The Skeleton Tank also known as the Spider Tank was an experimental prototype

tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful engi ...

built in 1918 by the Pioneer Tractor Company,

Winona, Minnesota Winona is a city in and the county seat of Winona County, Minnesota, Winona County, in the U.S. state, state of Minnesota. Located in bluff country on the Mississippi River, its most noticeable physical landmark is Sugar Loaf (Winona, Minnesota ...

for $15,000 ($ in ). The prototype was ready for trials by October 1918. Designed with several innovative features, some of which were controversial at the time, the Skeleton Tank project did not proceed beyond the single prototype.

Design

The objective of this prototype was to develop a lightweight vehicle capable of crossing wide

trenches A trench is a type of excavation or in the ground that is generally deeper than it is wide (as opposed to a wider gully, or ditch), and narrow compared with its length (as opposed to a simple hole or pit). In geology, trenches result from erosi ...

in a manner similar to the then-conventional heavy

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English, ...

tanks. Unlike the British tanks with their fully enclosed chassis, the Skeleton Tank achieved the requisite

lozenge Lozenge or losange may refer to: * Lozenge (shape), a type of rhombus *Throat lozenge, a tablet intended to be dissolved slowly in the mouth to suppress throat ailments *Lozenge (heraldry), a diamond-shaped object that can be placed on the field of ...

shape by supporting its tracks with a skeleton-like framework formed from ordinary iron pipes joined by standard plumbing connections. Suspended between these track frames was an armored fighting compartment carrying a machine gun turret. The engines were also housed in this armor-protected box. This arrangement dramatically reduced the weight of the vehicle as compared to the larger British and French tanks while preserving the trench-crossing capabilities of those machines, and there was a belief that most enemy bullets and cannon rounds would pass harmlessly through the structure. However, it eliminated the possibility of mounting weapons in

sponson Sponsons are projections extending from the sides of land vehicles, aircraft or watercraft to provide protection, stability, storage locations, mounting points for weapons or other devices, or equipment housing. Watercraft On watercraft, a spon ...

s as in the British tanks and thus limited the armament that could be carried. Motive power consisted of two Beaver four-cylinder

engines An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power g ...

with a final drive joining to a

gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...

suspended between the rear horns of the tracks. This allowed a maximum speed of .

Specifications

The Skeleton Tank weighed 9

ton Ton is the name of any one of several units of measure. It has a long history and has acquired several meanings and uses. Mainly it describes units of weight. Confusion can arise because ''ton'' can mean * the long ton, which is 2,240 pounds ...

s and carried a boxy fighting compartment protected by a of

armor Armour (British English) or armor (American English; see spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, especially direct contact weapons or projectiles during combat, or f ...

, which was in line with the armor thicknesses on other Allied tanks. The crew of two consisted of the driver and the commander/gunner who manned the .30 (7.62 mm) caliber

machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) ar ...

in the

turret Turret may refer to: * Turret (architecture), a small tower that projects above the wall of a building * Gun turret, a mechanism of a projectile-firing weapon * Objective turret, an indexable holder of multiple lenses in an optical microscope * Mi ...

. It was long, which compared favorably in trench-crossing potential to the then-standard heavy British Mk IV and Mk V tanks with lengths of but weights of 28 to 29 tons, and the French Schneider CA1 and Char d'Assault St. Chamond with lengths of and and weights of 13.5 and 23 tons respectively. It was wide, narrower than the to of the British tanks, and slightly higher at vice for the Mk IV/V due to its turret. It was never ordered into production.

Survivor

The cosmetically restored Skeleton Tank is preserved under a canopy at the

United States Army Ordnance Museum The United States Army Ordnance Training Support Facility (formerly known as the U.S. Army Ordnance Training and Heritage Center and U.S. Army Ordnance Museum) artifacts are used to train and educate logistic soldiers. It re-located to Fort Lee, ...

Aberdeen Proving Ground Aberdeen Proving Ground (APG) (sometimes erroneously called Aberdeen Proving ''Grounds'') is a U.S. Army facility located adjacent to Aberdeen, Harford County, Maryland, United States. More than 7,500 civilians and 5,000 military personnel work a ...

, Maryland.

Bibliography

Notes References * * - Total pages: 240 * - Total pages: 48 {{US WWI Vehicles World War I tanks of the United States World War I tanks Abandoned military projects of the United States History of the tank Trial and research tanks of the United States