Human Factors Challenges in Armored Vehicle Design

Countless examples of "human factors" engineering problems, or challenges, exist in the world today. I suppose that any time a human is in the loop in any way, there are human factors concerns that range from the simple to the complex, but this is particularly true of military systcrns. Three human factors challenges now face the U. S. Army in the design evolution of armored vehicles. The tank, like the fighter aircraft and the capital ship, is the major challenge facing the engineers who design U. S. Army land warfare equipment. Problem 1: Weight Versus Survivability The first problem is weight versus armor protection (or survivability). As in all military systems, the Threat drives the design parameters for the tank. We design our systems to survive, or defend against and defeat, what we believe the enemy can do. In terms of tank technology, the lethality of kinetic energy (KE) projectiles that travel in excess of one mile per second has driven the armor protection requirement to become increasingly heavy to provide an acceptable level of crew survivability. Aside from the survivability issue, should a KE round impact - which is a human factors concern in it'sown right - a more interesting human factors issue has risen. Tank crews have traditionally contained four to five crewmen. Yet, to retain the same weight, size, and protection levels, the armor has demanded a greater space and weight claim in the tank design. The Army is now faced with an interesting dilemma: do we go to an ever larger, heavier tank, with the attendant logistical problems, in order to maintain a four-man crew? Or do we select smaller soldiers as armored vehicle crewmen? Should we reduce the number of crewmen from four to three, or two, and use technology to allocate more functions to machines?" The answer is, "The jury is still out." There are some interesting arguments for each approach. For some time, the Soviets have selected shorter soldiers as tankers in order to keep down the size and weight of their tanks. The cramped interior has reduced combat effectiveness. By using automatic loaders on newer tanks, the Soviets have been able to reduce the crew from four men to three, unlike the crews on their NATO counterparts. The Future Soviet Tank 1 (FST 1) may have only a two-man crew.. The U. S. Army Armor Center, the responsible agency for establishing armor requirements, has argued against selecting crewmen by size, and not without good reason. First, the average American soldier is larger; to take this tack would reduce the available crewmcn from an already shrinking manpower reduce the number of crewmen would adversely effect human endurance and combat effectiveness, especially if the crew must fight "continuous operations" 24 hours a day, seven days a week until the war is over. An argument against fewer crewmen is that duties such as crew maintenance, security, communications, vehicle operations, and crew rest, which are now split between four crewmen, would still have to be accomplished with three or two crewmen, no matter how many lune-tions were allocated to machines. Sadly, both arguments are correct. The ultimate determinant is, can the tank be fought effectively under combat conditions? This leads to the conclusion that there are no easy answers short of a breakthrough in armor plate tcchnology. Problem 2: Worldwide Adaptabilty The second human factors problem is that U. S. contingencies call for the Army to light in extreme or desert environments, possibly under nuclear or chemical attack. Use of chemicals in the current conflicts in the Persian Gull and Afghanistan sugest this possibility may become reality. In hot climates, a tank is like a furnace, with temperatures as high as 120-135 degrees Fahrenheit. Such conditions are encountered every day of the summer at many Army posts in the western and southwestern U. S. Tough physical training and conditioning can help the pool. Second, they argue that to soldier cope with these tempera- 24 ARMOR - September-October 7988 tures, at least until the battlefield becomes "dirty." Then the soldier must put on his chemical protective suit to survive. The thick suit is hot and adversely affects human endurance, effectiveness in operating system displays and controls, and - in the extreme temperatures mentioned above - survivability. Because of the soldier's reduced combat effectiveness, he is more vulnerable both to the enemy's actions and to the elements. Having worn these suits in such environments, 1 can personally attest that the soldier can only be effective for an hour, at most, and probably much less time under actual combat conditions. The Army has many studies to corroborate this statement. Again, there are no easy solutions. The Army is investigating suits and protective masks made of different, more hospitable, materials that still protect the wearer from toxicants. In addition, the Army is investigating air conditioning for tanks, or cooling suits, along with overpressure systems that keep the air pressure inside the tank higher than atmospheric pressure so that contaminants can't enter. But once again, the old space trade-off bugaboo surfaces for the last two solutions. Air-conditioning or overpressure systems are both large and heavy, thus they impact on the first human factors problem - the size and weight of the tank. Much work is being done on this problem at the U. S. Army Human Engineering Lab at Aberdeen Proving Ground, MD, and at the U. S. Army Natick RDE Center in Massachusetts. Again, success has been evolutionary rather than revolutionary. "... As motivated and as excellent as are today's young soldiers, it is still an enormous task to make the machine work for, and with, the man as a synergistic unit. I' Problem 3: Information Overload Finally, armor crewmen are starting to experience information overload problems much as fighter aircraft pilots have known for years. As my unit fielded our new M1 tanks and Bradley Fighting Vehicles in 1981, my battalion commander was fond of saying, "You must train your men in switchology!" He was referring to the increasing proliferation of displays, gauges, and switches on our vehicles. As a qualified helicopter pilot, he knew that repetitious training would make performance a matter of reaction, rather than one depending on conscious thought. The situation is getting more complex. New information systems are being added to the vehicles for capabilities such as night fighting, command and control, built-in test, and built-in training, to name but a few. Can the human perceive and code this information and still fight the tank? The challenge is not new to those involved with aircraft design. Conclusions As motivated and as excellent as are today's young soldiers, it is still an enormous task to make the machine work for, and with, the man as a synergistic unit. This can only occur when our human factors I ARMOR - September-October 7988 engineers and MANPRINT (Manpower and Personnel Integration) specialists are included from the earliest stages of system design. In summary, human factors concerns play a major role in the design of armored vehicle systems. The aforementioned problems are not the only ones facing those responsible for thc design and production of the next generalion of armored vehicles. For example, how does the soldier wearing glasses use the sophisticated optics now available to maximum advantage? How does the tank crew, moving at rapid ground speeds while lighting the vehicle under conditions of impaired visibility, maintain orientation? This is extremely important because the crew has to engage and kill the enemy and not engage and kill their own fellow soldiers (fratricide). The list is endless, and confronts the designer at every level and phase of the design process. Only when the design of the system is approached with a locus on the human - the key element of the system - can acceptable tradeoffs and solutions be reached. Captain R. Mark Brown is assigned to the Armored Family of Vehicles Integration Group at HQ, U. S. Army Materiel Command. He has completed the Army's Training with Industry Program and has served in numerous field assignments with armor units. A 1977 graduate of the U. S. Military Academy, he is studying for his master's degree in systems engineering at Virginia Tech. 25