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Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary (2022)

Chapter: 3 Evaluation of Key and Essential Technologies

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Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
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3

Evaluation of Key and Essential Technologies

The U.S. Army Combat Capabilities Development Command (DEVCOM) Armaments Center (AC) demonstration development strategy is integrating mature technologies and models to achieve the Strategic Long Range Cannon (SLRC) science and technology (S&T) objectives. General considerations for development and unclassified assessments are in this chapter.

The committee evaluated the SLRC component and system development achievements to date and the program development and test plans. The SLRC program has developed a risk mitigation strategy of leveraging mature technologies. Most aspects of the SLRC technology development are at a higher classification level and are not discussed in this document.

3.1 HYPERSONICS FLIGHT

Hypersonic flights lead to high-temperature flows, air dissociation, and cumulative heating of airframes. Consequently, the performance of all on-board sensor systems such as the Global Positioning System (GPS), telemetry, communication, command and control, radar, laser ranging, and electro-optical (EO) sensors are adversely affected to varying degrees by the hypersonic environment. The range of parameters that characterize the flight environment is large and strongly influenced by many factors including the following:

  • Altitude,
  • Velocity,
  • Duration of flight,
  • Geometry of the vehicle,
  • Airframe, and
  • Heat-shield material.

On-board sensor systems encounter a variety of situations during launch and flight. These, for example, can include signal attenuation, communication blackout, signal distortion due to turbulent flow, radiation from heated optical windows, and emission from hot flows.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×

3.1.1 Fundamental Challenges of Hypersonic Projectiles

For an effective weapon, adaptive sensor systems that employ diagnostic tools to sense and match the environment will be needed. During flight, the boundary layer flow can be dispersive, inhomogeneous, fluctuating, and lossy, presenting challenges to the wideband radio frequency (RF) system using conformal arrays. Arrays also have the challenge of mutual coupling and impedance mismatch effects on beam forming. For telemetry, the signal transmitted from the vehicle can lead to nonlinear processes in the flow. Optical sensors are affected by hypersonic flow as density gradients caused by shock waves and turbulent fluctuations can distort optical wave fronts. In addition, the hot window can radiate at infrared (IR) frequencies, and the hot flow fields can emit and absorb at optical frequencies, thereby seriously affecting the optical and EO/IR sensors on board. In addition, pointing error and wave-front distortions are of concern in beam forming.

In general, hypersonic flight presents a number of challenges to sensors employed for navigation, guidance, and control sensors, including the following:

  • Adaptive vehicle control sensors,
  • RF/EO/IR terminal guidance,
  • Integrated maneuver control,
  • Sensors for on-board trajectory generation,
  • Sensor quality in service,
  • Communication/telemetry,
  • GPS limitations and alternate technologies, and
  • Time scale of airframe response.

3.2 GUN, LAUNCHER, AND PROJECTILE

The high-speed (hypersonic) delivery of munitions over strategic distances requires a significant transfer of energy to the projectile. In many hypersonic systems under development in the Department of Defense (DoD), that energy is provided by a rocket booster that may be launched from land, sea, or air. After separating from the booster, the projectile glides and maneuvers to the target. These are generally called Hypersonic Boost Glide Missiles (HBGMs). In some cases, further energy is added throughout flight using an air-breathing engine such as a scramjet allowing the vehicle to cruise, and these are generally called hypersonic cruise missiles. The Navy’s railgun system uses electro-magnetic energy. The SLRC uses the pressure rise from combustion of propellant to launch the projectile from a cannon and then adds further energy after exiting the gun using a rocket booster. Similar to a HBGM, the SLRC then glides and maneuvers to the target.

3.2.1 Gun Design, Material, and Manufacturing

3.2.1.1 Weapon Transportability

Numerous companies exist that can assist with developing transportability and mobility equipment for the SLRC weapon system (Figures 3-1 and 3-2). DEVCOM AC plans to work with this industry as design development further unfolds. These companies have expertise with moving larger and heavier things than the SLRC and have a range of commercial trailer, dolly system, and prime mover options. DEVCOM AC has said the SLRC is anticipated to be fielded in low quantities, but increasing weapons system quantities would be low risk.1

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1 U.S. Army Combat Capabilities Development Command Armaments Center, 2021, “Strategic Long Range Cannon (SLRC) Phase 2 Overview to NASEM Classified Breakout Session,” August 12, Washington, DC: National Academies of Sciences, Engineering, and Medicine.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Image
FIGURE 3-1 Example commercial options: SR71 transport (left) and steerable 3-axle dolly and beam deck (right).
SOURCE: U.S. Army Combat Capabilities Development Command Armaments Center, 2021, “Strategic Long Range Cannon (SLRC) Phase 2 Overview to NASEM Classified Breakout Session,” August 12, Washington, DC: National Academies of Sciences, Engineering, and Medicine.
Image
FIGURE 3-2 Commercial options: 13-axle steerable with natural gas compress 72 ft. on deck and 145,000 lb.
SOURCE: U.S. Army Combat Capabilities Development Command Armaments Center, 2021, “Strategic Long Range Cannon (SLRC) Phase 2 Overview to NASEM Classified Breakout Session,” August 12, Washington, DC: National Academies of Sciences, Engineering, and Medicine.

3.2.1.2 Weapon Mobility

The platform mobility trade space can be examined to determine how to best integrate the SLRC into the battlefield. Placement in secured areas may decrease platform exposure to attack, but could also reduce its operational flexibility. Options are possible for the Army to use emplacement flexibilities to these secured areas to determine how to maximize PRC system targeting delays and increase enemy battlefield confusion. The Multi-Domain Task Force (MDTF) organization contains short range air defense (SHORAD) units that may contribute to SLRC survivability.

3.3 SENSORS, QUALITY OF SERVICE, AND COMMUNICATIONS

Hypersonic flights lead to high temperature flows and cumulative heating of air frames. As a consequence, the performance of all on-board sensor systems—such as GPS, telemetry, communication, command and control, RF, and EO sensors—are all adversely affected to varying degrees by the hypersonic environment.

The range of parameters that characterize the flight environment is large and strongly influenced by many factors, including altitude, velocity, duration of flight, geometry of the vehicle, airframe, and heat-shield material.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×

Onboard sensor systems encounter a variety of situations during launch and flight. These, for example, can include signal attenuation, signal distortion due to turbulent flow, radiation from heated optical windows, and emission from hot flows.

3.4 WEAPON SYSTEMS ANALYSIS AND ENTERPRISE INTEGRATION

It is important to recognize where the SLRC project currently fits within the acquisition life-cycle model. As a research and development project,2 the SLRC objective is to adapt existing capabilities, where possible, and to identify, develop, mature, and integrate essential technologies to demonstrate that the concept for a SLRC is technically feasible.

The term “technology demonstration” has been used to characterize this project. Since Analysis of Alternatives occur before analysis at the end of the Materiel Solutions Analysis phase culminating in Milestone A, neither systems engineering nor manufacturing development has occurred; prototypes have not been developed. A formal program status has not been established, nor has a specific acquisition path among those that comprise the Adaptive Acquisition Framework been adopted (Figure 3-3).

Image
FIGURE 3-3 Adaptive Acquisition Framework.
SOURCE: Defense Acquisition University, “Adaptive Acquisition Framework Pathways,” https://aaf.dau.edu/aaf/aaf-pathways, accessed March 22, 2021.

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2 J. Rafferty, Army Futures Command, 2020, “Long Range Precision Fires Cross-Functional Team Brief to the National Academies of Sciences, Engineering, and Medicine,” presentation to the committee, September 24, Washington, DC: National Academies of Sciences, Engineering, and Medicine.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×

3.4.1 Weapon System Analysis

In 2020, acting Deputy Undersecretary of Defense for Research and Engineering Mark Lewis noted, “We often have difficulty transitioning department-funded basic research from universities through industry to operational applications. It is a particular challenge in hypersonics, where multiple disciplines must intersect precisely to move forward.”3

The system readiness level (SRL) index is a function of the technology readiness levels (TRLs) in a system and their subsequent integration points with other technologies, integration readiness levels (IRLs) (Table 3-1). The function of this interaction correlates to a nine level SRL index. The SRL index (Table 3-2) is defined by the current state of development of a system in relation to the Department of Defense’s (DoD’s) Phases of Development for the Life Cycle Management Framework.4

Conclusion: While TRLs are in use for the SLRC project, neither IRLs nor SRLs appear to be. Yet, “integrating” across the components and subassemblies that comprise the SLRC projectile and platform was frequently expressed as a significant concern: “getting it all to work together.” DEVCOM AC states that their greatest challenge now is “integration.”

Recommendation: Adapt and apply integration readiness levels and system readiness levels.

Dynamic programming (DP) should be considered as an optimization method to allocate component and subassembly reliability improvement investments in ways that cost-effectively achieve overall system reliability performance goals. DP formulates problems as multi-stage decision processes where the solution procedure, known as backward recursion, allows the problem to be solved stage by stage (Figure 3-4).5

Once the DP final stage is solved, the overall optimal policy (a set of solutions for the stages) can then be determined by utilizing the principle of optimality. The optimality principle states an optimal policy has the property that, whatever the initial state and initial decision are, the remaining decisions must constitute an optimal policy with regard to the state resulting from the first decision. DP has been applied to a variety of problems that can be structured as a sequence of decisions stages, including the optimal allocation “policy” of reliability improvement investments across components that comprise a system.

Conclusion: Neither reliability component diagrams nor dynamic programming methods appear to be used to cost-effectively allocate Reliability, Availability, Maintainability, and Dependability (RAM-D) improvement investments.

Recommendation: Use simple component and subsystem reliability block diagrams to understand where component reliability requires improvement. Apply dynamic programming methods to cost-effectively achieve projectile and weapon system reliability goals.

3.4.2 Operational Integration

The SLRC has been included in several war gaming exercises and simulations since fiscal year (FY) 2019. To date these have included the Fires Battle Lab (FBL) “Theater Fires Command Comparative Analysis” during FY 2020, and is planned for inclusion in other FBL simulations and exercises as they occur, including a FY 2021 exercise to examine the impact of the loss of Assured Precision Navigation and Timing. Center for Army Analysis

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3 M. Beinart, 2020, “Pentagon Establishes New Hypersonic Weapons Consortium, to Be Led by Texas A&M,” Defense Daily, October 26. .

4 Government Accountability Office, 2020, Technology Readiness Assessment Guide: Best Practices for Evaluating the Readiness of Technology for Use in Acquisition Programs and Projects [Reissued with revisions on February 11, 2020], GAO-20-48G, Washington, DC, January 7, p. 125.

5 R.E. Trueman, 1981, “Dynamic Programming,” Pp. 408–439 in Quantitative Methods for Decision Making in Business, Hinsdale, IL: Dryden Press.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×

TABLE 3-1 Government Accountability Office Integration Readiness Levels (IRLs)

IRL Definition Evidence Description
0 No integration No integration between specified components has been planned or intended.
1 A high-level concept for integration has been identified Principle integration technologies have been identified.
Top-level functional architecture and interface points have been defined.
High-level concept of operations and principal use cased has been started.
2 There is some level of specificity of requirements to characterize the interaction between components Inputs/outputs for principal integration technologies/mediums are known, characterized, and documented.
Principal interface requirements and/or specifications for integration technologies have been defined/drafted.
3 The detailed integration design has been defined to include all interface details Detailed interface design has been documented.
System interface diagrams have been completed.
Inventory of external interfaces is completed and data engineering units are identified and documented.
4 Validation of interrelated functions between integrating components in a laboratory environment Functionality of integrating technologies (modules/functions/assemblies) has been successfully demonstrated in a laboratory/synthetic environment.
Data transport method(s) and specifications have been defined.
5 Validation of interrelated functions between integrating components in a relevant environment Individual modules tested to verify that the module components (functions) work together.
External interfaces are well defined (e.g., source, data formats, structure, content, method of support, etc.).
6 Validation of interrelated functions between integrating components in a relevant end-to-end environment End-to-end functionality of systems integration has been validated.
Data transmission tests completed successfully.
7 System prototype integration demonstration in an operational high-fidelity environment Fully integrated prototype has been successfully demonstrated in actual or simulated operational environment.
Each system/software interface tested individually under stressed and anomalous conditions.
8 System integration completed and mission qualified through test and demonstration in an operational environment Fully integrated system able to meet overall mission requirements in an operational environment.
System interfaces qualified and functioning correctly in an operational environment.
9 System integration is proven through successful mission proven operations capabilities Fully integrated system has demonstrated operational effectiveness and suitability in its intended or a representative operational environment.
Integration performance has been fully characterized and is consistent with user requirements.

NOTES: The IRL scale does not attempt to address or account for programmatic life-cycle activities or responsibilities. This scale is intended to be used to assign integration readiness levels based on the applicable definitions and supported by the evidence descriptions.
SOURCE: M. Austin and D. York, 2015, Conference on System Engineering Research, GAO-20-48G, Washington, DC: Government Accountability Office, March.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×

TABLE 3-2 Government Accountability Office System Readiness Levels (SRLs)

Level SRL Definition
9 System has achieved initial operational capability and can satisfy mission objectives
8 System interoperability should have been demonstrated in an operational environment
7 System threshold capability should have been demonstrated at operational performance level using operational interfaces
6 System component integrability should have been validated
5 System high-risk component technology development should have been complete; low-risk system components identified
4 System performance specifications and constraints should have been defined and the baseline has been allocated
3 System high-risk immature technologies should have been identified and prototyped
2 System materiel solution should have been identified
1 System alternative materiel solutions should have been considered

SOURCE: Government Accountability Office, 2020, “Presentation of National Security Agency (NSA) System Readiness Assessment (SRA) Handbook SRL Information,” GAO-20-48G, Washington, DC, January.

Image
FIGURE 3-4 Dynamic programming model structure.
SOURCE: S.P. Bradley, A.C. Hax, and T.L. Magnanti, 1977, “Dynamic Programming,” Ch. 5 in Applied Mathematical Programming, Boston, MA: Addison-Wesley, http://web.mit.edu/15.053/www/AMP-Chapter-11.pdf, accessed March 22, 2021. Courtesy of Cengage Learning, Inc., reproduced by permission, http://www.cengage.com/permissions.

(CAA) conducted a modeling and simulation study to evaluate the SLRC, other Army and joint systems, on anti-access and area denial (A2/AD) penetration, dis-integration, and munition survivability using Advanced Framework for Simulation, Integration and Modeling (AFSIM), a high-fidelity physics based model. It is unusual for CAA to do this level of modeling, normally DEVCOM Data and Analysis Center (formerly Army Materiel Systems Analysis Activity) and The Research and Analysis Center (TRAC) at White Sands Missile Range are conducting the modeling. The SLRC was included in Joint Warfighter Assessment in FY 2019, and scheduled again for FY 2021 and beyond. It was included in table-top exercises for U.S. European Command and U.S. Indo-Pacific Command as part of the Strategic Fires Study series for FY 2020 and FY 2021. TRAC also modeled A2/AD penetration and munition survivability as part of the Strategic Fires Study.6

The LRPF CFT commissioned the Center for Army Analysis to conduct a modeling and simulation study focused on A2/AD penetration, dis-integration, and munition survivability utilizing AFSIM, a high fidelity physics based modeling tool. SLRC was included in this study along with other Army and joint systems. SLRC was included in the FBL Theater Fires Command Comparative Analysis during FY 2020 and will be included in other FBL simulations

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6 E. Halinski, U.S. Army Combat Capabilities Development Command – Armaments Center (DEVCOM AC), 2020, “Strategic Long Range Cannon Study (SLRC) Meeting 4 Follow-Up Response,” presentation to the committee, January 25, Washington, DC: National Academies of Sciences, Engineering, and Medicine.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×

and exercises as they occur, including the FY 2021 exercise focused on impacts due to loss of Assured Precision Navigation and Timing. All of these studies and results are conducted and briefed at the SECRET level or above.7

War-gaming exercises and simulation results that include the SLRC are the following:8

  • TRAC Strategic Fires Study 2019,
  • CAA 2020, and
  • Joint Warfighter Assessment 21 employed by U.S. Army Pacific Command and MDTF.

3.4.3 Enterprise Integration and System-of-Systems Performance

Enterprise integration has implications across Doctrine, Organization, Training, Materiel, Leadership and Education, Personnel, Facilities and Policy (DOTMLPF-P) domains for the institutional Army which functions as the generating force for the warfighting Army. Within the Army, doctrine has provided the coordinating mechanism around which the other DOTMLPF-P domains are aligned. Operational warfighting principles inform combat system, force development, and sustainment functions. However, the recent creation of Army Futures Command (AFC) has diminished this traditional Training and Doctrine Command (TRADOC) role since combat developments transferred from TRADOC to AFC. It is not yet clear what the mission essential tasks will be for this new strategic precision fires weapon system. This has implications for Field Artillery force structure, crew Military Occupational Specialty (MOS), and training.

ARIES analytic tools were created to provide requirements developers with an analytic capability to explore tradeoffs and gain insight to inform the requirements integration process. ARIES tools capture a representative set of the full spectrum of potential requirement values to identify low-level requirement interactions and allows decision makers to interactively explore these interrelationships (Figure 3-5). This real-time feedback facilitates discussions to reconcile conflicts between requirements from multiple disciplines early in a program, ultimately leading stakeholders to converge upon a set of simultaneously feasible system requirements while considering programmatic and technological constraints. This information also helps inform future technology investment decisions necessary to meet the desired objectives.9

Whole System Trades Analysis Tool (WSTAT) integrates subsystem models into a holistic system view, mapping critical design choices to desired performance outcomes. It is capable of solving highly complex optimization problems covering various technology areas and performance requirements while balancing costs, risk, and growth. WSTAT was developed and applied in partnership with the U.S. Army Program Executive Office for Ground Combat Systems to improve analytical capability and systems engineering during the system design phase.10

Conclusion: “System-of-systems” (SoS) reliability is among the biggest challenges for hypervelocity projectile development. The Center for Systems Reliability (CSR) was established at Sandia National Laboratories to partner with and support U.S. government agencies and commercial organizations on technical programs that involve systems and SoS reliability, readiness, and sustainment.

Across these three levels of integration, the committee observed few indicators of the application of operations research (OR). Thus, missing are the potential contributions of OR. This diminished role also affects other Army enterprise systems, as observed in several previous technical reports and special studies. In addition to noting the loss of analytical capacity in other Army enterprise domains, the committee also observed degradation in the use

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7 Ibid.

8 U.S. Army Combat Capabilities Development Command Armaments Center, 2021, “Strategic Long Range Cannon (SLRC) Phase 2 Overview to NASEM Classified Breakout Session,” August 12, Washington, DC: National Academies of Sciences, Engineering, and Medicine.

9 J. Christensen and J. Brown, Sandia National Laboratories, 2020, “Sandia’s Role in the Extended Range Cannon Artillery – II (ERCA-II) Project,” presentation to the committee, December 9, Washington, DC: National Academies of Sciences, Engineering, and Medicine; see the ARIES fact sheet at https://www.sandia.gov/csr/center-for-systems-reliability/tools/aries.

10 Ibid.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Image
FIGURE 3-5 ARIES (Advanced Requirements Integration and Exploration System) overview.
SOURCE: J. Christensen and J. Brown, Sandia National Laboratories, 2020, “Sandia’s Role in the Extended Range Cannon Artillery – II (ERCA-II) Project,” presentation to the committee, December 9, Washington, DC: National Academies of Sciences, Engineering, and Medicine; see the ARIES fact sheet at https://www.sandia.gov/csr/center-for-systems-reliability/tools/aries.

and applications of analytical methods for weapon system analysis, combat modeling, test and evaluation (T&E), and the broader land warfare analyses communities supporting the combat and force development functions within the institutional Army. Refer to Appendix E for further elaboration on the origination, evolution, and contributions of OR to the U.S. Army.

Conclusion: A concern frequently expressed during several presentations and discussions was a lack of communication and collaboration across various organizations with relevant S&T knowledge and experience. This observation applies to the Services, Office of the Secretary of Defense, industry, and federally funded research and development centers (FFRDCs); specific examples abound. One program manager lamented the lack of interaction across what he described as “three tribes” who speak completely different languages making communication, much less collaboration or even integration, an impossible challenge: S&T, programs, and operators. They all must be connected and synchronized to enable innovation. One by-product of the OR community’s focus on pursuing innovation is an inherent ability to coordinate across disciplines, organizations, and institutions, to connect the dots.11 Of course, these are long-persisting observations common to large, compartmentalized bureaucracies.

Nonetheless, improving unity of effort among key bureaucratic elements is as essential as it is painstaking. Key stakeholders include senior policy officials responsible for regulatory guidance, program directors who control funding, test and evaluation agencies that rigorously assess plausible alternatives, and the operators who own the problem but are constrained by insufficient authority and inadequate resources to pursue better options.

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11 G. Bussey, Joint Hypersonics Transition Office, 2020, “Strategic Long Range Cannon—An OUSD (R&E) Perspective,” presentation to the committee, September 23, Washington, DC: National Academies of Sciences, Engineering, and Medicine.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×

Recommendation: The committee believes that the Strategic Long Range Cannon highlights a broader problem and the Army would benefit from organizing the Army force modernization proponent and analytical community to better support the Research, Development, Test & Evaluation enterprise. Such an investment is expected to accelerate technology innovation and attain modernization excellence.

3.5 MODELING AND SIMULATION

The SLRC is a complex engineering system involving the interactions between multiple components and sub-systems that involve a number of different physical processes. Many of these individual processes are technically challenging and/or expensive to investigate experimentally. Testing of the fully coupled system is even more challenging and is unlikely to happen for several years. The effective application of modeling and simulation (M&S) is therefore critical to the initial development of the SLRC. In this section, the use of M&S in the SLRC program is evaluated in the context of individual components, such as aerodynamics, and aspects of the overall system, such as mission analysis.

Conclusion: The overall evaluation for this area is that M&S activities are adequate for the SLRC project. State-of-the-art computational tools are being employed; community leaders are being engaged as participants; test data is being used to validate models and to provide key inputs required by models. In addition to its application to individual components, DEVCOM AC12 also describes extensive use of M&S in support of the SLRC Test Strategy.

One important aspect that has not been highlighted in the M&S work presented to the committee, is the quantification of margins and uncertainties (QMU). No model is perfect, and it is essential to characterize the confidence with which M&S results can be used in the analysis and design of a system as complex as the SLRC. The development and application of techniques for QMU was pioneered in the Department of Energy research laboratories13 and these approaches are used pervasively as an integral part of hypersonic vehicle analysis by NASA14 and others.

Recommendation: The U.S. Army Combat Capabilities Development Command Armaments Center should institute a rigorous quantification of margin and uncertainty approach that quantifies uncertainty in each of the component systems (e.g., the uncertainty in prediction of axial drag force) and propagates all such uncertainties up to the system level to quantify overall uncertainties (e.g., the uncertainty in prediction of range).

3.5.1 Aerodynamics

The physical testing of the aerodynamics of high-speed projectiles in wind-tunnels and in flight is both technically challenging and expensive. This is an area that relies heavily on the application of computational fluid dynamics codes for vehicle design. For analysis of the aerodynamic forces and moments on the SLRC projectile, the project is making effective use of tools and procedures broadly accepted in the community.

3.5.2 Other Modeling Efforts

Most of the key and essential technologies with regards to materials and structures modeling cannot be outlined in this document due to classification restrictions. Detailed evaluations are in the committee’s Phase 1 and Phase 2 reports. To summarize the M&S assessments, the committee considers that the Army approaches are generally appropriate, using the right tools, but incorporation of uncertainty quantification into the analyses is recommended.

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12 U.S. Army Combat Capabilities Development Command Armaments Center, 2020, “Strategic Long Range Cannon (SLRC) Test Strategy,” presentation to the committee, November 12, Washington, DC: National Academies of Sciences, Engineering, and Medicine.

13 J.C. Helton, 2011, “Quantification of Margins and Uncertainty,” Reliability Engineering and System Safety 96(9):976–1013.

14 M.J. Wright, D. Bose, and Y.K. Chen, 2007, “Probabilistic Modeling of Aerothermal and Thermal Protection Material Response Uncertainties,” AIAA Journal 45(2):399–410.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×

3.6 ACQUISITION AND SUSTAINMENT

Ellen Lord, Under Secretary of Defense for Acquisition and Sustainment notes, “Our biggest sustainment concerns with hypersonics are ensuring that subcomponents have a resilient supply chain” and “that the military services have a strategy for spares and repairables that provide sufficient annual quantities to ensure predictability for suppliers and readiness for the warfighter.”15

3.6.1 Test and Evaluation

Currently, two relevant capabilities at Sandia National Laboratories are not being exploited by the SLRC project and could prove beneficial: the Mobile Gun Test Complex could be used to support aspects of the SLRC project and; as previously described and recommended above in Section 3.6, CSR should be engaged.

Conclusion: The SLRC project is executing an ambitious and comprehensive T&E campaign plan supported by several organizations and facilities. One particular FFRDC, Sandia National Laboratories, could contribute further to this effort with their Mobile Gun Test Complex and CSR.

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15 A. Baker, C. Contardo, and D. Edelman, 2021, “Hypersonics Illustrate Supply Chain Vulnerabilities,” National Defense, January 7.

Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 22
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 23
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 24
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 25
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 26
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 27
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 28
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 29
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 30
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 31
Suggested Citation:"3 Evaluation of Key and Essential Technologies." National Academies of Sciences, Engineering, and Medicine. 2022. Assessing the Feasibility of the Strategic Long Range Cannon: Unclassified Summary. Washington, DC: The National Academies Press. doi: 10.17226/26129.
×
Page 32
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The U.S. Army is working on a major science and technology development program to build the Strategic Long Range Cannon to fire a hypersonic projectile 1,000 miles. At the request of the Deputy Assistant Secretary of the Army for Research and Technology, the Committee on Assessing the Feasibility of the Strategic Long Range Cannon made recommendations for the U.S. Army in the following categories: organizational, operational, and technical demonstration development areas. This publication is the unclassified summary of the full, classified report.

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