Chieftain (tank)

Chieftain (FV4201)
British Chieftain battle tanks on the last Allied parade in Berlin's Tiergarten on June 18, 1989
General properties
crew	4 (commander, driver, gunner, loader)
length	10.795 m
width	3.5 m
height	2,895 m
Dimensions	55.0 t
Armor and armament
Armor	Armor steel
Main armament	120 mm (L11A5)
Secondary armament	2 x 7.62mm L7 MG
agility
drive	Diesel engine Leyland L60 760 PS (559 kW)
suspension	Horizontal coil spring suspension (HVSS) from Horstmann
Top speed	48 km / h
Power / weight	10.2 kW / t (13.8 PS / t)
Range	500 km (road)

The Chieftain was a British main battle tank developed in the 1950s and first presented to the public in 1961. At the time of its inception, the Chieftain was one of the best-armed and best-armored tanks in the world. The heavy armor, however, resulted in limited mobility. A total of around 1,800 copies were produced. The tank was used in various armed conflicts, including the First and Second Gulf Wars .

Development history

Work on a successor to the Centurion began in 1951 under the development name Medium Gun Tank No. 2 . After the turbulent developments of World War II, developers were given a free hand to research and test new technologies. Above all, the British Rhine Army in northern Germany was immediately confronted with numerous medium battle tanks of the Soviet Army : the T-34 and T-54 , which were supported by heavy tanks such as the IS-3 . That is why NATO pursued a “quality over quantity” strategy. The tank should have superior armament and strong armor; the mobility should at least correspond to that of the Centurion, with the emphasis on good mobility in the battlefield and not on a high maximum speed. The British General Staff also demanded a maximum weight of 45 tons. All these requirements could not be implemented with the available technology at this point in time, so that the so-called Concept Study Program was initiated, which was to develop the necessary techniques in a broad research process. The United States and Britain worked closely together on the development of the new tank, as at that time they were the only NATO members to develop new tanks and manufacture them in significant numbers.

As armament, the US 105-mm cannon T-104 was first considered, which was to be installed in a tower with a diameter of 2.54 m. However, since the space for this cannon was insufficient because of its size and the use of conventional cartridge ammunition and the turret could not be enlarged further because of the weight restriction, serious problems arose when handling the ammunition. An automatic loading machine was proposed as a solution to the complicated handling of the cartridges, but this was rejected because of its high complexity. In addition, only 40 cartridges could have been carried in the loading machine, which was not considered sufficient. In 1953, at a conference between weapons engineers and tank engineers, the possibility of installing a cannon with a liquid propellant charge was even considered. The liquid propellant charge would have offered some advantages, since the loader only had to load the projectile, not the propellant charge; a significant increase in muzzle velocity would also have been possible. However, due to insufficient financial resources and the fact that the depot for the liquid propellant charge would have taken up too much space, this idea was dropped. Instead, the developers considered combustible bag propellants, which have long been used on ships but never in a main battle tank. The bag propellants also offered some advantages over conventional ammunition: the weight of the metal cases was saved, the development of smoke from empty cases was prevented, and due to their small size, it was easier to accommodate them in the fighting compartment. The T-104 was ultimately not installed in the vehicle, but the concept of split ammunition was retained. The requirement of the military for a penetration capacity of 120 mm armor steel with 60 ° inclination at a distance of about 1800 m required the development of a new 120 mm cannon.

After Leyland Motors had been selected as the contract partner to manufacture the vehicles, the name was changed to FV4201. In order to stay within the weight limits and at the same time ensure sufficient ground clearance, the tub of the vehicle had to be designed very flat so that the driver had to sit in a lying position. The suspension also had to be adjusted as a conventional suspension with torsion bars could not be built into the shallow tub. The first three prototypes were produced in 1956 to test the feasibility of the driver's lying position. These first prototypes were essentially based on components from the Centurion. After the successful completion of these tests, development stalled for a short time as Great Britain and the USA tried to standardize as many parts of their respective tanks as possible and thus make them interchangeable. Both parties could not agree on a common concept for the weapon system. The British insisted on a 120mm drawbar cannon, while the Americans insisted on a 90mm or 105mm smoothbore cannon. Ultimately, no agreement was reached, so that both countries continued to pursue their own concepts.

In November 1957 there was a further delay in the project when the elevation range of the primary weapon was to be increased from previously −7.5 ° to + 15 ° to −10 ° to + 20 °. This required an increase in the size of the tower, which resulted in an increase in weight. At the same time, the army demanded that the armor protection on the turret and hull front should be improved, as experience from the Korean War had shown that splinters from artillery shells could not penetrate the armor, but partially tear open the welds.

At the end of 1957, the NATO standardization committee decided that all combat vehicles should be equipped with multi-fuel engines. This set the project back again as a new engine had to be found that could run on different fuels. The choice fell on an opposed piston engine from Junkers Jumo , which had been used in aircraft during World War II. In order to be able to use the engine designated as L60, however, the engine room had to be enlarged. At the same time, the total weight of the vehicle increased by a further ton and approached the 50-ton mark.

In August 1958, the first production orders were placed with various companies to produce the first complete prototypes. Leyland Motors made the hulls and drives, Vickers- Armstrong was responsible for making the turrets and installing the weapons systems, and Self-Changing Gears Limited made the semi-automatic gearbox and gear block. A total of 14 prototypes with the designations P1 to P6 and W1 to W6 were produced. Two nameless specimens were given to the newly founded Bundeswehr for test purposes, and the British Army received two prototypes of the Leopard 1 at the same time .

The first driving tests of the prototypes P1 and P2 began in the first quarter of 1960. This revealed serious problems with the engine and transmission. Converting the engine to a different type of fuel took too long, the crankshafts wore out too quickly, and the gearbox tended to overheat. Some of these problems could be resolved by throttling the engine and other measures, but the total weight increased to 50 tons. The suspension, which was designed for only 45 tons, then also had to be overhauled. Overall, the tests were very slow because of these problems.

The tests with the weapon system, which was designated as L11, began with the prototype W3 in April 1961. Despite some defects in the weapon system, the tests were very successful. After the night vision equipment had also been successfully tested on the prototypes P3 and P4, two vehicles were sent to Germany for troop trials. These showed some weaknesses of the tank - the off-road mobility was only very unsatisfactory because of the low ground clearance. Therefore, the rollers were replaced and changes were made to the suspension so that the ground clearance could be increased by 12.7 cm. In addition, the engine and transmission have been further revised to improve mobility and reliability. The Chieftain was accepted for series production on May 1, 1963, which began shortly thereafter.

After the introduction of the Chieftain Mark 5, older models were brought up to the technical standard of the Mark 5 using the so-called Totem Pole Conversion Program . The program was divided into three areas: Area X mainly concerned the fire control system, while Areas Y and Z concerned mobility aspects.

general description

Chieftain Mk.X

The Chieftain is a post-war second generation tank. It was designed for fighting enemy battle tanks. Until it was replaced by the Challenger 1 , it was the main weapon system of the British Army . The tank has a 120 mm drawbar cannon as main armament and three machine guns of different types as secondary armament. The first models only had a very simple fire control system, which was later replaced by a more modern model. Like most tanks from the Cold War, the Chieftain has NBC ventilation to ensure use in contaminated areas. The tank is able to wade through waters up to 1 m deep ; With the help of a built-on deep-water tower, deeper waters can also be crossed, but the deep-water equipment is not part of the standard equipment of the tank.

crew

The crew of the Chieftain consists of four soldiers: the driver, the gunner, the loader / radio operator and the commander. The driver sits in the center of the front of the tank. When the driver's hatch is open, he sits upright in the tub; when the hatch is closed, he is in a semi-recumbent position due to the low height of the tub. In an emergency, the driver can get back into the fighting area via his seat.

The commander sits in the right part of the tower next to the weapon system. He controls the tank and observes the battlefield through his optics in order to be able to assign targets to the gunner. The gunner sits in front of the commander and also watches the battlefield through his optics. In combat, he is responsible for aiming and firing the main 120mm weapon. The loader or radio operator sits on the left side of the tower. He loads the main weapon and fires the sighting machine gun and the axially parallel machine gun. At the same time, he conducts radio communications at the command of the commander.

Four Sterling submachine guns , a signal pistol and various hand grenades are available to the crew for self-defense .

technology

Armament and ammunition

The armament of the Chieftain consists of a 120 mm drawbar cannon with the designation L11, a parallel axis machine gun in caliber 7.62 mm with the designation L8A1, another machine gun in caliber 7.62 mm with the designation L37A1 on the commander's hatch and a heavy one Shot-in MG-L21A1 in .50 caliber , which is also mounted axially parallel to the main weapon.

The main weapon is equipped with a smoke extractor , which is supposed to prevent the penetration of powder fumes into the fighting area, and a heat protection sleeve, which is supposed to prevent uneven cooling caused by wind or rain when the pipe is hot. The weapon system is stabilized both horizontally and vertically. The aiming range of the main weapon is 360 ° in the horizontal and −10 ° to + 20 ° in the vertical. Pivoting the tower 360 ° takes about 13 seconds. The alignment of the weapon system and the pivoting of the turret are carried out by an electric drive, but also manually in an emergency. Newer versions of the weapon have a collimator mirror on the muzzle with which the gunner can adjust his target optics.

The weapon fires divided ammunition, i.e. the projectile and propellant charge are loaded one after the other. Tests during the development phase had shown that the rate of fire was not significantly affected by this concept. The disadvantage, however, was the risk of the propellant charges igniting if hit. To reduce this risk, the propellant charges and all projectiles containing explosives were stored in the tub below the tower, where they were less exposed to the risk of hits. The propellant charges are ignited by an ignition charge in the bottom of the propellant charge, which in turn is ignited by cartridge-shaped igniters in the breech block. The main weapon can fire various types of ammunition: APDS projectiles, squeeze-head projectiles, smoke projectiles, flares and anti-infantry ammunition, which consists of many small metal balls and is similar to the principle of a shotgun.

A .50 caliber gun was used to determine the distance to the target. It was a modified version of the Browning M2 . On the front of the tower, to the left and right of the main weapon, there is a smoke-throwing system with six tubes to create a smoke screen for camouflage.

Armor

Since the Chieftain would in all likelihood have fought in defense against a majority of enemy battle tanks in the event of an armed conflict in Central Europe , great importance was attached to strong armor and thus high survivability during development. The hull of the armor is made of rolled armored steel elements that were subsequently welded together. The tower is made of cast steel.

The armor has the following strengths:

Component	Tower front	Tub front above	Tub front below
against KE bullets	360 mm	350 mm	320 mm
against HEAT bullets	400 mm	360 mm	330 mm

Drive and drive

Leyland L60 6 cylinder engine

The Chieftain is powered by a two-stroke opposed piston diesel engine with six cylinders. The output was 585 hp in the first models and was later increased to 750 hp. In principle, the engine is suitable for several fuels, but was operated exclusively with diesel. The engine is located together with the transmission block and the radiator in the rear of the tub. The planetary gear has six forward and two reverse gears.

A Horstmann drive was chosen as the drive because it takes up little space and could be built into the shallow tub. The drive consists of three bogies on each side of the tub, each with two castors attached. Hydraulic shock absorbers are also attached to the first roller on each side. The chain consists of 96 chain links in which replaceable rubber chain pads are attached.

In order to ensure the power supply of the electrical systems even when the engine is switched off, a three-cylinder auxiliary power unit was installed in the machine room. This is also a two-stroke opposed piston engine with an output of 23 hp.

Optics and sensors

The commander has a total of nine corner mirrors at his disposal, which are housed in his dome which can be rotated through 360 °. He can also access the gunner's main telescopic sight via an optical link. This gives him all the options of the fire control system for on-board cannons and turret machine guns. At night, a night vision attachment can be attached to the optics. The commander can override the gunner in both axes.

The gunner has the primary optics with a day vision channel with single and eight times magnification. At night he can also use an infrared night vision attachment. In addition, it has emergency optics that are mounted in a small opening on the tower front. The driver has a single wide-angle lens that can be swapped for an IR viewing device at night.

There is an IR detector on the tower roof that covers 360 ° and indicates to the commander as soon as the tank is detected by an IR light source. On the left side of the tower there is a spotlight with a power of 2 kW, which is used for target lighting. The headlight has a switchable IR filter.

324 Chieftains of later production lots were retrofitted with a thermal display device.

Fire control system

The first models of the Chieftain used a range-finding machine gun. This fired three-shot bursts of fire, with which the necessary tube elevation was determined to hit a target with the main weapon. However, since the range of the machine gun was limited to about 1400 m, targets outside this range could only be fought with little success, although the effective range of the main weapon was above this distance. A laser rangefinder was retrofitted later, which could be used for distances of 500 to 10,000 m with an accuracy of ± 10 m. Together with the laser, the so-called Improved Fire Control System (IFCS) was installed, which included various sensors and a fire control computer. The sensors measured values ​​relevant for the fire control, such as temperature, air pressure, temperature of the pipe and the like, and sent these values ​​to the computer. With the help of this system, targets could be fought at greater distances and with greater accuracy.

Technical specifications

designation	Chieftain Main Battle Tank Mk. 5
Type:	Main battle tank
Crew:	4th
Engine:	Leyland L60, 6-cylinder 2-stroke opposed piston engine
Power:	750 hp at 2,100 rpm
Transmission:	David Brown Engineering TN-12
Landing gear:	Support roller drive with Horstmann suspension
Length over all:	10,795 mm
Width over everything:	3,657 mm
Height above everything:	2,895 mm
Ground clearance:	508 mm
Wading ability :	1066 mm
Trench crossing ability:	3,149 mm
Climbing ability:	914 mm
Gradeability :	60%
Bank slope:	40%
Combat weight:	55,000 kg
Maximum speed road:	48 km / h
Top speed terrain:	32 km / h
Fuel quantity:	950 liters
Driving range:	500 km (road), 300 km (terrain)
Armament:	120 mm L11 cannon, 2 × 7.62 mm machine guns, 1 × 12.7 mm sighting machine
Ammunition:	64 rounds for the main weapon, 6,000 rounds for the 7.62 mm machine guns, 300 rounds for the 12.7 mm machine gun

See also

• List of tank models after 1945

Individual evidence

1. ↑ Simon Dunstan: Chieftain Main Battle Tank 1965-2003. Pp. 4-15.
2. ↑ Simon Dunstan: Chieftain Main Battle Tank 1965-2003. P. 36.
3. ^ George Forty: Modern Combat Vehicles: 1 - Chieftain. P. 37 ff.
4. ↑ Christopher Foss: Jane's Armor & Artillery 2009-2010. P. 157.
5. ↑ Tank Protection Levels (accessed on May 31, 2010) ( Memento from December 2, 2001 in the Internet Archive )
6. ^ George Forty: Modern Combat Vehicles: 1 - Chieftain. P. 43 f.
7. ↑ Christopher F. Foss : Jane's Armor & Artillery 2009-2010. P. 156.
8. ↑ Christopher Foss: Jane's Armor & Artillery 2009-2010. P. 156.
9. ^ George Forty: Modern Combat Vehicles: 1 - Chieftain. P. 40.
10. ↑ www.FAS.org

Web links

Commons : Chieftain  - collection of images, videos and audio files

• Fire control system of the Chieftain