.[27] The 2006a was fitted for adapting to gyro angles, sometime after 1912.[28][29]

The directors had slides underneath permitting some lateral motion (3 inches?) to look around obstacles.[30]

In 1912, a design was approved to add a central bearing disc and a Carpenter's disc sight to the director.[31]

By 1916, displeasure with tangent bars was such that Pattern 2006 directors and later brought in for repair were sent back without their tangent bars.[32]

Pattern 2380/2380a

Similar to the Pattern 2390a, but larger and of improved construction.[33] By 1916 (at least), it had a possible shot scale and inclination disc.[34] It was a 50 degree sector model designed especially for light cruisers.[35] The enemy bar pivot was much stronger than on the 2390a. A lettered disc provided on the 2380 to set enemy heading in relation to the torpedo bar was obsolete by or before 1916. The 2380a differed by having the lettered disc removed in favor of an inclination disc and a Radiomir fore sight.[36]

Pattern 2389/2389a

Available by 1910 at least.[37] Same as the Pattern 2390, but fitted for use from the bridge, presumably by the addition of a tangent bar.[38] It almost certainly was a circular design.[Inference]

Pattern 2390/2390a

Disc added to 2390 to help set course of enemy as expressed as inclination.[39]
Note the lack of any graduations on the sighting arm.

Available by 1912 at least, supplied to torpedo craft with heater torpedoes. Similar to Pattern 1895, but graduated for higher torpedo and enemy speeds.[40][41][42] It was not circular, and probably a 60 degree arc like the 1895.[43][Inference] It lacked graduations on its sighting arm, but by 1916 at least, they sported inclination discs. The 2390a had more rigid pivots, sturdier construction, and a sighting arm that was solid rather than slotted, and made of hard rolled brass.[44]

Pattern 2387

Available from 1910 at least.[45] Same as Pattern 1192, but fitted for use from the bridge by addition of a tangent bar.[46]

Pattern 2388/2388a

Available by 1910 at least.[47] Same as Pattern 1193, but fitted for use from the bridge by addition of a tangent bar.[48] By 1916, they were considered obsolete.[49] They may have been semi-circular.[Inference]

Pattern 2391/2391a2392/2392a

A Pattern 2391 director similar to the 2392. The 2392 would differ by having its telescope mounted to the left of the sighting bar. The possible shot scale depicted is graduated for a Mark VI* heater torpedo (35 knots to 4,000 yards)[50]
Additional maximum firing range scales for use on Pattern 2391/2391a,2392/2392a directors using different tupes of torpedoes.

A "right handed" director for use in conning and director towers of ships from at least 1909-1910. They had open sights as well as the capability to mount a telescope.[51][52] The 2391a was fitted for gyro angling, sometime after 1912.[53][54]


In 1912, a design was approved to add a Carpenter's disc sight to the director.[55]

These were circular directors modified from the 2006.[56]

The telescopes used initially had crosswires, a 5-power magnification, and field of view of 7 degs, 10 minutes. It was not given illumination, as the regular sights would be used at night. Improvements in moving the rear sight along the tangent bar were incorporated, and an additional scale along the sighting bar allowed the maximum firing range to be read off directly. A disc labelled 0 to 180 degrees, port and starboard was added and a pointer on the speed and course of enemy bar. This disc was fitted only when a director was mounted on its ship, as the disc was oriented to own ship's keel, with 0 degrees being forward. The intent was that enemy heading could be communicated and set on the sight as a relative heading to own ship's course.[57]

The original telescope in use was a Pattern 2393 of 5 power and field 7 degrees 10 minutes, but in 1915, the need for the lower power scope for haze and rain was realised. A quick trial resulted in the Pattern 3341 of 2.5 power, ~25 degree field being introduced, likely sometime in 1916.[58][59]

Around 1910, as on the 2006, the directors were provided slides underneath permitting 3 inches of lateral motion to look around obstacles.[60]

Pattern 2236

Entering service in 1915 or 1916, and reflecting the disfavor accorded tangent bars, the 2236 was a modification of the 2391a with the tangent bar and the association telescopic member to offset the sighting telescope removed. It had an inclination disc, a Radiomir fore sight and a deflection bar.[61]

Royal Navy Submarine Torpedo Directors

Handbook of Torpedo Control plate V, VI: Pattern 3340

See Also

Footnotes

  1. ↑ Handbook of Torpedo Control, 1916, p. 12.
  2. ↑ Handbook of Torpedo Control, 1916, pp. 4-5.
  3. ↑ The Annual Report of the Torpedo School, 1915, pp. 31-32.
  4. ↑ Handbook of Torpedo Control, 1916, pp. 4-5.
  5. ↑ Handbook of Torpedo Control, 1916, Plate I.
  6. ↑ The Annual Report of the Torpedo School, 1911, p. 42
  7. ↑ The Annual Report of the Torpedo School, 1915, p. 59
  8. ↑ Handbook of Torpedo Control, 1916, p. 17.
  9. ↑ The Annual Report of the Torpedo School, 1911, p. 42-43. (C of N 26/9/11. N.S.G. 15583/14369)
  10. ↑ Handbook of Torpedo Control, 1916, p. 18.
  11. ↑ Handbook of Torpedo Control, 1916, p. 18.
  12. ↑ Handbook of Torpedo Control, 1916, pp. 77-78.
  13. ↑ The Annual Report of the Torpedo School, 1911, p. 42
  14. ↑ Torpedo Drill Book, 1912, p. 494.
  15. ↑ Torpedo Drill Book, 1914, p. 564.
  16. ↑ Handbook of Torpedo Control, 1916, p. 16.
  17. ↑ The Annual Report of the Torpedo School, 1909, p. 22.
  18. ↑ Torpedo Drill Book, 1914, p. 564.
  19. ↑ Annual Report of the Torpedo School, 1903, Plate 5.
  20. ↑ Handbook of Torpedo Control, 1916, p. 16.
  21. ↑ Torpedo Drill Book, 1914, p. 564.
  22. ↑ Handbook of Torpedo Control, 1916, p. 16.
  23. ↑ The Annual Report of the Torpedo School, 1909, p. 22.
  24. ↑ Annual Report of the Torpedo School, 1904, pp. 54-55.
  25. ↑ Torpedo Drill Book, 1905, p. 381.
  26. ↑ Torpedo Drill Book, 1912, p. 495.
  27. ↑ Handbook of Torpedo Control, 1916, Plate III.
  28. ↑ The Annual Report of the Torpedo School, 1912, p. 25.
  29. ↑ Torpedo Drill Book, 1914, p. 564.
  30. ↑ The Annual Report of the Torpedo School, 1910, p. 33. (C. of N., May 1906, G. 5965/06?)
  31. ↑ The Annual Report of the Torpedo School, 1912, p. 25.
  32. ↑ Handbook of Torpedo Control, 1916, p. 18.
  33. ↑ Torpedo Drill Book, 1914, p. 564.
  34. ↑ Handbook of Torpedo Control, 1916, p. 16.
  35. ↑ Handbook of Torpedo Control, 1916, p. 16, plate XIII.
  36. ↑ Handbook of Torpedo Control, 1916, p. 17. Contradiction of presence of inclination disc on 2380 is noted.
  37. ↑ The Annual Report of the Torpedo School, 1910, p. 32.
  38. ↑ Torpedo Drill Book, 1914, p. 564.
  39. ↑ The Annual Report of the Torpedo School, 1914, Plate 11.
  40. ↑ Torpedo Drill Book, 1912, p. 494.
  41. ↑ Torpedo Drill Book, 1914, p. 564.
  42. ↑ Handbook of Torpedo Control, 1916, p. 16.
  43. ↑ Handbook of Torpedo Control, 1916, p. 16.
  44. ↑ Handbook of Torpedo Control, 1916, p. 16.
  45. ↑ The Annual Report of the Torpedo School, 1910, p. 32.
  46. ↑ Torpedo Drill Book, 1914, p. 564.
  47. ↑ The Annual Report of the Torpedo School, 1910, p. 32.
  48. ↑ Torpedo Drill Book, 1914, p. 564.
  49. ↑ Handbook of Torpedo Control, 1916, p. 16.
  50. ↑ The Annual Report of the Torpedo School, 1909, p. 23.
  51. ↑ The Annual Report of the Torpedo School, 1910, p. 32.
  52. ↑ The Annual Report of the Torpedo School, 1909, Plate 7.
  53. ↑ The Annual Report of the Torpedo School, 1912, p. 25.
  54. ↑ Torpedo Drill Book, 1914, p. 564.
  55. ↑ The Annual Report of the Torpedo School, 1912, p. 25.
  56. ↑ Handbook of Torpedo Control, 1916, p. 17, plate XIV
  57. ↑ The Annual Report of the Torpedo School, 1909, p. 23.
  58. ↑ Handbook of Torpedo Control, 1916, Plate IV.
  59. ↑ Handbook of Torpedo Control, 1916, p. 17.
  60. ↑ The Annual Report of the Torpedo School, 1910, p. 33. (C. of N. 17th May 1910, G. 5217/10)
  61. ↑ Handbook of Torpedo Control, 1916, p. 18.

Bibliography

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