Chieftain (tank)


The FV4201 Chieftain was the main battle tank of the United Kingdom during the 1960s, 1970s and 1980s.
A development of the Centurion, the Chieftain introduced the supine driver position to British design allowing a heavily sloped hull with reduced height. A new powerpack and improved transmission gave it higher speed than the Centurion despite being heavier due to major upgrades to armour protection and the armament: this allowed it to replace both the Conqueror and Centurion while performing their roles effectively. It remained in service until replaced by the Challenger 1 which shared many of the Chieftain's features.

Development

The Chieftain was an evolutionary development of the successful cruiser line of tanks that had emerged at the end of the Second World War. Its predecessor, the Centurion main battle tank, is widely considered to be one of the most successful of post-war MBT designs. However, the introduction of the Soviet IS-3 /IS-4 heavy tank along with Soviet T-54/T-55 forced the introduction of their own Conqueror heavy tank armed with a gun. A single design combining the firepower of the Conqueror's 120 mm gun with the mobility and general usefulness of the Centurion was seen as the ideal combination.
Leyland, who had been involved in the Centurion tank, had built their own prototypes of a new tank design in 1956. Several aspects of the design were trialled by the production of the FV4202 "40-ton Centurion" with a reclined driver position and mantletless gun mounting. In effect, the FV4202 was a sightly modified Centurion chassis with a prototype of what would become the Chieftain turret, but armed with the 20pdr gun.
This work led to a War Office specification for a new tank. The General Staff specification drew on the experience of Centurion tanks in the Korean War as well as that of the Conqueror tank. The tank was expected to be able to engage the enemy at long range, from defensive positions, and be proof against medium artillery. To this end, the gun was to have a greater angle of depression than the 8 degrees of Conqueror and would be equipped with better frontal armour. The tank was expected to achieve a firing rate of 10 rounds per minute in the first minute and six per minute for the following four.
The first few prototypes were provided for troop trials from 1959 which identified a number of changes. Improvements to address engine vibration and cooling resulted in a redesign of the rear hull. This increased the design weight to nearly 50 tons and accordingly the suspension was strengthened. Trackpads had to be fitted to protect roads from damage and the ground clearance increased. The design was accepted in the early 1960s.
Britain and Israel had collaborated on the development in its latter stages with a view to Israel purchasing and domestically producing the vehicle. Two prototypes were delivered as part of a four-year trial. However, it was eventually decided not to sell the marque to the Israelis, which prompted them to follow their own development programme.
In 1957, NATO had specified that its forces should use multi-fuel engines. The early BL Engine delivered around to the sprocket, which meant a top road speed of around and cross-country performance was limited. This was further hampered by the Horstmann coil spring suspension, which made it a challenge to drive cross country and provide the crew with a comfortable ride. Due to the cylinder linings being pressure fitted, coolant leaks within the cylinder block were common, resulting in white smoke billowing from the exhaust.
In the late 1970s, engine design changed with the introduction of Belzona which was used to improve the lining seals. Engine output also increased, with later engines delivering some to the sprocket. This meant better performance and an increased speed. However, cross-country performance remained limited.

Design

The design of the Chieftain included a heavily sloped hull and turret which greatly increased the effective thickness of the frontal armour – on the glacis and on the turret. It had a mantletless turret in order to take full advantage of reclining the vehicle up to ten degrees in a hull-down position.
For security reasons early prototypes had a canvas screen covering the mantlet and a sheet metal box mounted over the sloping glacis plate to disguise the configuration of the vehicle.
The driver lay semi-recumbent in the hull when his hatch was closed down which helped to reduce the profile of the forward glacis plate. The commander, gunner and loader were situated in the turret. To the left side of the turret was a large searchlight with infra-red capability in an armoured housing.
engine pack displayed at the Bovington tank museum. The complete unit could be removed by the crane of the FV434.
The Leyland L60 engine is a two-stroke opposed piston design intended for multi-fuel use so that it could run on whatever fuel was available. In practice the engine did not deliver the expected power and was unreliable, estimated to have a 90% breakdown rate but improvements were introduced to address this. Primary problems included cylinder liner failure, fan drive problems and perpetual leaks due to vibration and badly routed pipework. However, as the engine power improved the tank itself became heavier.
The tank was steered by conventional tillers hydraulically actuating onto external brake discs. The discs worked via the epicyclic gearbox providing "regenerative" steering. The Merritt-Brown TN12 triple-differential gearbox was operated motorcycle-style with a kick up/kick down "peg" on the left, which actuated electro-hydraulic units in the gearbox, the accelerator cable was operated by the right foot. In the turret, the loader was on the left and the gunner on the right of the gun with the commander situated behind the gunner. The suspension was of the Horstmann bogie type with large side steel plates to protect the tracks and provide stand-off protection from hollow charge attack.
The main armament was the 120 mm L11A5 rifled gun. This differed from most contemporary main tank armament as it used projectiles and charges that were loaded separately, as opposed to a single fixed round. The charges were encased in combustible bags. Other tank guns such as the 120mm L1 gun on the Conqueror, needed to store the spent shell cartridges or eject them outside. The combustible charges were stored in 36 recesses surrounded by a pressurised water/glycol mixture – so-called "wet-stowage". In the event of a hit penetrating the fighting compartment, the jacket would rupture soaking the charges and preventing a catastrophic propellant explosion. As there was no shell case, the firing of the charge was by vent tubes automatically loaded from a ten-round magazine on the breech. Due to the length of the gun, which required balancing, and the need for storage space, the turret has a large overhang to the rear. This contains radios, ammunition and fire control equipment and has further stowage externally.
The gun could fire a wide range of ammunition but the most commonly loaded types were high explosive squash head, armour-piercing discarding sabot, or practice round equivalents for both types. The Chieftain could store up to 64 projectiles. The gun was fully stabilised with a fully computerized integrated control system. The secondary armament consisted of a coaxial L8A1 7.62 mm machine gun and another 7.62 mm machine gun mounted on the commander's cupola. An advantage of using two-part ammunition was that in the case of inert rounds like APDS the loader could reach for the next round and hold it in his lap, ready to load while the gunner was acquiring the target and firing. This practice increases the rate of fire but would be hazardous with one-piece ammunition.
Chieftain had an NBC protection system which Centurion lacked.
The initial Fire-control system was the Marconi FV/GCE Mk 4. A.50-inch ranging gun was mounted above the main gun. This fired ranging shots out to a maximum of, at which point the tracer in the ranging rounds burned out although the high explosive tip still created a visible "splash" on impact. The tank commander had a rotating cupola with nine vision blocks -giving all round view, plus the 7.62 mm machine-gun and an infrared capable projector coaxial with the weapon. The aiming systems were provided for both the gunner and the tank commander; they had 1x or 10x selectable magnification power, increasing to x15 in the Mk5 and beyond, and they were replaceable with IR vision systems for night operations. The commander could rotate his cupola to bring his sight onto a target and then engage the mechanism that brought the turret round on to the correct bearing so that the gunner could complete the aiming.
The commander's controls had over-ride capability on those of the gunner.
The left side of the turret had a large searchlight with an electrically controlled infra-red filter inside an armoured box, with a relatively long range – up to.
From the beginning of the 1970s, the Mk 3/3 version replaced the ranging gun with a Barr and Stroud LF-2 laser rangefinder with a range. This allowed engagements at much longer ranges, and also could be linked to the fire control system, allowing more rapid engagements and changes of target.
On later models, fire control was provided by the Marconi IFCS, using a digital ballistic computer. The upgrade was not finished until the end of 1980, when some examples had the IR searchlight replaced with TOGS. Many later examples had Stillbrew armour, intended to defeat Soviet 125 mm tank guns and heavy anti-tank missiles. These became the Mark 11 version.

Service

Chieftain equipped British units of the British Army of the Rhine during the Cold War, defending West Germany against possible Warsaw Pact attack.
Like its European competitors, Chieftain found a large export market in the Middle East, but unlike Centurion, it was not adopted by any other NATO or Commonwealth country.
Chieftain proved itself capable in combat and able to be upgraded, both for overall improvement and to meet local requirements. It was continuously upgraded until the early 1990s, when it was replaced by Challenger 1. The final Chieftain version, which was used by the British Army until 1995, incorporated "Stillbrew" armour named after Colonel Still and John Brewer from the Military Vehicles and Engineering Establishment, the Improved Fire Control System and the Thermal Observation Gunnery Sight. The last British Regiment equipped with Chieftain was the 1st Royal Tank Regiment, which was based at Aliwal Barracks, Tidworth.
2008
The first model was introduced in 1967. Chieftain was supplied to at least six countries, including Iran, Kuwait, Oman and Jordan. An agreement for sales to Israel and local production was cancelled by the British Government in 1969, despite considerable Israeli technical and tactical input into the development of the tank, especially the capacity to operate successfully in desert environments, and the provision for the tank to make good use of hull-down positioning. Two examples were delivered to and extensively trialled by the Israeli Armoured Corps. This experience spurred the creation of the indigenous Israeli Merkava, the development programme of which was led by General Israel Tal, who had worked closely with the British in the Anglo-Israeli Chieftain project. The largest foreign sale was to Iran, which, at the recommendation of General Tal, took delivery of 707 Mk-3P and Mk-5P, as well as 187 FV4030-1, 41 ARV and 14 AVLB before the 1979 revolution. Further planned deliveries of the more capable FV4030-2 and FV4030-3 series were cancelled at that point.
It was in the Middle East that the Chieftain was to see all of its operational experience. First, it was used extensively by Iran during the Iran–Iraq War of 1980–88, including the largest tank battle of the war, with mixed results as the Chieftain Mk 3/5 suffered from chronic engine problems and low power-to-weight ratio, making it unreliable and slow when manoeuvring over harsh terrain, which in turn made it prone to breakdowns in the midst of battle or a sluggish target and thus vulnerable to enemy tank fire. Out of the 875 Chieftain tanks that had started the war only 200 were left.
The Chieftain remains in service in Iran, the Mobarez tank being a locally upgraded version.

Kuwait and the Battle of the Bridges

Kuwait had 143 Chieftains on the eve of the 1990 Iraqi Invasion of Kuwait. Thirty-seven Chieftains of the Kuwaiti 35th Armored Brigade fought at the Battle of the Bridges against elements of the Iraqi Hammurabi and Medina divisions before withdrawing over the Saudi border. None of the brigade's tanks was lost in the battle, and the 35th Armored Brigade became part of Joint Command Forces East during the 1991 Gulf War and was able to return into Kuwait undefeated.
Besides those of the 35th Armored Brigade, the rest of the Kuwaiti Armed Forces' Chieftains were either destroyed or captured by the invading forces after they had been abandoned by their Kuwaiti crews when their ammunition ran out. After the liberation of Kuwait, the ageing Chieftains were replaced by the Yugoslav M-84.

Specifications (Mk. 5)

;Armament
Mark 1 and Mark 2 models had a coaxial Browning.50-inch ranging machine guns prior to the introduction of the laser rangefinder.
;Equipment
; FV4201 P1 - FV4201 P7:
; Chieftain Mk.1
; Chieftain Mk.1/2
; Chieftain Mk.1/3
; Chieftain Mk.1/4
; Chieftain Mk.2: First service model with 650 hp L60 Mk 4A2 engine, L11A2 or L11A3 main gun, NBC system fitted to rear of turret, revised turret stowage, one-piece commander's hatch cover, armour removed from searchlight cover, rigid flotation panels replaced by facility for deep wading, road speed 25 mph, range 250 miles, weight 51.5 long tons, first vehicles issued to 11th Hussars at Hohne in West Germany in early 1967, improved 650 hp L60 Mk 5A engine fitted 1969
; Chieftain Mk.3:Improved 650 hp L60 Mk 6A engine with two-stage air cleaner, improved auxiliary generator, better stowage, new No. 15 Mk 2 commander's cupola, road speed improved to 30 mph, range increased to 310 miles, weight 53 long tons, 1970
; Chieftain Mk 3/2: Fitted with 720 hp L60 Mk 7A, 1971
; Chieftain Mk 3/3: Fitted with 720 hp L60 Mk 7A, Improved main gun range finding, provision for Barr & Stroud TLS LF2 laser range finder, 1971
; Chieftain Mk 3/G: Chieftain Mk.3 with engine induction through fighting compartment. Prototype only
; Chieftain Mk.3/3P: Chieftain Mk 3/3 for Iran, 1973
; Chieftain Mk 3/S: Production version of Chieftain Mk 3/G with commander's firing control.
; Chieftain Mk.4
; Chieftain Mk.5: Final production variant, 750 hp L60 Mark 8A, with upgrades to the NBC protection system, weight 54 long tons, 1975
; Chieftain Mk.5/5P: Chieftain Mk.5 for Iran, 1975. Engine later upgraded to 750 hp L60 Mk 10A, 1977
; Chieftain Mk.5/2K: Chieftain Mk.5 for Kuwait, 1975
In 1975 all British Army earlier Marks of tanks except Mark 1's were upgraded to Chieftain Mk.5 standard as part of the 1975 "Totem Pole" programme, including addition of Clansman radios, fitting of TLS, fitment of Muzzle Reference System upon replacement of L11A3 barrel with L11A5 barrel, and fitment of 750 hp L60 Mark 8A. These vehicles were re-designated Chieftain Mk's.6 to Mk.8.
; Chieftain Mk.6
; Chieftain Mk.7
; Chieftain Mk.7C
; Chieftain Mk.8
In 1977 the engines of all British Army vehicles were upgraded to the 750 hp L60 Mark 9A, followed by further upgrading with the L60 Mark 11A or L60 Mark 12A in 1978 as part of the 1977 "Dark Morn" and the 1978 "Sundance" programmes.
; Chieftain Mk.9
; Chieftain Mk.10: Chieftain Mk.7 after completing all phases of "Totem Pole". Later upgraded with addition of Stillbrew Crew Protection Package to the turret front and turret ring, 1984–86
; Chieftain Mk.11: Chieftain Mk.8 after completing all phases of "Totem Pole". Later upgraded with Stillbrew, 1984–86
; Chieftain Mk.12: Chieftain Mk.5 after completing all phases of "Totem Pole". Later upgraded with Stillbrew, 1984–86
; Chieftain Mk.12/13: Proposed further upgrades, cancelled when the Challenger 1 was introduced.
; Chieftain 800: Re-engined Iranian FV4030/1 Chieftain Mark 5/3P fitted with the 800 bhp Rolls-Royce CV8 TCA engine and the fully automatic TN12 Mk. 5 transmission.
; Chieftain 900: Two Mk. 5/3 were converted by Royal Ordnance Factories by fitting the 900 bhp Rolls-Royce Condor 900E engine and the fully automatic TN12-1000 version of the Chieftain's gearbox, hence the name of Chieftain 900. The two Chieftain 900 prototypes were built in April 1982 and were exhibited the same year at the British Army Equipment Exhibition. They were not fitted with real Chobham armour but were mocked up with cosmetic sheet-metal cladding to simulate the Chobham armour package. The project was abandoned by 1986.
; FV4030/1 Chieftain Mk. 5/3 « Persia » : Also known as "Project 4030 Phase 1" or "Improved Chieftain". The Mk. 5/3P featured the Tank Laser Sight, the Muzzle Reference Sensor, a fully automatic controller for the TN12 gearbox, a fuel capacity increase, thickened underbelly mine armour and shock absorbers fitted to the front and rear suspension units. 185 vehicles were built between August 1976 and late 1977/early 1978.
; FV4030/2 Shir 1: Also known as "4030 Phase 2". This tank formed Phase 2 of the Iranian contract for the supply of a new generation of MBTs. This project began in 1974. Shir 1 incorporated the Chieftain hull front and turret casting. The rear of the hull was reconfigured to accept a new power pack comprising Rolls-Royce CV12 1200 HP engine, David Brown's TN37 transmission and new cooling group. An improved bogie suspension, new final drives and tracks were included. The first vehicle-ran in April 1977 and no production deliveries had taken place when the project was cancelled in February 1979.
; Khalid: Also known as "4030 Phase 2 Jordan". The sale of 274 MBTs was negotiated with Jordan in June 1979 following the cancellation of the Iranian contract. The Khalid tank is based on the Shir 1 design with the addition of the Integrated Fire Control System, Tank Laser Sight and the No 84 Day/Night Sight. The first 125 were reworked Shir 1's and the remaining 149 were new production tanks. The order has been completed, the first being delivered in July 1981.
;FV4030/3 Shir 2: "4030 Phase 3" Iranian variant. The Shir 2 represented a completely new-MBT incorporating Chobham armour to the hull and turret, with the rear of the hull similar in design to the Shir 1. The fire control, gun control and automotive systems were the same as Shir 1 with the following exceptions: Automotive - the option of adopting hydrogas suspension and command & control, the new No 84 commander's day/night sight. The project began in 1974 and the first vehicle ran in October 1978. The production order was for 1,200 MBTs and production release given for 250 before cancellation in February 1979. Not delivered, the Shir 2 tanks became FV4030/4 Challenger 1 tanks after reworking at ROF Leeds.
;Mobarez Tank:Iranian upgraded version of Chieftain. :
;Chieftain/ T95: Development of the FV4201 Chieftain allowed for the interchangeability of guns with the U.S. T95 tank by means of exchanging turrets. The project was discontinued because of numerous problems with training crews to master two artillery systems. Equipped with a 90mm T208 gun.
;FV4211: Test vehicle using Chieftain automotive sub systems , embodied in a new aluminium hull and turret structure incorporating Chobham Armour for the first time. The project began in October 1969. A feasibility study was completed by February 1970 which led to MVEE being asked to design and produce a prototype within a year. This timescale was achieved, the MVEE produced the first prototype in February 1971. Although the project was officially discontinued in 1972, research work within MVEE continued until 1974. A paper study on a Mk. 2 version was carried out and was considered during the FMBT studies in 1974.
; FV4204 ARV/ARRV: Armoured Recovery Vehicle, Armoured Recovery and Repair Vehicle.
; FV4205 AVLB Mk5: Bridge-laying vehicle
and towing Python on Salisbury Plain.
; Chieftain AVRE : Armoured Vehicle Royal Engineers, twelve early "Willich Chieftain AVRE" vehicles converted by 32 Armoured Engineer Regiment and 21 Engineer Base Workshop of the Royal Engineers, Willich, 1987, remaining 48 ex MBTs converted by Vickers Defence Ltd, 1991, to be a British Army combat engineering variant used by the Royal Engineers.
; Chieftain Marksman:Self-propelled anti-aircraft gun version, equipped with the Marksman twin gun turret.
; Chieftain Mineclearer: Mine-clearing development.
; Chieftain Sabre: Twin 30 mm AA turret.
; Chieftain SID: Chieftain Signature Integration Demonstrator.
; Chieftain Crazy Horse: Mobile Range Hard Target.
; Weapon Carriers: The Chieftain chassis was adapted to mount air defence weapons and a 155 mm howitzer in a number of variants.

Operators

Current operators