Torpedo Director

File:TorpedoAttackTrainerDiagramARTS1915.jpg A Torpedo Director is merely a sight for torpedo fire, more similar to a settable gunsight than to a gunnery director.

Director Triangle

The Royal Navy began the 20th century with a series of sights that characterized the torpedo firing problem according to the Director Triangle formed by the path of the torpedo, the line of sight at the moment of firing to the target, and the path of the target between firing and impact. It delivered a number of sights which embodied this geometry, including the Pattern 2006 Torpedo Director.

Deflection Triangle

In 1915, the Royal Navy started to migrate toward a different geometric model called the Deflection Triangle, formed by the path of the torpedo, the line of sight, and the speed-across of the target.^{[Fact Check]}

Tangent Bars

Basic torpedo directors were constructed such that they only worked precisely when mounted on or very near the torpedo tube they aimed. In some circumstances, it was desirable or necessary to have the sight function remotely from the torpedo tube by a considerable distance. In this case, a small additional arm called a "Tangent Bar" would be affixed to a director to offset the rear sighting arch a suitable distance so that the torpedo would converge on the target at the proper range. A consequence of adding this to the problem was that the range to the target had to be known (at least approximately... inaccuracy in ranging would just reduce the value of the correction).

Progress

1915

In 1915, trials were carried out to compare the "wire" and "theodolite" methods of aligning directors for submerged tubes, but results were not yet complete. Until they were available, contract-built ships were to have their directors aligned by theodolite means. Extensive description of the method is outlined in The Annual Report of the Torpedo School, 1915.

A new design of director for capital ships was being undertaken. It would not have a tangent bar, and would therefore offer a stronger design. Additionally, there was talk of using periscopes to keep personnel clear of gun blast. This blast was studied in Iron Duke when directors were placed in secondary hoods, and found to be so considerable that directors were to be placed in conning and torpedo control towers only, and no further hoods would be built. The tubes were to be dirigible from either position, with communications and firing circuits laid to both towers.

A director called Hallet's Director was tried, apparently unsuccessfully, as it was returned for disposal. Seven examples of Lambert's Attack Director were under trial at sea. Note was made of directors having been reassembled incorrectly after maintenance, resulting in poorly aimed torpedoes. One gotcha that was to be corrected was to ensure that sliders would be modified so they could not be reversed upon reassembly.

Hinged stands for directors were tried in Invincible and Hercules, but found not to be worth the expense or the possibility of errors in alignment. Henceforth, they would only be fitted where absolutely necessary.

Directors would henceforth be illuminated for use at night. An aperture with variable stop and violet glass would use a switch to turn on and off.

The director telescope Pattern 2393's 6-power magnification was criticised at sea as being too high, rendering it difficult to see in haze and rain. Six telescopes answering to a 3-power specification had been ordered for trial.

A promising wander mark telescope from the German Goertz company had been ordered before the war, but not taken before the war started. It was seen as having some promise as a director telescope or for use on the Middleton Plotter in lieu of electrical contacts.

An enterprising torpedoman aboard Blonde had added a 4-inch diameter brass disc plate to the enemy speed slider on his Torpedo Director Pattern 2390 to permit the enemy's heading to be expressed or read as an inclination to line of sight. This would especially help the adjustment of a director at a trainable tube, but no explicit recommendation was spelled out despite a supportive description of its utility.

It was concluded from practical experience that the deflection triangle was superior to the director triangle as a means of setting the director. Several systems probably based on plotting

Royal Navy Director Triangle Directors

Pattern 1192/1192a

A large, semicircular director, presumably of the director triangle principle, not used in any modern ships as of 1914. If a 1192a existed, it was similar, but made stronger in its pivots and sighting bar.

Pattern 1193/1193a

Had a 60 degree arc, used in early torpedo craft. If a 1193a existed, it was similar, but made stronger in its pivots and sighting bar.

Pattern 1895/1895a

Very similar to the 1193, the 1895 had a 60 degree arc and was used in early torpedo craft. If a 1895a existed, it was similar, but made stronger in its pivots and sighting bar.

Pattern 2006/2006a

Introduced about 1908, used in conning towers and director towers of earlier ships witha tangent bar, and perhaps also at times directly on tubes^{[Citation needed]}. The 2006a was fitted for adapting to gyro angles.

Pattern 2380

Similar to the Pattern 2390a, but larger and of improved construction.

Pattern 2389

Same as the Pattern 2390, but fitted for use from the bridge, presumably by the addition of a tangent bar.

Pattern 2390

Supplied to torpedo craft with heater torpedoes. Similar to Pattern 1895, but graduated for higher torpedo speeds.

Pattern 2387

Same as Pattern 1192, but fitted for use from the bridge by addition of a tangent bar.

Pattern 2388

Same as Pattern 1193, but fitted for use from the bridge by addition of a tangent bar.

Pattern 2391/2391a

A "right handed" director for use in conning and director towers of ships c1914. The 2391a was fitted for gyro angling.

Pattern 2392/2392a

A "left handed" director for use in conning and director towers of ships c1914, partner to 2391. The 2392a was fitted for gyro angling.

Bibliography

• Template:BibUKARTS1915