Dr. J. Richard Jones Tank Test Beds

Tank Test Beds Although the MI tank is still in the early stages of its production pre gram, it is not too early to think of its successor. One reason is the time that it takes to get anew tank into service. This is clearly illustrated by the fact that it is now 12 years since the development of the M1 was started. Moreover, the nature of the threats facing tanks is changing. And at the same time, the technology of tanks is advancing. There is a growing need, therefore, to develop new tank designs to respond to the changing threats and to exploit new technological opportunities. However, it is not obvious at this point in time which of the several possible designs is the most effective and which might lead, therefore, to a successor to the MI.

In these circumstances it is essential to explore and evaluate the most promising of the possible designs in advance of any firm commitment to proceed with the development of any one. The best way of doing this has proved to be through the construction of test bed vehicles, and it is very noteworthy that the Tank-Automotive Concepts Laboratory of the U. S. Army Tank-Automotive Command (TACOM) has initiated a Tank Test Bed program. Nature of Test Beds Before considering tank test beds further, it is necessary to establish clearly their nature and their value in the development of combat vehicles. by Richard M. Ogorkiewicz Test beds may be delked as experimental vehicles designed and built to explore and to evaluate new design concepts. This definition implies that test beds are much more than vehicles used for testing one particular compe nent or subsystem. On the other hand, test beds are not prototypes. In other words, they are not vehicles built to prove or to demonstrate designs developed to agreed military requirements and intended to be put into production and service.

The distinction between test beds and prototypes is important, because it implies that there is no commitment in the design of test beds to put them into production and service. Consequently, test beds need not be worked out in every detail to the degree required in prototypes. This results in considerable savings in time and money. For the same reason, test beds do not require any?f the elaborate program management organizations which are associated with the combat vehicles that are to go into production and field service.

The essentially tentative and exploratory nature of test beds also offers the advantage that new design concepts can be investigated without raising political issues or calling for major policy decisions.

In spite of these potential advantages, the construction of test beds might be questioned on the grounds 16 ARMOR that mathematical modeling now offers an alternative, and ostensibly more economical, way of exploring and evaluating new concepts. In fact, in spite of their undoubted value, computer models are not an alternative to test beds. One very simple reason for this is that computer models cannot anticipate all the practical problems which are bound to arise, to a greater or lesser extent, in any radically new design. What is more, many of the inputs into computer models are essentially and inevitably of a historical nature. In consequence, computer models can be of great value in opti-mising designs, but their value is severely limited when radically new design concepts are involved. Need for New Designs All this leads to the conclusion that test beds are an indispensable means of exploring and assessing new concepts. It should also be evident that the value of test beds increases with the novelty of the concepts, or with the degree to which the new designs depart from earlier ideas. In consequence, test beds should be of particular value at the present time when, on one hand, there is a great need to advance on the traditional configuration of tanks and when, on the other hand, there are unprecedented opportunities for doing this. One of the reasons for the great need to advance on the traditional designs is the level of the threats now facing tanks, due to the progress in the development of antitank weapons. The capabilities of antitank weapons have increased in the past and have already led to several major changes in tank design. In particular, they have caused successive increases in armor protedion, which has grown to the equivalent of more than 300 millimeters of steel over the fronts of hulls and turrets, or 20 times what it was when tanks were first built. However, still greater increases in armor protection are required to provide tank crews with a high degree of survivability in the face of hostile tank guns firing AF’FSDS projectiles with long-rod penetrators, or of antitank weapons using advanced shaped charge warheads. Such increases are possible, but not without departing from the traditional configuration of tanks. For example, frontal armor could be increased to as much as 900 millimeters of steel, or the equivalent of even more, if advanced forms of protection were used, but not if tanks are to retain their traditional form with threeman turrets, which has already led to some tanks weighing as much as 62 metric tons or 68 U. S. tons.

Another reason why new design concepts are needed is the growing threat of attack not only by traditional direct-&e weapons but also from above. Until now, attack from above has been largely ignored in tank design, except for artillery shell fragments, which have not presented a major threat. But now attack from above has to be taken more seriously and will demand more than a redistribution of armor. In fact, there is no way in which armor can be redistrib uted to improve significantly the protection of conventional tanks against top attack This leads, once again, to the need to depart from conventional layouts and to devise new configurations which would be less vulnerable to top attack.

So far as new configurations are concerned, the most important opportunity to devise them arises out of the development of automatic loading systems for tank guns. Until now tanks have had to have a human loader for their main armament and this has prevented major changes in the configuration of tanks for very many years. As a result, even the latest tanks, such as the US. MI and the German Leopard 2 have basically the same configuration as the AlOEl tank built in Britain by Vickers-Armstrong in 1934!

Now, without the need for a human Above, a scale model of General Dynamics’ tank test bed vehicle. The twin-gunned test bed vehicle below is the Krupp-MAK VT 1-1, powered by a 2050-hp engine. r loader, it is possible to design tanks which are very different from those of the past 50 years. In particular, it is now possible to have tanks with guns which are not only automatically loaded but also remotely controlled and, therefore, mounted externally on pedestals or in small-frontal-area, unmanned turrets. The advantages in either case include much smaller exposed areas in defilade positions, reduced internal volume and complete separation of ammunition from the crew.

There are also other possibilities which did not exist before. One of them arises out of the development of electro-optical vision devices, which offer much greater freedom with regard to the location of the crew within the tank. For example, indirect electro-optical vision devices make it possible to locate all crew members low in the hull where they can be better protected.

Value of Test Beds These and other opportunities call for the construction of test beds through which they may be explored and eventually assessed, not only from the technological, but also from the user points of view. In fact, test beds are essential if the user is to ARMOR properly evaluate any new concepts which might be proposed in place of the configurations with which he is familiar and, ultimately, to decide whether to accept them or not. Test beds certainly offer a much more realistic and sound basis for making the decisions than any amount of paper studies, computer simulations or intuitive judgments.

Hands-on experience with test bed vehicles is also bound to suggest improvements and changes to any new design, which is unlikely to be perfect in its initial form, no matter how promising it might be. The consequent changes can be made relatively easily while the design is still at the test bed stage because of the test bed’s flexible, experimental nature. In this way, new concepts can be refined or optimised before any decision is made to further develop them. This means that test beds can serve to advance the engineering development of new concepts as well as providing a sound basis for user judgments.

Systematic programs of test bed design and construction also make it possible to nurture, relatively economically, combat vehicle design teams. They do so by providing the necessary 17 The British COMRES 75 test bed vehicle was built in 1968 to explore externally-mounted main guns. continuity of work and the opportunity to develop specialist experience. None of these conditions exist when combat vehicles are developed by a series of discontinuous vehicle pro grams. This mode of development inevitably leads to disbanding, or at least to the running down, of design teams in between such programs. In consequence, transfer of experience suffers and every time anew program is started much of the necessary expertise has to be newly acquired at considerable cost in time and money. Test bed programs can also provide a reservoir of new designs which can be developed and put into service much more quickly in an emergency than any new design started from scratch. The classic example of this is the German Tiger of WWII. This heavy tank went into action in the remarkably short period of only 15 months from the start of its development. It did so not simply because the Germans worked very hard under the stress of wartime, but even more, because of the prior existence of experimental heavy tanks on which its design could be based.

British, German and Swedish Examples A much more recent example of the successful use of test beds is provided by the British FV 4211. This battle tank test bed was built in 1970-71 to explore for the first time the use of Chobham armor in a tank design. As a result of this test bed, Chobham armor was accepted as entirely practicable and this led directly to the decision to incorporate the special armor in the General Motors and Chrysler prototypes of the MI tank, or XM1 as it was then. The FV 421 1 also served as the basis for one of the designs developed as part of the abortive Angl&erman Future Main Battle Tank (FMBT) Program of the mid-19709, and through it, to the latest British tank, the Challenger. A little earlier, in 1968, the British Military Vehicles and Engineering Establishment (MVEE) built another important test bed, the COMRES 75. This consisted of an experimental vehicle with the first ever externally-mounted gun, which provided useful, practical experience with external gun installations heretofore unavailable. Several other examples of the judicious use of test beds are also provided by the Federal Republic of Germany. The most interesting of them is proh ably the series of twin-gun turretless VT-1 vehicles built during the mid-1970s by Krupp MaK. The VT-1 test beds enabled several novel features to be explored in depth, including the twin-105mm and 120-mm gun installations which could fire salvos for greater hit probability; fking on the 18 ARMOR move from turretless vehicles with semi-fixed gun mountings, and the effectiveness of power-toweight ratios of more than 50 hp per metric ton. As it happens, the concepts embodied in the VT-1 test beds have not been adopted by the German Army, but the experience gained with them fully justified their construction. Further examples of the effective use of test beds come from Sweden. Test beds have been used in Sweden not only to explore new design concepts but to do so with a minimum of development risk and at minimum cost. This happened in the case of the Stank when it was being developed in the 1950s and 1960s and much more recently with the UDES XX 20, which may become the forerunner of anew type of articulated tank destroyer with exceptional off-theroad capabilities. At first sight, the UDES XX 20 might appear to be full of technical risks, but, in fact, several of its features have been successfully validated with earlier test beds. For example, the novel way of controlling articulated vehicles embodied in it had been proven with an earlier, lowcost, 4-ton test bed. Similarly, the possibility of firing a 120-mm tank gun from a relatively light vehicle had been proven with the gun mounted on an infantry combat vehicle of approximately the same weight as the proposed tank destroyer. riesnoarmamentbutisfullyequipped with sights and controls so that it can be used to evaluate the capabilities of the threman crew located in the hull and to resolve other operational issues. the use of test beds. The history of their use has demonstrated that they are of considerable value in exploring and evaluating new design concepts. They have, therefore, a particularly ARMOR

Projects Agency. This is his 73d article for ARMOR. 19