British Director Firing Systems
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The Royal Navy's Director Firing Systems grew from a complete system which centralised elevation, training and firing of the main batteries of capital ships which was being fitted as the war began. As resources and opportunity permitted this system inspired less comprehensive systems suitable to cruisers, flotilla leaders and eventually event destroyers.
Tripod Director System
The first system produced, and the priority for deployment, was a comprehensive elevation-and-training system based upon the Vickers tripod directors in "light aloft towers" or in armoured hoods. On ships featuring both types, the light aloft director was deemed the primary director in recognition of its higher placement in the ship and the presumably better view it enjoyed.
Design
The two devices were similar, but the light aloft director tower's design included the cylindrical tower and its slightly domed roof, and the armoured tower one sat within a hood whose construction and operation were intrinsic to the ship's.
The directors were tilt corrected for range and dip to the guns was also accounted for. Moreover, drift was precisely corrected by a cam rather than the approximate correction achieved in most cases by inclining the sight.
The crew sat within a rotating tub that spun within a fixed base, facing inward to a large articulated gun sight on a tripod. It was much like a small gun mount without a gun.
Crew
There were 4 men within the light aloft director: a talker with a set of Telaupads and a voicepipe to the spotting top above, a Director Layer who elevated the sight and fired the guns, a Director Trainer who rotated the tower with either a large slewing handle or a smaller training handle, and a Sight Setter who applied the range and deflection being signaled to his FTP receivers from the Transmitting Station.
In the armoured tower, a separate man below the director revolved the armoured hood by separate hydraulic means; the director itself was mechanically separate and spun within the hood, loosely matching its angle of training. Simple interlocks prevents the hood from training further off the director's angle that might cause damage to the sighting scopes.
Outputs
Elevation and training was transmitted to the guns by Step-by-Step circuits to FTP elevation and training receivers; elevation in steps of 1.5 arc minutes, and training angle in steps of 4 arc minutes or in a slewing mode in steps of 2 degrees azimuth which had to be used in blocks of 6 degrees.[1]
The circuits could reliably handle 1000 steps per minute (16.67 per second), effectively limited elevation speed to less than a half degree per second, and training to 1 degree per second which eliminated the possibility of continuous aim. Moreover, 1 degree per second in training might be so modest that firing under helm would be impossible, especially when turning against the bearing rate. Slewing mode could achieve 30 degrees per second, which would be ample for any scenario.
Firing was done by either a main or aux trigger at the director layer's hand to any number of guns that were switched in at a gun ready board worked by the talker.
Lightweight Pedestal System
For smaller ships such as light cruisers or for use in the secondary batteries of capital ships, the large tripod directors gave way to a compact pedestal-mounted director whose crew stood around it rather than sat upon it.
Destroyer System
The destroyer system was similar to the lightweight director, but was a training-only director with gyroscopic firing to fire the guns "on the roll". The guns would be elevated to one of several fixed index marks on a scale, and the director set to the same elevation so that the gyroscope's action would accomplish the desired elevation for firing.
See Also
Footnotes
- ↑ Director Firing Handbook, 1917, p. 151.
Bibliography
- Template:BibUKDirectorFiringHandbook1917
- Template:BibUKDirectorFiringForDestroyers1918
- Template:BibUKFireControlInHMShips1919
- Template:BibBrooksDreadnoughtGunnery