FV4401 Contentious

FV 4401 Contentious was a prototype British air-portable tank destroyer of the early 1960s. At least one prototype was constructed and tested, although no production vehicles were built or saw service.

Project Prodigal
The vehicle was developed as part of Project Prodigal, as research into future armoured fighting vehicles. Prodigal would eventually give rise to the CVR(T) series of British light tanks and related vehicles. The intention here was to produce an air-portable tank destroyer.

The vehicle's role was for a flexible strategic response to conflicts around the last vestiges of Empire. Despite the low intensity of such conflicts, it was assumed that the increasing supply of Soviet T-54 tanks to satellite states would require an anti-tank capability greater than previous light tanks.

This was not seen as a substitute for a main battle tank; one which would have to be heavily armed to deal with the massed and heavily armoured Soviet tanks of the Cold War. In particular, there was no attempt made at protection against the NBC threat that was expected for any European conflict.

Contentious
This required a particularly lightweight vehicle, which restricted the possibility of a conventional tank with a conventional turret. The path chosen was that of a low-profile open hull with a semi-fixed gun, similar to the layout of the wartime Alecto. This small hull necessitated a small crew, of only two, which in turn required an autoloader, particularly for the heavy armament and ammunition in mind.

The gun chosen was the QF 20 pounder (84 mm), already in use in the Centurion tank, although now fitted with an autoloader. The mount was fixed in elevation and had only a limited traverse. Most aiming relied on steering the entire tank on its tracks. Elevation used an unusual system, a hydraulic suspension system with independent height control of each wheel station. This allowed the entire tank chassis to be tilted back and forth. This system had already been demonstrated in the Swedish S-tank. The chassis components were based on those of the Comet tank, although with only four roadwheels rather than the Comet's five.

The prototype was completed and tested on the firing ranges of Kirkcudbright Training Area. This was only a boilerplate example: it was not only unarmoured, but the armour layout design had not been completed and the actual body of relatively high and vertical plates is unlikely to have been the shape, let alone the material, used for a final example. In particular, the petrol tanks were exposed and mounted above the track guards.

The vehicle was also tested at Lulworth, in tests against a wheeled vehicle to test the virtues of both tracked and wheel arrangements for the Prodigal air-portable tank destroyer. The vehicle chosen was the Rhino, a six-wheeled skid-steered experimental chassis, powered by a Rolls-Royce Meteorite engine. Drivers were instructed to drive in pursuit of targets, both fixed and moving, and to attempt to track them with a simple windscreen-mounted sight. The Rhino's steering was infamously difficult to control precisely and it was found that the tracked Contentious performed better.

As with the Centurion, Contentious was later up-gunned. Although first tested with the 84 mm 20 pounder, the Bovington example later gained a L7 105 mm gun, a derivative of the 20 pounder. The replacement was relatively easy, as the 105 mm is largely a rebarrelled version of the 84mm and has a similar breech. Photographs of the prototype do show some change to the recoil cylinders between the two.

Twin recoilless design
A further design for the Prodigal requirement used a pair of the 120 mm recoilless rifles, as used for the WOMBAT, and fitted with seven-round revolver autoloaders. These were mounted on a swivelling mounting above a low boat-shaped hull with conventional suspension, crewed by a single commander / driver / gunner. The mounting could elevate conventionally. The autoloaders and their ammunition were carried in armoured boxes above the hull, with the reaction nozzles of the recoilless rifle protruding behind. Sighting for these recoilless rifles was to be the same M8C .50 spotting rifles, one for each barrel, as used with the WOMBAT.

Comparable vehicles

 * M56 Scorpion
 * M50 Ontos
 * ASU-57
 * Type 60 Self-propelled 106 mm Recoilless Gun
 * Stridsvagn 103 S-tank
 * VT tank

Survivors

 * The prototype, UXM127, is on display at the Bovington Tank Museum in Bovington, UK.