An Elevation Receiver is a F.T.P. instrument mounted near a gunlayer position which receives and indicates (usually by 2 red pointers for degrees and minutes) an angle of elevation transmitted by a director. The gunlayer works his controls to elevate the gun and bring the black pointers into alignment with the red.
An elevation receiver was required near each gun which would be fired under control of a director which controlled elevation (German directors did not). Similarly, each trainable mounting required a training receiver to guide its trainer in matching the director.
British elevation receivers were provided indication of the desired elevation angle quantized in steps of 1.5 arc minutes which was corrected for:
- Tilt to negate imperfection in the mounting's vertical installation.
- Dip (differences in mounting height relative to the ship's datum point).
- The muzzle velocity in the particular gun, subject to its accumulated number of firings.
- Use of alternate projectiles or reduced charges.
The British Director Firing Handbook from 1917 documents the following types:
- Turret Type (used in the capital ships)
- 6-in P. VIII Type (this one had just a single red and a single black pointer)
- 6-in P. VII Type
- 4-in Triple Type
- 6-in P. XIII Type
The director system used in destroyers and flotilla leaders did not transmit elevation to the guns at all, instead relying on a system by which gunlayers kept their sighting scopes level so the director could fire on the roll. This system meant that the small ships lacked elevation receivers.
An Admiralty Order of late 1913 asks all British ships with turret F.T.P. gear (except Princess Royal to report how often they've had to replace cabling to their receivers and whether they'd like to switch to having a junction box near the equipment so that the length of cables to the receivers that might wear out under motion could be reduced to simplify its replacement.
The German director system did not transmit elevation to the guns; the guns were locally laid and fired even under director control. Consequently, there was likely no such thing as a German elevation receiver in active service.
- Director Firing Handbook, 1917, p. 151.
- Director Firing for Destroyers and Flotilla Leaders
- Admiralty Weekly Order No. 653 of 21 Nov 1913.
- Admiralty, Gunnery Branch (1917). The Director Firing Handbook. O.U. 6125 (late C.B. 1259). Copy No. 322 at The National Archives. ADM 186/227.
- Admiralty, Gunnery Branch (1918). Director Firing For Flotilla Leaders and Destroyers. Pub. No. B.R. 934 (late O.U. 6127 and C.B. 1461 and 1461(A). The National Archives. ADM 186/234.
- Admiralty, Gunnery Branch (1945). The Gunnery Pocket Book. B.R. 224/45. The National Archives. ADM 234/545.