MBT-70 (KPz-70) Main Battle Tank (MBT)
The ill-fated MBT-70 program was a failed joint effort by the United States and West Germany to produce a next generation main battle tank.
Authored By JR Potts, AUS 173d AB; Content ©www.MilitaryFactory.com
The Cold War in Europe spanned from 1947 into 1991 and the undisputed enemy to the democratic world was the nuclear-armed Soviet Union led by Joseph Stalin. After its strong showing against the German Army in World War 2 (1939-1945), the Soviet military comprised of thousands of proven battle tanks, self-propelled guns, artillery pieces, aircraft and constantly evolving air defense systems. In 1949, the defeated Germans had been divided into an eastern and western section, the east under the control of the communist Soviets. West German authorities and US forces knew the tank force just over the border could destroy them by simple conventional means through massed numbers. The United States maintained a full tank division along the border and this was further backed by three M65 atomic cannons
(known as "Atomic Annie") that, if necessary, could be used to answer a large Soviet tank attack from the east. The major drawback of the Annie was in that it took a full day to position and set up for firing. As such, Annie positions could be overrun by a fast-moving enemy before her nuclear projectiles. The Soviets were anything but blind to these weapons and kept a close watch on the Annies. At the time, the US Army's Main Battle Tank (MBT) was the M60 "Patton"
and, for the Germans, the Leopard 1
- both tanks had been developed to counter the Russian T54/55 series tanks that were now further strengthened by the arrival of the advanced T-62. Both Germany and the US continued to make upgrades to their Leopard 1 and M60 tanks but inevitably looked forward to an advanced generation of tank to defeat future Soviet tank designs already in development.
In 1963, the US and Germany pioneered a joint venture project to develop a new Main Battle Tank - the German prototype being designated as the "KPz-70" and the US version to be known as "MBT-70" (for the purposes of this article, both will be collectively referred to as the MBT-70). The goal was to build a superior tank system making use of steel-layered tungsten alloy armor and an inner protective shell comprised of spaced layers of extra hard uniform rolled steel armor. Almost from the start the two design teams faced numerous disagreements as to the number of design features to incorporate. The language barrier was one obvious detrimental factor and the rivalry held between the two teams resulted in very little teamwork and major developmental cost overruns. Despite the same need for a combat tank, the requirements of each military differed based on battlefield theories and tactics. Different engines and main guns were selected by both sides and even the use of metric (or "SAE") measurements were argued about so both would, in fact, be used.
Testing began in 1965 and the two teams developed fairly advanced features such as a new crouching hydro-pneumatic suspension system that allowed the tank driver to lower its silhouette to within 4 inches from the ground. This would have helped the system conceal itself amongst tall underbrush while making for a harder target to hit. The suspension could then be raised to allow for better off-road mobility and superb travel on paved roads. The turret would be large enough to house the three-man crew which, in itself, was a vast departure from conventional approaches that always stationed the driver in the lower front hull - apart from the gunnery crew. The American team chose a 152mm gun "launcher" as main armament for their MBT-70 with an XM-150 auto loading cannon rated to fire AP/HE/WP rounds as well as the Shillelagh anti-tank missile - the latter being able to reach out and hit targets out to 3,000 meters. For infantry suppression, there was a 7.62 coaxial machine gun and to protect from low-flying aircraft, a 20mm remote-controlled anti-aircraft cannon would be made available, this installed along the side of the turret and hidden under two hatches. The Germans selected a relatively simpler approach with a 120mm automatic cannon as the primary armament.
Apart from these innovations, the MBT-70 was otherwise a very conventional tank arrangement. Both design teams elected for a rear-mounted diesel-fueled engine for reliability, power and efficiency. Again, however, both teams elected engines from different manufacturers - the American engine selection became a Continental AVCR air-cooled V12 diesel system developing 1,470 horsepower while the German team decided on an MTU diesel engine producing 1,500 horsepower. Both tanks could make headway at 43 miles per hour making the MBT-70 prototype the single most fastest MBT in the world at that time. The main innovation proved to be the relocated driver in the turret, residing within a cupola that rotated contrary to the turret itself, keeping the driver faced in the direction of travel at all times as the tank turret changed direction to engage the target at hand; during radical turns, however, the pilot drivers reported disorientation in the counter action though it was realized that such an arrangement allowed the vehicle to reach its full allowable speed in both forwards or reverse driving - an unheard of specification at the time and some 30% faster than the M60 Pattons already in service. For crew safety the design teams incorporated rear fireproof doors and, behind the ammunition storage area, a bulkhead system that would blow out when taking a direct hit. This action was also designed to throw the internal ammo out and away from the tank in an effort to further protect the crew from ammunition explosions.
As one can surmise, problems were many for the ambitious MBT-70 design: the projectiles were not intended to have a brass jacket - the entire round was, in fact, the projectile itself. While this saved on weight in the hull, the projectiles tended to swell when wet, essentially making them unusable or subject to premature firing inside the vehicle. The drivers despised the rotating cupola idea and the 20mm cannon proved to technical and never performed to the promised specifications. The MBT-70 weight concerns soon crept from the original 46 tons to the finalized 54 tons. She was eventually reduced to a little over 50 tons but this still precluded its use with current armored recovery vehicles of both armies as well as crossing over the standard issue portable bridges.
In the beginning, the project planners optimistically felt the entire project would run at $80 million US ($292.8 million German DM). However, the death nil for the project began with the lack of cooperation between the two design teams in working together to create one viable product at a reasonable price. By 1969, the price tag for fourteen pilot vehicles and their required trials had risen to $303 million US. Such issues ultimately forced the West Germans to back out of the project. The Germans took their completed prototypes and continued an indigenous MBT program which developed into the excellent modern-day Leopard 2. Back in America, the US Congress pulled the funding on the US program in 1970. This forced the US Army to follow the general German idea and request continued funding for evaluations of the completed prototypes with a lower budget scope under the new product designation of "XM803". That limited project ultimately failed but a resulting development turned into the "XM1" which would lead to the fine M1 Abrams MBT still in service today. The M1 would see exceptional use in combat actions ranging from the Persian Gulf War of 1991, the 2001 American invasion of Afghanistan and the 2003 American invasion of Iraq.
The included tank pictures presented on this website are of prototype #5 held at the Aberdeen Proving Grounds in Maryland taken in 2009. A keen observer will note boxes set along the turret on both sides of the 152mm gun, these steel weights were used in testing of the MBT-70 to simulate the weight of armor plate to be used in the final production form.