Chieftain Mk.5
Chieftain Mk. 5/2: Main battle tank
Statistics
Main gun: 120mm L11A5
Ammunition Stowage: 33 ready/19 stowed
Default Ammunition "A": 19/11 L15 APDS, 14/8 L31A7 HESH-T, 2/0 L34 WP
Coaxial machine gun: 7.62mm L8A1 (FN MAG)
Ammunition Stowage: 3600 ready/2400 stowed
Default Ammunition: 3600/2400 7.62mm NATO
AAMG: 7.62mm L37A1 (FN MAG)
Ammunition Stowage: 200 ready/800 stowed
Default Ammunition: 200/800 7.62mm NATO
Grenade Dischargers: Grenades
Ammunition Stowage: 2 ready/2 stowed
Default Ammunition: 2/2 Smoke
Armour protection:
Frontal Turret Armour: ~250-300mm
Side Turret Armour: ~90-196mm
Front Hull Armour: ~270-280mm
Side Hull Armour: ~38-50mm
Combat Weight: 54 tonnes
Length: 7.51m (Hull)
Width: 3.66m
Height: 2.9m
Engine: 750hp Leyland L60 Mk.8A 6-cylinder opposed-piston Multi-fuel
Top speed: 48kph
General
The result of a General Staff specification to combine the firepower and armour protection of the Conqueror heavy tank with the mobility of the Centurion, the FV4201 Chieftain is a second-generation medium main battle tank that entered service in 1968. A continuation of the British line of cruiser class tanks, formal development began in 1958.
Initial armament consisted of a stabilized 120mm L11A2 rifled tank gun backed by a coaxial 7.62mm L8A1 (FN MAG) machine-gun, and an L37A1 machine-gun (also an FN MAG) at the commander's station. A .50 cal L21A1 ranging machine-gun was fitted above the main gun and this was later adjunct to a Barr and Stroud LF-2 laser rangefinder on the Mk. 3/3 version in 1969. Basic fire-control encompasses the FV/GCE Mk 4 FCS designed by Marconi with passive infra-red capability combined with a large xenon white-light/infra-red searchlight on the left side of the turret. Ammunition is of the separate loading type (three-part) with charges protected in jacketed “wet storage” bins.
Motive power for the first in service vehicles was a 650hp Leyland L60 6-cylinder opposed-piston multi-fuel engine coupled with an David Brown Defense Equipment Limited TN12 transmission offering six forward and two reverse speeds. Chosen to meet NATO multi-fuel requirements, this powerpack combination suffered reliability and performance issues throughout the Chieftain's service life, although most problems were finally ironed out by the mid 1980s. Suspension is of the Horstmann coil spring type.
Both the hull and turret feature cast construction, which were of comparable thickness to Soviet designs of the time – namely the T-54/55 and T-62 – but inferior to the more advanced T-64 and T-72 series. Despite this, thanks to the high degree of slope on the Chieftain's armuor and the poor performance of early Soviet APDS and APFSDS rounds with angled impacts, the design proved moderately resistant to such rounds until the mid 1970's. Unfortunately, as was common for almost all western tank designs of the era, the Chieftain's armour package was wholly inadequate against most HEAT warheads above 90mm.
The modeled version is the Chieftain Mk.5/2. Considered the definitive Chieftain mark, the Mk.5 is the final production version with all subsequent marks being either upgrades of previous versions to Mk.5 standards (Mks.6-8) or armour (Mk.11 and 12) and fire-control (Mks.9-12) modifications to existing Mk.5 tanks. Entering service in 1972 the Mk.5/2 features an uprated 750hp hp Leyland L60 Mk.8A engine, improved NBC protection, revised engine covers, improved air cleaners, battery heaters, an enhanced starter, and rearranged ammunition stowage. The gunner's sight was upgraded to the Barr and Stroud Tank Laser Sight (TLS) with a Nd:YAG [Neodymium: Yttrium Aluminum Garnet] laser rangefinder and improved L3A1 active-IR periscope. Additionally, a new thermal sleeve was fitted to the main gun and a compatible travel-lock added, the ranging machinegun’s ammunition stowage was halved, and the gun drive/stabilizer and commander’s collimator were replaced with improved versions. Lastly a stabilized active IR detection device was added and the vehicle was fitted with the muzzle reference system found on the Mk.3/3 but missing on early Mk.5s.
Phased out of UK service in the early 1990's, the Chieftain family was moderately exported to, and still in use by, several Middle-Eastern nations including Iran, Oman, Jordan, Kuwait, and Iraq (captured from Iran). ARRV, AVLB, and AVRE versions continue to serve with the UK in limited numbers.
Thermal Signature
Reference
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