Click for next page ( 65


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 64
5 Operational and Tactical Mobility The AAN will be designed to project power via a battle force in the United States that can be moved rapidly to the battle area to engage in decisive combat. The force might be moved to a staging area first or, perhaps, directly to the battle area. In either case, the force will have to move across land and water before engaging the enemy in combat. This chapter discusses the operational and tactical mobility of the AAN battle force. Operational mobility is defined as movement from the staging area to the battle area. Tactical mobility is defined as movement in the battle area. Strategic mobility, the movement of the battle force from the United States over several thousand kilometers of land or sea to the staging area, is discussed in Chapter 9. Mobility is critical because it dictates the pace of battle and the pace of resupply. Fuel, one of the major logistics burdens, is closely linked to mobility. The capability to resupply the force depends directly on the capability of moving supplies, equipment, and personnel, as well as fuel and ammunition, to the battle area. A major objective of the AAN will be to move the battle force to the battle area and close with the enemy at speeds averaging 200 km/in, five times as fast as the speed in the Gulf War. OPERATIONAL MOBILITY For this discussion, the committee defined the range of operational mobility, the movement from the staging area to the battle area, as 300 to 1,000 km. Two programs that would address the operational mobility requirement are the loins Transport Rotorcraft Program to develop an advanced transport helicopter and an advanced tiltrotor program to develop a successor to the current V-22 Osprey ("super-Osprey"~. According to briefings by representatives of the ARL and the Army aviation community (Bill, 1997; Kerr, 1997; Scully, 1998), the present goals of both Arrny programs are to lift 15 tons (the desired maximum weight of an advanced fighting vehicle) up to 1,000 hen and to consume less fuel than present Army aircraft. Meeting these ambitious goals will require more than tripling the lift capability of present Anny utility helicopters or quadrupling the lift capability of the V-22 Osprey. Many insiders are skeptical that the Army can meet these goals. For example, the chief of the Aviation and Missile Command was reported to have said that a range of perhaps 500 km, half the goal, was realizable. Increases in the fuel efficiency of aircraft engines of up to 25 percent could be demonstrated, but 60 percent, the estimate for AAN systems, would require "radical engine redesign" (Winograd, 1998~. If the Army did meet its goals and could field a helicopter or tiltrotor aircraft capable of lifting 15 tons, with a mission radius of 1,000 km and a cruising speed of 64

OCR for page 64
OPERATIONAL AND TACTICAL MOBILITY TABLE 5-1 Battlefield Mobility Trade-offs for Transport Aircraft Fleet Size Fleet Flyaway Cost Flying Timeb (billions of dollars) (hours) 250 1 1.75 49.3 500 23.50 24.7 750 35.25 16.4 1000 47.00 12.3 1250 58.25 9.8 1500 70.50 8.2 1750 82.25 7.0 2000 94.00 6.2 aAssumes cost of $47 million per aircraft bAssumes the staging area is 1,000 km from the area of operations, 2,000 ground vehicles are transported, arid a cruising speed of 325 km/in 65 325 km/in, it could cost as much as $47 million per vehicle. The Army Mobility Integrated Thea Team estimated that the fuel required for such an air carrier mission would weigh 22 tons (Bill, 1997; Kerr, 1997; Scully, 1998~. Table 5-] shows the estimated flyaway cost and flying time for several sizes of rotorcraft fleets that could transport 2,000 ground vehicles for a nominal AAN battle force. The flying time in Table 5-1 was calculated by assuming that one vehicle would be transported each trip, the cruising speed was 325 km/in, and the aircraft returns to the staging area empty (or with a minimal loads. The estimates include only the time the aircraft is in the air. No time was allotted for loading, transporting, or unloading anything other than vehicles, such as fuel or other supplies. No time was allotted for refueling, crew rest, etc. The smallest fleet in the table comprises 250 aircraft, which would cost $11.75 billion and would require more than 48 hours of continuous flying time to transport 2,000 ground vehicles to the battle area. The largest fleet shown in the table is 2,000 aircraft, which could transport 2,000 vehicles in a single six-hour trip. However, this fleet would cost $94 billion to build. The JP-8 fuel required to transport the 2,000 vehicles to the battle area is 44,000 tons (2,000 trips x 22 tons/trip) for all of the fleets in the table. Assuming the deployment weight of this nominal battle force with no replenishment for two weeks is around 12,585 tons (see Chapter 2), the fuel required" to transport just the combat vehicles by air would weigh as much as three times the entire battle force. One could legitimately argue that this burden would be incurred in the staging area and not by the battle force and that commanders would select staging areas with ready supplies of fuel and water. Even so, the aircraft providing for the operational mobility of an AAN battle force would add to the logistics burden, and might not be affordable. The aviation community has initiated a study to reduce the unit flyaway cost of the lift rolocraft from an estimated $128 million per aircraft to $47 million.

OCR for page 64
66 RED UCINrG THE LOGISTICS BURDEN FOR THE ARMYAFTER NEXT In some scenarios, the U.S. Air Force C-17 fleet planned for strategic airlift could be used to convey the battle force from the staging area to the battle area. A single C-17 could carry as many as five 15-ton AAN vehicles, and the flying time for one round trip would be 2.2 hours. The planned fleet of C-17s will comprise 120 aircraft. Using the entire fleet would require 400 trips, or three-plus trips per aircraft, for a nomi- nal seven hours of flying time. In other words, this C-17 fleet is comparable to a fleet of 1,750 to 2,000 rotorcraft. (The obvious obstacle to relying on C-17s for operational mobility would be the need for airfields in the battle area.) The last Army-operated fixed-wing aircraft was the C-7 Caribou, which was based on late-19SOs technology and could carry 30 passengers or a load of 5 tons. This aircraft had excellent short take-off and landing characteristics, even from unimproved air strips. The Army relinquished the Caribou to the Air Force in the 1960s, however, as part of a redefinition of roles and missions by DoD. The Army, therefore, faces a dilemma. On the one hand, the aviation research and development domain of the Arrny is in rotorcraft, including tiTtrotor craft. Even if planned developments are completely successful, the aircraft would not be able to meet the AAN fuel efficiency goal, and a fleet big enough for the nominal force structure and rapid operations of current AAN mission concepts would not be affordable. On the other hand, aviation technology that would be better suited to the AAN force structure and tempo of operations has been removed from the domain of the Army's roles and missions. For example, some aerodynamic studies suggest that control of the airflow over fixed wings could increase lift significantly (Bushnell, 1998~. Even if the Army undertook a program to develop or improve fixed-wing aircraft, based on existing defense policy, the Arrny would probably be denied pe~ission to procure it. In short, although considerable basic and applied research would be necessary to field improved fixed-wing aircraft to meet the Army's operational mobility needs, the Anny would find it difficult, if not impossible, to support this research and insert the results into its programs. The capability of moving the battle force from the staging area to the mission area is the prerequisite for battle. Operational mobility will be the first essential phase of the combat and logistics operations for an AAN battle force. Even with major fiscal support, the two present Army programs for transporting combat vehicles by air have little chance of providing operational mobility for a nominal AAN battle force by 2025. The loins Transport Rotorcraft could provide operational mobility in the range of the AAN requirement (1,000 km), but only for a much smaller force than the AAN battle force. A fleet required for an 8,000-man, 2,000-vehicle battle force would probably not be affordable, either to acquire or to operate. Unless the battle force concept can be altered to reduce the need for soldiers and vehicles on the ground, the AAN will have to depend on the Air Force and Navy not only for strategic mobility (see Chapter 9) but also for a significant part of its operational mobility. But neither of the Army's sister services is now planning capabilities that could support an AAN battle force. TACTICAL (BATTLEFIELD) MOBILITY AAN doctrine not only emphasizes ground mobility and agility, but also greatly increases the distances associated with tactical mobility. Combined with the objective of reducing the logistics tail, the AAN mobility doctrine exemplifies the principles of

OCR for page 64
OPERATIONAL AND TACTICAL MOBILITY 67 maneuvering and logistics support described by Sun Tzu in The Art of War more than 2,000 years ago: The condition of a military force is Mat its essential factor is speed, taking advantage of others' failure to catch up, going by routes Hey do not expect, attacking where they are not on guard. When you do battle, even if you are winning, if you continue for a long time it will dull your forces and blunt your edge.... If you keep your armies out In the field for a long time, your supplies will be insufficient. Transportation of provisions itself consumes 20 times the amount transported. Sun Tzu, lOO B.C. Three generic solutions to the need for AAN tactical mobility are potentially feasible. The first is the use of aircraft. Despite the problems described in the previous section, the Arrny will have some rotorcraft (rotary wing or tiltrotor aircraft) that could be used to move high priority troops or supplies for critical missions. But rotorcraft have not been planned to move the bulk of a battle force on and around the battlefield as rapidly as necessary to increase the rate of advance and engagement with the enemy to an average of 200 km/in. A second potential solution is a surface ground-effect (SGE) vehicle, such as the wing-in-ground (WIG) vehicles being evaluated by the Navy (Box 5-~. These vehicles, which are based on research begun in the former Soviet Union, operate close to a resisting surface like water, ice, or snow (Skinner, 1998; Reeves, 19981. The aerodynamic mechanisms that provide the lift are not well understood but appear to use the air flow between the vehicle and the surface for more efficient lift and higher forward speed than older ground-effect concepts for "air cushion" vehicles that propel air downward against a resisting surface. WIG vehicles might be used for tactical and operational mobility. However, the lift will first have to be better understood, which will require some basic research. Also, the feasibility of flying in and out of the SGE flight regime, to traverse broken or steep terrain must be explored. The fuel consumption rates of WIG aircraft are estimated to be one-half to one- third of rates for conventional aircraft at comparable speeds. This could translate to a corresponding savings in the logistics fuel burden for strategic or operational airlift. In addition, the speed and capacity of WIG aircraft could enable deployment, within AAN time constraints and mission environments, of heavier materiel and ground systems than could be transported by conventional aircraft. The U.S. Special Operations Command, the U.S. Atlantic Command, and the Chief of Naval Operations Strategic Study Group have all expressed an interest in WIG technology, but fundamental research would be necessary (~) on decreasing wing loading to facilitate entering the SGE aerodynamic regime, (2) understanding the type of air flow, and (3) determining why the flight of a WIG aircraft is so quiet. The third solution is to use ground-traction vehicles. Ideally, the AAN battle force will operate with an advanced fighting vehicle weighing no more than 15 tons, but, to provide tactical mobility for the entire force, it would also employ other ground- traction vehicles weighing 15 tons or less. The committee made a considerable effort to examine the technological underpinnings of this scenario and the obstacles and opportunities it presents. Will a 15-ton, highly mobile, ground-traction vehicle with o a , , ,, ~ _ _ , , ,

OCR for page 64
68 REDUCING THE LOGISTICS BURDEN FOR THE ARMY AFTER NEXT BOX 5-1 Russian WIG Vehicles The former Soviet Union secretly developed wing-in-ground (WIG) aircraft, also called surface-ground effect (SGE) aircraft. Their lift capability comes from an incompletely understood fluid phenomenon in which a high-pressure zone is created between a low-flying object and the surface beneath it, such as ground or water. For properly designed aircraft above a certain velocity, a high-pressure air cushion forms, which keeps the aircraft above the surface. A possible explanation is that the laminar (nonturbulent) flow of air beneath the vehicle enables it to maintain high forward speed with little effort, resulting in high fuel economy compared to more conventional aerodynamic concepts. The phenomenon can be observed in nature when large waterfowl glide effortlessly close to the water. The aircraft developed during the 35-year WIG program were designed to fly at low altitudes over water, ice, and snow. WIG designs fall into three categories: (1) aircraft that fly by SGE at all times, (2) aircraft that fly in and out of the SGE regime, and (3) aircraft that use SGE only on takeoff and landing. Several Russian design bureaus are currently selling WIG technology commercially. The Russians have developed this technology to the point of demonstrating large WIG aircraft, notably the Caspian Sea Monster, which has a maximum takeoff weight of 540 metric tons. This large aircraft has flown at 650 km/in (350 knots) just above a surface of water or over very level terrain. The Caspian Sea Monster was considered to be a threat to U.S. submarines and surface ships. It had four turbojet engines on each side near the nose, and up to four power-augmented ramjets on the tail. Numerous smaller WIG craft were designed and prototyped in the former Soviet Union. For example, an early prototype of the Orlyonok (Eaglet) was about the size of a C- 130, had a takeoff weight of 100 metric tons, and a payload of 13.5 metric tons. A later design for an Orlyonok (not constructed) would have carried a payload of 27 tons. Another WIG design, known as the Lun, weighed 380 tons and was considered to be a threat by Russia's Scandinavian neighbors because a fleet of 10 could have crossed the Baltic Sea with minimal radar signature in 12 minutes and deposited 5,000 troops without warning. Although WIG craft designed after the Caspian Sea Monster were smaller, a WIG craft that could transport 2,000 metric tons was considered feasible. The Soviets pursued WIG technology for naval and military concepts to the point of test-f~ring a missile from the Lun. Once developed, this capability could have posed a serious threat to U.S. surface ships. A large WIG could fly at 650 km/in, undetected by radar, and launch antiship missiles. The program to develop a WIG missile capability ended when the Soviet Union broke up. The British reportedly confirmed the SGE phenomenon when a Vulcan bomber, a 210-ton aircraft, experienced an unexpected increase in speed of 20 to 30 percent and a dramatic reduction in fuel consumption in low altitude flight (approximately 100 feet). The speed was as high as 937 km/in. Although the delta-wing geometry of the Vulcan is not optimized for SGE, the aircraft displayed unexpected endurance in this test flight. Source: Skinner, 1998; Reeves, 1998 greatly reduced logistics demand possible by 2025? If so, what would the vehicle be like? To answer these questions, the committee drew heavily on the Tong-term work of the Anny's TARDEC (Tank-Automotive Research, Development and Engineering Center) and the Corps of Engineers Waterways Experiment Station (WES) on vehicle dynamics and the development of ground-traction vehicles.

OCR for page 64
OPERATIONAL AND TACTICAL MOBILITY Wheeled Versus Tracked Vehicles 69 Ground-traction vehicles move either on wheels or tracks. Other factors being equal, wheeled vehicles are generally weigh less than tracked vehicles, have greater fuel economy, and require less maintenance. Tracked vehicles typically provide more robust mobility over difficult terrain, soils, and obstacles (that is, they are less likely to become stuck). Therefore, a reasonable objective for AAN is a wheeled vehicle, either manned or unmanned-provided it is demonstrably either equivalent to a tracked vehicle in mobility or "mobile enough" for a particular mission. In many terrains, wheeled vehicles are fully capable of performing the mission; witness the large number of wheeled combat and support vehicles used by armies worldwide. In addition, many wheeled vehicles use commercial engines and transmissions and have far better fuel economy than tracked vehicles (Petrick, 1990~. Many studies have been done comparing the performance of wheeled and tracked vehicles. Choosing between wheeled and tracked vehicles has, in fact, at times been an emotional subject in Anny circles. In most cases, the Army has selected the "safest" approach for combat missions, namely, tracked vehicles, even though the cost of acquisition and logistics support has been higher than for wheeled vehicles. Previous studies have led to the generalization that wheeled vehicles are most suitable below 10 tons, tracked vehicles above 20 tons, with a gray area in between where the choice depends on operating and support costs, terrain, and logistics. Based on this general rule, a 15-ton wheeled vehicle for AAN would be the Army's preference but would not be a clear-cut choice. M&S (modeling and simulation) can yield some insights into the advantages and disadvantages of wheeled and tracked vehicles for AAN operations. As noted previously, a starting point for M&S of combat vehicle performance is the NRMM (North Atlantic Treaty Organization Reference Mobility Model). The NRMM describes the following five factors as limits to vehicle mobility. Maneuver-controlledt speed is the limit imposed by man-made or natural obstacles, such as forests or rivers. Force-controlled speed reflects the inability of a vehicle to move through unfavorable soil conditions or up a steep slope. Visibility-controlledt speed is the limit on speed imposed by the driver's inability to see what is over the next hill or around the next corner. Rid~e-contro1~ledt speeds is the limit on speed imposed by the amount of energy the human body can absorb while moving over rough terrain. Tire-controlled speed is the speed at which tires begin to disintegrate. WES has conducted exhaustive tests comparing wheeled and tracked vehicles in tees of these five factors (DA, 19911. As expected, tracked vehicles exhibited a higher maneuver-controlled speed. (The wheeled vehicles that were tested tended to nose down and had insufficient traction to exit linear obstacles, such as ditches.) The tracked vehicles also moved better over unfavorable soil because of their larger area of ground contact. However, tracked vehicles had no advantage in visibility-controlled situations and no inherent advantage in ride-controlled situations. (WES has found that combat vehicle speed in many areas of the world is ride-controlled.) Enabling technologies that could raise the limit of each speed-limiting factor are described below.

OCR for page 64
70 Maneuver-Controlled Speed REDUCING THE LOGISTICSBURDENFOR THEARMYAFTER NEXT Some obstacles, such as dense forests and large rivers, cannot be traversed by either wheeled or tracked vehicles. Remote sensing could offer the commander alternative routes to an objective (see the discussion of situational awareness in Chapter 6~. Software to speed processing of obstacle information gathered by the sensors is especially important. Active suspension and some type of"ditch-ejector" would assist a wheeled vehicle in breaching minor linear obstacles. A "smart" suspension system would increase both cross-country speed and improve the crossing of small trenches and obstacles. Force-Controlled Speed A high ratio of horsepower to weight would help overcome this limit. Remote sensing of soil conditions would be useful for determining the soil conditions of various routes. Guaranteed traction to each wheel can be accomplished with slip control. Articulated powered joints, to permit both the coupling of modular vehicle units and the powered elevation of selected units, would also help overcome this limitation and would enhance the vehicle's ability to cross trenches and small obstacles. Visibility-Contro/~led Speed Visibility-enhancing sensor systems will be key to overcoming this limitation. These sensors could "peer through" (penetrate) smoke, obscurants, and foliage far enough to allow the driver to increase speed. Decision aids, a heads-up display, and elevated optics would also help drivers maintain high ground speeds when normal line- of-sight vision is limited. Ride-Controlled Speed The impact energy transmitted to the driver could be limited by active- suspension technology or mechanical isolation of the cab. A radical approach that would eliminate this limitation would be to remove the driver (and crew) from the vehicle; that is, to use uncrewed vehicles. Evidence has shown that drivers can adapt to the severe "jostling" (trilateral acceleration) associated with cross-country driving, but soldiers rarely experience these conditions frequently enough during training to become acclimated because the risk to both the driver and the vehicle is considered unacceptable to most commanders. Vehicle simulation trainers with three-dimensional movement would be useful for training drivers to operate at high speeds over rugged terrain. Tire-Controlled Speed New tire materials and centrally controlled tire inflation capability (assuming the tires are pneumatic) could help overcome this limitation. Control of tire pressure would

OCR for page 64
OPERATIONAL AND TACTICAL MOBILITY 7 r 1 match the vehicle tires to the soil conditions. Run-flat tires, which will soon be commercially available, would also be useful for wheeled combat vehicles with pneumatic tires. Tire and tread materials that minimize the heat caused by deformation would reduce not only the wear due to thermal deterioration but would also reduce the significant thermal signature of both wheeled and tracked vehicles. General Comments . The committee compared the advantages and disadvantages of future wheeled vehicles supported by the enabling technologies described above with tracked vehicles in terms of meeting AAN performance objectives, as well as in terms of reducing logistics burdens. Given the AAN objectives, the committee concluded that the Army should focus on advanced wheeled vehicles for the AAN. Of course, trade-off analyses will be necessary to confirm this preliminary conclusion. The trade-off analyses should quantify the relative advantages of various wheeled and tracked vehicle configurations using the distributed M&S environment. A suitable family of vehicles for the AAN would incorporate lightweight, high- performance materials, possibly organic-matrix or metal-matrix composites, nonconven- tional metal alloys, or intermetallics (see Chapter 4 and Appendixes C and D). These vehicles would consume less fuel and require fewer spare parts and maintenance support than current vehicles. Most important, the AAN commander would have a mobile force that could traverse moderate terrain at more than 130 kilometers per hour (80 miles per hour). ("Moderate terrain" excludes both impassable areas, such as the Swiss Alps, and favorable areas, such as the Saudi Arabian desert; in the latter, higher speeds may be possible.) The vehicles would have a rich array of sensors to ensure situational aware- ness and could be operated with a minimal or even no crew. However, the 15-ton vehicles in this family will have much less protective armor than current battle tanks. They may be equipped with a variety of active protection devices in addition to armor (see Appendix D). To survive the most lethal enemy fire, they would depend mostly on avoiding being hit through situational awareness, agility, and stealth. The committee, unlike many individuals in the Army, is not convinced that the power plant for future vehicles ought to be either electric or hybrid-electric. As the committee noted in Chapter 4, the duty cycles typical of suggested AAN operational concepts might not give hybrid vehicles an advantage in fuel economy over straight mechanical drives. Careful exploration of the likely duty cycles for typical AAN missions, as part of rigorous design trade-off analyses that include other considerations, such as electric power for armaments and other subsystems, will be necessary to determine the optimal power plant and drive configuration (see Appendix E). The main armament of the lead combat vehicle may not be a gun capable of kinetic energy penetration of heavy armor. A quantified study of trade-offs other platforms or systems to defeat heavy armor (see Chapter 6~. The committee believes that M&S is the only way the Army can evaluate and assess requirements for AAN combat vehicle designs. may favor competing

OCR for page 64
72 REDUCING THE LOGISTICS BURDEN FOR THE ARMYAFTER NEXT Remote Sensing to Enhance Battlefield Ground Mobility A continuing concern of the Arrny mobility community has been that detailed, accurate terrain data for cross-country movement might not be available from pre- operation mapping. An initiative under way by the National Imagery and Mapping Agency is to map more than 80 percent of the worId's surface (the missing areas will be in the polar regions). However, the data will have a vertical resolution of only 30 meters, which is not adequate for planning cross-country movement. Although the sensor technology, when used with a conventional aircraft as the platform, can acquire data at a 10-meter resolution, translating the data into a usable digital product at maximum resolution requires enormous computational capabilities; each hour of data acquisition would require 50 hours of processing time. The U.S. Army Corps of Engineers' objective for supporting military operations is to provide a digitized elevation map for a 90-km2 area to a vertical resolution of one meter within 72 hours, from the start of data acquisition by an aircraft (possibly a UAV) until the digital product is delivered to the operational commander. Although this capability would provide a terrain baseline, many things can change in a combat area in 72 hours. The enemy could blow up a bridge. Rain could make a route impassable. The destruction of a dam could flood an area. Enemy sappers could construct an impassable abatis. In addition to baseline data, a commander planning or executing a maneuver from point A to point B would benefit from real-time updates of changes in the terrain (i.e., physical and cultural geography). The sensor system, perhaps linked to the global positioning system for accuracy, would report changes to the terrain database in the area of potential maneuver routes for all operations. Developing this capability would require the resources and cooperation of WES, TARDEC, the Corps of Engineers Topographic Laboratory, and perhaps others. Reducing the Size of Vehicle Crews Reducing the crew size in a fighting vehicle can reduce the vehicle weight considerably because the enclosed volume can be reduced, requiring less material, particularly less armor. Reducing the size of the vehicle can also aid in stealth and agility trade-offs with the weight of passive armor (Appendix D). The ultimate in crew reduction is an unmanned (robot) vehicle. Besides the 15-ton crewed fighting vehicle, the Army has considered 7-ton crewed and uncrewed vehicles. if progress is made in research and development, even smaller unmanned ground vehicles (UGVs) designed for special combat purposes may be feasible. Specialized UGVs might range in weight from a ton down to just a few kilograms. The various military services are developing UAVs (unmanned aerial vehicles) and unmanned undersea vehicles (UUVs), in addition to UGVs. At present, the principal drivers for these programs are operational and performance objectives rather than logistics. Many factors specific to each vehicle concept and its intended use in the force affect whether an unmanned vehicle will increase or decrease logistics support requirements. Smaller UAVs and UGVs could be used as sophisticated mobile sensor systems, " or soldier-safety alternatives (e.g., for clearing mines and "smart weapons,

OCR for page 64
OPERA TIONALAND TACTICAL MOBILITY 73 reconnaissance), rather than as potential substitutes for crewed vehicles (or dismounted soldiers), and they may add to the logistics burdens. If an unmanned vehicle partially or completely replaces a crewed vehicle, a key consideration is the extent to which the unmanned vehicle (or several of them) reduces the number of manned vehicles necessary for a given operational capability. Logistics support requirements will also depend on whether an unmanned vehicle is tale-operated, semi-autonomous, or fully autonomous. Rational decisions about these complex trade-offs require at least unit-level engagement analyses based on detailed system/subsystem engineering models (see Chapter 3~. The use of robotics science and technology to provide automated vehicle subsystems-enabling reductions in crew size for manned systems- seems a promising way to reduce vehicle weight and volume. Furthermore, this incremental approach to removing the human soldier from fighting platforms seems more realistic than unmanned vehicles for reducing logistics burdens in the AAN time frame. Over time, the general approach of subsystem automation could be extended to the automation of some of the vehicles in a platoon of vehicles (or analogous tactical unit that maneuvers and fights in close coordination), with human platoon commanders or other crew in one or more of the vehicles. in effect, the platoon would become a "minimally crewed system," with some vehicles acting as automated subsystems. This "semi-automated platoon" approach to vehicle automation would provide invaluable experience and a test bed for technologies that could eventually (well after 2025) lead to fully autonomous fighting vehicles with the flexibility and effectiveness of today's mounted soldiers. UGVMobility The five NRMM (NATO Reference Mobility Model) factors that affect the cross-country mobility of crewed vehicles can also be applied to UGVs: . . . . . Maneuver-Controlled Speed. If UGVs are smaller than crewed vehicles with similar functionality, they may be more capable of traversing some terrains, such as narrow trails. There will always be some obstacles that a ground vehicle cannot overcome, whether or not a human is aboard. Force-Controlled Speed. Because a UGV does not need a crew cabin, the engine can be larger for the same total system weight, yielding a higher ratio of horsepower to weight. Increasing this ratio is useful for attaining high force- controlled speeds. Visibility-Controlle`1 Speed. The observer-operator of a tale-operated UGV could have a wider range of vision than the driver of a crewed vehicle. The development of sensor systems to improve access to terrain data for drivers of crewed systems will also contribute to UGV development. Ride-Controlled Speed. UGVs may have the greatest advantage over crewed vehicles in this area. The ride-conkolled speed limit for a UGV is the speed at which mechanical shock and vibration will damage the vehicle's mechanical or electronic assemblies. For a given terrain, this speed may be much greater than the speed at which a human occupant can avoid injury and retain operational control of a vehicle. Tire-Controlled Speed. Unless the tires are lighter or of a different type, UGVs would have no direct advantage over crewed vehicles in this area.

OCR for page 64
74 Robot Vehicles REDUCING THE LOGISTICS BURDEN FOR THE ARMYAFTER NEXT A large number of robot vehicles are either in production or under development worldwide. As Table 5-2 shows, most of them are in the United States, where more than 50 percent of the manufacturers and developers for all of the vehicles in the table are located (UVH, 1997~. In terms of the concepts under development and expenditures, most of them are UAVs. However, even after 20 years and $3 billion dollars, the devel- opment of UAVs has not been a complete success. Some of the problems are with the aircraft itself, but the major difficulties involve nonaeronautical problems, such as com- munications, control, electromagnetic interference, and video transmission (Crock, 1997~. Although much of the UAV activity has been led by the Air Force and Navy, the Anny also had a program for a high-attitude UAV called "Hunter" (terminated in 1998) and has been given the responsibility of testing a tactical UAV, the Outrider, for low altitude operation. These UAVs, as well as the rest of the U.S. military developmental program, are platforms for sensors and the communication of intelligence, not weapons platforms. At the research level, however, both the Navy and Air Force have expressed interest in potential weapons-bearing air vehicles (uncrewed combat air vehicles). Table 5-2 also shows that UGVs have not received as much emphasis as UAVs and WVs. Only 17 percent of the worldwide programs by number are for ground vehicles, and only one is currently in development in the United States. Research on UGVs, which the committee considers to be prime candidates as special-purpose vehicles in AAN applications, has laggedfar behind the research on US Vs. The reason for the lag may be that the mobility control environment for traversing terrain is more complex than the relatively homogenous control environments for flight through air or travel under water. in addition to communications and control challenges similar to but greater than those faced by UAVs and UUVs, UGVs must traverse varied soils and terrain. Determining and executing a path, negotiating or avoiding obstacles (natural and man-made), and maintaining or recovering functional traction (avoiding upsets) are challenges UAVs and WVs do not face. ideally, UGVs will operate autonomously, but most existing models are tale-operated; that is, they have partial autonomy but are operated by humans at a distance from the vehicle. Among the various means being investigated to control UGVs in this difficult environment are radio line-of-sight, fiber- optic cable, and hard wires. The UGVs currently produced in the United States run the gamut from small special-purpose devices used by police departments for explosives detection and surveillance, to vehicles the size of construction backhoes used for ordnance removal, to armored bulldozers or tank-like vehicles used for mine detonation (UVH, 1997~. Although these vehicles are listed in Table 5-2 as "in production," in most cases the production volumes are very small. The Arrny hopes to benefit from progress in the development of communication and control for UAVs and UUVs and has several memoranda of understanding with other service programs to share in the technological progress on unmanned vehicles. Obviously, Army resources should be invested in Army-unique ground mobility requirements for UGVs rather than in duplicating the efforts of other programs on unmanned vehicles.

OCR for page 64
76 Current UGVApp/tications REDUCING THE LOGISTICS BURDEN FOR THE ARMYAFTER NEXT When the committee reviewed the Army-unique technological requirements for robot vehicles, it became apparent that the present Army program is part of the consolidated effort under the loins Robotics Program (IRP) directed by the Office of the Secretary of Defense. The IRP program includes a number of components whose names indicate their objectives: Vehicle Teleoperation Capability, Tactical Unmanned Vehicle, Robotic Ordnance Clearance System, Basic Unexploded Ordnance Gathering System, UGV Technology Enhancement and Exploitation (UGVTEE) Program, and the loins Architecture for Unmanned Ground Vehicles (DoD, 199764. The focus of the UGVTEE program is on exploiting research by other DoD and government agencies, as well as industry and academia that meets current Army needs. UGVTEE includes field experiments to help develop the optimal interaction between soldier users and robot-vehicle technologists. A successful robotics program requires, first, that the robot vehicles have the mechanical and technical capabilities to execute the missions assigned to them. Second, the soldier users must know how to make the best use of those capabilities. Third, users must become acclimated to (i.e., "comfortable") working with a mechanical adjunct. A series of UGVTEE field exercises, under the headings of Demo ~ and Demo 1l, are using tale-operated and supervised high mobility multipurpose wheeled vehicles (HMMWVs) to test and evaluate the relationships between users and machines (DoD, 19973; DoD, 1997c). The committee believes these exercises should be continued as more advanced robotics and control technologies for automated vehicle systems are developed. The next step will be Demo III, sponsored by DARPA and intended both to increase the capabilities of supervised and semi-autonomous vehicles and to develop the user-vehicle interface. The committee recommends that the Army continue lending its full support for UGV demonstrations and development. Demo {IT will be necessary to the Army's continuing effort to understand and exploit UGVs. The Army programs in UGVs are conducted by the ARL, TACOM, with support from the WES, and the Army Aviation and Missile Command. Demonstrations of UGVs for the Army are coordinated by the Joint Program Office, Unmanned Ground Vehicles and Systems, which is located at Redstone Arsenal in Huntsville, Alabama, and is similar in organization and function to the Joint Program Office for UAVs. Future Applications for UGVs and Required Technologies A variety ot programs have been proposed for UGVs, ranging from somewhat simplistic tethered vehicles to tale-operated units and semi-autonomous and fully autonomous vehicles. These concepts range in size from full-scale vehicles to matchbox- sized surveillance devices. A summary of proposed applications, compiled by the Institute for Defense Analyses, is listed below (IDA, 1996b). security, such as interior and exterior security of facilities, rear area security, and convoy security robot engineer vehicles to perform specialized functions, such as breaching obstacles and mine fields; digging emplacements and fortifications; detecting, recovering, and detonating mines; and crossing gaps

OCR for page 64
OPERA TIONAL AND TACTICAL MOBILITY 77 combat support functions, such as decoy and deception, laying wire or cable, evacuating casualties, and eliminating obstacles robot trucks and other logistic vehicles for resupplying, rearming, and refueling other vehicles RSTA (reconnaissance, surveillance, and target acquisition) vehicles for robot scouts, special forces vehicles, and reconnaissance for nuclear, biological, and chemical warfare agents . specialized vehicles for urban operations robot vehicles as direct-f~re platforms, howitzers, air defense weapons, nonlethal weapons carriers, or countersniper vehicles Advanced capabilities required to support autonomous vehicles will vary, depending on the tasks the vehicle is required to perform. For autonomous vehicles to serve as RSTA vehicles or as direct-fire platforms, they will have to have the following capabilities: secure communications and control data compression enhanced displays for remote vehicle control autonomous path following and obstacle avoidance automatic target tracking precise real-time location and identification of friendly and enemy units and equipment, including onboard identification of Fiend or foe (TFF) precision targeting and target servicing automatic registration of killed targets By 2025, fully automated, autonomous systems should be capable of emulating various functions of a crewed vehicle or dismounted soldier, but they will still lack abstract decision-making capabilities and other "thought-like" capabilities that involve creativity and ingenuity. These robots will range in size from less than a cubic centimeter to full-sized air and ground vehicles. Autonomous vehicles will be capable of engaging in combat missions involving reconnaissance or mine detection and clearance, as well as serving as weapons platforms for direct and indirect fire. Autonomous vehicles may also deliver supplies and ammunition to ground troops, carry bulk supplies to ports of embarkation, and perform other combat support tasks. Some of the logistics issues related to automated subsystems in a vehicle, as well as to fully autonomous vehicles, are obvious. Compared to a soldier, automated subsystems do not eat or drink, do not need medical care, do not sleep, do not need billeting, and can be squeezed into small volumes. Nevertheless, the logistics support to maintain fully autonomous systems could be considerable, including mechanical maintenance, computer software, and mission planning requirements, in addition to fuel and energy requirements. Less obvious advantages, but the primary logistics advantage for AAN planning, are potential reductions in weight that could be achieved by incorporating robotic technologies into future combat vehicle designs to reduce crew size and to increase combat effectiveness, which could ultimately reduce the number of vehicles needed for the battle force. The committee does not foresee a completely autonomous AAN battle force. One Army officer told the committee that he could foresee a robot wingman for his tank, but he was convinced that there had to be at least one manned vehicle for effective

OCR for page 64
78 REDUCING THE LOGISTICS BURDEN FOR THE ARMYAFTER NEXT combat (Brendel, 19974. If automated vehicles are used in the AAN, the committee believes that a combined force of autonomous and semi-autonomous vehicles, rather than a fleet of fully automated vehicles, will best meet AAN mission requirements. The committee suggests that the Arrny reevaluate the modes of combat in 2025, when the purpose of"combat" vehicles will not be limited (as current tanks are now limited) to "shock," intimidation, and engaging enemy combat vehicles. Designing a single combat vehicle that can play multiple roles will diminish its overall effectiveness. A family of vehicles with common logistics support characteristics, designed to perform complementary functions that increase the survivability of the entire force, would probably be more effective. The evolution of weapons platforms in both the Air Force and Navy demonstrates that direct "eyeball to eyeball" engagement with an enemy in the air or on the sea is not practical (Wilson, 1996~. The Army should consider whether direct engagements by future ground combat systems will be practical. DISTRIBUTED MODELING AND SIMULATION ENVIRONMENT FOR VEHICLE DESIGN Status of Current Modeling and Simulation Tools The NRMM resulted from a significant development program, carried out primarily by WES and TACOM in the late 1960s and continuing through the 1970s, to develop the M&S capabilities required for vehicle system mobility (DoD, 1974~. It is based on speed and tractability parameters that characterize a vehicle's mobility. Once specific values for these parameters have been established (or assumed) and a terrain database characterizing the field of operation is available, the NRMM can predict the time required to move from position A to position B in a tactical environment. Routing algorithms in the mode! select the path of shortest time, avoiding areas of low speed or poor traction. However, the mobility criteria in the NRMM are based on empirical characterizations of vehicle performance, which are significantly influenced by the characteristics of past and present vehicles. Although the NRMM's basic predictive capability for ground vehicles will require some improvements, it represents an asset that could be used effectively and built upon to assess AAN vehicle design and mobility requirements. The NRMM has no capability to model vehicles or mobility concepts that travel off the ground, that is, in the vertical dimension that AAN planners wish to use for in- theater air-mobile operations. In addition, current NRMM implementation, together with supporting M&S tools for engineering analysis of vehicle performance, has significant limitations in the simulation of key elements of vehicle performance (see Box 5-2~. For instance, the VEHDYN (vehicle dynamics subsystem) in the NRMM represents only one-dimensional mobility, straight-line motion on the ground. The NRMM has no capability to represent the three-dimensional dynamic motion of a vehicle traveling at high speed over rough terrain, so it cannot simulate the effects of active suspension or traction control, hybrid-electric propulsion systems, and related new technologies that will have to be assessed to find the best design for achieving the revolutionary mobility objectives of the AAN.

OCR for page 64
OPERATIONAL AND TACTICAL MOBILITY Existing vehicle modeling tools cannot be used to assess the perform- ance or logistics benefits of advanced subsystems and related mobility- enhancing technologies that might en- able a vehicle to operate cross-country at high speed. Nor can they predict fuel consumption or plan routes for ad- vanced technology systems, based on realistic simulations of duty-cycles and corresponding engine power demands (see Appendix E for an example of this kind of analysis for a civilian vehicle). Engineering models that can accurately predict speed, traction, and fuel con- sumption for vehicles with active sus- pension, all-wheel traction control, electric drive, power sources other than internal combustion engines, and a host of other advanced technologies that may be required to achieve AAN off-road mobility objectives have yet to be developed. Tractional force models that represent fundamental physical interactions between the traction surface and a soil or similar soft surface are not yet adequate to mode! high-speed cross-country travel. Accurate simulations of differences in fuel consumption or traction of various system designs under varying operational scenarios (duty cycles), will require models that include realistic representations of the physical processes that determine these important system-level performance characteristics. Without these "first-principles" models, trade-off analyses for alternative designs will be inadequate- unless physical prototypes of the alternative systems are constructed and tested to obtain validated initializing data for the heuristic relationships used by simpler models. Unfortunately, the committee found no evidence that the Army has begun to develop, or has plans to develop, models at the vehicle-system or mobility-subsystem level that would incorporate sufficient "f~rst-principles" modeling to simulate traction and fuel consumption for ground vehicle concepts that are still in the design stage (before prototyping). First-principles modeling capability is a prerequisite for the distributed hierarchical M&S environment to become a reliable too! for making rational trade-offs among vehicle characteristics, tactical alternatives, and force structures in terms of logistics burdens and revolutionary mobility. Advances have been made in characterizing soil surface conditions as a function of weather, but accommodating terrain data from remote sensors will require further refinements. Recent developments reported by WES in predicting soil or terrain characteristics based on historical weather information appear to be promising, but they must be linked with (1) advanced information systems for situational awareness and (2) mobility M&S tools for system performance and analyses of logistics trade-offs. 79 BOX 5-2 Limitations in M&S Tools for Engineering Analysis of Ground Vehicle Concepts Engineering models do not accurately predict speed, traction, and fuel consumption. Model parameters do not account for vehicles with: active suspension all-wheel traction control electric drives (including hybrid electric) power sources other than internal combustion engines Tractional force models based on soil mechanics are not adequate for AAN speeds.

OCR for page 64
80 REDUCING THE LOGISTICS BURDEN FOR THE WAFTER NEXT Technology Extensions Considering the myriad tactical and materiel alternatives that must be integrated to create an effective, logistically supportable AAN battle force, better M&S tools will be critical to making rational trade-offs in the time available. Systematic development of highly mobile systems will require advances in M&S technology in three areas: (1) off-road mobility analysis, (2) mission rehearsal analysis, and (3) driver training for high mobility. Each of these areas is discussed below. OJ/-Roadt Mobility Analysis M&S capabilities to support off-road vehicle mobility have not kept pace with technological advances in vehicle subsystems or with AAN mobility requirements. A broad base of M&S tools will have to be developed (Box 5-3) to meet AAN vehicle system performance and logistics objectives. Significant advances are required in the technology for modeling off-road traction, surface and air propulsion, and related mobility factors. The Anny can take advantage of basic developments in vehicle dynamics, M&S software, hardware-and-driver-in-the-Ioop vehicle driving simulators, and DTS (distributed interactive simulation) of vehicle concepts. The obsolete VEHDYM subsystem of NRMM should be replaced with the simulation software already being used by TARDEC and commercial vehicle manufacturers. Predicting the Faction of highly mobile vehicles on soft soils, including the effects of traffic on soil, will require significant improvements in modeling. Both theoretical and empirical models of the interactions between tires or Packs and soil will be necessary. These models must give reasonably accurate predictions of tractional and lateral forces as a function of spindle position, velocity, and tire or Back speed. Extending the current modeling capability will enable the Arrny to evaluate the benefits of advanced technology subsystems, such as active suspension and Faction control, electric drives, and articulated vehicles. With this capability, the Anny would have the data necessary for making tactical mobility assessments using the NRMM. Synthetic environment modeling of soil characteristics, terrain geometry, and cultural features affecting both ground and air mobility will have to be substantially improved for AAN system analyses. Soil characteristics, both surface and subsurface, which are critical to mobility modeling, must be incorporated into databases that can be populated with data obtained through field tests or in-theater measurements. Terrain geometry and databases should be fully three-dimensional, including the characteristics of obstacle types, such as rocks, Togs, and other geometric features that affect mobility. Cultural features, such as brush, small Pees, and human-buiTt obstacles, that can influence both ground and air mobility should also be incorporated. Empirically based mobility models contained in the NRMM will have to be updated to take advantage of improved capabilities for simulating vehicle dynamics. Knowledge bases and expert systems technology could be incorporated to help the Arrny assess AAN mobility alternatives. Mobility characteristics associated with active suspension and Faction control, local sensing of terrain data, and other advanced technologies for vehicle subsystems must be incorporated into the NRMM tactical mobility representation. These and other extensions to the existing NRMM will be essential for assessing the kade-offs among a wide range of concepts and technologies for AAN vehicles and advanced mobility.

OCR for page 64
OPERATIONAL AND TACTICAL MOBILITY 81 BOX 5-3 Mobility M&S Technology Developments Tractional models for high-speed vehicles on soft soils . effects of prior traffic on soil tire/track soil interaction Synthetic AAN environment modeling for distributed interactive simulation soil characteristics terrain geometry . cultural features affecting surface and air mobility Extended empirically based NRMM mobility models . dynamic simulation capability High fidelity, real-time models of AAN vehicle concepts for hardware and soldier-in-the-loop simulation . traction and vehicle suspension models active suspension and traction control models hybrid-electric power train models Air mobility models . in-theater mobility of an AAN force . integration into next-generation mobility analysis software Fuel consumption models that account for energy dissipation at interface of tire or track with soil interaction with cultural features active suspension and traction control hybrid-electric power trains . vehicle speed and maneuvers Motion-based simulators can test hardware concepts in interactions with human drivers (hardware-and-soldier-in-the-Ioop simulators). Simulators would provide a rapid and relatively inexpensive way to experiment with AAN vehicle concepts and technologies in a "virtual proving ground." The uncertainties associated with vehicle and driver performance at the high cross-country speeds being considered for AAN could be quantified through simulators. In summary, the mobility assessment models currently implemented in the NRMM are based on conventional vehicle configurations and are limited to land mobility; they cannot represent all of the technology and subsystem options available for the AAN. The Army will need engineering M&S extensions, and their associated mobility representations in the NRMM, to analyze revolutionary AAN land-based systems. The following high fidelity, real-time modeling capabilities will be required: traction and vehicle suspension models active suspension and traction control models hybrid-electric power train models

OCR for page 64
82 REDUCING THE LOGISTICS BURDEN FOR THE ARMYAFTER NEXT hardware-and-soldier-in-the-Ioop vehicle concept simulators that can incorporate results from the subsystem models into a virtual proving ground approach for system testing DTS models for analyzing the performance of multiple vehicles as a fighting unit, incorporating results from the virtual proving ground This degree of linking across levels of M&S capability while simulating the real- time behavior of systems and drivers with enough fidelity to yield dependable predictions of the performance characteristics of vehicle systems and tactical units will require advanced computing capabilities. Models and their computer implementation will have to be targeted for the specific class of simulator (e.g., DIS nodes and developmental virtual proving ground simulators). In addition to these M&S extensions and improved linkages for modeling and simulating ground mobility, air mobility models that can represent the in-theater mobility of an AAN force should be developed and integrated into a next-generation mobility analysis software package. These models should focus on the chosen air mobility mechanism (e.g., helicopter, tiTtrotor, or fixed-wing aircraft). in addition, if any of the surface-effect vehicles prove to be viable, realistic design and trade-offs among design alternatives will require an entirely different set of terrain data. The Army will also require fuel consumption models for both air and ground systems. The ground versions of these models should account for energy dissipation at the interface of tire or track with soil, interaction with terrain cultural features, effects of active suspension and traction control technologies, the performance of hybrid-electric power trains, and the effects of vehicle speed and maneuvers. First-principles models of vehicle power train and propulsion subsystems and their interactions with the tactical environment could predict consumption rates as a function of vehicle design and use. Fuel supply is emerging not only as a major AAN logistics burden but also as a critical hurdle to meeting AAN sustainment objectives. Therefore accurate predictions of fuel consumption will be essential to meeting AAN goals. Mission Rehearsal Analysis Mission rehearsal analysis could be based on the same M&S capability used for AAN logistics trade-off analysis. During the committee's deliberations, high-fidelity mission rehearsals using mobility M&S tools was identified as an important means of improving logistical efficiencies through better tactical and mission sup- ply planning (Box 5-4~. Credible mis- sion rehearsal simulations would enable commanders to estimate the supplies required for a specific AAN mission more accurately. Logistics provisioners could then transport "just enough" ma- terie! into the battle zone, reducing the logistics burdens of transporting more materiel than is needed and having to manage the excess during the operation. BOX 5-4 M&S Tools for AAN Mission Rehearsal Analysis Planning tactics Determining supply requirements Designing supportable vehicles Predicting fuel requirements . . . . . . . . M~mmlzmg mlsslon loglshcs

OCR for page 64
OPERATIONAL AND TACTICAL MOBILITY Implementations of the NRMM on personal computers, which were demonstrated to the committee at WES, showed that these mobility M&S tools could be the foundation for mission rehearsal analyses. Although significant development and extension of the basic tools will be necessary to represent AAN vehicle systems and tactical operations, most of this work would also be applicable to analyses of performance and logistics trade-offs. The technological challenge will be to create tools that can be used by war fighters and to implement aIgorithrns that can run on inexpensive field computers. Driver 1 raining Moving combat forces at the high speeds required for AAN operations will require that drivers achieve and maintain speeds as high as 130 km/in across open terrain. Training Army drivers to meet this challenge will require fundamental improvements in driving simulators (Box 5-5~. Committee members discussed the possibilities for training vehicle drivers with test engineers at WES, who noted that experienced professional drivers can achieve much higher cross-country speeds than soldiers who have not been adequately trained. Training simulators that would train soldiers to function effectively at high speeds would have to have very high fidelity and include the harsh motion cues encountered during high-speed cross-country maneuvers. Systematic testing and evaluation with advanced motion-based simulators could be used to determine the level of fidelity of simulator motion cues in a training simulator for AAN applications. The M&S capabilities required for this functionality would be derivatives of those required for determining vehicle system trade-offs and defining logistics requirements. However, none of these capabilities exist today. The development of M&S technology for driver training simulators should be integrated with the development of vehicle systems. Driver training simulators would be effective tools for assessing human factors, optimizing training simulations, and assisting in development of vehicle system designs. Training simulators could also be integrated into a DIS environment for operational testing and evaluation. This would 83 BOX 5-5 Vehicle Motion Simulators Test drivers are capable of much higher cross-country speeds than soldiers in the same vehicles because: soldiers are not permitted to train at speeds that would damage vehicles motion cues are essential for training soldiers to achieve high vehicle speeds High fidelity models for training soldier drivers: . are developed with trade-off analysis models will require computational advances to run in real-time training simulators Simulators to meet AAN speed objec- tives: will use tests and existing simulators to determine required motion cues. should be built for use during design and system trade-off analyses . . ~ . . . . . . . . . . . . .. . . . require that a tralnmg simulator be cleveloped prior to the actual venlcle system.

OCR for page 64
84 REDUCING THE LOGISTICS BURDEN FOR THE ARMY AFTER NEXT SCIENCE AND TECHNOLOGY INITIATIVES TO REDUCE MOBILITY LOGISTICS BURDENS Based on the preceding analysis of the logistics burdens associated with mobility requirements for AAN-style operations and the technological opportunities for reducing these burdens, the committee concluded that the Army should pursue the following areas of research and technology development. The order of the numbered items under a heading reflects a rough order of priority. Operational Mobility Air Mobility Alternatives. The committee is not optimistic that the Army's current or planned aircraft programs will provide the operational mobility necessary for AAN missions. The R&D risks in this area are high, and the acquisition costs may be prohibitive. In addition, even if the R&D objectives are realized, the resulting aircraft will add significantly to overall logistics demand for the AAN battle force mission. Nonconventional, novel concepts for air mobility, however, might lead to a revolutionary breakthrough. The WIG concept is one example of an approach that seems to warrant a careful and open-minded evaluation. Although WIG technology has been demonstrated to some extent, both fundamental research on the aerodynamic principles and thorough feasibility studies would be essential before the Army could make a commitment to technology development. A similar combination of foundational research and exploratory testing for feasibility in military operations would apply to other novel air mobility concepts. The search for new approaches to air mobility should be a joint effort; at the same time, the Army must ensure that Army requirements are fully met in the process. (This initiative pertains to reducing logistics demand for the operational mobility requirements for the AAN battle force. Obviously, the battle force will also have a continuing need for a limited number of aircraft for combat and support missions the battle area.) Tactical Ground Mobility 1. Mobility M&S Environment for System Design and Trade-off Analyses. Decisions regarding vehicles will be critical to determining AAN logistics needs. These decisions must be made from a total systems perspective. The choice of fuel, for example, cannot be made without considering the vehicle power plant. The choice of vehicle power plant cannot be made without careful consideration of the vehicle duty cycle. The choice of power plant may also determine the main gun; conversely, the choice of the main gun may influence the choice of power plant. The development of a family of vehicles that weigh 15 tons or less is not only feasible but also desirable for meeting AAN operational goals. The technologies for an advanced wheeled vehicle can be developed in the near term because many of them have already been implemented and could be integrated into a total system with relative ease. Unfortunately, the current vehicle mobility models (the NRMM) are inadequate to assess the performance and logistics benefits of active suspension and traction control, electric drive power trains, or other advanced subsystem technologies. These models cannot simulate cross-country speeds as high as 130 km/in, certainly not 200 km/in. They

OCR for page 64
OPERATIONAL AND TACTICAL MOBILITY 85 cannot be used to optimize route planning for both speed and fuel conservation. Therefore, the NRMM is only a starting point for the development of AAN mobility concepts. The Anny should support updates and extensions of the NRMM for the kinds of design and trade-off studies discussed in this chapter and in Chapter 3. Developments in M&S technology that would support off-road mobility analyses are listed below: . traction models for high-speed vehicles on soft soils that can represent the effects of prior vehicle action on soil and the interaction of tires or tracks with the soil and can incorporate soil characteristics, terrain geometry, and cultural features enhanced NDMM with an updated VEHDYN simulation subsystem high-fidelity, real-time motion simulators for hardware-and-soldier-in-the-Ioop simulations that can be used as virtual proving grounds for advanced vehicle technologies and design concepts, as well as for modeling human-vehicle interactions and for driver training air mobility models, integrated with next-generation mobility analysis software, to analyze the in-theater mobility of an AAN battle force M&S capability for fuel consumption that accounts for energy dissipation at the tire or track interface with soil, for vehicle interaction with cultural terrain features, and for assessing candidate technologies and design concepts for AAN vehicles 2. Technology Development to Support a 15-Ton Wheeled Combat Vehicle. In contrast to the aircraft program, major improvements in ground vehicle mobility are possible and not excessively challenging. The committee considers a number of advanced technologies and design concepts to be well within the realm of near-term development. Use of these technologies would enable the expanded use of wheeled vehicles for AAN, achieve the principal AAN objectives, and enable meaningful logistics trade-offs during system design. The committee recommends that a research and development program be established to demonstrate these capabilities within a five- year period. TARDEC and WES are currently doing some research in ground mobility; however, the Army has not placed a high priority on developing a wheeled vehicle, and the WES program has suffered from lack of financial support. 3. Look-Ahead Sensor Systems to Increase Vision-Controlled Speed. Sensors for cross-country mobility have enormous potential and little technical risk. A program in this area would require the resources and cooperation of WES, TARDEC, the Corps of Engineers Topographic Laboratory, and perhaps others. 4. Reducing Crew Size through the Evolution of Automated Systems Technologies. Fully autonomous ground vehicles will be important for performing specialized functions, but UGVs will not replace crewed vehicles and will not lessen the logistics burden. In the Tong term, as automated subsystems are incorporated into manned systems, UGVs may become a component of platoon-like fighting units, in which fewer vehicles will require human operators. The UGVTEE Demo Ill programs previously discussed appear to be worth pursuing for the specialized capabilities it could offer an AAN battle force, although logistics burdens may not be immediately reduced.

OCR for page 64
86 REDUCING THE LOGISTICS BURDEN FOR THE WAFTER NEXT 5. Mission Rehearsal Extensions to Mobility M&S Tools. Mission rehearsal mobility analyses will be essential for tactical planning and for determining logistics support requirements. A mission rehearsal capability based on mobility M&S tools can be helpful for designing supportable vehicles, forecasting fuel requirements for AAN operations, and minimizing mission logistics. 6. Driver Training Extensions to Mobility M&S Tools. The high-fidelity models and simulators required to train drivers without risk to them or their vehicles could be developed along with M&S simulators for mobility trade-off analyses. However, running training simulators in real time will require computational advancements.