Tortoise heavy assault tank
Encyclopedia
The Tank, Heavy Assault, Tortoise (A39) was a British
heavy assault tank design developed in World War II
but never put into mass production. It was developed for the task of clearing heavily fortified areas and as a result favoured armour protection over mobility.
Although heavy, at 78 tons, and not readily transported, it was reliable and a good gun platform.
In the early part of 1943 the Allied forces anticipated considerable resistance in the projected future invasion of Europe, with the enemy fighting from heavily fortified positions such as the Siegfried Line
. As a result, a new class of vehicles emerged, in the shape of Assault tanks, which placed maximum armour protection at a higher priority than mobility. Initially, work was concentrated on the Excelsior tank (A33), based on the Cromwell tank
. There was also a program to upgrade the armour of the Churchill tank
. For similar work in the Far East, the Valiant tank
(A38), based on the Valentine tank
was considered although weight was specified to be as low as possible.
The Secretary of State for War
and the Minister of Supply
issued a Joint Memorandum in April 1943 which gave a vague specification for an Assault tank, classing it as a special purpose vehicle to operate in heavily defended areas as part of the specialist 79th Armoured Division.
The Nuffield Organisation
responded with 18 separate designs (AT1 through AT18) drafted between May 1943 and February 1944, each design larger and heavier than the last. By February 1944 design AT16 was complete and was approved by the Tank Board who proposed that month that 25 be produced directly from the mockup stage without bothering with a prototype, to be available for operational service in September 1945. An order for 25 was placed by the War Office
and work was begun.
Following the end of the war the order was reduced and only 6 vehicles were built. One example was sent to Germany for trials where it was found to be mechanically reliable and a powerful and accurate gun platform, however at a weight of 80 tons and a height of 10 feet (3 m) it was extremely slow and proved difficult to transport.
Internally it was split into three compartments, the transmission to the front, the crew in the centre and the Rolls-Royce Meteor
engine at the rear. The suspension consisted of four bogies on each side each of the hull. Each bogie had two pairs of wheels, with each pair linked to a transverse torsion bar. The Merritt-Brown transmission was fitted with an all speed reverse, giving approximately the same speed backwards as forwards.
gun design was adapted from the British 3.75 inch anti-aircraft gun. The ammunition used a separate charge and shell, the latter a 32 pound (14.5 kg) armour piercing shot (APCBC). In tests the gun was successful against a German Panther tank
at nearly 1,000 yards.
The 32-pdr gun was mounted in a power-assisted limited traverse mounting; rather than being mounted on the more traditional trunnion
s, it protruded through a large ball mount in the front of the hull, protected by 225 mm armour. To the left of it was a Besa machine gun
in an armoured ball mount. A further two Besa machine guns were mounted in a turret on the top of the hull to the right.
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
heavy assault tank design developed in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
but never put into mass production. It was developed for the task of clearing heavily fortified areas and as a result favoured armour protection over mobility.
Although heavy, at 78 tons, and not readily transported, it was reliable and a good gun platform.
Development
Siegfried Line
The original Siegfried line was a line of defensive forts and tank defences built by Germany as a section of the Hindenburg Line 1916–1917 in northern France during World War I...
. As a result, a new class of vehicles emerged, in the shape of Assault tanks, which placed maximum armour protection at a higher priority than mobility. Initially, work was concentrated on the Excelsior tank (A33), based on the Cromwell tank
Cromwell tank
Tank, Cruiser, Mk VIII, Cromwell ,The designation as the eighth Cruiser tank design, its name given for ease of reference and its General Staff specification number respectively and the related Centaur tank, were one of the most successful series of cruiser tanks fielded by Britain in the Second...
. There was also a program to upgrade the armour of the Churchill tank
Churchill tank
The Tank, Infantry, Mk IV was a heavy British infantry tank used in the Second World War, best known for its heavy armour, large longitudinal chassis with all-around tracks with multiple bogies, and its use as the basis of many specialist vehicles. It was one of the heaviest Allied tanks of the war...
. For similar work in the Far East, the Valiant tank
Valiant tank
The Tank, Infantry, Valiant was a British tank design of the Second World War that only reached the prototype stage. The design was so infamously bad that the sole example was retained by the School of Tank Technology post-war as a dire lesson to its students.- Origins :The A38 Valiant began as a...
(A38), based on the Valentine tank
Valentine tank
The Tank, Infantry, Mk III, Valentine was an infantry tank produced in the United Kingdom during the Second World War. More than 8,000 of the type were produced in 11 different marks plus various purpose-built variants, accounting for approximately a quarter of wartime British tank production...
was considered although weight was specified to be as low as possible.
The Secretary of State for War
Secretary of State for War
The position of Secretary of State for War, commonly called War Secretary, was a British cabinet-level position, first held by Henry Dundas . In 1801 the post became that of Secretary of State for War and the Colonies. The position was re-instated in 1854...
and the Minister of Supply
Minister of Supply
The Minister of Supply was the minister in the British Government responsible for the Ministry of Supply, which existed to co-ordinate the supply of equipment to the national armed forces...
issued a Joint Memorandum in April 1943 which gave a vague specification for an Assault tank, classing it as a special purpose vehicle to operate in heavily defended areas as part of the specialist 79th Armoured Division.
The Nuffield Organisation
Nuffield Organisation
The Nuffield Organisation was a vehicle manufacturing company in the United Kingdom. Named after its founder, William Morris, 1st Viscount Nuffield, it was formed in 1938 as the merger of Nuffield's Morris Motor Company , another of Nuffield's companies the MG Car Company and Riley.Morris Motors...
responded with 18 separate designs (AT1 through AT18) drafted between May 1943 and February 1944, each design larger and heavier than the last. By February 1944 design AT16 was complete and was approved by the Tank Board who proposed that month that 25 be produced directly from the mockup stage without bothering with a prototype, to be available for operational service in September 1945. An order for 25 was placed by the War Office
War Office
The War Office was a department of the British Government, responsible for the administration of the British Army between the 17th century and 1964, when its functions were transferred to the Ministry of Defence...
and work was begun.
Following the end of the war the order was reduced and only 6 vehicles were built. One example was sent to Germany for trials where it was found to be mechanically reliable and a powerful and accurate gun platform, however at a weight of 80 tons and a height of 10 feet (3 m) it was extremely slow and proved difficult to transport.
Description
In strict terms, since the Tortoise had a fixed superstructure instead of a turret, it should be classified as a self propelled gun or an assault gun and not a tank. The crew included a commander, driver, and gunner, with two loaders for the 32-pounder gun and two machine gunners.Internally it was split into three compartments, the transmission to the front, the crew in the centre and the Rolls-Royce Meteor
Rolls-Royce Meteor
The Rolls-Royce Meteor was a British tank engine of the Second World War.It was developed from the Rolls-Royce Merlin aero-engine by W. A. Robotham and his chassis design and development division at Belper, as they were not involved in aero-engine work...
engine at the rear. The suspension consisted of four bogies on each side each of the hull. Each bogie had two pairs of wheels, with each pair linked to a transverse torsion bar. The Merritt-Brown transmission was fitted with an all speed reverse, giving approximately the same speed backwards as forwards.
Armament
The Ordnance QF 32 pounderOrdnance QF 32 pounder
The Ordnance QF 32 pounder or ' was a British 94 mm gun, developed as a replacement for the Ordnance QF 17 pounder anti tank and tank gun....
gun design was adapted from the British 3.75 inch anti-aircraft gun. The ammunition used a separate charge and shell, the latter a 32 pound (14.5 kg) armour piercing shot (APCBC). In tests the gun was successful against a German Panther tank
Panther tank
Panther is the common name of a medium tank fielded by Nazi Germany in World War II that served from mid-1943 to the end of the European war in 1945. It was intended as a counter to the T-34, and to replace the Panzer III and Panzer IV; while never replacing the latter, it served alongside it as...
at nearly 1,000 yards.
The 32-pdr gun was mounted in a power-assisted limited traverse mounting; rather than being mounted on the more traditional trunnion
Trunnion
A trunnion is a cylindrical protrusion used as a mounting and/or pivoting point. In a cannon, the trunnions are two projections cast just forward of the centre of mass of the cannon and fixed to a two-wheeled movable gun carriage...
s, it protruded through a large ball mount in the front of the hull, protected by 225 mm armour. To the left of it was a Besa machine gun
Besa machine gun
The Besa Machine Gun was a British version of the Czechoslovak ZB-53 air-cooled, belt-fed machine-gun, which in the Czechoslovak army was marked as the TK vz. 37...
in an armoured ball mount. A further two Besa machine guns were mounted in a turret on the top of the hull to the right.
Survivors
- One of the six production Tortoises has been preserved at the Bovington Tank MuseumBovington Tank MuseumThe Tank Museum is a collection of armoured fighting vehicles in the United Kingdom that traces the history of the tank. With almost 300 vehicles on exhibition from 26 countries it is the second-largest collection of tanks and armoured fighting vehicles in the world.The Musée des Blindés in France...
in Bovington, UK. The vehicle is in running condition. A 2011 overhaul saw it running under its own power for the first time since the 1950's. It was shown to the public in June 2011 at Tankfest 2011, the Bovington museum's annual display of running vehicles. - A Tortoise, without its gun, lies on the Kirkcudbright military training area near KirkcudbrightKirkcudbrightKirkcudbright, is a town in Dumfries and Galloway, Scotland.The town lies south of Castle Douglas and Dalbeattie, in the part of Dumfries and Galloway known as the Stewartry, at the mouth of the River Dee, some six miles from the sea...
, Scotland. As the Kirkcudbright training area has been designated a Site of Special Scientific InterestSite of Special Scientific InterestA Site of Special Scientific Interest is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon...
, removal of the Tortoise to a museum is now unlikely.
See also
- T-28 Super Heavy TankT-28 Super Heavy TankThe T28 super heavy tank was a prototype heavily armored self-propelled gun designed for the US Army during World War II. It was originally designed to be used to break through German defenses at the Siegfried Line, and was later considered as a possible participant in an invasion of the Japanese...
: An American tank with a roughly similar design and fate. - Super Heavy Tank
- JagdtigerJagdtigerJagdtiger is the common name of a German tank destroyer of World War II. The official German designation was Panzerjäger Tiger Ausf. B. The ordnance inventory designation was Sd. Kfz. 186. It saw service in small numbers from late 1944 to the end of the war on both the Western and Eastern Front...
External links
- Photos of A39 Tortoise at Bovington Museum
- Armor in Focus - A39 Tortoise Heavy Assault Tank Specifications, Pictures
- A39 Tortoise at WWII Vehicles