Editing Torpedo (section)

==Warhead and fuzing==
The [[warhead]] is generally some form of [[aluminum|aluminized]] explosive, because the sustained explosive pulse produced by the powdered aluminum is particularly destructive against underwater targets. [[Torpex]] was popular until the 1950s, but has been superseded by [[polymer bonded explosive|PBX]] compositions. [[Nuclear torpedo]]es have also been developed, such as the [[Mark 45 torpedo]]. In lightweight antisubmarine torpedoes designed to penetrate submarine hulls, a [[shaped charge]] can be used. [[Detonation]] can be triggered by direct contact with the target or by a [[proximity fuze]] incorporating sonar and/or magnetic sensors.

===Contact detonation===
When a torpedo with a contact fuze strikes the side of the target hull, the resulting explosion creates a bubble of expanding gas, the walls of which move faster than the [[Speed of sound#Speed of sound in liquids|speed of sound in water]], thus creating a [[shock wave]]. The side of the bubble which is against the hull rips away the external plating, creating a large breach. The bubble then collapses in on itself, forcing a high-speed stream of water into the breach which can destroy [[Bulkhead (partition)|bulkhead]]s and machinery in its path.<ref name ="Branfill_Cook_2014">{{cite book |last=Branfill-Cook |first=Roger  |date=2014 |title=Torpedo: The Complete History of the World's Most Revolutionary Naval Weapon |url=https://books.google.com/books?id=Fk2uBQAAQBAJ&pg=PA157 |publisher=Seaforth Publishing |page=157 |isbn=978-1848322158 }}</ref>

===Proximity detonation===
A torpedo fitted with a proximity fuze can be detonated directly under the [[keel]] of a target ship. The explosion creates a gas bubble which may damage the keel or underside plating of the target. However, the most destructive part of the explosion is the upthrust of the gas bubble, which will bodily lift the hull in the water. The structure of the hull is designed to resist downward rather than upward pressure, causing severe strain in this phase of the explosion. When the gas bubble collapses, the hull will tend to fall into the void in the water, creating a sagging effect. Finally, the weakened hull will be hit by the uprush of water caused by the collapsing gas bubble, causing structural failure. On vessels up to the size of a modern [[frigate]], this can result in the ship breaking in two and sinking. This effect is likely to prove less catastrophic on a much larger hull, for instance, that of an [[aircraft carrier]].<ref name ="Branfill_Cook_2014"/>

===Damage===
The damage that may be caused by a torpedo depends on the "[[shock factor]] value", a combination of the initial strength of the explosion and the distance between the target and the detonation. For ship hull plating, the term "hull shock factor" (HSF) is used, while keel damage is termed "keel shock factor" (KSF). If the explosion is directly underneath the keel, then HSF is equal to KSF, but explosions that are not directly underneath the ship will have a lower value of KSF.<ref name=Reid1996/>

====Direct damage====
Usually only created by contact detonation, direct damage is a hole blown in the ship. Among the crew, [[Fragmentation (weaponry)|fragmentation]] wounds are the most common form of injury. Flooding typically occurs in one or two main watertight compartments, which can sink smaller ships or disable larger ones.

====Bubble-jet effect====
The bubble-jet effect occurs when a mine or torpedo detonates in the water a short distance away from the targeted ship. The explosion creates a bubble in the water, and due to the pressure difference, the bubble will collapse from the bottom. The bubble is buoyant, and so it rises towards the surface. If the bubble reaches the surface as it collapses, it can create a pillar of water that can go over a hundred meters into the air (a "columnar plume"). If conditions are right and the bubble collapses onto the ship's hull, the damage to the ship can be extremely serious; the collapsing bubble forms a high-energy jet that can break a meter-wide hole straight through the ship, flooding one or more compartments, and is capable of breaking smaller ships apart. The crew in the areas hit by the pillar are usually killed instantly. Other damage is usually limited.<ref name=Reid1996/>

The [[Baengnyeong incident]], in which {{ship|ROKS|Cheonan|PCC-772|6}} broke in half and sank off the coast South Korea in 2010, was caused by the bubble-jet effect, according to an international investigation.<ref>{{cite news |url=http://news.bbc.co.uk/nol/shared/bsp/hi/pdfs/20_05_10jigreport.pdf|title=Investigation Result on the Sinking of ROKS "Cheonan" by The Joint Civilian-Military Investigation Group|date=20 May 2010|access-date=27 January 2014|work=BBC News}}</ref><ref>{{cite news|url=https://www.nytimes.com/2010/04/26/world/asia/26korea.html|title=South Korea Cites Attack in Ship Sinking|newspaper=The New York Times|date=25 April 2010|access-date=25 April 2010 | first=Choe | last=Sang-Hun}}</ref>

====Shock effect====
If the torpedo detonates at a distance from the ship, and especially under the keel, the change in water pressure causes the ship to resonate. This is frequently the most deadly type of explosion if it is strong enough. The whole ship is dangerously shaken and everything on board is tossed around. Engines rip from their beds, cables from their holders, etc. A badly shaken ship usually sinks quickly, with hundreds or even thousands of small leaks all over the ship and no way to power the pumps. The crew fares no better, as the violent shaking tosses them around.<ref name=Reid1996>{{cite web |first=Warren D. |last=Reid |url=https://apps.dtic.mil/dtic/tr/fulltext/u2/a326738.pdf |archive-url=https://web.archive.org/web/20200327122839/https://apps.dtic.mil/dtic/tr/fulltext/u2/a326738.pdf |url-status=live |archive-date=March 27, 2020 |title=The Response of Surface Ships to Underwater Explosions |id=DSTO-GD-0109 |date=September 1996 |publisher=Ship Structures and Materials Division, Aeronautical and Maritime Research Laboratory, Defence Science and Technology Organisation. Department of Defence}}</ref> This shaking is powerful enough to cause disabling injury to knees and other joints in the body, particularly if the affected person stands on surfaces connected directly to the hull (such as steel decks).

The resulting gas cavitation and [[shock-front]]-differential over the width of the human body is sufficient to stun or kill [[Frogman|divers]].<ref>{{cite report |author1=Cudahy, E |author2=Parvin, S |title=The Effects of Underwater Blast on Divers |series=US Naval Submarine Medical Research Lab Technical Report |id=NSMRL-1218 |year=2001 |url=http://archive.rubicon-foundation.org/7518 |access-date=2009-03-22 |archive-date=2009-07-03 |archive-url=https://web.archive.org/web/20090703203738/http://archive.rubicon-foundation.org/7518 |url-status=usurped }}</ref>