Handbook of Captain F. C. Dreyer's Fire Control Tables 1918
Handbook of Captain F. C. Dreyer's Fire Control Tables
1918
Repository |
Document ID |
Pages |
Dimensions |
Plates |
Admiralty Library |
C.B. 1456 |
|
28cm x 16cm
|
46 |
A distribution notice inside the cover indicates a date of June 25th, 1918 and expresses in stronger than usual terms the need to keep its contents confidential. My copy of this handbook is a black and white photocopy of an original Copy No. 10, generously provided me by Bill Schleihauf.
This manual is totally indispensible for those wishing to learn of Dreyer equipment.
My copy lacks a table of contents, but I have reconstructed one from the text. It also appears to be missing several plates. The original plates are in color, and quite glorious, so you might inquire after color processes if ordering a copy.
|
Page |
List of ships carrying Dreyer Fire Control Tables (see Notes section) |
3 |
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CHAPTER I. |
Definitions |
|
|
Overview of the Components |
4 |
|
Definitions |
8 |
|
Notes on Manufacture |
9 |
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Ball Bearings, Bicycle Chain, Flexible Shafting , Tapered Pins, Lubrication and Upkeep, Stripping |
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CHAPTER II. |
Description, with Photographs and Diagrams |
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Table Mark I. |
13 |
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Rangekeeping Unit, Range Plot, Bearing Plot |
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Table Mark I.*, Table Mark II. |
15 |
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Table Mark III. |
17 |
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Rangekeeping Unit, Range Plot, Bearing Plot |
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Table Mark III.* |
19 |
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Rangekeeping Unit, Range Plot, Bearing Plot |
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Table Mark IV., IV.* |
21 |
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Rangekeeping Unit, Range Plot, Bearing Plot |
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Table Mark V. |
23 |
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Rangekeeping Unit, Range Plot, Change of Bearing Gear, Bearing Plot, Bearing Tell-Tale |
|
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Stripping the Mark IV.* Table |
25 |
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Main Drive Motor, Backboard, Range Plot, Dumaresq, Bearing Plot |
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CHAPTER III. |
Components of the Table |
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|
The Range Plot |
29 |
|
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Range Scale, Typewriter, Range-rate Grid, Plot, Typical Range Plot, Clock Range Screw, Tuning Handle, Pedalling Clutch, Spotting Corrector, Gun Range Counter, Gun Range Pencil, Minute Marker |
|
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The Bearing Plot -- Standard Pattern |
35 |
|
The Bearing Plot on Mark V. Tables |
36 |
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The Deflection Totaliser |
37 |
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The Deflection Corrector Link Gear |
40 |
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The Corrector Link as Fitted in "Ramillies" (Plate 19) |
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The Corrector Link as Fitted to Mark V. Tables other than in "Ramillies" (Plate 20) |
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The Corrector Link as Fitted to Mark III.* Tables (Plate 20) |
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The Dumaresq in the Mark I., I.*, and III.* Tables |
46 |
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The Dumaresq in the Mark III. Table |
49 |
|
The Electrical Dumaresq in the Mark IV., IV.*, and V. Tables |
51 |
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|
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Other Dumaresqs |
60 |
|
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Mark IV., Mark VII.*, Wind Dumaresq |
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The Clock (Plates 26 & 27) |
61 |
|
The Change of Bearing gear, Tables Mark IV., IV.*, and V. |
61 |
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The Compass Control Gear |
64 |
|
The Main Drive Control and Governor |
67 |
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The Watch Box |
68 |
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The Rate Transmitter |
70 |
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The Range Master Transmitter |
72 |
|
The Deflection Master Transmitter |
75 |
|
The Repeater |
76 |
|
The Standard Pattern Transmitting Commutator |
78 |
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The Motor-- Standard (2-Pole_ Pattern as used in the Bearing Plot |
78 |
|
Signal Lamps on the Table |
78 |
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CHAPTER IV. |
Description, Photographs and Diagrams of the Turret Table |
|
|
The Rangefinder Plot |
81 |
|
The Clock Range Disc |
82 |
|
The Electric Motor Drive |
83 |
|
Lining up the Turret Table |
83 |
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CHAPTER V. |
The Positions which are recommended for the operators of the various marks of Table |
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Lining Up |
87 |
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Instructions in Closing Up at the Table |
87 |
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Testing the Clock |
87 |
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On Tables Mark IV., IV.*, and V. |
87 |
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On Tables Mark I., I.*, III., and III.* |
88 |
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Table Giving the Relation Between Range, Dumaresq Deflection, and Rate of Change of Bearing |
89 |
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Dimensions of the Tables |
90 |
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The Rangefinder Plot |
|
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|
70 |
PLATES
No. |
|
1. ? |
Untitled -- a plan view of a generic Dreyer table |
2. |
Missing |
3. |
Mark I Table - diagram |
4. |
Mark I* Table - diagram |
5. |
Missing |
6. |
Missing |
7. |
Missing |
8. |
Missing |
9. |
Missing |
10. |
Missing |
11. |
Missing |
12. |
Missing |
13. |
The Range-rate Grid |
14. |
The Spotting Corrector and Tuning Gear-boxes |
15. |
The Gun Range Commutator and a typical Counter |
16. |
The Bearing Plot -- standard pattern |
17. |
The Bearing Plot - Mark V table |
18. |
The Deflection Totaliser |
19. |
The Deflection Corrector Link Gear |
20. |
The Deflection Corrector Link Gear - Mark V and III* Tables |
21. |
Mark I Table - front view |
22. |
The Dumaresq Dials |
|
|
Mark I, I*, and III* Tables and Mark IV, IV* and V Tables |
23. |
The Dumaresq in the Mark III Table |
24. |
The Electrical Dumaresq |
25. |
The Electrical Dumaresq - centrework |
26. |
The Range Clock Mechanism |
27. |
The Clock Drive and the Change of Bearing Gear |
28. |
The Compass Control Gear |
29. |
The Motor and Governor |
30. |
The Rate Transmitter |
31. |
The Range Master Transmitter |
32. |
The Deflection Master Transmitter |
33. |
The Repeater |
34. |
The Standard Commutator |
35. |
The Staandard Motor |
36. |
The Turret Table - in use |
37. |
The Turret Table - diagram |
38. |
Title missing apparently, a turret table with covers removed |
39. |
Position of Operators - Mark I and I* tables |
40. |
Position of Operators - Mark III table |
41. |
Position of Operators - Mark III* table |
42. |
Position of Operators - Mark IV and IV* tables |
43. |
Position of Operators - Mark V table |
44. |
Testing Diagram |
45. |
The Original Table |
46. |
Analysis of the Plot |
NOTES
On page 3 a table shows which ships are fitted with which Mark of Dreyer table. Many of the names are crossed out in pencil, owing to their passage from service after the time the document was created or because their equipment has been altered from the original noted, or the equipment noted was never supplied. The table is reproduced here, but with red being used to denote a ship name that was crossed out in pencil and blue to note a ship name pencilled in in a section other than where it had originally been printed.
Mark I. Tables |
Dreadnought |
Colossus |
Hercules |
Neptune |
Collingwood |
St. Vincent |
Agincourt |
Erin |
Bellerophon |
Marlborough |
Superb |
Temeraire |
Austrailia |
New Zealand |
Inflexible |
|
|
Mark I.* Tables |
Cavendish |
Effingham |
Frobisher |
Hawkins |
Raleigh |
Glatton |
Gorgon |
|
|
Mark II. Tables |
Ajax |
Centurion |
Conqueror |
Orion |
|
Mark III. Tables |
King George V. |
Monarch |
Thunderer |
Excellent |
Chatham Gunnery School |
|
|
|
|
Mark III.* Tables |
Cairo |
Calcutta |
Capetown |
Carlisle |
Colombo |
Delhi |
Dunedin |
Durban |
|
Mark IV. Tables |
Queen Elizabeth |
Benbow |
Emperor of India |
Iron Duke |
Tiger |
|
|
|
|
Mark IV.* Tables |
Resolution |
Revenge |
Royal Oak |
Royal Sovereign |
Barham |
Malaya |
Valiant |
Warspite |
Canada |
Renown |
Repulse |
Lion |
Princess Royal |
Courageous |
Glorious |
Tiger |
Ramilllies |
Queen Elizabeth |
|
|
|
Mark V. Tables |
Ramillies |
Anson |
Hood |
Howe |
Rodney |
Gunnery School Chatham |
Gunnery School Portsmouth |
Gunnery School Devonport |
|
Turret Control Tables |
Ramillies |
Resolution |
Revenge |
Royal Oak |
Royal Sovereign |
Barham |
Malaya |
Queen Elizabeth |
Valiant |
Warspite |
Benbow |
Emperor of Indeia |
Iron Duke |
Marlborough |
Renown |
Repulse |
Tiger |
Courageous |
Glorious |
|
|
Turret Control Tables in Light Cruisers |
Ceres |
Chester |
Carysfort |
Comus |
Melbourne |
Royalist |
|
|
The Mark numbers of the Dreyer tables do not reflect the order in which the machines were devised and fielded. The Mark III. was actually the first version and the Mark I. tables were conceived later as a smaller installation able to fit into the comparatively smaller Transmitting Stations of the earlier ships. The Mark II series and IV series had more features and automatic functionality, but the essence of these devices remained as follows throughout their life span.
A Dreyer table had 3 primary elements: a Range Plot, a Dumaresq fitted with a Range Clock, and a Bearing Plot. Additionally, several secondary elements on the table or nearby helped tie the table's function together: Deflection Drums, Deflection Totaliser, Spotting Corrector, and devices to relay its results to the ship's gunnery positions. Apart from those common elements, different Marks diverged considerably. Between 5 and 12 people would directly operate the table, with an additional 10 to 30 people assisting.
It is easiest to start by examining the Dreyer's function, which was one of calculation and prettifying noisy data. Viewed as a computational black box, a Transmitting Station equipped with an early model Mark III Dreyer table had the following inputs and outputs.
Data |
Input From/Output To
|
Units |
Notes |
Range reports |
From rangefinders |
yards |
discrete, infrequent, noisy, 25 yard granularity, relayed electro-mechanically, manually plotted on Range Plot |
Bearing reports |
From main rangefinder |
relative degrees |
discrete, 1/4 or 1/15th degree granularity, relayed electro-mechanically, automatically plotted on Bearing Plot |
Own Heading |
From gyrocompass |
true degrees |
continuous, automatically fed to Dumaresq and Bearing Plot |
Own Speed |
From Forbes log |
knots |
continuous, manually fed to Dumaresq |
Spotting corrections (range) |
From spotting officer in top |
yards |
verbally relayed, usually incremental |
Spotting corrections (deflection) |
From spotting officer in top |
Left/right knots |
verbally relayed, usually incremental |
Range Rate settings |
From rate officer topside |
yards per minute |
verbally relayed, manually fed to Range Clock |
Range Rate suggestions |
To rate officer topside |
yards per minute |
verbally relayed |
Gun Range |
To director & guns |
yards |
continuous, relayed electro-mechanically |
Gun Deflection |
To director & guns |
Left/right knots |
continuous, relayed electro-mechanically |
A Dreyer table generally had 3 main elements arranged left to right as you faced it: a Bearing Plot, a Dumaresq with an integral range clock, and a Range Plot. The position, degree of interconnectedness and exact character of the elements differed between the Marks, but we'll discuss each in turn. The explanations that follow pertain most closely to the Mark III. table, but many of the principles are helpful when examining the later versions although one might care to take the details with a grain of salt.
The Range Plot was a moving paper scroll 36 inches wide which advanced at 2 inches per minute and provided a range-vs-time graphing area where pencil lines and typewritten letters could respectively plot a range hypothesis and the discrete range data from which it was derived. A ruler-like range gauge marked from 2000-16,400 yards (it could be thrown into a long range setting of 10,000-24,400 yards) was positioned across the face of the paper, and a small, specialized typewriter equipped with an index could slide back and forth along this gauge until its index precisely matched a range observation called down from a rangefinder above-decks. By typing the typewriter key corresponding to the rangefinder making the report, a small letter or symbol would be tacked onto the paper at the proper position. Over time, as various reports were received and typed onto the paper, the operators would have assembled a noisy set of datapoints which statistically indicated the range as it changed over time.
Another operator could then employ a circular grid of wires positioned over the paper to try to discern the "range rate", or a linear approximation of how rapidly range was changing over time as a result of the relative maneuvering of own ship and target ship. By working small knobs on this grid, the wires within could be deflected to various angles and the operator would look through these wires to the pointset beyond and try to determine a visual regression of the data.
The Dumaresq was a clever analog computer to relate the motion of one's own ship, the target ship and target bearing to the Range Rate in yards per minute along the line of fire and the "speed across" (in knots) across the line of fire . On the Dreyer tables, the Dumaresq was additionally fitted with a Vickers Range Clock which could represent a constant derivative of range over time. Just as the range grid was used to visually estimate a constant range rate, the simple nature of the Vickers implies one of the general characteristics of Dreyer equipment: it liked to think of range as a variable which changed linearly over time, and any other dynamics to this relationship had to be accommodated either by manual corrections or by the additions of ancillary mechanisms to the basic table design.
The Range Clock's output was not a range per se, but a sequence of changes in range. It was tied into an odometer-like "gun range counter" which would count upward (or downward) at the range rate set on the clock. It would also drive a worm screw that lay across the face of the range clock and on which was fitted a plotting pencil. When the clock was stopped, the pencil would remain in place, drawing a line down the advancing paper at its present position on the range scale. In this case, the pencil could be said to be plotting a constant range versus time. But if a closing or opening range rate were applied on the range clock, the worm screw would then act to drag the pencil to the left or right across the paper at constant speed, and the result would be a pencilled curve depicting a linear range versus time hypothesis-- a graphical analog to the data being digitally displayed on the Gun Range Counter.
The Bearing Plot was the last primary component of the Dreyer table. It resembled a smaller version of the Range Plot but it tracked the target's True Bearing over time. Relative bearings to the target observed by the main range finder were signalled down electrically, rectified by gyroscope input to True Bearings, and pricked into the paper by a small pin actuated by a solenoid. A Bearing Grid similar to the Range Grid could be twisted until its wires seemed parallel to the trend of bearing data, and in this way the Bearing Rate in degrees per minute could be estimated.
Situated near the Bearing Plot was a set of Deflection Drums etched with curves. One of these drums indicated Corrected Deflection (or Sight Deflection) and the other related Dumaresq Deflection (Speed Across) as a function of Bearing Rate (across the drums) to Gun Range (the rotation of the drums). Conveniently, a flexible drive from the Gun Range Counter rotated the drums to the proper Gun Range and an index across the drums pointed to the proper point as the operator adjusted the Bearing Grid to match the trend indicated on the Bearing Plot.
The last supportive element on the table itself was a simple adding machine called the Deflection Totaliser which could add the Corrected Deflection indicated on the Deflection Drum to any other necessary sources of deflection to yield a total deflection. It was this total Deflection and the Gun Range which constituted the primary outputs of the Dreyer Table.
Dreyer Table Crewing and Dimension
|
Crew Required |
|
RGrid Height, Dumaresq Height |
I. |
8 |
|
|
I.* |
8 |
|
|
II. |
7 (+1)? |
N/A |
N/A |
III. |
7 (+1 if motor breaks) |
|
|
III.* |
7 (+1) |
|
|
IV. |
7 (+1) |
|
|
IV.* |
7 (+1) |
|
|
V. |
7 (+1) |
|
|
- The Mark II. table is largely glossed over in this handbook.
- "RGrid Height" is the height to the top of the Range Grid.
- Width and Depth figures include any protruding handles
Dreyer Table Dumaresq and Change of Bearing Gear Data
|
Dumaresq |
Own Heading via |
Enemy Inclination Maintained? |
Change of Bearing Gear |
I. |
VI.* |
handwheel input |
yes |
none |
I.* |
VI.* |
automatic input |
yes |
none |
II. |
VI. ? |
automatic input ? |
no? |
manually set to a constant bearing rate?, +/-15 degs/min maximum? |
III. |
VI. |
automatic input |
no |
manually set to a constant bearing rate, +/-15 degs/min maximum |
III.* |
VI.* |
" |
yes |
C.B. |
IV. |
electrical |
" |
? |
C.B. |
IV.* |
" |
" |
? |
C.B. |
V. |
" |
" |
? |
C.B. plus bearing tuning handle |
- The C.B. (change of bearing) gear of the III.* and later marks was sensitive to the Gun Range, and would "do the right thing" to update the bearing as range changed.
- Prior to the Mark V., any corrections to bearing required the bearing clock to be declutched and the dial plate moved to the correct position. The Mark V. added a tuning handle that would allow correction without declutching.
- The electrical dumaresq was electrical in the sense that small gears driving commutators would transmit the enemy speed and inclination on the dumaresq, allowing its settings to be remotely indicated on repeaters aloft. In other dumaresqs, this data would have to be manually recorded and verbally reported.
|
Range Clock |
I. |
Vickers, external, clockwork driven |
I.* |
" |
II. |
Argo |
III. |
Vickers, integral to dumaresq, motor driven |
III.* |
" |
IV. |
" |
IV.* |
" |
V. |
" |
- The clockwork Vickers in the Mark I family did not have sufficient power to drive the plotting pencil worm screw or the gun range counter. Instead, it merely drove a clock hand around an integral range dial and an operator chased this pointer with another worked by handwheel, and this action drove the counter and pencil.
- Generally, the range clocks ran from 1200 yards per minute closing to 1200 yards per minute opening
|
Range Plot Width |
Power |
Yards per Inch |
Lower Range Scale |
Upper Range Scale |
Paper Speed |
I. |
45 inches |
Hand cranked |
400 |
2,000 to 20,000 |
|
2 inches per minute |
I.* |
" |
" |
" |
" |
" |
" |
II. |
36 inches ? |
Electric motor with handcrank back-up |
" ? |
|
|
" ? |
III. |
36 inches |
" |
400 |
2,000 to 16,400 |
10,000 to 24,400 |
2 inches per minute |
III.* |
45 inches |
" |
600 |
|
none |
4/3 inches per minute |
IV. |
37.5 inches |
" |
400 |
2,000 to 17,000 |
10,000 to 25,000 |
2 inches per minute |
IV.* |
45 inches |
" |
400 |
2,000 to 20,000 |
10,000 to 28,000 |
" |
V. |
45 inches |
" |
600 |
2,000 to 29,000 |
none |
4/3 inches per minute |
- The tables with two range scales could shift between them by flipping a small tab that would add 8,000 yards to the gauge markings, pressing a clutch, and then tuning the range pencils up or down by 8,000 yards (20 inches). The clutch would prevent the gun range counter's reading from changing. The clutch would be re-engaged and operation could continue.
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