Tonight in our Cold War tank series by Ed Francis the Vickers Medium Cruiser Tank Mk. 1
The Vickers medium Cruiser Tank Mk.1 is an enigmatic vehicle often shrouded in myth or erroneously rehashed on various forums. Although based on the FV300 platform it was an entirely separate project from the FV300 in as much as it was a private contract by Vickers to capitalise on the knowledge gained in the FV301 development and was aimed at an unrecorded but French speaking nation.
Overall the machine had some passing semblance to the FV301, it has a well sloped glacis and the steep lower plate angled well back. The driver had three periscopes and a large hatch that lifted up and to the right to him for access. To his rear, a separate aperture was made via the transverse bulkhead to allow the driver access to the fighting compartment. The driver’s controls consisted of accelerator, brake and clutch pedals with the gear stick located centrally between his knees. Steering levers could be found on either side as well as a parking brake to his right hand side.
The hull itself has vertical sides running the length of the vehicle with the rear of the hull roof raised over the engine with smaller sloping plates. Access to the engine was gained via four louvered access hatches over the back hinged on the lower rear end and the turret would need to be facing perpendicular to the access ports to gain access to the engine. The transmission and gearboxes has a single large access port that incorporated air exit louvres as well as a smaller inset right inspection hatch for oil changes. For engine changes, the whole plate and four hatches could be lifted and the entire engine or transmission removed in one piece, as was also planned for the FV300.
The engine for the Medium Cruiser Mk. 1 (sometimes written as ‘Medium Cruiser 77mm’ - ‘MC77’) consisted of a Rolls Royce Meteorite Mk. II P.I engine delivering 530 bhp at 2,800 rpm via a plate type clutch to a David Brown V52 gearbox providing five speeds forwards and one in reverse. The V52 was chosen over the experimental TN10 being tested on the FV300 for reasons of state secrecy as the new TN10 was planned to go into FV4201 also under development. The engine was air cooled with two engine driven fans located in the engine bulkhead between the gearbox and engine. This system drew the air in through the front louvres, over the engine manifolds, past the oil coolers, and though two Morris radiators, before being expelled over the gearbox and brakes via the rear louvres. Two filtered oil bath cleaners were provided for the engine air intakes (that being the air passing over a sump pool which would pick up and retain any dirt or pollutants in the air). Exhaust was carried out and ejected from the sides above the rear track guard and had a similar protective shroud and silencer as fitted to Centurion with fishtail outlets facing horizontally. If the engine, transmission, and cooling apparatus required removing as one piece, then the entire rear plate was also hinged at the base and the separating bulkhead lifted out allowing the whole powerpack to be slid back on built in rollers.
Two fuel tanks were found on the MC77, one located either side of the upper engine and access to each was gained via covers found on the sloping upper sides of the engine covers. The oil tank was also located on the right hand side along with a small auxiliary engine.
The V52 gearbox mounted to the rear was driven from the engine clutch by a short coupling shaft and mounted on the powerpack subframe. To the left and right were drum type steering brakes with the track brakes mounted on the hull sides and were of the Girling internal expanding type. Track tensioning could be achieved by adjusting the front idler which was mounted on a bracket pivoted under the idler axis with the idler locked by a screw system similar to that found on Centurion.
The suspension running the length of the vehicle side consisted of five points on each side mounting a 28 inch (711 mm) diameter pair of rubber rimmed road wheels (although at least one drawing shows all steel varieties fitted). Suspension was by means of independent torsion bars mounted across the inner face of the hull floor with a secondary torsion bar on wheels one, two, and five which was brought into action by a cams on the axle arm. The result increasing in the spring rate absorbed by the shocks on the more heavily laden wheels, although Newton Bennet shock absorbers were also fitted to the first and last stations. It should be noted that this system differs somewhat from that proposed for FV300. The FV300 by this point was in two main version a front and back engined variety with work on FV402 and 304 having taken priority over the FV301. Originally, the Alecto style wheels had been planned for FV300 (as was fitted to A.46) however that project had moved over to the CT26 carrier project. A new set of wheels, which would later go onto FV400, and eventually on the FV432 were designed for the FV300’s although the shock absorbers were on the second and final stations instead.
The turret for the MC77 was quite different from that of the FV301 proposal. Gone was the sweeping and curved shapes found on A.46 which was known as ‘M131’ and ‘M132’ in Vickers’ records. In place was a more convention and cheaply made design with a large piece of cast plate welded to a five-piece back and sides. The whole turret sat on a caged ball race over a 64-inch (1625.6 mm) diameter turret ring. The front of the turret has a small incline facing rearwards and the turret top sloped up to the cupola and down towards the large rear bustle. The gunner, located conventionally to the right of the gun had a periscope, and three were provided for the commander located behind and above him. To the left of the breach was the loader who was provided with a single periscope but did have his own access hatch. The commander’s cupola offered 360 degree vision, but unlike the FV300 did not have the Reflector-cum-Periscope (RCP) which was also still under development.
The main weapon was the high pressure 77mm gun developed for FV301 although it did not have the experimental automatic reload developed by Elswick (Vickers plant) having a semi-automatic breech. Recoil was reported at 11.25 inches (285.75 mm) and was dampened by two hydraulic buffers with spring recuperation. Traverse was electric although it could be hand wound for fine tuning and the fighting compartment rotated with gun. The gun fired Armor Piercing Capped Ballistic Capped (APCBC at 823 meters per second and penetration was 120mm and 90 mm at 500m and 2000 m respectively against a 30 degree inclined plate. Secondary armament came from a 7.92 mm Besa machine gun mounted coaxially with 5750 rounds of ammunition. It is not known why Vickers stopped work on the MC77 it may have been linked to the dwindling interest in the FV300 project. It is possible that the funding for one was leached from another, something which was certainly a Vickers speciality to develop its own projects on the back of government contacts. Likely though, the potential, and unidentified customer simply lost interest. Although never put into production the work carried out on the development of the Vickers Medium Cruiser and the FV301 would go on to help them build the Vickers MBT Mk.1 via the Vickers VAPT, Light tank No. 45569 and Vickers Varmint projects.
The two machines often overlap on various sites and even quite authoritative sources have mistaken the two due to their similarities.
The key differences can be found in the suspension and engine placement. The FV300 series was initially to be built in two variants as M131 and M132. The difference being primarily in engine placement, either fore or aft. The original working prototype stemmed from A.46 and became the CT26 carrier with the distinct Alecto type wheels. The FV301 was quickly turned into FV302 and FV304 mock-ups. The FV302 20 pdr. tank destroyer has only two return rollers, the engine is still at the front, and the road wheels differ. The same is true of the early FV304 work. The later FV310 testbed also has the same road wheels, return rollers, and forward engine. The model of the Medium Cruiser 77 mm had 3 rollers, different wheels, and rear drive, although is often thought to be FV301.
Dimensions:
Length: 7.13 meters / 23.5 ft
Total width: 2.97 meters / 9.8 ft
Hull width: 1.67 meters / 5.6 ft
Total height: 2.60 meters / 8.6 ft
Trunnion height: 2.04 meters / 6.8 ft
Track width: 546 mm / 21.5 inches
Nominal track pitch: 102 mm / 4 inches
Number of links: 118 per side
Length of track on ground: 3.17 meters / 10.5 ft
Ground clearance: 457 mm / 18 inches
Fording depth: 1.44 meters / 4.9 ft
Vertical step: 792 mm / 2.6 ft
Maximum trench: 1.98 meters / 6.6 ft
Main weapon: QF 77 mm Tank gun
Secondary weapons: 7.92 mm Besa MG
Engine: RR Meteor Mk II 530 bhp Petrol Injected.
Max Torque 1040 lb/ft at 2000 rpm
Clutch: Borg and Beck type
Fuel consumption: .045 km per litre (roads)
Fuel capacity: 545 litres
Oil capacity: 45 litres
Operating range: 245 km / 153 miles or 87 miles CC
Suspension: 10 primary and 6 secondary Torsion bars
Newton Bennet shock absorbers
Maximum speed: 48 kph / 30 mph
Maximum climb: angle 35 degrees
Ground pressure nominal: 76 kg per sq centimetre
Armour thickness:
Lower plate: 31.75 mm @ 55 °
Upper plate: 44.5 mm @ 36°
Hull sides: 19 mm
Rear: 19 mm
Hull top: 10 mm
Hull floor: 10 mm + 20 mm plate for mines near front.
Turret front: 51 mm
Turret sides: 25.4 mm
Turret rear: 25.4 mm
Turret top: 12 mm
