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Defense Manufacturing Capabilities Required for 2010
Introduction
Historical events have always influenced the United States' perception of its defense needs, which, in turn, have influenced the nation's commitment to maintaining defense manufacturing capacity and supplies. Threats to national security today are substantially different, although no less demanding, than those of the Cold War period. Currently, defense policy focuses on regional rather than global conflicts that will most likely involve conventional rather than nuclear weapons. Therefore, conventional weapons and related manufacturing systems are being given higher priority for research, development, and procurement funding than nuclear systems.
Although many nuclear systems have been removed from alert status, decommissioned, or destroyed as required by the Strategic Arms Limitation Talks II (SALT II) and other agreements with the former Soviet Union, the United States maintains a nuclear deterrent. As long as Russia, China, or other potential adversaries have a nuclear strike capability, U.S. policy will require that a credible nuclear retaliation force be maintained. Strategic nuclear forces, although significantly reduced in size, must remain reliable and effective. Modifications and upgrades to the residual nuclear-capable force must continue as needed to maintain their readiness and effectiveness.
Today's force structure, personnel, and military equipment have been adapted to fulfill stated national policy requirements. Weapons systems designed and produced today must meet a broader range of mission requirements and must be reconfigurable in the field. This requires improved design methods and
manufacturing processes, and manufacturing systems that enable the customization of weapons systems. In addition, manufacturing facilities must have production surge capacity to make rapid modifications and provide additional inventories in times of crisis.
Defense Needs for 2010
The committee reviewed DOD documents to determine the technology areas that will be important for future defense manufacturing, including a DOD technology forecast regularly generated in an effort to plan for future needs. This forecast, known as the Defense Technology Area Plan (DTAP), presents DOD's objectives and investment strategies for the technologies considered to be critical to its acquisition plans, war-fighting capabilities, and joint war-fighting needs. The DTAP contains defense technology objectives in 10 technology areas: air platforms, ground and sea vehicles, weapons, sensors, electronics and battlefield environment, information technology systems, materials processes, chemical/biological defense and nuclear systems, biomedical systems, and space platforms (DTAP, 1997).
Defense-Critical and Defense-Unique Technologies
Product and process technologies are classified by DOD as "defense-critical," "defense-unique," or both, and they span the industrial technology spectrum. Whether or not a product technology is considered defense-critical depends on its applications. A manufacturing process technology is considered defense-critical if it is required to produce a defense-critical product. For example, microprocessors and other electronic technologies, which are indispensable to many defense systems, are defense-critical. A product or process technology is considered defense-unique if it is used only for defense purposes and has no commercial application. Therefore, a defense-critical technology may or may not be defense-unique, whereas a defense-unique technology is always defense-critical.
There are literally hundreds of technologies, subsystems, and systems that could be characterized as either defense-critical or defense-unique. The committee made no attempt to list them all or to describe them all in detail. Instead, the committee analyzed the range of DTAP defense-critical technologies under consideration and concentrated on those that were either defense-unique and, therefore, not likely to be developed by commercial industry, or those that had defense-unique applications, although the technology itself was not defense-unique. The committee then selected the technology areas that were most dependent on advances in manufacturing.
Weapons Systems Platform Technologies
Aircraft Weapons Systems
Weapons systems for air warfare, such as long-range bombers and maneuverable supersonic stealth fighters, will be necessary for the foreseeable future. Systems capable of carrying and employing a variety of weapons and of finding, engaging, and defeating enemy air, land, and sea forces and targets require many defense-unique technologies and manufacturing capabilities not available in the commercial world.
Although all air weapons systems require some cross-cutting technologies with defense-unique applications, only fighters and bombers require defense-unique technologies. Military transports, trainer helicopters, and utility aircraft require essentially the same technologies as their civilian counterparts. Because many military aircraft platforms are expected to be long-lived, several manufacturing considerations have become significant including: repair techniques for aging aircraft and nonintrusive, real-time methods for monitoring flight loads and damage (DTAP, 1997).
High g Loads and Acceleration.
An aircraft's ability to sustain loads of eight to nine times the force of gravity (g) and to accelerate rapidly at high-speeds requires high structural strength, unusual aerodynamic characteristics, a high thrust-to-weight ratio, and protecting the crew from the high g loads. A key manufacturing capability is the design and processing of high strength-to-weight materials, particularly composites, for which new design concepts and processing methods are needed to reduce costs. Electronic systems must also be designed and packaged to withstand the high g forces and vibrations in this severe environment.
Weapons Containment.
The ability to carry guns, air-to-air and air-to-ground missiles, rockets, and bombs is a defense-unique requirement for aircraft. Bombers generally carry loads internally in a large fuselage designed to accommodate them; fighters generally carry loads externally on suspension and launch equipment. Different types of launch equipment include multiple-ejector and triple-ejector racks for bombs and ejector launchers for some air-to-air missiles (e.g., the Sparrow) on F-14, F-15, and F-18 fighters. Other air-to-air missiles (e.g., the Sidewinder) are rail launched. All types of launch equipment have two things in common: (1) they add a significant amount of drag to the aircraft, and (2) they have a large radar signature. Research and development in recent years has focused on stealth racks that reduce drag and have a smaller radar signature. With state-of-the-art manufacturing techniques, these racks could be designed and produced, but they would be expensive and would still compromise aerodynamics and stealth performance. Breakthroughs will be necessary to overcome these problems.
Stealth fighters, such as the F-117, F-22, and B-2, carry weapons internally, which reduces compromising the radar signature and does not as severely affect aerodynamic performance. But fighters with internal weapons bays require thicker fuselages and are, therefore, more expensive. The design and low-cost processing of high strength-to-weight materials would be an important step in solving this problem. The acoustic environment in a weapons bay with the bay door open is notoriously severe, particularly at high-speeds, which has design and production implications for the weapons carried, particularly their electronic components. Another defense-unique requirement is that aircraft be able to eject munitions from the weapons bay at very high-speeds and g loadings.
Surface and Subsurface Sea Combat Vessels
Defense-unique challenges for surface sea combat vessels include: reducing topside weight and volume while reducing signature and increasing sensor performance; minimizing the weight and volume of hull, mechanical, and electrical (HM&E) systems while increasing combat tolerance and decreasing life-cycle costs; improving damage fight-through and recovery while minimizing crew size and equipment redundancy; and developing automated intelligent monitoring and control systems for HM&E equipment. In terms of manufacturing, the overall requirement is affordability, which translates into new design concepts and low-cost processes, as well as effective sustainment techniques.
Defense-unique needs for subsurface sea combat vessels (submarines) include: reducing acoustic signatures and increasing shock resistance while reducing costs. These will require new system-level design approaches. Simulations during the design could accurately assess performance and couple cost data to high-level system designs, enabling necessary trade-offs.
Land Combat Vehicles
Land combat vehicles include the M-1 Abrams tank family, the Bradley fighting vehicle system, and the M-113 vehicle family. Some of these vehicles were first designed and produced several decades ago and, although they have been upgraded, most vehicles are at least 15 years old. Because they are expected to remain in the inventory for many years to come, their continued sustainment and tactical effectiveness must be ensured.
New vehicles planned for acquisition prior to 2010 include the future main battle tank; the future scout and cavalry system; the reconnaissance scout vehicle; the future combat system; the future infantry vehicle; and the advanced amphibious assault vehicle. All of these new vehicles will feature innovative technologies. Some of the technologies being considered for new vehicles and for upgrading existing vehicles are better weapons, advanced armor, new lightweight materials, composite structures, semi-active suspension, advanced propulsion
systems, electric drive, new electronic architectures, intervehicle and intravehicle digitization, an intravehicle electronics suite, advanced crew station technology, new methods of signature suppression, fire suppression systems, laser protection, hit avoidance techniques, active protection systems, and new turret technologies.
The broad range of technology requirements for land warfare systems are related to meeting deployment requirements while increasing survivability and lethality. Requirements include: smaller crews, automated drivers, training, smaller radar signatures, reduced mobility component weight and volume, and increased power. Integrated product and process development and virtual prototyping are two of the manufacturing capabilities that will be critical to meeting these challenges (DTAP, 1997).
Weapons Technologies
Expendable Munitions
The military services use hundreds of different types of expendable munitions. The term ''munitions" is used here to refer to expendable ordnance other than large missiles (e.g., fuzes, land and sea mines, and aimable warheads). The production of munitions, in this narrow sense of the term, requires technologies and manufacturing capabilities that are defense-unique (i.e., they generally have no commercial application) with the exception of ammunition for personal and law enforcement weapons and explosives used in mining and construction. Although all expendable munitions have specific requirements, some requirements are common to all of them, including quantity, quality, long-term storability, and affordability. Critical technologies in the munitions field are generally related to the safety and efficiency of manufacturing processes, affordability, storage and handling, the effectiveness of hydrocodes and warheads, sensors, arming and fuzing, and methods of tactical delivery or deployment. A high-yield, robust process for fuze production is required.
The manufacturing process of filling munitions with explosive materials, called "load, arm, and pack," is usually done at military arsenals, depots, or government-owned, contractor-operated (GOCO) plants located at arsenals (although filling of ammunition up to 30mm is often done in contractor-owned facilities). A key requirement is precision filling of the explosive (i.e., filling without voids). In some cases, costly 100 percent inspection is required. Precise metering methods could bring down this cost. New automated processes for filling munitions with explosive materials could minimize human intervention, promote safety, improve process yield, and ensure performance.
Missiles and Torpedoes
Missiles and torpedoes have no commercial application, with the exception
of space launch vehicles, and can therefore be considered defense-unique technologies. Compared to expendable munitions, missiles and torpedoes are more expensive to manufacture, more capable, and are produced in smaller quantities.
Manufacturing requirements for missiles identified in DTAP include: efficient packaging of all components in a missile the size of a tube-launched, optically-tracked, wire-guided (TOW) missile; the development, design, and integration of miniaturized guidance and control actuators with an advanced composite propulsion system in a small-diameter hypervelocity missile; a low-cost, small, producible, strap-down mechanism and guidance components for precision guidance of a highly rolling small rocket; the design of shipboard launch systems that can accommodate a wide range of missiles; the incorporation of attachments in missile airframes constructed of composite materials that do not compromise operational capability; low-cost, lightweight-composite external surfaces that meet the high temperature and stiffness requirements of a tactical missile; improved strength-to-weight/volume ratios and reduced erosion and weight of insulation (for solid propellant rockets); and smaller ramjet components. These technical challenges in manufacturing requirements are aimed at miniaturization, low-cost production processes, and advanced composite materials and processes and should be addressed in an integrated manner.
Many of the requirements and challenges identified for missiles also apply to torpedoes. Undersea weapons, however, also have their own manufacturing challenges, including a 40 percent reduction in development and ownership costs by 2005 and the use of more than 50 percent common subsystems by 2010. The first of these challenges requires reductions in development cycle time, reductions in nonrecurring costs, and the development of efficient sustainment methods. The second challenge requires overall system designs based on common subsystems.
Guns
The small arms industry sells more guns commercially than it does to the military, but the remainder of the gun industry is basically defense-unique. Artillery tubes, mortars, machine guns, fully automatic and large-caliber personal weapons, armored vehicle guns, naval guns, and their associated aiming and loading mechanisms have no civilian counterparts, although law enforcement agencies use certain types of fully automatic personal weapons. Military guns are not produced in the same quantities as expendable munitions, but most are produced in quantities ranging from thousands to tens of thousands. Cycle times and nonrecurring costs will have to be reduced.
Mobile Weapons Systems
Mobile and transportable crew-operated guns, rockets, and missile systems include crew-operated machine guns; self-propelled and towed artillery,
howitzers, and rockets; and missile systems. Specific examples are the Paladin, the Crusader, the advanced tactical missile system, the multiple launch rocket system (MLRS), and the TOW missile. New subsystems that can be inserted into existing systems to upgrade their capability and sustainability include the XM982 extended range 155mm artillery projectile, the XM297 Crusader solid propellant cannon, the XM291 120mm tank gun, and the electrothermal chemical version of the XM291 tank gun. New systems on the horizon include the high mobility artillery rocket system as a replacement for the MLRS, the guided MLRS, a countermissile rocket launcher, a follow-on to the TOW missile, the objective-crew-served weapon, and the extended range guided missile. Longer-range technologies in this area include electromagnetic guns and directed energy weapons. Several major manufacturing and design challenges are associated with these weapons, including: packaging constraints for electrothermal chemical technologies; the development of high-efficiency plasma ignitors; the development of high-energy-density propellants; the development of an advanced medium-caliber composite barrel with high-efficiency rail design; weight minimization; and smaller component sizes for electromagnetic and directed energy weapons.
Cross-cutting Technologies
Several technology areas for defense products, which are broadly applicable to defense systems, are discussed below. These cross-cutting technologies include: low observability techniques, sensors, electronics, and information systems.
Low Observability Techniques
The need for low observability, or "stealth," is clearly a defense-unique requirement that has no meaningful commercial counterpart. Although the public usually associates stealth with aircraft, such as the F-117, F-22, and B-2, the need for stealth is a characteristic of all weapons and weapons systems used by the armed forces. Stealth will be a prominent performance characteristic in the design of many new manned and unmanned vehicles, missiles and weapons, and other equipment. As potential adversaries develop the means to counter low observability technology, designers and manufacturers of defense systems must find ways to reduce observables even further. New designs for achieving low observability must be affordable and must address the issues of manufacturability and supportability, as well as stealth performance. Manufacturing tools, methods, and practices may have to be modified to accommodate the affordable production of equipment.
Systems with Stealth Requirements.
Personal dress and accouterments for soldiers and marines have been designed for low observability. Camouflage-
patterned clothing and helmets and grease paint for faces and hands have been used for many years. Personal and crew-operated weapons must also be designed for low observability in order to enhance survival, as well as combat effectiveness. Reduced muzzle and rocket blasts, as well as reductions of other telltale signature elements, all contribute to stealth.
Ships need reduced radar, infrared, visual, and acoustic signatures. The latest Nimitz class aircraft carrier (CVN-77), scheduled to be delivered to the Navy in 2008, will have significantly lower observability than its predecessors, including a redesigned and smaller island, fewer angular protuberances, and rounded deck edges. The CVX carrier, scheduled to enter the fleet in 2013 to replace the U.S.S. Enterprise (CVN-65) built in 1965, will be a new design from the keel up. Low observability will be one of the principal design characteristics of the CVX, which is expected to be in service throughout most of the next century.
For many years, the 688 Los Angeles class submarine was the world' s quietest attack submarine; however, according to the Office of Naval Intelligence, the newest Russian submarines, the improved Akula boats, are quieter (ONI, 1995). The commissioning of SSN-21 Seawolf in July 1997 reclaimed the title for the United States. The Seawolf was designed to be the world's stealthiest submarine, but because of its high cost, the Navy procured only three vessels. The Navy is concentrating now on the new attack submarine to replace the Los Angeles class. The new attack submarine will be designed to operate effectively not only in the blue ocean areas of the sea, but also in green and brown water littoral areas. It will feature low observability characteristics, such as a modular isolated deck structure, an ultra-quiet propulsion system, sail and hull blending, limber hole covers, and flow control strakes. The design will also take advantage of nonacoustic stealth characteristics, such as an order of magnitude reduction in magnetic signature to avoid magnetic mines, to improve operation in relatively shallow waters. To keep up with the growing use of nonacoustic signatures in antisubmarine warfare, such as wake detection by satellites and improved detection of submerged vessels' infrared and magnetic signatures, the Navy will have to continue to monitor developments in this area.
Both tracked and wheeled tactical vehicles will have built-in low observability features. For example, the future scout and cavalry system will be designed to avoid detection; the Marines' advanced amphibious assault vehicle will have reduced radar, acoustic, and infrared signatures; even self-propelled artillery and tanks, arguably the least stealthy systems, will have reduced visual, acoustic, infrared, and muzzle blast signatures. The design of the Crusader 155mm howitzer and the follow-on to the M1-A2 heavy tank, although still far from stealthy, will also attempt to reduce signatures.
Coatings.
Various kinds of coatings have been used on the external surfaces of military vehicles, aircraft, and ships for many years to lessen observability by sensors operating at radar, infrared, and other frequencies. These coatings are
generally of three types: appliqué, gel, and liquid. Coatings on new weapons and weapons systems are generally applied in liquid form, and the committee expects this method to continue in the period of interest to this study. Early coatings were applied by hand-held apparatuses operated by highly skilled technicians. This was a reasonable approach when only a few systems had to be treated, although controlling quality and thickness was difficult and the process was expensive. As the demand for coatings grew, robotic and automated application systems were designed and fielded. Various methods of controlling quality and thickness are adequate for coating relatively simple surfaces, but automated application on complex shapes is a difficult engineering feat, with correspondingly high costs. Point of origin process control of the nozzle position and other process variables will have to be improved. Sensors that can operate in the hostile processing environment while the spray is being applied would require a breakthrough in technology and would be valuable for many stealth applications.
Shaping.
The shaping of surfaces to deflect radar or acoustic energy away from the emitting source is a well known and commonly used technique. Aircraft and vessels have always been shaped for aerodynamic or hydrodynamic efficiency and performance. However, shaping the surfaces of vessels or aircraft for optimal stealth performance could conflict with aerodynamic or hydrodynamic requirements. According to DTAP, controlling vortex flow and flow separation in low observable configurations is a major technical challenge for air platform technology (DTAP, 1997). DTAP also lists technical challenges for the acoustic signatures of submarines in complex hydrodynamic flows, including improved understanding of hydrodynamic forcing mechanisms and the resulting response and acoustic radiation of structural components, and improved prediction of highly complex hydrodynamic flows to reduce the need for experimental evaluations and to enable the development of propulsors and maneuvering concepts.
Designers of low observable aircraft and submarines have often been forced to make trade-offs between aerodynamic and hydrodynamic performance and stealth performance characteristics. These trade-offs, in turn, have significantly affected the manufacturability of the vessels. An effective balance was reached for the F-22 Raptor and SSN Seawolf , which have good aerodynamic/hydrodynamic characteristics as well as good stealth characteristics. Nevertheless, the development costs, as well as the fabrication and assembly costs, would have been lower if this balancing act had not been required.
The next generation of low observable aircraft and submarines will require even more difficult design trade-offs, because of projected improvements in the adversary's ability to detect stealth vehicles and the improved performance of potential adversary systems. More affordable manufacturing techniques, processes, and tools that can produce the unusual and complex shapes required for both stealth and aerodynamic/hydrodynamic performance will be necessary, as
well as process modeling based on finite-element analysis of materials characteristics during forming.
Gaps and Edges.
Manufacturing considerations are often at odds with the requirement for minimal signatures created by weapon structure interfaces. Close horizontal and vertical edge and gap tolerance are necessary to control the reflective surface presented to a radar signal. Another approach is to limit the number of interfaces because systems with few access panels and openings are much less observable to radar. These panels and openings must be designed and manufactured with low observability in mind. A disadvantage of restricting the number of access panels is that it also makes access for maintenance purposes more difficult, time consuming, and, consequently, more expensive. Conformal mold line technology, a relatively new method of covering hinge lines and edges between surfaces, is another approach to closing gaps and covering edges. Like the other new techniques, however, it is expensive and design trade-offs have to be made.
Radar-Absorptive Materials and Structures.
New radar-absorptive materials (other than coatings) and radar-absorptive structures could also reduce radar signatures. These materials might have to be load bearing, able to withstand extreme heat (e.g., from jet exhaust), lightweight, formable into very complex shapes with high structural strength, or able to pass some radio frequency signals while preventing the passage of others (e.g., bandpass radomes). These materials and structures are difficult and costly to manufacture.
Shielding.
Designers commonly shield hot areas or elements of weapons and weapons systems to reduce their infrared signatures. Sufficient shielding that does not degrade performance or overburden the system with extra weight poses serious challenges for designers and manufacturers.
Sensors
The need for situational awareness and the effective use of weapons requires that most combat systems be equipped with defense-unique sensor systems, e.g., radar, visual aid, forward-looking infrared (FLIR), infrared search and track (IRST), and other multispectral sensor systems.
Radar Sensors.
The radar used in military combat systems, such as fighters, bombers, and tanks, is different in purpose and technical requirements from the radar used in commercial aircraft and by law enforcement agencies. Commercial aircraft radar are mainly used for avoiding bad weather and determining the aircraft height above ground in landing approaches. Radar is also used by military aircraft to measure height above ground and help avoid bad weather, but in general, military radar are of the following three types:
- radar designed to find, acquire, and track enemy vehicles, aircraft, or ships and to provide data for missiles or guns used to destroy them
- radar designed to help the crews of combat systems navigate and find, identify, and attack targets on the land or sea surface
- radar designed to enable aircraft to fly "nap-of-the-earth" in terrain-avoidance or terrain-following mode
Radar of any kind on a stealthy combat system poses obvious design and manufacturing problems. Radar dishes or arrays, for example, must be designed to minimize stray and out-of-band emissions. This often requires absorptive coatings and bandpass radomes that allow the transmission of their own energy but shut out externally generated energy. Currently, bandpass radomes are expensive both to design and manufacture.
Infrared Sensors.
Many combat systems in service today and planned for the future employ infrared sensors, including FLIR sensors, targeting infrared sensors, and IRST sensors, either installed or carried in pods. These sensors are used for navigation and low-level flight at night and to locate and attack some types of targets. Infrared sensors are not entirely defense-unique because they have limited applications in law enforcement helicopters and light aircraft and are used by agencies involved in border patrol, drug interdiction, and search and rescue operations.
Infrared windows can be made from various materials, all of which are costly. For sensors in high-performance, stealth aircraft like the F-22, both the materials and manufacturing processes are expensive. The military needs less expensive, easier to manufacture, high-performance infrared windows.
Other Electro-optical Systems and Aiming Devices.
Gunsights on combat systems are defense-unique but do not pose significant manufacturing challenges. Some combat systems (e.g., the Navy F-14 and some Russian fighters) have telescopes mounted on the wings or fuselage to help identify unknown aircraft at long distances. Although telescope technology is not a defense-unique technology, the application and installation on a combat system can be challenging to both designers and manufacturers (e.g., minimizing aerodynamic drag and signature in fighters).
Self-Protective Sensors.
Combat crews and systems are necessarily exposed to enemy defenses in performing their missions. Adversaries around the world are now equipped with sophisticated systems that have high technology sensors and weapons. As 2010 approaches, their equipment will become even more sophisticated and effective.
Aircraft, land vehicles, and ships must be equipped with passive sensors that alert the crew when they are being illuminated by threat radar or other target
illuminators and identify the type of illuminator being used, the kind of fire control system associated with it (and thus the type of weapons system it controls), and the direction and approximate range of the emitter. They will also need sensors that can tell them when a missile has been launched against them and its location so they can take countermeasures.
Once the illuminating enemy radar is detected, the combat system crew has several options: evade the enemy system, if feasible; attack the enemy system; or use electronic countermeasures to jam or confuse the system. The latter option is enabled by on-board electronic systems that can receive, analyze, and either jam or deceive the enemy illuminator. Electronic countermeasure equipment has no commercial counterpart. Active protection can be provided by stand-off jammers (e.g., the Navy EA-6B) and by fighters that seek out enemy radar systems and destroy them with defense-unique munitions, such as radar homing missiles. DTAP lists several major technical challenges in the area of warnings against radar threats, including the development of a high-accuracy direction-finding capability; the development of functional elements using monolithic microwave integrated circuits (MMICs); and pulse-level specific emitter identification extraction, processing, and automation (DTAP, 1997).
DTAP also discusses several major technical challenges in the area of missile warning systems, including increasing the detection range of electro-optical/infrared sensors by 100 percent; improving their angle-of-arrival determination to better than one degree; enhancing the probability of detection to more than 95 percent; and reducing false alarms to less than one per hour (DTAP, 1997).
The cost of radomes and infrared windows for these sensors is very high. Therefore, designs for manufacturability and the development of low-cost production processes will be necessary. Low-cost designs and processing will also be necessary for the next generation IRST sensors, as well as the development of packaging for functional elements using MMIC, which promises to reduce electronics to one-third of their current volume.
Electronics
Semiconductor electronics and photonics are critical for avionics, communications, surveillance, control, and other military applications. By 2010, they will be ubiquitous in all elements of defense systems from sophisticated space platforms and sensors to communications and vision systems carried by individuals. They will have to operate in a wide range of temperatures, extremes of humidity, high radiation, and other hostile environments.
Military applications will require that more and more high-performance transistors and lasers be packaged at a higher density while simultaneously improving the quality and reliability of the system. Consistent with industry trends, system-on-a-chip architecture is expected to play an increasing role, as chip-level integration is used in lieu of system packaging to achieve the desired functional
density. Even though the use of electronic devices in the engine compartments of automobiles is driving improvements in technology performance in hostile engine environments, certain military systems will expand the performance envelope significantly beyond evolving commercial capabilities.
The annual cost of avionics maintenance in the four services is staggering. The Rand Corporation recently estimated that the annual cost of avionics maintenance in the F-16 system alone was more than $100 million (Stevens et al., 1997). The cost of avionics is steadily increasing in all defense systems, with software maintenance and nondigital functions being the main drivers of life-cycle costs. The corrosion and fatigue/structural failure of connectors are prominent problems. Past studies by the ManTech program have shown that fatigue, corrosion, and thermal cycling failures are critical factors that must be addressed in the specifications of a system (ManTech, 1998).
Avionics software management budgets are routinely inadequate. For instance, the projected cost of required F-15 development and flight testing for fiscal years 1997 through 2002 is approximately $500 million; the shortfall in the projected budget is about $140 million. If emulators and automated validation tools could be used to replace flight tests and proprietary interfaces and technology could be eliminated by using existing commercial open systems, software management costs in many systems could be reduced significantly.
Periodic updates or modifications of avionics systems are often hindered by the high cost of rewiring older systems. Bridging existing networks by means of field programmable gate arrays, with new wiring and commercial protocols, could ameliorate this problem.
Avionics maintenance costs in older aircraft often consume the funds available for periodic updates. The following measures could be taken to correct this situation:
- improve packaging to increase structural reliability and reduce connector problems
- improve built-in test diagnostics to reduce "retest OKs" and reduce the amount spent on automated external test equipment
- use modular/throwaway components to facilitate maintenance by eliminating the need to return the components to a depot and repair them
- develop prognostic capabilities, or intelligent system health monitors, to facilitate maintenance and reduce life-cycle costs
- replace military specification cards with COTS hardware to lower costs substantially and improve reliability (provided that the hardware can withstand the required environmental stresses or can be mounted on shock mountings or otherwise protected)
- replace or interface, where feasible, existing buses and networks with commercial programmable network protocols to reduce costs
- develop and test/demonstrate software reengineering tools to facilitate upgrades to cope with the rapid obsolescence of electronic technology
Closing the gap between the needs of defense system electronics and commercial developments will require specific technological improvements, such as lightweight chip-on-board (also called flip chip or direct chip attachment) platforms that feature electronic miniaturization. These platforms reduce board area by as much as 50 percent and component weight by as much as 80 percent over packaged devices; the thermal load, however, is increased dramatically. Widespread commercial applications of this technology for single-chip packaging, multichip packaging, and direct attachment to printed wiring boards are expected by 2010. For advanced military applications, reliability measures will include thermal shock resistance, thermal cycling fatigue, temperature or humidity bias, and mechanical shock and vibration resistance. In addition, new materials and processes may be needed for use in harsh environments.
Failures in electronic interconnects are of ongoing concern in defense applications. Fatigue, corrosion, and wear contribute to both short-term and long-term failures. As data rates and bandwidth increase, the manufacture of high-precision, high-reliability connectors, back planes, and traces will confront physical barriers. Connector fretting studies, plated-through-hole thermal fatigue studies, studies related to dendritic growth phenomena in fine-pitch devices, studies of chip-on-board packaging technology, and other studies and experimentation will be necessary to ensure reliability.
High-speed electronics are susceptible to failure from microsecond interruptions. As the speed of electronics increases, interruption-free connector systems will have to be designed and connector integrity will have to be quantified in severe vibration environments. Optical interconnections will be essential to meeting the challenge of ultra-high data rates. Improved fiber-optic connectors and wiring capable of functioning reliably in severe vibration environments should be investigated. As the thickness of multilayer boards continues to increase, plated-through-hole thermal fatigue will become even more of a problem than it is today. Military applications for multilayer boards are numerous and will continue to increase. The Japanese electronics industry has addressed the problem at the first indenture by improving the ductility of copper used in plated-through-hole applications, but much more remains to be done in both in the laboratory and to improve manufacturing processes.
As electronic devices become more densely packaged, the fine-pitch aspects of the designs become more susceptible to dendritic growth, which results in intermittent failures. Studies could address the limits of fine-pitch capabilities in humid environments with thermal cycling and power cycling. Various conformal coating techniques and capacities could be investigated and documented, if not improved.
The United States, which has no significant commercial liquid crystal display
(LCD) manufacturing industry and a very limited military LCD industry, depends on foreign sources for LCD technology. No growth in U.S. commercial capabilities is expected by 2010, and economic pressures are expected to continue to erode the military base. Existing foreign commercial LCD technology cannot satisfy future military requirements for display panel and electronic interconnections. Areas that will require study, documentation, development, and testing include: basic glass manufacturing technology; brightness, dynamic range, and viewing angle; mechanical shock and vibration resistance; and thermal cycling fatigue and temperature/humidity. In addition, competing technologies, such as electroluminescent and plasma technologies, require study.
Information Systems
Applications for information technology are pervasive in defense operations and weapons systems. However, this section will deal only with the capabilities of information technology for defense manufacturing. Based on DTAP, defense technology objectives, and Mantech planning documents, the capabilities of information technology required for defense manufacturing fall into three categories: interoperability with commercial systems; information requirements for defense-specific products; and information security. Some of the specific capabilities are listed below:
- systems architectures that permit the secure use of COTS computers, software, and networks
- interoperability of defense logistics systems and the diverse systems used by suppliers
- network management and control protocols for data security in distributed design and manufacturing operations to prevent interruption, jamming, sabotage, and interception
- models for defense products with multiple levels of resolution to enable simulation-based design
- databases of weapons system life-cycle costs that can be integrated into design systems to enable life-cycle cost trade-offs simultaneously with design evolution
- production process capabilities and cost databases that can be integrated into design systems to provide simultaneous assessments of design alternatives and production costs, manufacturing risks, and manufacturing systems designs
- product data models and storage and retrieval architecture capable of seamlessly handling all data modalities
- product structure directories to meet unique structural requirements for defense products that also have open architecture and meet commercial standards
- mechanisms, including intelligent agents, for locating and retrieving information from complex database structures
- automated systems for reverse engineering based on scanning of an actual part
- parametric modeling to enable design trade-offs at the conceptual level
Manufacturing Processes and Technologies
Production Rate Transparency
Because of declining defense budgets and the resultant reductions in new weapons systems, few, if any, major weapons systems will be produced at a high volume in the foreseeable future. This is not to say that certain defense items, such as munitions, will not be produced in high volume. But the production of complex systems will be characterized by very low throughput, which raises the question of whether industry is prepared for the economical production of goods and systems at very low-rates.
Experience has shown that unit costs increase significantly as production rates drop. The committee believes this problem could be ameliorated by focusing attention on manufacturing technology for low-rate production. Ideally, the production of defense goods will be ''rate transparent," i.e., a component, subsystem, or complex weapons system will be produced at the same cost regardless of the production rate. Manufacturing capabilities that will be critical to minimizing unit production cost at low production rates include: flexible production lines, procurement of materials in bulk, modeling of production during the design process, and adaptive process control to achieve 100 percent first time yields.
Repair of Parts Made of Composite Materials
Currently, repairs of parts made of composite materials require a high degree of operator skill and long cycle times. An automated process could make machine-generated scarf cuts. Because much of the patch bonding will be done on aircraft, ships, vehicles, or other systems with composite skins and structures, efficient and affordable technologies and processes will be required for on-system, on-site repairs, as well as depot repairs of damaged composite structures and surfaces.
Dimensional Control
The need for close gap tolerances in systems requiring stealth was discussed earlier. But many other areas of defense manufacturing also require dimensional control and tight tolerances. For instance, submarine construction requires circularity and hull fairness, as well as close control of tolerance stack-ups to facilitate
modular construction. Interestingly, the same techniques are now being used to achieve low observability for the surface fleet.
Controlling distortion, hardware variability, and dimensional accuracy can minimize dimensional variations and ensure the efficient manufacture and assembly of parts. The goal is to achieve a highly capable fabrication/assembly/construction process that consistently meets required specifications without reworking. Ideally, dimensional control will begin in the early stages of design when construction process capabilities and design specifications are being assessed for compatibility.
Tight tolerances are required for many defense systems, such as those produced in modules (e.g., modern jet engines, submarines, ships, avionics, aircraft, and land vehicles). Modular construction requires more stringent fit and tolerance control than nonmodular construction. Manufacturing process capabilities and assembly sequences must be clearly and accurately defined to determine the dimensional tolerance stack-ups associated with efficient modular construction. Tolerance stack-ups at interfaces between modules or assembled parts must be planned for early in the design phase by design details that accommodate expected variations.
As tolerances are tightened, manufacturing becomes more difficult, rejection and reworking increase, and costs go up. Experienced designers and production engineers always try to allow for the loosest tolerance for the end product to function effectively. Many modern defense systems, however, such as stealth aircraft, submarines, and other systems, require tolerances that were not even considered achievable a few years ago without significant added expense and manufacturing process time.
Modern tooling and processes have significantly reduced the cost of maintaining very tight tolerances in fabrication and assembly. The design part geometry from computer-aided design and manufacturing (CAD/CAM) is used in a variety of manufacturing applications related to dimensional control. This geometry can be expanded to account for shrinkage due to welding and incorporated into the numerically controlled code for the automated marking, forming, cutting, fitting, and welding of parts. The electronically developed geometry representing the ideal condition at different stages of fabrication, construction, and assembly can be used for comparison with as-built part dimensions. Industrial measurement systems, such as photogrammetry, multitheodolite laser trackers, and total stations, which provide highly accurate electronic capture of as-built parts, can provide a statistical definition of process capability. This capability can be used as a scientific basis for improving processes and reducing rework. The application of advanced computer-aided visualization techniques can provide a thorough understanding of dimensional changes throughout the construction process and help determine specific process changes to improve dimensional quality.
The key term in dimensional control is "as-built," which assumes postoperation (e.g., after the part has been machined) inspection. This approach
usually results in some degree of scrapping, reworking, and repair. To minimize these, noncontact inspection during the operation will be necessary.
The committee was informed by several industry and laboratory sources (West, 1998) that little is currently being done to integrate, in an automated way, product analysis and design with tool design and manufacturing processes. The key to improving dimensional quality is the systematic identification and control of process variables. The data sampling and analysis needed for constant monitoring of manufacturing processes and continuous improvement of quality must be done in an integrated way. Process data systems will be required that can capture and transmit data between manufacturing processes and design and analysis systems in an integrated way, cost-effectively, accurately, and quickly. Data systems should fully integrate all facets of product analysis and design, manufacturing process analysis and design, tool analysis and design, and inspection/control system analysis and design.
CAD systems should be capable of automating the expansion of part geometry and associated attributes, such as layout and reference lines, to account for weld shrinkage. In addition, these systems should be able to transfer numerical control data to automated marking, cutting, fitting, and welding processes; efficiently transfer geometric configuration data to and from industrial measurement systems; and provide efficient analysis and visualization of comparative data between ideal and as-built products.
Automated manufacturing processes and inspection and measurement systems should provide highly accurate and automated dimensional quality control in making, cutting, forming, assembling, and welding parts using tools and processes, such as lasers, water jets, electron beams, and high-speed machining. Automated, highly accurate systems are needed for verifying the accuracy of assembly tools and component locations. Today's labor-intensive methods require inspectors, tool templates, and gauges. A new verification method should use advanced photographic or laser technology.
Titanium Processes
Problems are caused in titanium investment casting when small pieces of the ceramic face material used on the inside of the investment casting mold break loose and migrate into the molten titanium. There is currently no nondestructive inspection (NDI) method capable of reliably detecting fusion defects, ceramic shell inclusions, and regions of dissolved shell in titanium castings. These problems are particularly burdensome in certain modern aircraft, which have significant weight constraints and require large titanium castings for high strength. Improved NDI methods are especially important for the F-22 program, which requires two 5-foot-long (1.5 m), 200-pound (90.7 kg) castings as part of the wing attachment fittings. Currently, extensive radiographic inspection is necessary to ensure that castings are free of these defects. Even after extensive
inspections after casting, defects are sometimes detected after machining, which has significant cost implications.
A method of detecting defects early in the casting cycle would allow a decision to be made to rework a part prior to heat treatment or to discard the part without incurring additional costs; this might also help to identify the cause of the defects and lead to process improvements. An effective NDI method would have to reveal defects for complex geometries and thickness up to three inches with more than 90 percent reliability. In addition, the method would have to have a minimal effect on casting times and cost.
At present, no robust coating for large structural titanium investment castings exists that produces limited reaction with molten titanium and is readily detectable by available NDI techniques. Such a coating would significantly reduce shell inclusions and make it easier to detect inclusions when they occur. In addition, reducing the reaction with the shell material would improve the quality of the casting surface and reduce the need for reworking surfaces. If titanium honeycomb could be produced from alloy 15–3, it would provide a much better strength to-weight ratio, would not be subject to node failures, and would be an order of magnitude less expensive than graphite composite core.
Overall Process Optimization above the Plant Floor
Optimal effectiveness and efficiency of manufacturing systems will require improvements "above the plant floor," as well as improvements on the floor. The establishment of a nonrecurring manufacturing process control requires simultaneous product and process views, single view management, a single numbering system (e.g., for work orders, work breakdown structure, shop orders, drawing numbers, part/assembly numbers), a visual statusing system, visibility of upstream problems and downstream impacts, and drill-down expansions and database linkages.
Summary
Required manufacturing capabilities, based primarily on DTAP, are summarized in Table 2-1. The committee analyzed these and determined that they fall into six broad technology categories: composite processing and repair; electronics processes; information technology systems; sustainment; design, modeling, and simulation; and production processes. Table 2-2 lists the manufacturing capabilities that fall under each of these categories. Some of the required manufacturing capabilities identified by the committee are specific to certain weapons systems (e.g., processes for radomes and infrared windows and processes for munition fuzes). Others are applicable to a number of weapons systems. Widely applicable capabilities are listed below:
- simulation-based design (including product and process models) able to make cost versus performance trade-offs during design and simultaneously design products and their manufacturing processes
- cost versus performance trade-offs at the conceptual level of the design process
- product data structures that meet the unique characteristics of defense products
- interoperability of defense information systems and commercial systems
- low-cost composite structures through novel designs and new processing concepts
- new system and component design concepts to enable electronics (including COTS products) to operate reliably in harsh military environments
- open-system architectures (including modular designs) to facilitate upgrading systems and accommodate unexpected changes in the availability of parts
- intelligent health monitoring systems for electronic mechanical subsystems with predictive capabilities to facilitate maintenance
- dimensional control in large structures
- adaptive process controls to improve first-time yields
- life-cycle cost analyses concurrent with design
- low-rate production methods
TABLE 2-1
Required Defense Manufacturing Capabilities Based on the Defense Technology Area Plan
Technology Area |
Manufacturing Capability |
Weapons System Platform Technologies |
|
Aircraft weapons systems |
Repair techniques for aging systems Nonintrusive, real-time monitoring techniques for flight loads and damage Design techniques and processing methods for high strength-to-weight materials, particularly composites Design concepts and processing methods that reduce the costs of composite structures Electronic systems able to withstand high g loads and severe vibrational environments Affordable processing methods for launch equipment with reduced drag and signature Weapons systems capable of launching weapons at high-speeds and under high g loadings |
Surface and subsurface sea combat vessels |
Design concepts that minimize weight and volume of vessel systems and reduce life-cycle costs Automated, intelligent monitoring and control systems System-level design approaches to reduce acoustic signatures and cost, and increase shock resistance Design simulations to enable accurate performance versus cost trade-offs |
Land combat vehicles |
Maintenance and upgrade technologies for aging systems Integrated product and process development Virtual prototyping |
Weapons Technologies |
|
Expendable munitions |
High-yield, robust fuze production process Methods for precise filling of explosives in munitions Automated filling of explosives in munitions to increase safety, improve process yield, and ensure performance |
Technology Area |
Manufacturing Capability |
Missiles and torpedoes |
Methods for miniaturizing system components Low-cost production processes Composite materials for advanced propulsion systems Methods to reduce cycle time and nonrecurring costs in production processes Overall system designs based on common subsystems |
Guns |
Methods to reduce cycle time and nonrecurring costs |
Mobile weapons systems |
Methods for packaging electrothermal chemical technology Designs for high-efficiency plasma ignitors and high-energy-density propellants Designs for high-efficiency rails Designs to minimize weight and size of components |
Cross-cutting Technologies |
|
Low observability technology |
Precise, automated methods for applying low observability coatings Process control sensors that can operate in hostile processing environments Affordable manufacturing techniques, processes, and tools that can form complex shapes with high stealth and aerodynamic/hydrodynamic performance Process models based on finite-element analysis of materials characteristics during forming Conformal mold line technology Methods for design trade-offs to minimize signatures created by gaps and edges Radar-absorptive materials and structures that are strong, lightweight, able to withstand extreme heat, formable into complex shapes, and affordable Designs for lightweight, effective infrared shielding |
Sensors |
Designs for high-performance radomes and infrared windows that are affordable and easy to manufacture Designs for electro-optical systems that are affordable, easy to install, and that have minimal drag and signatures High-density packaging for functional elements using monolithic microwave integrated circuits |
Technology Area |
Manufacturing Capability |
Electronics |
Automated validation tools to replace flight testing Commercial software systems to replace proprietary systems Methods to bridge existing networks using field programmable gate arrays, new wiring, and commercial protocols Avionics packaging with increased structural reliability and reduced connector problems for aging systems Built-in test diagnostics for aging systems Modular components to facilitate maintenance of aging systems Intelligent health monitors for aging systems Commercial hardware to replace military specification cards and improve reliability Commercial programmable network protocols to replace existing buses and networks and reduce costs Software engineering tools to facilitate upgrades and cope with rapid obsolescence of electronic technology Lightweight chip-on-board platforms that feature electronic miniaturization Platforms with reliability in terms of thermal shock resistance, thermal cycling fatigue, temperature and humidity tolerance, and mechanical shock and vibration resistance. Materials, components, and processes that can be used in harsh military environments High-precision, high-reliability connectors, back planes, and traces Interruption-free connector systems Optical interconnections for ultra-high data rates Manufacturing processes for multilayer boards Conformal coating techniques and capacities to prevent dendritic growth Glass manufacturing technology for liquid crystal displays |
Technology Area |
Manufacturing Capability |
Information systems |
Systems architecture that permits secure use of commercial-off-the-shelf computers, software, and networks Defense logistics systems that are interoperable with the diverse systems used by suppliers Network management and control protocols to ensure data security in distributed design and manufacturing operations Product models with multiple levels of resolution for simulation-based design Databases containing weapons system life-cycle costs for integration into design systems Production process capabilities and cost databases for integration into design systems Product data models and storage and retrieval architectures capable of handling data seamlessly Product structure directories that are open and meet commercial standards Intelligent agents for locating and retrieving information Automated reverse-engineering systems based on scanning of the actual part Parametric modeling to enable design trade-offs |
Manufacturing Processes and Technologies |
|
Production rate transparency |
Flexible production line Procurement of materials in bulk Methods for modeling production processes during design Adaptive process controls to enable 100 percent first time yields |
Composite repairs |
Automated composite repairs On-system, on-site repair technologies and processes that are affordable and efficient |
Technology Area |
Manufacturing Capability |
Dimensional control |
Manufacturing processes and assembly sequences that determine dimensional tolerance stack-ups for modular construction Design methods that incorporate tolerance stack-ups at interfaces between modules or assembled parts Measurement systems that provide highly accurate electronic information on as-built parts Computer-aided visualization techniques Noncontact inspection during manufacturing operations Process data systems that integrate product analysis and design, manufacturing process analysis and design, tool analysis and design, and inspection/ control system analysis and design Computer-aided design systems that integrate design, production processes, measurement processes, and compare ideal and as-built products Automated, highly accurate dimensional control systems using advanced photographic or laser technology |
Titanium processes |
Nondestructive inspection technology for titanium castings Method for coating structural titanium investment castings that produces limited reaction with molten titanium and where inclusions are detectable Process for producing titanium honeycomb from alloy 15–3 |
Overall process optimization above the plant floor |
Nonrecurring manufacturing process control with plant floor single view management, single numbering system, visual statusing system |
TABLE 2-2
Broad Categories of Required Defense Manufacturing Capabilities
Category |
Manufacturing Capability |
Composites processing and repair |
Design methods and processes for low-cost structural composites Design methods for low-cost composite materials Composite materials for advanced propulsion systems Low-cost composite surfaces for tactical missiles Automated composite repairs On-system, on-site composite repair technologies that are affordable and efficient |
Electronics processes |
Intelligent health monitoring systems Electronic systems able to withstand high g loads and severe vibrational environments High-density packaging for functional elements using monolithic microwave integrated circuits Electronics packaging with increased structural reliability Built-in test diagnostics Commercial programmable network protocols to replace existing buses and networks Software engineering tools to facilitate upgrades Lightweight chip-on-board technology for miniaturization High-precision, high-reliability connectors, back planes, and traces Interruption-free connector systems Optical interconnections for ultra-high data rates Designs to prevent dendritic growth in high-density electronics Manufacturing technology for liquid crystal displays |
Information technology systems |
Commercial software systems to replace proprietary systems Systems architecture that permits secure use of commercial off-the-shelf computers, software, and networks Defense logistics systems that are interoperable with the diverse systems used by suppliers Network management and control protocols to ensure data security in distributed design and manufacturing operations Databases containing weapons systems life-cycle costs for integration into design systems Production process capabilities and cost databases for integration into design systems |
Category |
Manufacturing Capability |
Information technology systems |
Product data models and storage and retrieval architectures capable of handling data seamlessly Product structure directories that are open and meet commercial standards Intelligent agents for locating and retrieving information Automated reverse-engineering systems based on scanning of the actual part Nonrecurring manufacturing process control with single view management, single numbering system, and visual statusing system |
Sustainment |
Repair techniques for aging systems Nonintrusive, real-time monitoring techniques for flight loads and damage Maintenance and upgrade technologies for aging systems Automated validation tools to replace flight testing Avionics packaging with increased structural reliability and reduced connector problems for aging systems Built-in-test diagnostics for aging systems Modular components to facilitate maintenance of aging systems Software engineering tools to facilitate upgrades |
Design, modeling, and simulation |
Product models that enable accurate life-cycle performance versus cost trade-offs Integrated product and process development Virtual prototyping System designs based on common subsystems Process simulations based on finite-element analysis of materials characteristics during forming Product models that enable stealth versus other performance characteristics trade-offs Designs for affordable, high-performance radomes and infrared windows Designs for affordable, easy-to-install electro-optical systems with minimum drag and signature Product models with multiple levels of resolution to enable simulation-based designs Parametric modeling to enable design trade-offs |
Category |
Manufacturing Capability |
|
Integrated product, tool, and manufacturing process designs Design methods that incorporate tolerance stack-ups Computer-aided design systems that integrate design, production processes, measurement processes |
Production processes |
Affordable processing methods for launch equipment with reduced drag and signature High-yield, robust fuze production process Methods for precise filling of explosives in munitions Automated filling of explosives in munitions to increase safety, improve process yield, and ensure performance Methods to reduce cycle time and nonrecurring costs in production processes Precise, automated methods for applying low observability coatings Affordable manufacturing techniques, processes, and tools that can form complex shapes Conformal mold line technology Manufacturing processes for multilayer boards Conformal coating techniques to prevent dendritic growth Glass manufacturing technology for liquid crystal displays Flexible production lines Adaptive process controls to enable 100 percent first-time yields Manufacturing processes and assembly sequences that determine tolerance stack-ups for modular construction Measurement systems that provide highly accurate electronic information on as-built parts Computer-aided visualization techniques Noncontact inspection during manufacturing operations Automated system for accurate location of assembly tools and components Nondestructive inspection for inclusions in titanium castings Process for producing titanium 15–3 honeycomb |