Editing Torpedo (section)

===Unguided===
The Victorian-era [[Brennan torpedo]] could be steered onto its target by varying the relative speeds of its propulsion cables. However, the Brennan required a substantial infrastructure and was not suitable for shipboard use. Therefore, for the first part of its history, the torpedo was guided only in the sense that its course could be regulated to achieve an intended impact depth (because of the sine-wave running path of the Whitehead,<ref>Fitzsimons, Bernard, ed. "Bliss-Leavitt", in ''The Illustrated Encyclopedia of 20th Century Weapons and Warfare'' (London: Phoebus, 1978), Volume 4, p.386.</ref> this was a hit or miss proposition, even when everything worked correctly) and, through gyroscopes, a straight course. With such torpedoes the method of attack in [[Torpedo boats#Motor torpedo craft|small torpedo boats]], [[torpedo bomber]]s, and small submarines was to steer a predictable collision course abeam to the target and release the torpedo at the last minute, then veer away, all the time subject to defensive fire.

In larger ships and submarines, fire-control calculators gave a wider engagement envelope. Originally, plotting tables (in large ships), combined with specialized [[slide rule]]s (known in U.S. service as the "banjo" and "Is/Was"),<ref name=Beach55>{{cite book |first=Edward L. |last=Beach |title=Run Silent, Run Deep |url=https://books.google.com/books?id=v6D1DAAAQBAJ |orig-year=1955 |date=2016 |publisher=Naval Institute Press |isbn=978-1-68247-167-8}}</ref> reconciled the speed, distance, and course of a target with the firing ship's speed and course, together with the performance of its torpedoes, to provide a firing solution. By the Second World War, all sides had developed automatic electro-mechanical calculators, exemplified by the U.S. Navy's [[Torpedo Data Computer]].<ref>The British called theirs the "fruit machine".</ref> Submarine commanders were still expected to be able to calculate a firing solution by hand as a backup against mechanical failure, and because many submarines existed at the start of the war were not equipped with a TDC; most could keep the "picture" in their heads and do much of the calculations (simple trigonometry) mentally, from extensive training.<ref name=Beach55/>

Against high-value targets and multiple targets, submarines would launch a spread of torpedoes, to increase the probability of success. Similarly, squadrons of torpedo boats and torpedo bombers would attack together, creating a "fan" of torpedoes across the target's course. Faced with such an attack, the prudent thing for a target to do was to turn to parallel the course of the incoming torpedo and steam away from the torpedoes and the firer, allowing the relatively short-range torpedoes to use up their fuel. An alternative was to "comb the tracks", turning to parallel the incoming torpedo's course, but turning towards the torpedoes. The intention of such a tactic was still to minimize the size of the target offered to the torpedoes, but at the same time be able to aggressively engage the firer. This was the tactic advocated by critics of Jellicoe's actions at [[Battle of Jutland#Controversy|Jutland]], his caution at turning away from the torpedoes being seen as the reason the Germans escaped.

The use of multiple torpedoes to engage single targets depletes torpedo supplies and greatly reduces a submarine's [[combat endurance]].<ref>''The Attack Submarine'' suggests ''shorter'' patrols actually improve effectiveness.</ref> Endurance can be improved by ensuring that a target can be effectively engaged by a single torpedo, which gave rise to the guided torpedo.