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Australian Centurions in Vietnam - additional information

Some of you may be aware that I wrote a book on Australian Centurions in South Vietnam some time ago. As part of this project I collected a huge amount of information. Editorial restrictions resulted in slabs of text being removed. I have included some of this below. It should be noted that most Australian modifications fitted in the 1950/60s were exactly as specified for British service. This means some can also be seen on Canadian and other country vehicles that were linked into the UK.

"By the deployment to South Vietnam over 60 internal and external modifications had been accepted for installation on Australian Centurions. It should be noted that tanks fitted with many of the more complex modifications purchased in the 1960s were not issued to 1st Armoured Regiment until just prior to the South Vietnam deployment.

The vast majority of modifications accepted for Australian Centurions originated at the UK Fighting Vehicle Research and Development Establishment (FVRDE), Chobham. Information on equipment development regularly flowed to Australia due to the intimate relationship that existed between the RAC and RAAC. This extended to bilateral consultation on tank policy and the attendance of RAAC members on UK technical courses and representatives were frequently invited to view trials and demonstrations.

Since most of the modifications discussed in this section originated from the UK they are equally applicable to UK, Canadian and other Centurion users that sourced modifications from the UK.

Mk 5 Standardisation

Equipped with both Centurion Mk 3 and Mk 5 the Australian Army followed UK practice and standardised its fleet on the Mk 5 in 1956. As already noted, this required the substitution of the Besa 7.92 mm coaxial machine gun with the US manufactured M1919 .30 inch machine gun. In UK and Commonwealth service the M1919 .30 inch received the designation L3.

A trial mounting, developed by FVRDE, was accepted into UK service on 14 December 1954 and to distinguish between vehicles mounting the different weapons those fitted with the .30 cal were designated Mk 5. British authorities quickly realised that the provision of two types of machine gun ammunition to Centurion equipped units was a logistical nightmare and authorised the upgrading of all Mk 3 to Mk 5 standard in 1956.

Australia, faced with a similar logistic problem decided to follow the UK policy and standardise its fleet on the Centurion Mk 5 and 60 conversion kits were purchased from the UK. Conversion of the first tanks commenced in May 1957 and occurred over a number of years, records indicating that many vehicles were not upgraded until 1959/60.

Removal of the two inch bomb thrower

Early and mid production Centurion turrets embodied a 2 inch bomb thrower mounted in the turret top plate forward of the loaders hatch. Unpopular as it impeded the loaders movements when facing forwards the bomb thrower was removed and the remaining mounting hole covered by a blanking plate.

Acceptance of this modification into Australian service was promulgated in Australian Army Orders dated 30 April 1957 as EMEI 357 – 21. It effected the initial 1949 purchase of 60 vehicles (ARN 169000-059) and some of the 1955 purchase (ARN 169115-120).
All vehicles dispatched to South Vietnam appear to have undergone the modification.

Crew Commanders Machine Gun and Stowage Brackets

In early 1957 a crew commanders machine gun capable of engaging both ground and air targets was accepted into Australian service for fitting to Centurion Mk 3/5. Adoption into Australian service was promulgated in Australian Army Orders of 31 March 1957, the fitting to be undertaken according to EMEI M357- 44.

Developed by FVRDE during 1956, the mounting had its origin in a tri-partite agreement on tank design characteristics and requirements, agreed between the UK, Canada and the United States. Using the L3A4 Browning .30 cal (A4 signifying the fitting of a pistol grip) a mounting was accepted into UK service in December 1956, with production commencing in 1957.

The crew commanders machine gun comprised three components:
• two mounting lugs welded to the crew commanders periscope guard above the Reflector Cum Periscope (RCP) sight;
• a base plate that bolted to the mounting lugs; and
• the machine gun cradle.

Initially, the cradle fitted was the Mount No 7 Mk 1, however the mounting No 5 Mk 2 was later authorised as an alternative fitting.

Photographic evidence indicates that the crew commanders machine gun was rarely fitted during tactical exercises in Australia. Most likely it was only fitted during range practices to prevent wear and tear on the weapons.
The crew commanders machine gun and mounting was a standard fitting throughout the deployment to South Vietnam. Photographic evidence indicates that while initially consisting of the No 5 Mk 2 Mounting, this was increasingly replaced by the No 7 Mk 1.

To secure the machine gun when not mounted two brackets were bolted on the rear of the turret top plate. Each bracket comprised a webbing strap and buckle into which the machine gun could be secured. Securing the machine gun in this position proved unpopular due to the additional cleaning necessary because of dust created by the movement of the tank.

The brackets were standard fittings on Centurions deployed in South Vietnam though no evidence exists to support their use to secure the machine gun as they were always mounted on the weapon station.

Gunners Sight Hood Wiper and Brush Guard

To improve the gunners visibility in wet weather an improved gunners sight hood incorporating a windscreen wiper entered Australian service in mid 1958. The Demister No 1 Mk 2, developed in the UK, was promulgated in Australian Army Orders of 31 August 1958, the fitting to be undertaken according to EMEI P517-1/1.

The Demister No 1 Mk 2 consisted of a new gunners sight hood incorporating a motorised wiper unit and arm. The motor for the wiper unit was enclosed in a rectangular case mounted above the gunners sight and linked to the vehicle main electrical system by a power cable at the rear of the wiper motor. Attached to the front of the unit was the wiper arm.

To protect the wiper unit from damage caused when negotiating thick vegetation a U shaped metal strip brush guard was welded in front of the periscope. This modification is unique to Australian Centurions and adoption into service was promulgated in Australian Army Orders of 31 December 1959, the fitting to be undertaken according to EMEI M357- 74.

Both the demister unit and brush guard were standard fittings on Centurions deployed to South Vietnam

Fitting of B47 and C42 Radios

In 1958 the Australian Army commenced Project L196, the replacement of all vehicle mounted radio installations using Second World War vintage No 19 set radios with modern Very High Frequency (VHF) equipment. Centurions were, at this time fitted with No 19 Mk 3 and No 88 AFV sets.

The chosen replacements were the C42 and B47, manufactured by the UK company Plessey and already adopted for the British Army Centurion fleet in the mid-1950s. Choosing the C42 and B47 provided the advantages of continued standardisation with British vehicles and a number of already proven installations that could be accepted into Australian service with a minimum of modification.

An additional requirement of the Australian Army was the inclusion of a rebroadcast facility for all Centurion radio installations. This required the fitting of an additional control box in the turret.

Trial installations for both gun and control tanks designed by the Army Design Establishment (ADE) were not accepted into service until 8 December 1960. This resulted from delays in obtaining installation kits from the UK. Of the 117 medium tanks, 92 were configured as gun tanks with a single C42 and B47 radio. 25 tanks were configured as control tanks with two C42 and one B 47 radio.

The first Centurions of 1st Armoured Regiment commenced conversion at the Puckapunyal Area Workshop in mid 1961. The B47 and C42 radios equipped all medium tanks deployed to South Vietnam.

Glacis Plate Uparmouring

In mid 1961 the Australian Army commenced upgrading 96 Centurion medium tanks to Mk 5/1 standard through the addition of an applique plate to uparmour the glacis plate. The original offer to purchase the uparmouring kit occurred in January 1958 the War Office approached the Australian Army with the offer to purchase. The uparmouring kit had been developed, along with the L7 105mm tank gun, as part of a War Office policy, ‘to up-armour and up-gun Centurion so that it will as nearly as economically possible match the Russian T54 in its gun/armour configuration.’ The upamouring kit consisted of an applique plate of 44mm thickness that was welded to the glacis plate. This increased the total thickness of the glacis armour to 120mm at 57o. Up armoured Centurion medium tanks received the nomenclature Mk 5/1.

Purchase of the up armouring option was initially rejected by AHQ, in spite of support from the RAAC, being caught up in wider debate within AHQ on Australian tank policy. A vocal lobby within AHQ argued that the weight of Centurion excluded its effective use in South East Asia and the additional weight through up armouring merely added to the problem.

Approval to purchase 96 uparmouring kits was granted by the Chief of the General Staff on 23 Feb 1961 after a reassessment of the weight issue revealed many of the previous concerns to be spurious. The decision to procure 96 kits was made on the basis of, “AMF contact estimate is 9 months ‘contact’ and 3 months ‘quiet’ [over a twelve month period]. War Office wastage rates are 14% for contact 1.5% for quiet, per month… This gives a requirement of 108 tanks for a regiment for a year…Taking wet season into account this would be reduced to 96 tanks.” The remaining 21 Mk 5s were identified for training use only and were not to be issued to 1st Armoured Regiment or leave Australia .

Fitting of the applique plate was undertaken by RAEME staff during vehicle overhauls. Photographic evidence suggests that uparmoured tanks had the drivers wet weather march hood stowage bin relocated from the glacis plate to the hull roof, to the left of the drivers hatch.

All Centurion medium tanks deployed to South Vietnam including tank dozers were Mk 5/1s. Where necessary this was undertaken by 4 Base Workshop prior to dispatch.

Infra Red Driving and Gunnery Sights

After several trials in the early 1960s the RAAC received approval to purchase and fit an infra red installation for Centurion medium tanks. Adoption of the installation culminated a long RAAC interest in US and UK infra-red developments and was prompted by the development installation for UK Centurions. Developed to counter the introduction of new Soviet tanks with an infra-red capability, the installation utilised optical equipment developed by the Dutch company Phillips UFSA, of Eindhoven and an electrical system developed by FVRDE.

The optical equipment comprised infra red sights for the driver, gunner and crew commander. An active system in which a beam of infra red light is projected and then viewed, the drivers light source was two lights fitted with infra red lenses attached to the glacis plate. The gunners and crew commanders light source was a 1000 watt white light searchlight with a clip on infra-red lens. When not in use the searchlight was stowed in an external stowage basket attached to the turret rear containing two compartments, one for the searchlight and a second for general stowage.

The electrical installation kit provided power to the optical sights and searchlight, as well as to the revised driving lights positioned on the glacis plate. Two versions of the electrical installation kit were developed by FVRDE, one for the Centurion Mk 3/5 family and a second for the Centurion Mk 7 family. The hybrid optical and electrical system was accepted into UK service after trials in February and March 1960.

Trialed for Australian service under Project L 275 within the AHQ Equipment Development List two sets of infra red equipment were purchased. A successful trial between 12 March and 25 May 1962 at the Armoured Centre, Puckapunyal, involving Centurions 169046 and 169073 resulted in the decision to purchase one squadrons worth plus spares. Demands for 26 optical sets were placed with Phillips USFA at a cost of £A126,500.00 and 29 installation kits with the War Office costing £A38,000.00.

Meanwhile further trials were conducted, including user trials and the writing of EMEIs detailing the infra red installation. By 8 November 1966, Colonel Miles, DRAC recommended, “…considering fitment trials completed satisfactorily, installation should commence immediately and take precedence of the refurbishment programme for Staghounds” .

4th Base Workshop commenced the fitting of a near infra-red system to 26 Centurion medium tanks in late 1966. The first modified Centurion was 169006, completed in early 1967.

Ranging Machine Gun

A Centurion based ranging machine gun to increase 20 pdr first round hit probability utilising a .50 calibre machine gun main armament was developed by FVRDE in the late 1950s. Mounted in the mantlet and aligned to the main armament it replaced the three round range estimation technique then in use. Fed with tracer ammunition and configured to fire three round bursts, the ranging machine gun allowed the gunner to observe the fall of shot on a target and make final sighting adjustments prior to firing a main armament round. Successfully trialed in September 1959 the installation was adopted for UK service.

The installation consisted of a .50 cal ranging machine gun, its mounting and ammunition stowage. Fitting required the replacement of the .30 cal coaxial machine gun mounting with a .50cal mounting. The .30 cal coaxial machine gun mounting was subsequently moved to the right and a new aperture for the barrel drilled in the mantlet.

The additional weight of the .50 calibre mounting and weapon necessitated a counterweight be placed in the barrel. On B Type barrels, three strip metal counter weights were welded longitudinally on top of the fume extractor and are sometimes mistakenly referred to as iron sights. On A Type barrels the counterweight was placed at the barrel muzzle.

Ranging machine guns were ordered for Australian Centurions in 1963. Procurement demand C840109 placed with the War Office ordered:

Stowage Qty 88
(26 previously purchased)
RMG Installation Qty 117

Long Range Fuel Tank

Development of a long range fuel tank in the early 1960s addressed one of the few weaknesses of the Centurion design, its limited range. Fitted with two internal tanks, one of 50 and another of 70 gallons, Centurions range was restricted to approximately 40 miles on roads and less moving cross country.
The long range fuel tank held 100 gallons. It was constructed of armoured plate and was bolted to metal spacers welded to the upper rear hull.
Pre existing fittings such as the tank–infantry telephone, tow rope bracket and guides were removed and relocated on the fuel tank. The tank–infantry telephone was relocated on the left side of the tank in a horizontal position. The tow rope bracket and guides were relocated on the rear of the tank, in the same positions they had been previously.

Vehicles fitted with the long range fuel tank also required replacement tow ropes. This occurred to accommodate the additional length that the fuel tank added to the hull.

Introduction of the armoured fuel tank culminated A number of s olutions evolved in the UK, from the carriage of spare 44-gallon drums on the rear of the hull to the development and production of a wheeled fuel mono-trailer attached to the rear of the tank. These were, however, for a variety of reasons all were singularly unsuccessful.

The long range fuel tank was also fitted to Australian ARVs and bridgelayers. It was a standard fitting for vehicles deployed to South Vietnam."

Shane Lovell
Canberra, Australia

Centurion turret development

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