The FV4005 Story: Britain's Colossal Tank Dream

The FV 45 was a British tank prototype developed during the early Cold War to counter Soviet heavy tanks. Equipped with a massive 183 mm cannon, the largest ever fitted to a British tank, it was designed to engage targets at long ranges. Despite its impressive firepower, including a high-explosive squash head (HESH) round that weighed more than the people loading it, the FV 45 never made it past the prototype stage. The tank was enormous, measuring 31 feet in length, 11.5 feet in width, and 9 feet in height, yet operated by a modest crew of five. Its armor was relatively thin, with 3 inches on the hull front and 0.55 inches at the turret's thickest point. Power came from a 650 horsepower Rolls-Royce Meteor petrol engine, giving it a top speed of 22 mph on roads. The FV 45's development history and performance characteristics are explored, revealing why this formidable machine remained an interesting footnote in Cold War history.

This section delves into the comparison between the FV 45 and the Soviet IS-3 heavy tank, which it was designed to counter. The IS-3, measuring 32.5 ft in length and 10.7 ft in width, had significantly thicker armor than the FV 45, with 6.2 inches on the hull and 9.8 inches on the turret, compared to the FV 45's 3 inches on the hull and 0.55 inches on the turret. However, the FV 45's role as a tank destroyer, designed for long-range engagements, contrasted with the IS-3's role as a heavy tank for close combat. The FV 45's L4 cannon could penetrate 11.3 inches of armor, sufficient to defeat the IS-3's maximum armor thickness. Yet, despite its potential effectiveness, the FV 45 never progressed beyond the prototype stage due to changing tank design philosophies and the emergence of anti-tank guided missiles (ATGMs), which rendered large cannons like the L4 obsolete.

The development of the FV 45 and its L4 cannon is outlined, beginning with the realization in 1950 that existing British heavy gun tanks might not be sufficient to counter new Soviet heavy tanks like the IS-3. A formal requirement was issued for a cannon capable of penetrating a 6-inch plate at 60° from 2,000 yards. The L4 cannon, with a 7.2-inch bore, was developed under Major General Stuart B. Rawlings and was accepted into service in December 1952. The L4 fired HESH rounds, which were designed to maximize damage to heavily armored targets by causing a disruption rather than complete destruction. The FV 45's development began with its more advanced sibling, the FV 215, but due to the high cost and time consumption of such projects, a requirement was filed for a stop-gap vehicle using the L4 cannon that could be produced quickly. The FV 45 was designed as a lightly armored, self-propelled gun, utilizing existing production parts for potential production by December 1952.

The FV 45 underwent two stages of development. Stage one involved testing the gun and mount on the Centurion chassis, while stage two represented the finalized design. The stage one prototype featured an unenclosed platform over the original Centurion turret ring, with the L4 gun mounted in a fixed, rigid position. It allowed for two crew members, a Gunner and a loader, with a mechanical loading assist device. The stage two was intended as a pre-production model, featuring an enclosed turret and a hydroneumatic recoil system. The stage two carried 12 rounds and had a turret crew of five men. Both stages underwent firing tests, with the stage two proving satisfactory in terms of overall performance. However, the FV 45 project was terminated due to the evolving threat landscape and the advent of ATGMs, which made large cannons like the L4 obsolete.

The FV 45 project was terminated in August 1957, following the realization that the tank was obsolete before it went into production. The rise of the main battle tank (MBT) concept and the development of ATGMs made the need for large-bore tank killers like the FV 45 increasingly irrelevant. The three FV 45s produced had varied fates: the stage one was returned to service as a normal Centurion, while the two stage twos had their turrets removed and the chassis returned to service. One of the stage two turrets eventually found its way to the Bovington Tank Museum, where it was mounted on a spare Centurion chassis, providing a representation of the original FV 45 design. The FV 45 remains an intriguing example of a powerful tank design that was ultimately rendered obsolete by changing military technology and strategies.