Bob Semple Tank
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The Bob Semple tank was a
light tank A light tank is a Tank classification, tank variant initially designed for rapid movements in and out of combat, to outmaneuver heavier tanks. It is smaller with thinner vehicle armour, armor and a less powerful tank gun, main gun, tailored for ...
designed by Bob Semple, the
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
Minister of Works during
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
. Originating out of the need to build military hardware from available materials, the tank was built from
corrugated iron Corrugated galvanised iron (CGI) or steel, colloquially corrugated iron (near universal), wriggly tin (taken from UK military slang), pailing (in Caribbean English), corrugated sheet metal (in North America), zinc (in Cyprus and Nigeria) or ...
on a tractor base. Designed and built during a period of uncertainty in which New Zealand feared having to defend itself from
Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...
invasion without external assistance, these tanks were a civilian effort to design and create a means to protect New Zealand. Designed and built without formal plans or blueprints, it had numerous design flaws and practical difficulties, and was never put into mass production or used in combat.


Design and construction

At the onset of the Second World War, New Zealand—like its neighbour
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
—had no indigenous armoured fighting vehicle industry, and it was expected that armoured fighting vehicles would be imported from
Britain Britain most often refers to: * Great Britain, a large island comprising the countries of England, Scotland and Wales * The United Kingdom of Great Britain and Northern Ireland, a sovereign state in Europe comprising Great Britain and the north-eas ...
. Although Australiasee Sentinel tank and New Zealand had some
heavy industry Heavy industry is an industry that involves one or more characteristics such as large and heavy products; large and heavy equipment and facilities (such as heavy equipment, large machine tools, huge buildings and large-scale infrastructure); o ...
that could be turned to the production of armour and armoured vehicles, little such preparation had been done. The idea of mechanising the
New Zealand Army The New Zealand Army (, ) is the principal Army, land warfare force of New Zealand, a component of the New Zealand Defence Force alongside the Royal New Zealand Navy and the Royal New Zealand Air Force. Formed in 1845, as the New Zealand Mil ...
had been suggested before the war but without much progress. The use of the American Disston "Six Ton Tractor Tank", a 1937 vehicle constructed of an armoured box on a Caterpillar Model 35 chassis which had been sold to
Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan, is a landlocked country located at the crossroads of Central Asia and South Asia. It is bordered by Pakistan to the Durand Line, east and south, Iran to the Afghanistan–Iran borde ...
, was suggested. New Zealand had built some improvised armoured trucks, and unable to get any tracked carriers from Australia, were building their own with armour plate imported from Australia. After the
Fall of France The Battle of France (; 10 May – 25 June 1940), also known as the Western Campaign (), the French Campaign (, ) and the Fall of France, during the Second World War was the German invasion of the Low Countries (Belgium, Luxembourg and the Net ...
in mid-1940, and the loss of most British tanks there, there was no likelihood of production being spared for New Zealand. Rather than obtain the armoured superstructures from America, they decided to produce their own using local materials and resources. It was decided that a 'tractor-tank' would be an adequate design; if the need for defence arose, a large tank superstructure could be bolted upon a tractor base within a few hours, allowing for quick transformation and deployment of the tanks. The first (
mild steel Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: * no minimum content is specified or required for chromium, cobalt ...
) prototype was built on a
Caterpillar D8 The Caterpillar D8 is a track-type tractor designed and manufactured by Caterpillar since 1935. Today, the largest in Caterpillar's medium range,Bren light machine gun The Bren gun (Brno-Enfield) was a series of light machine guns (LMG) made by the United Kingdom in the 1930s and used in various roles until 1992. While best known for its role as the British and Commonwealth forces' primary infantry LMG in Worl ...
s — one in each side, two facing the front, one in the turret and one at the rear. The vehicle was very tall at 12 ft (3.5 m) and performance was poor. Due to the lack of armour plate, corrugated (
manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...
) plating was used in the expectation it would deflect bullets. The crew of eight included one gunner who had to lie on a mattress on top of the engine to fire his Bren gun. The tanks were constructed without the use of any formal plans or blueprints. Working from an American postcard depicting the conversion of a tractor to a 'tractor-tank', Bob Semple and TG Beck (Christchurch District Works Engineer), improvised the design of the tanks. Using resources available to Bob Semple as Minister of Public Works, work on the first tank commenced at the PWD's
Temuka Temuka is a town on New Zealand's Canterbury Plains, 15 kilometres north of Timaru and 142 km south of Christchurch. It is located at the centre of a rich sheep and dairy farming region, for which it is a service town. It lies on the north ...
workshops in June 1940. The additional two were built at the NZR Addington Workshops. The first cost £5,902, and the second and third together cost £4,323, for a total cost of £10,225 (although the Army was only billed £3,414). The intention was to disperse the hulls at locations ready in case of a Japanese invasion at which point they would be mounted on tractors for use. The idea was discarded after the tanks attracted public ridicule; however, Bob Semple stood by his design and even stated "I don’t see anyone else coming up with any better ideas."


Handling and performance

Due to the limitations of requirements and resources, the tank was a functional failure. By using a large tractor as a base, and bolting on a hastily designed and poorly constructed tank superstructure, the resultant tanks were inadequately armored, extremely heavy (20–25 ton), unstable, restricted by tractor gearing to slow speeds, and had to stop to change gears. Furthermore, due to the shape of the underlying tractor and undue vibrations, shooting from the tank was both difficult and inevitably inaccurate. These limitations have caused the Bob Semple Tank to frequently make lists of "Worst ever tanks".


Final result

In the end, due to their impracticality, the tanks were disposed of by the Army. They had been given Army serial numbers NZ6292 (held at
Papakura Papakura is a suburb of South Auckland, in northern New Zealand. It is located on the shores of the Pahurehure Inlet, approximately south of the Auckland CBD, Auckland City Centre. It is under the authority of the Auckland Council. The ar ...
) and NZ3494 & NZ3495 (held at Burnham). Only one went to the Pacific in 1944, after having its armour stripped. It is possible that the Bob Semple tank could have been potentially useful in battle, as it was planned to have a 37 mm anti-tank gun rather than the Bren gun in the turret; the armour was also bullet-resistant to some degree, so it might have been at least somewhat effective in the event of an invasion.


See also

*
Disston Tractor Tank The Disston Tractor Tank, also called the Six-Ton Tractor Tank, was an American light tank of the mid 1930s. It was cheap to make, but few were sold as it was primitive and markedly inferior to the other light tanks of the era. Development The t ...
– American production tank based on a tractor * NI Tank – Soviet improvised tank design based on a tractor *
KhTZ-16 The KhTZ-16 () (after the Kharkiv Tractor Factory; ) was a Soviet improvised fighting vehicle of the Second World War, built on the chassis of an STZ-3 tractor. The vehicles were built in Kharkiv until the factory was evacuated to the east, at ...
- Another Soviet improvised tractor tank * Schofield tank – New Zealand indigenous tank design * Sentinel tank – Australian indigenous tank design *
Plastic armour Plastic armour (also known as plastic protection) was a type of vehicle armour originally developed for merchant ships by Edward Terrell of the British Admiralty in 1940. It consisted of small, evenly sized aggregate in a matrix of bitumen, simi ...
– contemporary ersatz armour of asphalt concrete


Notes


References

* * * * *
Pratt, J, fl 1974 :Photograph of tank designed by Robert Semple


External links


Bob Semple tank or New Zealand's "NI" (Russian)

A Bob Semple tank in Christchurch (photo)
{{DEFAULTSORT:Bob Semple Tank Tanks of New Zealand World War II tanks of New Zealand Improvised armoured fighting vehicles Military equipment of New Zealand New Zealand design Improvised fighting vehicles