Editing Challenger 2 (section)

== Design ==
=== Armament ===
[[File:Challenger 2 Tank Firing a Shell MOD 45157421.jpg|thumb|A Challenger 2 firing its main armament during an exercise. The shell is visible to the left of the smoke cloud.]]
[[File:Challenger 2 main battle tank.jpg|thumb|Close-up of muzzle showing rifling]]
[[File:Challenger 2 Tank Firing at BATUS MOD 45157782.jpg|thumb|A row of Challenger 2 on a firing range at [[British Army Training Unit Suffield|BATUS]], Canada]]

The Challenger 2 is equipped with a {{convert|120|mm|in|adj=on}} 55-[[caliber (artillery)|calibre]] long [[Royal Ordnance L30|L30A1]] tank gun,<ref name="janes.com"/> the successor to the L11 gun used on [[Chieftain tank|Chieftain]] and Challenger 1. The gun is made from high strength [[electro-slag remelting]] (ESR) steel with a chromium alloy lining. Like earlier British 120&nbsp;mm guns, it is insulated by a [[thermal sleeve]]. It is fitted with a muzzle reference system and [[fume extractor]], and is controlled by an all-electric control and stabilisation system. The turret has a rotation time of 9 seconds through 360 degrees.

Uniquely among [[NATO]] main battle tank guns, the L30A1 is [[Rifling|rifled]] and along with its predecessor, the [[Royal Ordnance L11A5]], the only Third Generation Main Battle Tank Guns to use a rifled barrel. This is because the British Army continues to place a premium on the use of [[high explosive squash head]] (HESH) rounds in addition to [[armour-piercing fin-stabilized discarding-sabot]] (APFSDS) rounds. HESH rounds have a longer range (up to {{convert|8|km|mi|0|disp=or}} further) than APFSDS, and are more effective against buildings and thin-skinned vehicles.<ref>{{cite book |last1=Kaplan |first1=Philip |title=Rolling Thunder: A Century of tank Warfare |date=2013 |publisher=Pen and Sword |page=161}}</ref>

Forty-nine main armament rounds are carried in the turret and hull. These are a mix of L27A1 APFSDS (also referred to as CHARM 3), L31 HESH and L34 [[white phosphorus]] smoke rounds, depending on the situation. As with earlier versions of the 120&nbsp;mm gun, the propellant charges are loaded separately from the shell or KE projectile. A combustible rigid charge is used for the APFSDS rounds and a combustible hemicylindrical bag charge for the HESH and smoke rounds. An electrically fired vent tube is used to initiate firing of the main armament rounds. The main armament ammunition is described to be "three-part ammunition", consisting of the projectile, charge and vent tube. The separation of ammunition pieces aids in ensuring lower chances of unfired [[cooking off|ammunition detonating prematurely]].

The Challenger 2 is also armed with a [[L94A1 chain gun|L94A1]] EX-34 7.62&nbsp;mm [[chain gun]] coaxially to the left of the main gun, and a 7.62&nbsp;mm [[L7 (machine gun)|L37A2]] (GPMG) machine gun mounted on a pintle on the loader's hatch ring. 4,200 rounds of 7.62&nbsp;mm ammunition are carried. The Challenger can also mount a Leonardo "Enforcer" [[Remote controlled weapon station|remote control weapons system]], bearing a 7.62&nbsp;mm [[L7 (machine gun)|L37A2]] (GPMG) machine gun, a 12.7&nbsp;mm heavy machine gun or a 40&nbsp;mm automatic grenade launcher.<ref>{{cite web |title=Enforcer Remote Control Weapons System Data Sheet |url=http://www.leonardocompany.com/documents/63265270/66465238/mm08109_Enforcer_RWS_LQ_.pdf |website=Leonardo Company |access-date=28 February 2018 |archive-url=https://web.archive.org/web/20180301044344/http://www.leonardocompany.com/documents/63265270/66465238/mm08109_Enforcer_RWS_LQ_.pdf |archive-date=1 March 2018 }}</ref>

=== Fire control and sights ===
[[File:Challenger 2 Tankfest 2009.jpg|thumb|A close up view of a Challenger 2]]

The digital fire control computer from [[General Dynamics|Computing Devices Co]] of Canada contains two 32-bit processors with a MIL STD1553B databus. It has capacity for additional systems, such as a Battlefield Information Control System.

The commander has a panoramic [[SAGEM]] VS 580-10 gyrostabilised sight with [[laser rangefinder]]. The elevation range is +35° to −35°. The commander's station is equipped with eight [[periscope]]s for 360° vision.

The Thermal Observation and Gunnery Sight II (TOGS II), from [[Thales Group|Thales]], provides [[night vision]]. The thermal image is displayed on both the gunner's and commander's sights and monitors. The gunner has a stabilised primary sight using a laser rangefinder, with a range of {{convert|200|m|abbr=on}} to {{convert|10|km|abbr=on}}. The driver's position is equipped with a Thales Optronics image-intensifying Passive Driving Periscope (PDP) for night driving and a rear view thermal camera.

=== Protection ===
[[File:Challenger Main Battle Tank with Improved Armour MOD 45149015.jpg|thumb|right|Challenger 2 with armour upgrades to the sides of the turret, skirts, bar armour to rear. Smoke grenade launchers visible on turret front. [[Counter-IED equipment|Counter-IED]] ECM antennas are on the platform on the turret, and additional [[electronic countermeasure|ECM]] equipment overhangs the left and right front fenders. A remote controlled weapon systems (RCWS) has also been fitted to the turret.]]

The Challenger 2 is a heavily armoured and well protected tank.<ref name="Fprado">{{cite web |url=http://www.fprado.com/armorsite/chall2.htm |title=Main Battle Tank: Challenger 2 |publisher=Fprado.com |access-date=16 January 2011 |archive-url=https://web.archive.org/web/20070522041934/http://www.fprado.com/armorsite/chall2.htm |archive-date=22 May 2007 |url-status=live}}</ref> The turret and hull are protected by second-generation [[Chobham armour]], also known as Dorchester, the details of which are classified but which is said to have a mass efficiency more than twice that of [[rolled homogeneous armour]] against [[high-explosive anti-tank]] (HEAT) projectiles. Crew safety was paramount in the design. It uses a [[Solid-state electronics|solid state electric drive]] for turret and gun motion, instead of hydraulic systems that can leak fluid into the crew compartment.

[[Explosive reactive armour]] kits and additional [[bar armour]] may be fitted as needed. The nuclear, biological, and chemical (NBC) protection system is located in the turret bustle. The tank's shape is designed to minimise its radar signature. On each side of the turret are five L8 [[smoke grenade]] dischargers. The Challenger 2 can create smoke by injecting diesel fuel into the exhaust manifolds.

=== Drive system ===
[[File:The King's Royal Hussars take on Bavarian Challenge during Exercise COMBINED RESOLVE APOG-OFFICIAL-20240604-006-136.jpg|thumb|[[Royal Electrical and Mechanical Engineers|REME]] mechanic performing field maintenance on the power pack of a [[King's Royal Hussars]] Challenger 2.]]

The tank's drive system comprises:
* Engine: [[Perkins Engines|Perkins]] 26.1&nbsp;litre, 60° vee, twin turbocharged, CV12-6A four-stroke, four-valve-per-cylinder (pushrod), direct-injection [[diesel engine]] delivering {{convert|1200|bhp|kW|abbr=on}} at 2300&nbsp;rpm. Torque 4126&nbsp;Nm at 1700&nbsp;rpm.<ref>https://www.thefreelibrary.com/building challenger 2.-a09038700</ref> The engine and gearbox are controlled by a Petards Vehicle Integrated Control System (VICS).<ref>{{cite web |url=http://www.petards.com/our-solutions/defence-services/control-systems |title=Control Systems |publisher=Petards Group |access-date=10 March 2018 |archive-url=https://web.archive.org/web/20180313031444/http://www.petards.com/our-solutions/defence-services/control-systems/ |archive-date=13 March 2018 |url-status=live}}</ref>
* Gearbox: [[David Brown Limited|David Brown]] Santasalo TN54E epicyclical transmission (6 fwd, 2 rev.) rated at 1200&nbsp;bhp and upgradable to 1500&nbsp;bhp.<ref>{{Cite web |url=https://dbsantasalo.com/industries/defence/land-defence/tn54-tracked-vehicle-transmission/ |title=TN54E Tracked Vehicle Transmission |access-date=19 February 2018 |archive-url=https://web.archive.org/web/20180220033059/https://dbsantasalo.com/industries/defence/land-defence/tn54-tracked-vehicle-transmission/ |archive-date=20 February 2018 |url-status=live}}</ref>
* Suspension: Horstman Defence Systems second-generation [[Hydropneumatic suspension|hydrogas]] suspension units (HSU).
* Track: William Cook Defence hydraulically adjustable TR60 414FS double-pin.<ref>{{cite web |url=https://www.william-cook.co.uk/gb/news/cook-defence-systems-is-track-supplier-of-choice-at-dsei-2019 |title=Cook Defence Systems is track supplier of choice at DSEI 2019 |publisher=William Cook |date=10 September 2019 |access-date=7 January 2020}}</ref>
* Maximum speed: {{convert|37|mph|km/h|abbr=on}} on road; {{convert|25|mph|km/h|abbr=on}} cross country
* Range: {{convert|342|mi|km|abbr=on|disp=or}} on road with external fuel; {{convert|156|mi|km|-1|abbr=on}} cross country on internal fuel.

The tank is fitted with an Extel Systems Wedel auxiliary power unit, an APU, also referred to as a generating unit engine (GUE), based on a 38&nbsp;kW Perkins P404C-22 diesel engine. It has a 600&nbsp;A electrical output, which can be used to power the vehicle's electrical systems when it is stationary and the main engine is switched off. This replaces the Perkins P4.108 engine fitted when the tank was first introduced.<ref>{{cite web |url=http://ted.europa.eu/udl?uri=TED:NOTICE:411049-2016:TEXT:EN:HTML&src=0 |title=Repair of Challenger 2 ESW APU |publisher=Official Journal of the EU |date=22 November 2016 |access-date=8 March 2018 |archive-url=https://web.archive.org/web/20180310010421/http://ted.europa.eu/udl?uri=TED:NOTICE:411049-2016:TEXT:EN:HTML&src=0 |archive-date=10 March 2018 |url-status=live}}</ref> The use of an APU allows fuel consumption to be reduced, and lowers the audio and thermal signature of the vehicle.

By 2013 the British Army had, at various events featuring the Challenger 2, begun to state the on-road range as 550&nbsp;km as opposed to an earlier stated value of 450&nbsp;km.<ref name="youtube.com"/> They also publicly stated a maximum road speed of 59&nbsp;km/h while equipped with 15&nbsp;tons of additional modules.<ref name="youtube.com"/>

=== Crew and accommodation ===
The British Army maintained its requirement for a four-man crew, including a loader, after risk analysis of the incorporation of an [[autoloader|automatic loader]] suggested that autoloaders reduced battlefield survivability. Mechanical failure and the time required for repair were prime concerns.

Similar to every British tank since the [[Centurion tank|Centurion]], and most other British AFVs, Challenger 2 contains a [[boiling vessel]] (BV) for water, for use preparing and heating food and drink.<ref>{{Cite web |url=http://www.theguardian.com/world/2003/apr/07/iraq.military |archive-url=https://web.archive.org/web/20071017155330/http://www.guardian.co.uk/Iraq/Story/0%2C%2C931139%2C00.html |title=A brew brings coalition forces closer together |date=7 April 2003 |archive-date=17 October 2007 |website=The Guardian}}</ref>