Line of Sight Director
This does not appear to depict the Clear Range Indicator Mark II this device was reported to feature, at least by 1918.[3]
The Line of Sight Director (sometimes "Torpedo Line of Sight Indicator") was a British torpedo director designed around 1913, to be located on a fixed stand on the fore bridge of a destroyer or a light cruiser. It was lettered and adapted to work in concert with a Pattern 2380 being worked on the tube. Fourteen were purchased for trial in the Boadicea class cruisers.[4]
In 1916-1917, as the Royal Navy switched to deflection sight triangle, these devices were adapted along those lines, being then re-designated as the Torpedo Deflection Sight Mark II.
Design
The circular device was fixed on a stand and in many ways resembled the Torpedo Director Pattern 2006, except that the torpedo bar (graduated up to 48 knots) could rotate about the fixed outer ring to any angle of torpedo tube training from 0 to 180 degrees green or red and be clamped into position. The original design mention indicates that all its bars and scalings would be in luminous paint.[5]
The enemy bar was graduated to 40 knots and the sight bar carried a Possible Shot Scale for the torpedo and setting in use. A Robinson's Disc permitted enemy inclination to be read clearly, and an half-disc allowed director angle to be read off, 0 to 90 degrees either side of the torpedo bar.[6]
By 1916, all 2480a directors had radium foresights.[7]
By mid 1917, they had been supplied to light cruisers armed with 21-inch torpedoes as well as to destroyers of "F" Class and later.[8]
Alterations
| Legend for Deflection Modifications | |
|---|---|
| A | Circular ring fitted to torpedo bar |
| B | Deflection ring, locks to A |
| C | Spring locking pin to engage B |
| D | Sight bar and 2 sights |
| E | Deflection pointer |
| F | Spring washer nut |
| G | Deflection limit stops |
| H | Torpedo bar |
| J | Torpedo training pointer |
By mid 1917, possibly even in 1916,[9] in conformance with the Royal Navy's change to deflection sighting, these devices were considerably simplified to work by deflection. The resulting device was designated the Torpedo Deflection Sight Mark II.[10]
The enemy bar, the existing sight bar and both discs were removed. The torpedo bar and its rotation clamp remained in place. A circular ring (A) rode on the torpedo bar (H) and carried the rest of the mechanism. A deflection ring (B) rode within the circular ring A and could be locked in any of three positions by a spring catch (C), such that a deflection scale suitable for the torpedo speed in use could be read directly from a pointer (E) on the new sight bar (D) in knots deflection, left or right. Stops (G) could limit the deflection (deviation of sight bar from torpedo bar) for use at night.
The user would verify that he had the correct portion of the deflection scale showing and that the deflection ring (B) was locked into place by the spring catch. The sight bar would be rotated against friction washer (F) to the desired deflection. The torpedo bar would then be rotated until torpedo pointer (J) matched the tube training angle or the departure angle of the tube and the gyro angle in use.[11]
At some point, at least some of the T.D.S. Mark IIs were augmented by the addition of a Clear Range Indicator Mark II.[12]
Allocation
By 1916, there were enough instruments on hand that all light cruisers and T.B.Ds. with 21-inch torpedoes were to receive one, and those light cruisers with an after control position would receive a second. Each would be delivered with two stands so it could be swapped between port and starboard rails. The destroyers, however, were eventually authorized to receive a single, central stand atop their fore bridge canopy with an all-round view so there would be no need to run around with the director in hand.[13]
By August, 1918, the T.D.S. Mark IIs had been issued to T.B.D.s for use on the bridge, except in "V" class and later which had T.D.S. Mark III in this position.
As the early designs were before the introduction of a medium speed setting,[14] and so the deflection rings are each for the 3 speeds of a given Mark of torpedo.
If and when ships with these devices receives medium-speed-capable torpedoes, these rights would require adaptation.[15]
By mid 1919, delivery of all the rings was still being completed. The J/J1 rings were proving slowest to appear for some reason.
| Small Deflection Rings for T.D.S. Mark II [16] The distinguishing letters would be circled. Subscripts denote the reverse side of another ring. | ||
|---|---|---|
| Distinguishing Letter | Graduated Speeds (knots) | for Torpedo Marks |
| H | 25, 29, 35 | 21-in Marks IV* and V with 35-knot setting |
| H1 | 25, 29, 44.5 | |
| B | 21, 25, 35 | 21-in Mark IV with 35-knot setting |
| B1 | 21, 25, 44.5 | |
| A | 21, 25, 44.5 | 21-in Mark IV |
| A1 | 19, 24, 44.5 | 21-in Mark II***** |
| G | 19, 24, 35 | 21-in Mark II***** with 35 knot setting |
| G1 | 18, 23, 35 | 21-in Mark II-II**** E.R. 3 with 35-knot setting |
| C | 19, 24, 44.5 | 21-in Mark II***** |
| C1 | 18, 23, 44.5[17] | 21-in Mark II-II**** E.R. 3 |
| D | 18, 23, 44.5 | 21-in Mark II-II**** E.R. 3 |
| F | 18, 23, 44.5 | 21-in Mark II-II**** E.R. 3 |
| F1 | 18, 29, 45 | 21-in Mark I-I* |
| J | 19, 29, 41 | 18-in Mark VII-VII***** |
| J1 | 19, 29, 35 | |
Obsolescence
In 1921, it was approved that all "R" class destroyers should land their Torpedo Deflection Sight Mark IIs so they could be replaced by replaced by Torpedo Deflection Sight Mark IIIs.[18]
See Also
Footnotes
- ↑ Annual Report of the Torpedo School, 1915, Plate 10.
- ↑ Handbook of Torpedo Control, 1916, Plate 12.
- ↑ Annual Report of the Torpedo School, 1918, p. 165.
- ↑ The Annual Report of the Torpedo School, 1913, p. 28. (N.S. 12168/18196)
- ↑ Annual Report of the Torpedo School, 1913. p. 28.
- ↑ Annual Report of the Torpedo School, 1915, p. 59.
- ↑ Handbook of Torpedo Control, 1916. p. 25.
- ↑ Handbook of Torpedo Control, 1916. p. 18.
- ↑ Annual Report of the Torpedo School, 1916, p. 25.
- ↑ Annual Report of the Torpedo School, 1917, p. 190.
- ↑ Handbook of Torpedo Control, 1916, pp. 25-26, Plate 14.
- ↑ Annual Report of the Torpedo School, 1918, p. 165.
- ↑ Annual Report of the Torpedo School, 1916, p. 26.
- ↑ Annual Report of the Torpedo School, 1916, p. 45.
- ↑ Annual Report of the Torpedo School, 1917, p. 190.
- ↑ Annual Report of the Torpedo School, 1918, p. 156.
- ↑ Discrepancy noted with Torpedo Deflection Sight Mark I
- ↑ Annual Report of the Torpedo School, 1921. p. 137. V.W.O. 11/21.
Bibliography
