2007-2008 Assessment of the Army Research Laboratory (2009)

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6 Vehicle Technology Directorate INTRODUCTION The Vehicle Technology Directorate (VTD) was reviewed by the Panel on Air and Ground Vehicle Technology of the Army Research Laboratory Technical Assessment Board (ARLTAB). The director- ate has three divisions (Mechanics, Propulsion, and Unmanned Vehicle Technologies) and one program office (for management of the Army Research Laboratory [ARL] Robotics Collaborative Technology Alliance [CTA]) that were reviewed by the panel. Appendix A shows the funding and staffing profiles for VTD (see Tables A.1 and A.2). The assess- ment below reflects visits by the Panel on Air and Ground Vehicle Technology to the VTD sites at the NASA Glenn Research Center (August 15-17, 2007) and the ARL facilities at Aberdeen Proving Ground, Maryland (June 2-4, 2008). CHANGES SINCE THE PREVIOUS REVIEW Many significant changes have occurred since the 2005-2006 review of the Vehicle Technology Directorate. VTD began relocation to Aberdeen Proving Ground, Maryland, as part of the 2005 Base Realignment and Closure (BRAC) action. This move resulted in major adjustments in every aspect of the operation of the directorate, especially for the Propulsion Division. The move presents an opportunity to centralize the activities of the directorate and to align activities more closely with Army needs and other Army organizations. The ARL and VTD leadership is effectively moving forward in the face of these major events. In addition to the fiscal and facilities changes, planned program changes include reduced activities in some technologies (e.g., active rotor technology development and large-turbine-engine concepts) and increased (or refocused) activities in other technologies (e.g., microsystem mechanics, small-engine technology, and prognostics and diagnostics). To some extent, these changes also reflect changes in facilities and access to laboratories and equipment previously shared with NASA. The Board 71 

72 2007–2008 assessment of the army research laboratory exhorts the Army to support ARL’s efforts to maintain effective levels of staffing and equipment in order to continue essential work in such areas as propulsion and aircraft structures and materials. ACCOMPLISHMENTS AND ADVANCEMENTS Significant accomplishments were achieved by several divisions and programs of the Vehicle Tech- nology Directorate during the past 2 years. Several parts of the propulsion effort, which is potentially at some risk in the transition from NASA Glenn, showed advances. The Active Stall Control Engine Demonstration (ASCED) (also noted in ARLTAB’s 2005-2006 report) continues to combine state-of- the-art analysis with full-engine tests to advance the understanding and control of performance changes during service in environments of interest to Army missions. Other programs that have shown promise include the development of technology for high-efficiency wave-rotor-topped gas turbine engines, with initial results showing reduction of the specific fuel consumption by about 15 percent while increasing the power-to-weight-flow ratio by about 18 percent. In the context of increasing cost (and threat of loss of supply) of battlefield fuel, work of this type has obvious importance in reducing gas turbine engine specific fuel consumption while increasing the power-to-weight flow—progress that will make a sig- nificant contribution to Army missions. However, this work, which began as a NASA/ARL effort in the 1990s, has a rather long technical horizon for application, and it is also subject to possible disruption by the BRAC activities. In general, the engine research is appropriately focused on a balanced program of near-term and fundamental research. The computational fluid dynamics (CFD) simulation of compressor stall avoidance and the work on hot restart is excellent work that addresses near-term operational issues and provides a sound foundation for future developments and more refined research. A second example of a significant advancement is the Robotics Collaborative Technology Alli- ance. The Robotics CTA is a well-organized and well-executed interlocking consortium of industry, academia, and government laboratory personnel that seems to offer a best-practice model for VTD and ARL. It was established through a competitive pre-award process and is managed in a centralized but intellectually fluid process capable of adapting to the changing features of the research landscape in this still-maturing field. The Robotics CTA presentations evidenced state-of-the-art and often pioneering results from some of the most qualified researchers in their fields. An example of cutting-edge research is the real-time extraction of geometric and semantic terrain representation from raw ladar point clouds. An example of the intellectual fluidity in allocating new resources to track potentially game-changing advances in technology is provided by the new RIVET simulation environment. A growing number of transition successes into fielded application platforms within the Tank-Automotive Research, Develop- ment, and Engineering Center (TARDEC) and the Future Combat Systems (FCS) validate the up-front positive impression conveyed by the CTA program portfolio itself. The very high quality research and its record of well-knit practical integration in Army-relevant field demonstrations at the Fort Indiantown Gap, Pennsylvania, facility suggest that this approximately $10 million per annum investment—roughly one-third of the VTD budget—is paying off. Finally, VTD is moving toward building its effort in the health and usage monitoring (HUMS)/­ condition-based maintenance (CBM) field with the addition of the new Mechanics Division chief. This should be encouraged as a real opportunity to apply the existing VTD expertise in rotorcraft, composite materials, fracture/fatigue, and nondestructive evaluation and diagnostics into an area that has a strong potential benefit to the Army. Structural health monitoring, HUMS, CBM, and so on constitute a rapidly  NationalResearch Council, 2005-2006 Assessment of the Army Research Laboratory, Washington, D.C.: The National Academies Press, 2007. 

VEHICLE TECHNOLOGY DIRECTORATE 73 growing field that requires the integration of sensors, signal processing, mechanics, and material ­behavior. VTD’s effort to achieve excellence and critical mass is a significant program advance, which could be significantly strengthened by putting together a collaboration similar to a CTA that might include the rotorcraft industry, sensor companies, and university researchers. Close integration with other activities in this field is also encouraged. OPPORTUNITIES AND CHALLENGES At this time of realignment and redefinition, it is especially important to maintain a systems focus, such that each individual researcher is able to clearly state how his or her research, if successful, will enable additional desirable capability for the warfighter. VTD has a window of opportunity because of the changes dictated by the BRAC to ensure that all of its programs across the VTD divisions mutually support one another and that all programs are aligned to meet the needs of the Army. For example, the Robotics CTA is an excellent program that is clearly demonstrating an approach that is producing a great leveraging of ARL’s limited funds and personnel to produce the artificial intelligence and vision necessary for a robot to autonomously get from point A to point B. However, there were no presentations from the Propulsion Division or the Mechanics Division indicating that they were developing the supporting technologies in their areas that would be needed by these robots. The directorate should use this window of opportunity to ensure that it has an integrated program across all of its divisions. In addition, the CTA approach, which is demonstrating excellence, should be considered in other areas, as appropriate, to leverage VTD limited personnel and funds to produce the technology needs of the Army. VTD is in the process of establishing a group that will have responsibility for integrating the port- folio of research and communicating both internally and externally. The establishment of this group is appropriate. It should be responsible for items such as the following: 1. A clear statement of the directorate’s vision, related to Army needs; 2. A statement for each division that defines how its portfolio of research in total meets the directorate’s vision and mutually supports other divisions; 3. Notional definitions of vehicles of each type required by the warfighter, to focus the directorate’s vision and to ensure that key technologies are not missed; 4. For each program, limit calculations that show how much of the total potential capability would be enabled by a successful completion of the research project(s), to help to focus the researcher on the importance of his or her research; and 5. Identification of crosscutting technologies and disruptive concepts and technologies for shared responsibilities and focus. The directorate is undergoing changes as it consolidates its workforce at Aberdeen Proving Ground. In particular, there is new staff in the Mechanics Division; the Board looks forward to this staff’s estab- lishing a portfolio of research programs that meets the directorate’s vision. Similarly, the Propulsion Division is in large part moving from NASA Glenn. The Board recognizes several improvements in the Propulsion Division’s research portfolio and looks forward to its continued development. VTD is rigorously involved in a strategic planning activity that will bring the entire structure of VTD and its divisions into focus. As enumerated below, at least three areas of crosscutting issues are appropriate for discussion during that planning effort. 

74 2007–2008 assessment of the army research laboratory One of these crosscutting needs is to define a platform for the future that will identify, for example, what the next helicopter or ground vehicle engine, robotic system, or other system is going to be (to the extent that is possible), what its goals will be, and what technologies are necessary to achieve these goals. Progress in this effort will help to set consistent, shared directions in a directorate that is clearly addressing future needs in addition to essential present improvements. A second opportunity has to do with awareness of the technical activities and horizons in the com- munity at large. This is especially challenging, considering the remarkable technical scope of VTD. VTD should continue to emphasize refereed publication of advances and the participation of investigators in teams, partnerships, and cooperative activities with other organizations. Areas of particular importance include analysis and computation (e.g., predictive methods for material properties from first principles) and systems analysis. A companion issue is the question of focusing on a comparatively small number of fundamental issues of broad importance versus the expedient (but sometimes isolated) addressing of many technical matters of smaller scope. The greater community’s awareness and perception of direc- torate technical activities and leadership are important in the ability to leverage the work of others and to recruit and retain the best individuals for Army laboratories. Being seen as the place to go to work on state-of-the-art technologies is a worthy goal, deserving of an investment of time and resources to ensure achievement. A third opportunity is the consideration of shared capabilities and facilities for computational work. Analysis and computation are becoming (with good reason) a more consistent aspect of what the director- ate (and everyone else) does. There is a special opportunity for VTD to generalize its capability in this important area and at the same time to focus on a few areas; to support and create data sets, especially those specific to VTD experience; to validate codes and establish diagnostics; to organize round-robins; and to interpret results. Given the Army-specific advantage of data sets for many specialized hardware embodiments, this is thought to be a significant opportunity for leadership. The success of shared objec- tives turns on communication both within the directorate and with the greater community of investigators at large whose work and insights can be leveraged. OVERALL TECHNICAL QUALITY OF THE WORK The Vehicle Technology Directorate has established the tradition of a research approach that has successfully applied analytical tools and experimental methods in controlled environments to hardware- based problems at various scales. With new directions and realignments under way, it is especially important to revisit the need for a statement of specific requirements, goals, and schedules for each individual project. Exploratory areas (such as flapping wing structures and self-healing) are certainly appropriate for best-effort work for an initial trial period, but long-term goals and deliverables in the Army context are final requirements. Bringing new technical horizons into the mix (e.g., robotics and unmanned vehicle technologies) presents new opportunities and challenges to the task of establishing methodology. For example, while the organizational research model is to be applauded and the notable per-project success rate within the Robotics CTA is to be recognized, there are a number of broader issues that VTD and ARL might wish to consider as this and similar activities move forward. Foremost, despite the growing number of single-point successes in transitioning CTA technology to more-applied Army programs, it is not clear that individual projects’ principal investigators, or even the CTA central leadership, have been able to find a fundamental, long-term view of the CTA’s mission within the Army. This may reflect the constraints imposed by the Army’s continued focus on FCS as its defining activity center for robotics. 

VEHICLE TECHNOLOGY DIRECTORATE 75 One programmatic consequence of this perceived standoff from direct soldier-on-the-ground prob- lem statements may be the seemingly incomplete vision of how the various constituent perceptual and reasoning capabilities now being vigorously developed, fielded, and transitioned will be integrated and deployed in functioning Army systems. A corresponding intellectual feature of this standoff is the very premise that perception and intelligence capabilities may be split off from equally fundamental consid- erations about the mechanical systems and their environmental settings. VTD should develop specific requirements, goals, and schedules for each individual project, reflecting systems engineering analyses that clarify the links of the projects to Army needs. The organization of VTD’s new Unmanned Vehicle Technologies Division provides a useful oppor- tunity to reassess this premise and to explore the extent to which intelligent bodies and minds are linked by the environments within which they carry out specific mission capabilities. On a more general level, bringing operational and human-factor objectives into the methodologies that enable research success without diluting the rigor of the fundamental research is a paramount challenge, but worthy of address. As it happens, VTD and ARL have many of the elements of that discussion at hand, with a strong foun- dation in mechanical systems and a growing excellence in intelligent autonomous systems. This is an outstanding technical environment in which to make those associations and connections. A benefit (or at least opportunity for benefit) of the BRAC activities is an enhancement of the VTD contributions to the Army’s needs, although the record of VTD in this regard is already generally excel- lent. This is especially true in the traditional areas of materials and propulsion, and it is increasingly true in the new technical directions of robotics and unmanned vehicles. Near-term benefits from work on engine and gear box deterioration (e.g., ASCED) and work on materials degradation and damage detec- tion (e.g., Air Coupled Thermography Inspection) are easy to identify. Propulsion and critical structure research and development translate directly into extended equipment deployment, extended missions, and reduced demands on depot assets. Other work may have longer lead times but great potential effect. The directorate has a long history of excellence in high-temperature materials that have the collective capability to create game-­changing capabilities in warfighter vehicles. An example of this type of effort is the ceramic composite and coat- ings work, which has the additional advantage of industry partners. The development of unmanned engines should also be mentioned in this context. And the development of analytical and computational methodologies and capabilities is a clear investment in future design and development capabilities, especially for active rotor design, tiltrotor aeroelasticity, high-resolution CFD, and a host of nonlinear problems associated with technologies such as flapping wings. Examples of this work include the ­Parallel Unsteady Domain Information Transfer effort and the development of robot algorithms for uncertain environments. Propulsion for unmanned vehicles would also appear to be an opportunity. At a more general level, while the Army Energy Program addresses installations and many Army programs address soldier power, vehicle power and energy would appear to have a natural home in this directorate. It is clear that the VTD programs are contributing to the greater technical community at the funda- mental and applied levels. Much of the high-temperature material work being done by VTD personnel, especially in cooperation with NASA Glenn Research Center, is unique and essential and is not being emphasized by many (if not most) other mission organizations or by academia. Some elements of the rotorcraft work are also clearly on the forefront of technical community efforts. Efforts to maintain aware- ness and involvement in frontier work at the community level need to be redoubled in some cases. As an example of this need, the active-passive rotor performance project is a refocused effort from prior smart rotor (active twist) activities in the noise and vibration area to assess performance. This refocus is based on this review’s (and other) comments indicating that improved performance is the key attribute that needs to be proven to justify active rotor applications. At the moment, the effort involves 

76 2007–2008 assessment of the army research laboratory analysis only. The project staff is a talented group of investigators with expertise in this area, and they are focused on a topic of significance to the community—performance—but at this early stage, in some respects, they are playing catch-up to others in the field. This work would benefit from the identifica- tion of a path that will distinguish this effort from others in this area. One opportunity that does exist is to seek collaboration in the upcoming NASA Ames Research Center testing on Boeing and Sikorsky active rotors (which may be in advance of the next VTD active twist rotor test in late 2009) and to see if those data can be the catalyst to the VTD work. A second example is the structural dynamics for rotorcraft activity, which is an effort to address one building-block component of comprehensive rotorcraft analysis—that being the dynamic modeling of redundant, nonlinear airframe structures. In reality, this is one element of a very broad and robust rotorcraft community of existing and past efforts along these lines. The focus on addressing fastener/ bolted joints has been the subject of prior work (e.g., by the National Rotorcraft Technology Center and Rotorcraft Industry Technology Association). This effort will benefit from detailed discussions within the structural dynamics community to best define an approach that can leverage past work. A third example has to do with mesoscale flapping wing structures. The scope of the VTD work, to design and construct mesoscale flapping wings capable of generating forces similar to those gener- ated by a fruit fly, is impressive and applauded. The study combines experimental and modeling work on millimeter-scale flapping wings. The modeling so far is limited to two-dimensional modeling using corrections (history integrals, added mass) to the quasi-steady formulas for lift and drag. The Reynolds number is larger than 1 but still low so that viscous effects are significant. The Strouhal number for the flapping action is of order 1 so that the unsteady effects are significant. Because of the values of these similarity parameters, classical wing theory does not apply, as the investigators recognize. A CFD solution rather than the modeling with corrections should be pursued. Clear objectives and a systematic approach could result in a considerable contribution to the greater community, because this is a research area of very broad activity with support coming from a variety of agencies and organizations. Well- defined goals and specific concentrations will help to ensure success in this context.