Difference between revisions of "Mechanical Aid-to-Spotter Mark I"
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The '''Mechanical Aid-to-Spotter Mark I''' was the first [[Mechanical Aid-to-Spotter]] deployed by the [[Royal Navy]] to better ensure that all members of the fire control staff were in harmony as to which ship their own was targeting. | The '''Mechanical Aid-to-Spotter Mark I''' was the first [[Mechanical Aid-to-Spotter]] deployed by the [[Royal Navy]] to better ensure that all members of the fire control staff were in harmony as to which ship their own was targeting. | ||
| − | It seems likely that supply commenced in late 1916 at the earliest. | + | It seems likely that supply commenced in late 1916 at the earliest.{{FCHMShips|pp. 25}} |
==Design== | ==Design== | ||
The device consisted of a turntable capable of supporting a pair of binoculars or spotting glasses that also received flexible shafts conveying the present bearing of the director (obtained by a gearbox reading the Evershed rack of the aloft director tower) and from a separate Evershed transmitter. The optics could be clutched in to follow the director's training angle plus any deflection entered by a handwheel, or it could be unclutched to train freely. The indications of director and Evershed could be separately examined to see whether they coincided.<ref>''Manual of Gunnery for HM Fleet, Volume III, 1920'', p. 34.</ref> | The device consisted of a turntable capable of supporting a pair of binoculars or spotting glasses that also received flexible shafts conveying the present bearing of the director (obtained by a gearbox reading the Evershed rack of the aloft director tower) and from a separate Evershed transmitter. The optics could be clutched in to follow the director's training angle plus any deflection entered by a handwheel, or it could be unclutched to train freely. The indications of director and Evershed could be separately examined to see whether they coincided.<ref>''Manual of Gunnery for HM Fleet, Volume III, 1920'', p. 34.</ref> | ||
| − | The deflection dial had an index marked "S.T.Z." for "Sight Testing Zero", which is the true zero-deflection mark. The zero mark used generally is at 5 knots left deflection, meant to be an average drift deflection at all ranges. | + | The deflection dial had an index marked "S.T.Z." for "Sight Testing Zero", which is the true zero-deflection mark. The zero mark used generally is at 5 knots left deflection, meant to be an average drift deflection at all ranges.{{FCHMShips|pp. 26}} This design feature reflects the difference between turret facing and line of sight. Drift was essential to the viewing angle so that the optics would be lined up with the splash of shot, which of course should lie on director training angle plus deflection — which would be gun training angle — plus drift, which would be where the shells would fall. |
==Deployment== | ==Deployment== | ||
| − | By 1920, it was installed in 22 capital ships:<ref>''Manual of Gunnery for HM Fleet, Volume III, 1920'', p. 34.</ref> | + | By 1920, it was installed in 22 capital ships:<ref>''Manual of Gunnery for HM Fleet, Volume III, 1920'', p. 34.</ref> {{UK-Dreadnought}}, the three [[Bellerophon Class Battleship (1907)|''Bellerophons'']], {{UK-Agincourt}}, {{UK-Erin}}, the two surviving ships of the [[St. Vincent Class Battleship (1908)|''St. Vincent'' class]], {{UK-1Neptune}}, the two [[Colossus Class Battleship (1910)|''Colossus'' class]], the two surviving [[Invincible Class Battlecruiser (1907)|''Invincible'' class]], the two surviving [[Indefatigable Class Battlecruiser (1909)|''Indefatigables'']], the four [[Orion Class Battleship (1910)|''Orions'']], and the three surviving [[King George V Class Battleship (1911)|''King George Vs'']]. |
==See Also== | ==See Also== | ||
| Line 25: | Line 25: | ||
==Bibliography== | ==Bibliography== | ||
{{refbegin}} | {{refbegin}} | ||
| − | *{{ | + | *{{FCHMShips}} |
| − | *{{ | + | *{{UKManGun1920III}} |
* Handbook for this device (not read by me) C.B. 1285 | * Handbook for this device (not read by me) C.B. 1285 | ||
{{refend}} | {{refend}} | ||
Latest revision as of 15:10, 10 November 2016
The Mechanical Aid-to-Spotter Mark I was the first Mechanical Aid-to-Spotter deployed by the Royal Navy to better ensure that all members of the fire control staff were in harmony as to which ship their own was targeting.
It seems likely that supply commenced in late 1916 at the earliest.[3]
Design
The device consisted of a turntable capable of supporting a pair of binoculars or spotting glasses that also received flexible shafts conveying the present bearing of the director (obtained by a gearbox reading the Evershed rack of the aloft director tower) and from a separate Evershed transmitter. The optics could be clutched in to follow the director's training angle plus any deflection entered by a handwheel, or it could be unclutched to train freely. The indications of director and Evershed could be separately examined to see whether they coincided.[4]
The deflection dial had an index marked "S.T.Z." for "Sight Testing Zero", which is the true zero-deflection mark. The zero mark used generally is at 5 knots left deflection, meant to be an average drift deflection at all ranges.[5] This design feature reflects the difference between turret facing and line of sight. Drift was essential to the viewing angle so that the optics would be lined up with the splash of shot, which of course should lie on director training angle plus deflection — which would be gun training angle — plus drift, which would be where the shells would fall.
Deployment
By 1920, it was installed in 22 capital ships:[6] Dreadnought, the three Bellerophons, Agincourt, Erin, the two surviving ships of the St. Vincent class, Neptune, the two Colossus class, the two surviving Invincible class, the two surviving Indefatigables, the four Orions, and the three surviving King George Vs.
See Also
- Mechanical Aid-to-Spotter Mark II
- Mechanical Aid-to-Spotter Mark II*
- Evershed Bearing Indicator
- Usborne Fall of Shot Indicator
Footnotes
- ↑ Manual of Gunnery for H.M. Fleet, Volume III, 1920, Plate 46.
- ↑ Manual of Gunnery for H.M. Fleet, Volume III, 1920, Plate 45.
- ↑ The Technical History and Index, Vol. 3, Part 23. pp. 25.
- ↑ Manual of Gunnery for HM Fleet, Volume III, 1920, p. 34.
- ↑ The Technical History and Index, Vol. 3, Part 23. pp. 26.
- ↑ Manual of Gunnery for HM Fleet, Volume III, 1920, p. 34.
Bibliography
- Admiralty, Technical History Section (1919). The Technical History and Index: Fire Control in H.M. Ships. Vol. 3, Part 23. C.B. 1515 (23) now O.U. 6171/14. At The National Archives. ADM 275/19.
- Admiralty, Gunnery Branch (1920). Manual of Gunnery (Volume III) for His Majesty's Fleet, 1920. (G. 13018/10) Copy No. 2 is Ja. 013 at Admiralty Library.
- Handbook for this device (not read by me) C.B. 1285
