Component Advanced Technology Testbed (CATTB)

The Army completed five Advanced Technology Demonstrations (ATD) in FY 1993. These included AirLand Battle Management (ALBM), Soldier Integrated Protective Ensemble (SIPE), Advanced Air Defense Electro-Optical System (AADEOS), Multi-Role Survivable Radar (MRSR), and Component Advanced Technology Testbed (CATTB). The ATDs were risk-reducing, integrated exhibitions conducted in an operational or simulated environment rather than in a laboratory. They were expected to assist materiel developers and the Army in assessing operational capability, technological maturity, and cost effectiveness.

The CATTB ATD demonstrated the feasibility of integrating advanced vehicle components and subsystems, such as integrated propulsion, external suspension, more durable track, and standard Army electronics architecture on a combat vehicle testbed (modified Abrams tank chassis). The ATD successfully examined CATTB's integration of lethality, mobility, and durability features. The testbed spotlighted the latest in propulsion, track, suspension, fire suppression, electronics, and NBC protection technologies. It demonstrated the Army's capability to meet its needs through the application of integration techniques and generated the foundation for the development of the digital electronic battlefield to facilitate future Army operations.

The U.S. Army Tank-Automotive Research, Development and Engineering Center (TARDEC) Technology Integration Division led a group of AMC engineers in the devdopment of an ad- vanced combat vehicle test bed referred to as the Component Advanced Technology Test Bed (CATTB). The division directed a matrix team comprised of many government agencies and contractors. This group combined it expertise in many emerging technical areas to create an advanced automotive chasis and turret that was used for various signature- reduction efforts. The test bed, which was built for TARDEC Design and Manufacturing Iechnology Directorate, allowed engineers to evalume new technologies for use in future Army combat vechicles. The CATTB chassis was a modified M-1A1 tank hull. It featured a new propulsion package, new track and suspension designs and the Army's new "Vehicle Electronic System (called Vetronics). The turret was redesigned to carry two crew members instead of the three required in the MlA turret. There was a commander and gunner but no loader. The turret was designed to accommodate an advanccd tank cannon system that included a new lightweight 120mm gun and an automatic loader.

Several changes were made in the hull: floor blow off panel removed; reduce hole in middle bulkhead; extending hull casting plate; reduce hight of rear bulkhead. The M1A1 hull was used and modified where necessary to assure strength and space utilization. However "modern" APFSDS (which means that ammunition, that was availble to Soviet-Russia back then) does "bounce" at angles below 10°. This is why the glacis was considered safe, despite being only ~310mm thick. The fuzes of shaped charges warheads as used on ATGMs, HEAT ammo and RPGs have problems with fuzing at high angles of impact. Even modern fuzes as used on the Panzerfaust-3 RPG from Germany have trouble at fuzing at angles below 15°.

The CATTB's power was provided by the diese1 version of the Army's Advanced Integrated Propulsion System (AIPS) developed by the Cummins Engine Company. It was one of two competing propulsion systems then under development for use in the next generation of heavy combat vehicles. The other concept used a gas turbine engine and was developed by General Electric.

The Cummins AIPS engine was a V-l2, l682-cubic-inch turbocharged diesel that developed 1450 horsepower. It differed from existing diesels in several ways. For one thing, it used advanced heat-resistant materials that enabled it to retain part of the combustion heat, normally rejected to the cooling system, which appeared as additional energy in the exhaust gas entering the turbocharger. Another important difference was that this engine is cooled by oil rather than water. The same oil that provideed lubrication was pumped through the engine where necessary to cool it. Then it flowed through a radiator, where it rejected the heat just as a water-based coolant does in a conventional system.

The oil was a special high-temperature diesel lubricant that can withstand higher temperatures than other types of oil. An important advantage of these difference wa that the amount of heat rejected to the cooling system was reduced substantially and was easier to transfer to the atmosphere. As a result, the cooling system was much more compact. The 240 horsepower normally needed to run cooling fans in a 1500-horsepower diesel tank engine was cut in half. Fuel economy is also improved because there was more power available to move the vehicle for the same rate of fuel flow.

The transmission in the Cummins concept was a seven-speed automatic built by the Allison Transmiion Diviion of Germany's Zahnradfabrik Friedrichshaten AG (formerly a General Motors division). It provides three more gear ratios than the Ml-series tank's four-speed gearbox, and it was designed to allow the engine to be mounted transversely rather than longitudinally to make more efficient use of engine-compartment space.

Another CATTB feature was a new track design that had 50 percent fewer parts than the standard M1 track and was expected to provide longer life and reduce operating and maintenance costs. In the current design, two 9-inch- wide track shoes are mounted side by side and span the width of the track pins. Track guides (prongs that extend between dual sets of road wheel to keep the track properly aligned as it rotates around the wheels) are bolted between the hoes. The new track, on the other hand, uses a single 25-inch-wide shoe to pan the pins, and the track guide is an integral part of the shoe.

This track was designed as a high-durability track. By using a single shoe to span the full width of the track pins, the design uniformly distributed pin loading and bushing pressure, which helped to increase track life. Designers hoped to get 5,000 to 6,000 miles of track life, compared to about 2,000 miles with the standard track.

The CATTB has a new suspension concept that represeted a dramatic departure from the traditional design. Tanks currently use a torsion-bar suspension. In such a system, one torsion bar for each road wheel is mounted transversely inside the hull. One end of each bar is anchored to the hull, while the other end is attached to a road arm, which extends downward from the hull and is connected to a road wheel and shock absorber. As the track encounters a bump, each road wheel is kicked upward, and the torsion bar end of each arm pivots. This causes the bar to twist, and the bar's resistance to being twisted creates the opposing spring force that provides the needed cushion between the vehicle and the terrain.

In the new design, all components were outside the hull. The concept had no torsion bars, but instead fea tured a different type of spring that, along with the shock absorber, was located within each road arm. The system was thus referred to as the external suspension. The external suspension spring differed from conventional mechanical leaf, coil, and torsion-bar systern in that it was hydropneumatic. It consisted of a cylinder filled with nitrogen under high pressure and a piston situated at the top of the cylinder. When the vehicle track encountered bumps, each piston, which was mechanically linked to the vehicle hull, remained stationary while each road wheel forceed its respective cylinder to move upward. This causes the nitrogen to compress and act much like a mechanical spring, The CATTB was set up to test two versions of the system, one by Cadillac Gage, which was tested first, and tbe other by Teledyne-Continental Motors.

The concept would have two significant advantage over conventional designs, First, elimination of torsion bars would mean designers could either provide more space inside the hull, or lower vehicle silhouette to make enemy detection more difficult. Also, it would mean a weight saving of about 1,000 pounds in a heavy combat vehicle.

The SAVA was developed by Armored Vehicle Technology Associates (AVTA), a joint venture comprising FMC Corporation and General Dynamic Land Systems, in conjunction with General Electric and Texas Instruments. It was designed as a computer- controlled system with common hardware and software modules that would be suitable for both combat and tactical vehicles. It integrated the electronic subsystems and simplified the complex vehicle wiring harnesses now in use. The control and display functions were standardized and common for ali subsystems, thereby making vehicle operation easier.

While the Abrams had been equipped with the M256 120mm smooth-bore cannon since the 1980s, the survivability of its targets increased greatly. The T-90, the most advanced tank fielded by Russia and other states, combined composite armors and Kontakt-5 explosive reactive armor to achieve a protective power equivalent to 4.4 feet (1.34 meters) of solid steel. When the effects of APSs are factored in, the current weapon systems suite in the Abrams seems barely adequate. A future tank will likely be fielded initially with a version of the M256, but a potential for a more lethal weapon must be built into the turret of the new vehicle.

Shortly before the end of the Cold War, American and West German tank designers projected that future Soviet tanks would be immune to the 120mm and began design work on 140mm cannons. The 140mm cannons were intended to provide muzzle energies of roughly 18MJ, or twice that of the 120mm cannons deployed on Abrams and Leopard II. A gun of this size will make an autoloader a near necessity and will require a larger breach block and larger recoil space, all of which will impact turret design before a 140mm gun is even ready for fielding.