Editing Torpedo (section)

===Torpedo boats and guidance systems===
[[File: HMS Lightning - Torpedo Boat 1877.jpg|right|thumb|{{HMS|Lightning|1876|6}}, built in 1877 as a small attack boat armed with torpedoes.]]

[[Ship of the line|Ships of the line]] were superseded by [[ironclad warship|ironclads]], large steam-powered ships with heavy gun armament and heavy armor, in the mid-19th century. Ultimately this line of development led to the [[dreadnought]] category of all-big-gun battleships, starting with {{HMS|Dreadnought|1906|6}}.

Although these ships were incredibly powerful, the new weight of armor slowed them down, and the huge guns needed to penetrate that armor fired at very slow rates. The development of torpedoes allowed for the possibility that small and fast vessels could credibly threaten if not sink even the most powerful battleships. While such attacks would carry enormous risks to the attacking boats and their crews (which would likely need to expose themselves to artillery fire which their small vessels were not designed to withstand), this was offset by the ability to construct large numbers of small vessels far more quickly and for a much lower unit cost compared to a capital ship.

The first boat designed to fire the self-propelled [[#Self-propelled torpedoes|Whitehead torpedo]] was {{HMS|Lightning|1876|6}}, completed in 1877. The [[French Navy]] followed suit in 1878 with {{ship|French torpedo boat|Torpilleur No 1||2}}, launched in 1878, though she had been ordered in 1875. The first torpedo boats were built at the shipyards of Sir [[John Isaac Thornycroft|John Thornycroft]] and gained recognition for their effectiveness.

At the same time, inventors were working on building a guided torpedo. Prototypes were built by [[John Ericsson]], [[John Louis Lay]], and Victor von Scheliha, but the first practical guided missile was patented by [[Louis Brennan]], an emigre to Australia, in 1877.<ref name=gray/>

[[File: Brennan torpedo launching.jpg|thumb|left|The [[Brennan torpedo]] was the first practical guided torpedo.]]
It was designed to run at a consistent depth of {{convert|12|ft|m}}, and was fitted with an indicator mast that just broke the surface of the water. At night the mast had a small light, visible only from the rear. Two steel drums were mounted one behind the other inside the torpedo, each carrying several thousand yards of high-tensile steel wire. The drums connected via a [[Differential (mechanical device)|differential gear]] to twin [[contra-rotating]] propellers. If one drum was rotated faster than the other, then the rudder was activated. The other ends of the wires were connected to steam-powered winding engines, which were arranged so that speeds could be varied within fine limits, giving sensitive steering control for the torpedo.<ref>National Archive in WO32/6064 In minute to Director of Artillery from Inspector General of Fortifications.</ref>

The torpedo attained a speed of {{convert|20|kn}} using a wire {{convert|0.04|in|mm|order=flip}} in diameter, but later this was changed to {{convert|0.07|in|mm|order=flip|abbr=on}} to increase the speed to {{convert|27|kn}}. The torpedo was fitted with elevators controlled by a depth-keeping mechanism, and the fore and aft rudders operated by the differential between the drums.<ref name="Beanse">The Brennan Torpedo by Alec Beanse {{ISBN|978-0-9548453-6-0}}</ref>

Brennan traveled to Britain, where the Admiralty examined the torpedo and found it unsuitable for shipboard use. However, the [[War Office]] proved more amenable, and in early August 1881, a special [[Royal Engineer]] committee was instructed to inspect the torpedo at Chatham and report back directly to the Secretary of State for War, [[Hugh Childers]]. The report strongly recommended that an improved model be built at government expense. In 1883 an agreement was reached between the Brennan Torpedo Company and the government. The newly appointed Inspector-General of Fortifications in England, [[Andrew Clarke (British Army officer, born 1824)|Sir Andrew Clarke]], appreciated the value of the torpedo, and in spring 1883 an experimental station was established at [[Garrison Point Fort]], [[Sheerness]], on the [[River Medway]], and a workshop for Brennan was set up at the [[Chatham Barracks]], the home of the Royal Engineers. Between 1883 and 1885 the Royal Engineers held trials, and in 1886 the torpedo was recommended for adoption as a harbor defense torpedo. It was used throughout the [[British Empire]] for more than fifteen years.<ref name="Beanse" />