FV 4030 Challenger I main battle tank

In 1974 Iran ordered 125 Shir 1 and 1225 Shir 2 to the Royal Ordnance Factory of Leeds. The Shir 1 was actually a latest model of the Chieftain, already in service in large numbers in Iran, fitted with a new propulsion plant constituted by a Rolls-Royce 1200-horsepower Diesel engine, coupled to a David Brown TN37 automatic transmission, and an Airscrew Holden cooling system. The armament comprised the L11A5 120-millimeter rifled cannon which was assisted by an improved fire control system manufactured by Marconi Space and Defense Systems and a rangefinder manufactured by Barr & Stroud. In return, the Shir 2 was a brand-new model which, albeit equipped with the same propulsion plant, cannon and fire control system of the Shir 1, had a hull and a turret incorporating Chobham armor, which provided a high protection against any anti-tank weapon that could be used back then in the battlefield, in particular missiles fitted with a HEAT (shaped charge) ogive. Besides, the new hydropneumatic suspension allowed the new tank to maneuver with ease on different types of terrains and sped up the maintenance and repair labors.

The British Army should have replaced the Chieftain by a British-German collaboration project which however was cancelled in March 1977, so the British continued working on their own in a new project denominated MBT-80. After the overthrow of the Sha in 1979, the order formulated by Iran was cancelled before the deliveries had started, even though the new tank was already in production. Eventually, Jordan ordered 278 Khalid tanks, which were very similar to the Shir 1 and began to be delivered in 1981. In 1980, the British Ministry of Defense informed that the MBT-80 project had been cancelled, not only because the expenses were escalating disproportionately, but also because the date of entry into service was subject to successive postponements. Instead, it was ordered from the Royal Ordnance Factory of Leeds an initial lot of 237 exemplars of the Challenger main battle tank, which was basically a Shir 2 modified to operate in the European theater rather than in the Middle East. The first Challenger were delivered to the British Army in March 1983, entering service with the British Army in the United Kingdom and in Germany, along with the Chieftain, and at the end of the decade there were about 450 exemplars in service.



Characteristics of the Challenger 1

At first sight, the configuration of the Challenger 1 strongly resembled that of the Chieftain. The most visible difference was the much more angular shape of the new tank. There were many indications about the Challenger being built in base of flat armor plates made of Chobham (a composite material including different types of metal, ceramics and other materials) applied to a frame, as in the Leopard 2. It was not as noticeable the replacement of the Hortsmann suspension system by a hydropneumatic one, which granted much better cross-country prestations to the new tank. The wheel arrangement was similar to that of the Chieftain, with six road wheels, a rear drive sprocket and three return rollers on each side, with the entire ensemble being protected by armored skirts. The engine was the same Perkins/Rolls-Royce Condor used in the Chieftain "Khalid", which granted to the Challenger a top speed of 57 kilometers/hour in road, even with a weight of 62 tonnes. With 1200 horsepower, this engine was much more powerful than that installed in the standard Chieftain, but still not as powerful as those installed in the Leopard 2 or the M1 Abrams. Thus, the agility of the Challenger was not exceptional, being more on par with that of Soviet tanks. Still, the propulsion plant was a well devised component. The engine and the transmission were mounted in a module which could be replaced in field conditions within 45 minutes, and it was included an auxiliary power unit which could power the diverse systems when the engine was turned off. Additional fuel tanks could be mounted at the rear of the hull for extended operational range.

The Challenger was armed with the standard L11A5 120-millimeter rifled cannon manufactured by the Royal Ordnance Factory of Nottingham which was installed in the Chieftain. As in the preceding tank, the cannon had an elevation angle ranging from +20 to -10 degrees. It was fully stabilized and assisted by an integrated fire control system fitted with stabilized night vision sights and Nd:YAG laser rangefinder. A visible novelty was the muzzle reference system - whose reflector raises over the muzzle - which allowed to measure the current value of the barrel bend in order to send this data to the ballistic computer to improve the accuracy of firing. The cannon was protected against bending by thermal sleeves. The largest part of projectiles carried should be of the armor piercing subcaliber type, including those with a core of depleted uranium. The L11A5 could fire six types of projectiles, being one of these the HESH (High Explosive Squash Head), profusely used by British forces during the First Gulf War. This special ammunition uses a ductile plastic explosive capable of creating a strong shockwave when impacting on an homogeneus (not laminated) steel armor, causing the projection of lethal shrapnel detached from the internal face. It seems that the attachment of the British Army to this particular type of ammunition has determined the continued adoption of rifled cannons in British tanks. This choice slightly reduces the muzzle velocity of projectiles but may greatly increase their accuracy.



The propellant charge of the ammunition that the L11A5 fires is stored in fully combustible separate sachets, unlike the German 120-millimeter smoothbore cannon, which uses semicombustible non-separate cases, or the Soviet 125-millimeter smoothbore cannon, which uses non-combustible or semicombustible separate cases. The separation of the propellant charge eases the manipulation of the ammunition in the forcibly restricted space inside the turret. The problem of identifying the different charges was solved in the Challenger by means of grooves which are applied to the base of the projectiles to prevent mistakes. The L11A5 was to be replaced by a high technology cannon which was back then in process of investigation in the Royal Armament Research and Development Establishment (RARDE) of Fort Halstead. This weapon was to be manufactured with steel refined on the vacuum with conductive slag, on a process called Electro-Slag Refined (ESR), and to have a new two-piece breechblock; the purpose was to have a cannon able to fire projectiles at a very superior muzzle velocity, to achieve an increased piercing power in respect of the current ammunition. It should be able to fire as well the new APFSDS projectile, which was able to pierce through any armor known back then. This new cannon would be eventually installed in the upgraded version Challenger 2.

The driver sat in a semi-reclined position, which allowed to reduce the height of the hull, and looked through a simple episcope which could be upgraded for night vision. The commander and the gunner were placed one behind the other in the right part of the turret, while the loader occupied the left part. The cannon was accompanied by a co-axial 7.62-millimeter machine gun and a similar weapon was mounted in the commander's cupola, being possible to aim and fire it from the interior. Also the cupola was similar to that of the Chieftain, having nine large vision blocks and being a rotating element to which the commander's periscope and machine gun were fixedly attached. A system of NBC (Nuclear-Bacteriological-Chemical) protection was installed in the rear part of the turret, where it filtered the contaminated air, sending clean air to the interior. There was also an automatic fire suppression system for the engine and crew compartments. The active protection system included ten smoke launchers to conceal the tank from both normal and infrared observation. Later exemplars of the Challenger were upgraded with the addition of a system developed by Barr & Stroud, known as the Thermal Imaging Surveillance and Gun Sighting Sight (or alternatively, Thermal Observation and Gunnery Sight), placed inside an armored box on the right side of the turret; this system can separately serve the commander and the gunner.


The Challenger of the 4th and 7th Armored Divisions of the British Army (with 43 and 114 tanks respectively) entered action in occasion of Operation Grandby, the British contribution to the war for the liberation of Kuwait in 1991, during which these tanks showed good performance.

In the late 1980s it was clear that the time to replace the Chieftain had arrived. And even if the Challenger was in general a suitable replacement regarding firepower and protection, its fire control system began to receive critics, being its characteristics undoubtedly insufficient. The British Army wanted a lighter - but not less protected, thanks to the advances in the technology of armor - tank fitted with more sophisticated equipment and a more powerful engine. Thus it was started what seemed a serious evaluation between the M1A1 Abrams, the Leopard 2, the AMX-56 Leclerc and a Challenger updated by Vickers, which however kept the same engine. But from the beginning the British Army saw little chance to get what it wanted and a decision was soon taken. In the mid 1991 it was announced that the Army would adopt the Challenger 2, a tank which, except for the main armament and the new fire control system, would appear as a rather shallow modification of the original. The new cannon, originally denominated XL30 and later L30A1, had been initially developed for the cancelled MBT-80. It was expected to offer a longer life expectancy and superior ballistic prestations with the same ammunition. It was announced as well that the Challenger 1 would be submitted to an upgrade program to approximate its prestations to those of the Challenger 2.

Categories: Tanks - Cold War - 20th Century - [General] - [General]

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Website: Military History

Article submitted: 2018-03-07

Article updated: 2018-12-29