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8 Soldier Sustainment The Chief of Staff of the Army has stated that "Soldiers are our credentials." The committee strongly endorses this credo and believes it will still be true in 2025. No matter how many tons of ammunition and fuel are available in the battle area, soldiers must be present to use them. Therefore, sustaining the soldier is the sine qua non of any logistics systems. The soldier sustainment logistics burden is not measured in tons but in necessity. If soldiers cannot sustain themselves, the battle will come to a halt and be lost. Therefore, the committee believes that the soldier's logistics load should be reduced and that every effort should be made to enable soldiers to conduct continuous operations with minimum personal resupply. Reducing the soldier's load will require improvements in compact electric power, lightweight protective garments and ballistic protection, nutrition and medicine, food and water production and delivery, and other technology areas. Reducing the soldier's logistics burden will increase fighting effectiveness and will ultimately reduce the number of soldiers needed to accomplish any given mission. COMPACT POWER The combat soldier will become increasingly dependent on portable electronic systems, and the provision of adequate power for dismounted soldiers is a major logistics consideration. Research objectives and relevant technologies for improving energy sources and electronics were reviewed in a 1997 NRC report, Energy-E~icient Technologies for the Dismounted Soldier MARC, 1 997a). The committee is aware of several technological developments that may ultimately reduce the weight burden associated with energy needs for the individual soldier in the AAN time frame. One of these is rechargeable fuel cells, which were discussed in Chapter 4. Dramatic increases in stored energy will require that the Army move away from traditional electrochemical batteries toward nontraditional energy storage concepts, such as microturbines and nuclear "batteries," which are discussed below. Microtu rb in es The compact gas turbine, which uses hydrogen as its primary fuel source, appears to be an appropriate area of investigation for AAN, and the Army has sponsored 128

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SOLDIER SUSTAINMENT significant research in microturbines (NRC, 1997a). However, these power systems will still have to meet the same requirements as large power systems in terms of their capacity to produce net electrical power. Because the capability of a turbine power plant to provide net power output is a function of the pressure ratio, turbine efficiency, compressor efficiency, and maximum temperature at turbine inlet, the characteristics of these new devices will have to be assessed to determine if they meet the requirements. Efficiencies of aerodynamic compression and expansion devices decrease as surface-to- volume ratios increase, so mechanical, compressor, and turbine efficiencies will have to be high enough to provide enough net power output to drive the power generator. The overall efficiency of the power plant may not matter as long as the machine is capable of providing enough net power. (Limitations on using hydrogen, instead of JP-8, as a battlefield fuel are discussed in Chapter 4.) Nuclear "Batteries" One way to minimize the weight burden of batteries for the individual soldier would be to develop radioisotope-based power sources to replace small batteries. Commercial, radioactive energy sources are already found in smoke detectors and some wrist watches with luminous dials. One of several means of converting isotope power to electric output is thermoelectric (TE) conversion (utilizing the heat generated by iso- topes). Some DARPA projects are focused on increasing the performance of TE junctions by an order of magnitude, which would greatly improve heat-to-electric power conversion efficiency. Past experiments have shown that the direct conversion of nuclear to electric power by bombarding silicon "solar" cells with low level nuclear particles is feasible (AsTange and Emin, 1997~. Unfortunately, the life of silicon cells under these conditions is extremely limited because of atomic lattice damage. Researchers at the University of New Mexico and Sandia National Laboratories have presented data sug- gesting that alternate semiconductor materials, the so-called icosohedral borides (e.g., B~2P2 or B~2As2), may be "self-healing" under low-level nuclear bombardment and might be more feasible for battery-like nuclear-to-electric power converters (AsTange and Emin, 1997~. DARPA has recently initiated an experimental feasibility study of this con- cept. Because of the low levels of radiation associated with the gamma radiation of the power source, typically 40 keV, shielding would have to be the equivalent of lead foil. A nuclear battery would be a lightweight, "eternal" power source. These technologies would be most beneficial for low-power batteries for individual soldiers and for remote sensors. PROTECTION OF PERSONNEL In a general sense, the functional requirements for body armor are the same as those for vehicle armor. The objective is to increase protection per unit of mass or vol- ume. Lightweight building blocks for body armor for combination systems particularly polymer and ceramic composites, look promising. Unlike vehicle armor, however, body armor must be flexible enough so it does not interfere with the mobility and effective- ness of the soldier. A "lightweight" armor on a 15-ton vehicle is likely to be much too heavy for a 1 80-pound soldier who is already carrying a combat load. 129

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130 REDUCING THE LOGISTICS BURDEN FOR THE ARMYAFTER NEXT Body Armor Traditional designs for body armor restrict mobility and can significantly limit a soldier's performance. This is mainly because conventional armor systems (such as steels, aluminum alloys, ceramics, and monolithic reinforced polymers) are clumsy and heavy. In bulletproof vests, for example, hard ceramic provides an impact-resistant surface, but the vest is large and may not conform to the contours of the body. Even relatively light vests constructed of woven polymeric composites (including Keviar and spectra fibers) can be uncomfortable to wear in hot weather. An ideal armor system would be lightweight, flexible, and easy to manufacture. Two technological challenges for body armor are weight and practicality. These may be overcome by using a segmented design for the armor system, for example, ce- ramic plates supported by energy-absorbing woven polymer backing. Polymer materials that mimic spider silk, mollusk shells, and other natural materials could also be used as building blocks for lightweight body armor to reduce the vulnerability of limbs to bullets and shrapnel. Body armor systems could be equipped with sensors and detectors that monitor body functions in case of a hit and assess the degree of injury. These could be in-situ sensors (e.g., piezoelectric polymers that sense mechanical changes and detect electrical signals) that are part of the composite armor material. The body armor systems may also be combined into protective garments providing protection from chemical and biological agents and nuclear radiation. Research in the area of polymers for personnel protection, especially on new fiber technologies and biomimetic (protein-based) polymers, could lead to important building blocks for body armor, such as filaments, cloth, or matrix materials that could be filled with ceramic powders. Other building blocks for body armor include micro- layered composites (such as ceramic-metal, ceramic-polymer), gradient materials with hard coatings (such as carbonitrides), and hybrid materials with smart properties. Active Protection Systems In the AAN time frame, it may be feasible to develop active protection systems for soldiers using technologies and techniques developed for active protection systems for vehicles (see Appendix D). When sensors detect a projectile threat, a smart defeat or energy-absorbing system could be activated to increase the soldier's survivability. MEDICINE AND NUTRITION The soldier in the AAN will have complete SA of his position, the location of his unit and other friendly forces, and the location of enemy forces. Similarly, each unit will have SA of the individual soldier" his location, how much ammunition he has, how much water and food he has, and his state of health. The Navy already has a system under development for transmitting medical information. The system is a vest with a grid of fibers. When a group of fibers is tom by a projectile, the location and the extent of the wound (as well as the location of the sailor) are transmitted to a central location where medical personnel perform triage. Because medical support on the battlefield will be minimal, the decision of whether or not first aid is required will be critical.

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SOLDIER SUSTAINMENT 131 Up to now, the Army has had limited success with exoskeletal arrays. However, as new sensors and controls and new materials are developed, the Anny may decide to reevaluate these areas. It is certainly well within the Army's research and development capability to develop a medical patch through which wounded soldiers could receive blood coagulants, pain killers, and other medicines. Uniforms, boots, and gloves could be structured to serve as splints for broken bones. With telemedicine, diagnoses can be made from outside the battle areas and enable minimally trained soldiers to perform life- saving procedures. The space program could be a mode! for sustaining soldiers in AAN combat scenarios. Astronauts can function for long periods of time without resunnIv. without resupply "Toothpaste tube meals," for example, already weigh less than the predicated combat ration weight of 0.S pounds per meal. By 2025, a nutrient patch could be developed that would minimize the requirement for bulky food rations. Astronauts also recycle urine, which reduces the need for an external water supply. Pills could be developed to improve the soldier's performance in combat. To paraphrase the motto of DuPont, we would have "better soldiering through chemistry." One pill might enable an individual to operate effectively for 24 hours a day while another might increase visual acuity or hearing. Pills might also enhance physical and cognitive abilities or reduce susceptibility to biological and chemical attacks. OTHER TECHNOLOGIES Research in several other areas important to AAN soldier logistics has been promising but has progressed slowly and has not received significant support. Some of the potential benefits are described below. Lightweight protective garments could reduce the weight of current chemical protective garments from 15 Ibs. to 6 Ibs., possibly even 3 Ibs. Anny planners should also carefully consider the benefits of thermal management. Cooling the soldier ensem- ble could significantly reduce the need for large quantities of water in arid areas. The current overgarment for thermal management weighs 15 Ibs. and uses 200W of electric- ity for three hours. Improved protective garments could weigh 6 Ibs. and use 300W for 12 hours or more. The weight of rations for an AAN battle force of 8,000 soldiers deployed for 14 days would be about 135 tons, which is only a small fraction of the total deployment weight. Improved ready-to-eat meals (MREs) could reduce the weight of combat rations carried by the individual soldier from 1.5 Ibs. to 0.8 Ibs. Current DoD planning for portable water consumption is 20 gallons per soldier per day, with 3.9 to 7.7 gallons for drinking, personal hygiene, field feeding, and treatment for heat injury. Water weighs 8.34 Ibs. per gallon. In high temperature areas, as many as 200,000 gallons, weighing approximately 650 tons will be required per day for the AAN battle force. The total water requirement for a 14-day deployment would weigh more than 9,000 tons. In contrast to food rations, this is a significant fraction of total deployment weight. Therefore, developing storage, distribution, quality control, and treatment technologies for water will be essential. Rapid bioremediation of nonpotable water sources could be available by 2025. In addition, AAN concept developers should address questions of water usage and reassess their assumptions about the amount of bottled water to be supplied.

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132 REDUCING THE LOGISTICS BURDEN FOR THE ARMYAFTER NEXT Current capabilities for field feeding include burner units, containerized kitchens, and nameless ration heaters. The capabilities that will be necessary for AAN are on-demand feeding, automated ration dispensing, self-heated rations, and self-chilled beverages. If AAN soldiers could subsist solely on combat rations, these technology and support requirements would be reduced considerably. FINDINGS The individual soldier will be the single most essential combat system in the AAN. As part of a battle force with minimal logistical support, technologies will have to extend the soldier's range and duration of self-sustained operations. Reducing soldier logistics will have a multiplier effect of increasing combat effectiveness and reducing logistics burdens for medical support, water, and food. Because individual soldier logistics are an essential part of AAN, the Army should consider establishing a science and technology objective (STO) to focus on technologies to extend the range of self-sustained soldier performance to distances and durations that would enhance AAN operations. The STO would adapt M&S tools to analyze and determine objectives for the soldier as a system that would both reduce logistics demand and increase combat effectiveness. Although it may appear that the potential for reducing soldier logistics is small in comparison to reducing the logistics burdens for fuel or ammunition, the committee believes that soldier logistics deserve special attention and that research and technology development for AAN soldier sustainment should be treated in a separate context. The Army's Soldier System Command (or successor organization) that is now responsible for development of soldier systems, should be expanded to include management, funding, and trade-off analyses for the AAN soldier.