Citation
Aircraft survivability

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Title:
Aircraft survivability
Place of Publication:
Arlington, VA
Publisher:
Joint Aircraft Survivability Program Office (JASPO)
Creation Date:
Summer 1998
Publication Date:
Copyright Date:
1998
Frequency:
Three times a year
regular
Language:
English

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Subjects / Keywords:
Aeronautics -- Safety measures -- Periodicals -- United States ( lcsh )
Aeronautics -- Safety measures ( fast )
United States ( fast )
Genre:
Periodicals. ( fast )
newspaper ( marcgt )
serial ( sobekcm )
periodical ( marcgt )
Periodicals ( fast )

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Dates or Sequential Designation:
Began with 1998.

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Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
This item is a work of the U.S. federal government and not subject to copyright pursuant to 17 U.S.C. §105.
Resource Identifier:
656541464 ( OCLC )
ocn656541464
Classification:
TL553.5 ( lcc )

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Digital Military Collection

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CAD GEOMETRIES AND BALLISTIC VULNERABILITY ANALYSESpage 6EXCELLENCE IN SURVIVABILITY Chad Rytherpage 16Development of Multiple Impact Transparent Armor Systemspage 10Physics-Based Models for Infrared (IR) Countermeasurespage 22

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Aircraft Survivability is published three times a year by the Joint Aircraft Survivability Program Ofce (JASPO) chartered by the US Army Aviation & Missile Command, US Air Force Aeronautical Systems Center, and US Navy Naval Air Systems Command. JAS Program Ofce 735 S Courthouse Road Suite 1100 Arlington, VA 22204-2489 http://jaspo.csd.disa.mil Views and comments are welcome and may be addressed to the: Editor Dennis Lindell Assistant Editor Dale B. Atkinson To order back issues of the AS Journal, please visit http://www.bahdayton.com/ surviac/inquiry.aspx On the cover: An F-35A Lightning II approaches a KC-135 Stratotanker during aerial refueling May 13, 2013, near Eglin Air Force Base, Fla. (U.S. Air Force photo/Master Sgt. John Nimmo) TABLE OF CONTENTS4 NEWS NOTESby Dennis Lindell4 JCAT CORNERby CAPT Cliff Burnette, Lt Col Doug Jankovich, LCDR Peter Olsen, and Mr. Greg Fuchs, CIV -USA6 COMPUTER-AIDED DESIGN GEOMETRIES AND BALLISTIC VULNERABILITY ANALYSESby Rod StewartBallistic vulnerability analyses are highly complicated endeavors that utilize and create voluminous amounts of data. As computing technology has progressed over the years, our ability to handle this type of analysis has improved exponentially. Todays computers complete these studies, once performed by hand many years ago, more quickly than ever before with an everincreasing degree of precision.10 DEVELOPMENT OF MULTIPLE IMPACT TRANSPARENT ARMOR SYSTEMSby Dr. Marc A. Portanova, Richard M. Delmont, and Michael C. BreslinOver the past several decades, signicant improvements in small arms protection have provided increased protection levels to virtually all Department of Defense (DoD) rotary wing aircraft. Unlike ground vehicles, where the application of high-hard or rolled homogeneous armor (RHA) steel plate is often an acceptable solution, the obvious weight sensitivity of aircraft platforms prohibit such a simple approach. 14 INTEGRATED BATTLEFORCE SURVIVABILITY: BUILDING A BETTER MOUSETRAPby Lee Venturino, David Black, and William DooleyThe concept of integrated aircraft survivability equipment needs to be expanded to the entire Battleforce structure. In addition to individual platform survivability, the entire strike package must maintain the ability to execute the complete kill chain of detect, track, ID, target, engage, and assess. Survivability becomes even more critical when fth generation aircraft are operating with their fourth generation cousins and may be called upon to provide an overarching Battleforce protection role. Advanced threats will attempt to disrupt our integrated capability by jamming our global positioning system and Link-16 sensors. 16 EXCELLENCE IN SURVIVABILITYCHAD RYTHERby Maj Ron PendletonThe Joint Aircraft Survivability Program (JASP) is pleased to recognize Air Force Lieutenant Colonel (Lt Col) Chad Ryther, personally and as a representative of all the Joint Combat Assessment Team (JCAT) assessors that have deployed to Iraq and Afghanistan, for Excellence in Survivability.

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http://jaspo.csd.disa.mil AS Journal 13 / FALLMailing list additions, deletions, changes, and calendar items may be directed to: SURVIAC Satellite Ofce 13200 Woodland Park Road Suite 6047 Herndon, VA 20171 Fax: 703/984-0756 Email: E_JAS_FEEDBACK@bah.com Promotional Director Jerri Limer Creative Director Jerri Limer Art Directors Michelle Meehan Karim Ramzy Technical Editor Alexandra Svem Journal Design Donald Rowe Illustrations, Cover Design, Layout Addie Huynh Michelle Meehan Karim Ramzy Distribution Statement A: Approved for public release; distribution unlimited, as submitted under OSD/DOT&E Public Release Authorization 14-S-0008. 18 OPERATIONAL EVALUATION OF AIR COMBAT EFFECTIVENESSby Ronald Thompson, Hugh Grifs, and Josef SeidlTo allow weapon systems to be used most effectively when elded, the Joint Anti air Combat Effectiveness (J-ACE) DVD is providing the Department of Defense (DoD) warghting community with the means for quantitative operational evaluation of air combat. J-ACE includes a suite of interfaced analysis software application packages, RED and BLUE system performance data sets, a soldier-friendly graphical user interface (GUI), various output displays tools, and an analyst manual. 22 PHYSICS-BASED MODELS FOR INFRARED (IR) COUNTERMEASURESby Caroline Wilharm and Brent WaggonerModeling and simulation is an important component in the development and employment of airborne expendable infrared countermeasures (IRCM) to protect military aircraft from hostile missiles. As more sophisticated threats emerge, new countermeasures and techniques are needed to defeat these threats.25 A POTENTIAL AIRCRAFT CASUALTY EVALUATION APPROACH FOR LIVE FIRE TEST AND EVALUATION (LFT&E)by Joel Williamsen, James Rhoads, and Mark CouchTraditional approaches to aircraft casualty evaluation within aircraft LFT&E programs have focused on direct threat effects on pilots, treating them as just one of many critical components that could lead to aircraft attrition or mission loss. In 2007, Director, Operational Test and Evaluations (DOT&Es) of LFT&E directed the Joint Aircraft Survivability Program (JASP) to develop and expand tools to predict casualties from all potential casualty sources and identify casualty reduction features. 28 CRITICAL COMPONENT PROTECTION (CCP)INCREASED VULNERABILITY REDUCTION FOR ROTORCRAFTby Dr. Marc A. Portanova, Nicholas C. Gramly, and Michael C. BreslinA recent article published in Aircraft Survivability states that the combat hostile action loss rate for aircraft in Operation ENDURING FREEDOM and Operation IRAQI FREEDOM was 8 times lower than that seen in Vietnam. This assertion is supported by data collected in a previously released document, Study on Rotorcraft Survivability Summary Report and is attributed largely to improved aircraft vulnerability design and the resulting reduction of cheap kills caused by small arms and automatic weapon threats.

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 4 DONALD W. MOWRER MEMORIAL CONFERENCE ROOM DEDICATEDOn 28 March 2013, the SURVICE Engineering Company, headquartered in Belcamp, MD, dedicated the main conference room at its Aberdeen Area Operation to Don Mowrer, an aircraft survivability pioneer, long-time govern ment leader, and former SURVICE Vice President who passed away on 2 November 2012. During the dedication ceremony, which was attended by Dons family members, friends, and former coworkers, SURVICE CEO Jeff Foulk unveiled a sign and a placard that will hang on the conference rooms wall. Mr. Foulk also highlighted some of the major accomplishments that Don made during his +50-year career in survivability. Most notably, Don helped to establish survivability as a formal engineering discipline, was a charter member of the Joint Technical Coordinating Group on Aircraft Survivability, and was an early visionary for the establishment of the Survivability/Vulnerability Information Analysis Center and the development of the Computation of Vulnerable Area Tool. In addition, in 1997, the National Defense Industrial Association honored Don with its Lifetime Achievement Award in Combat Survivability. The 100-person Donald W. Mowrer Memorial Conference Room will continue to be used by SURVICE employees and other government and industry organizations for a wide variety of technical meetings and events. It is located adjacent to the Walter S. Thompson Memorial Library, which SURVICE posthumously dedicated to Dons fellow survivability leader and long-time coworker, Walt Thompson, in June 2008. The casual observer may think that a Joint Combat Assessment Team (JCAT) assessment is merely taking pictures of battle damage, when in fact photos are only one part of a JCAT assessment. A practical way to explain the value of the JCAT assessment activity is to think of Operation ENDURING FREEDOM (OEF) as a large live re test range. A JCAT assessor collects and documents all of the information available as if he or she were recreating the parameters of the test as well as clarifying the effects and outcome of the test. All data is captured in a database where engineers and other stakeholders can then review and exploit the event for future design activities. The improvement advantages that are derived from JCAT data can come about in the short, midor longterm; they can take many different forms, such as via tactics, techniques, and procedures (TTPs) or maintenance practices, or in the aircraft through considerations such as ballistic protection, system separation, system redundancies, re suppression, threat countermeasures, or other design changes. To this end, it is JCATs responsibility to: Support battleeld commanders by rapidly validating threats that impact combat aviation assets Support the Survivability community by documenting aircraft survivability performance data with high delity reporting of hostile re damage to support survivability stakeholder efforts in continuous improvement to sub-systems, systems, and whole aircraft solutions to reduce suscepti bility and vulnerability to enemy threat systems In its critical role, JCAT has recently made signicant progress advancing the assessor training curriculum, developing innovative training facilities, and providing survivability engineers with meaningful data. In March 2013 at Naval Air Warfare Center (NAWC) China Lake, CA, JCAT completed Phase 2 training of 30 assessors preparing to deploy. This years Phase 2 curriculum included several rsts:JCAT CORNERby CAPT Cliff Burnette, Lt Col Doug Jankovich, LCDR Peter Olsen, and Mr. Greg Fuchs, CIV -USA NEWS NOTESby Dennis Lindell Figure 1. CDR Sean Neally, JCAT OIC conducts assessment at Camp Leatherneck

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5 http://jaspo.csd.disa.mil AS Journal 13 / FALL The amount of eld time conducting hands-on work signicantly increased. For rst time ever, the class partici pated in a day and night rocket-propelled grenade (RPG) live re, which provided students an invaluable opportunity to witness the capability and characteristics of the weapon. Both RPG shots were captured in high speed from three views: entrance, overview, and exit. Lieutenant Commander (LCDR) Scott Quackenbush and Ensign Mark Buffum considerably advanced another signicant JCAT initiative at NAWC China Lake in August 2013 that involved the development of the remote 200+ acre JCAT Training Facility. They facilitated one of the two H-1 helicopters JCAT acquired for training purposes to be shot with two different RPGs for future instruction purposes. Ultimately, the H-1 helicopters and other airframes will be placed in the facility for JCAT students to assess as part of their scenario-based training. When completed, the JCAT Training Facility will feature damaged aircraft based on shoot-down events experienced in Operation IRAQI FREEDOM (OIF) and OEF. JCAT WARFIGHTER SUPPORTJCAT-Army, Air Force, and Navy ofcers continue to support the overseas JCAT mission in OEF. The current OEF JCAT team includes Ofcer in Charge (OIC) Commander (CDR) Sean Neally and LCDR(s) Calvin Martin at Camp Leatherneck supporting 2d Marine Aircraft Wing (MAW); Major (Maj) Dave Garner supporting the 3 Combat Aviation Brigades (CABs) in Kandahar, Afghanistan; and Captain Gary Roos is supporting the 10 CAB in Bagram, Afghanistan. Every assessor has been busy, especially in the month of August. Lieutenant Colonel (Lt Col) Arild Barrett is in the nal stages of preparing for a couple of weeks in theater where he will be assisting the current JCAT-Air Force team with investigations. Lt Col Barrett brings a wealth of rotorcraft and aircraft battle damage repair expertise to the team and his assistance in theater will be welcomed. Likewise, LCDR Jorge Anaya is completing his pre-deployment training with 3d MAW at Marine Corps Air Station (MCAS) Miramar, CA. JCAT-Army supports the soldier forward by providing event-driven rapid response to catastrophic events. JCAT-Army activities continue at a high operating/operations tempo. While training for deploying units is slowing datajust over 600 deployers trained this FYthe data collection continues with the training imbedded in Army Aviations Professional Military Education program. As of July 2013, over 2,500 personnel, from Chief Warrant Ofcer 1 to colonel, were provided some form of combat damage data collection education. This effort ensures both aircrew and unit staffs understand the JCAT mission. The Air Force has brought Lt Col Doug Jankovich on active duty to work the day-to-day operations of the JCAT-Air Force. Lt Col Jankovich is handling all training, equipping, and deploying of members as well as reviewing incident reports. Lt Col Jankovich is also planning the JCAT service lead conference that will be held at Wright Patterson Air Force Base, OH from 6-8 September 2013. The purpose of the meeting is to discuss future deployment requirements, training curriculum, special projects, and the 2014 TWE.JCAT PERSONNEL CHANGESOn the personnel front, the Army component has seen a number of changes. Chief Warrant Ofcer (CW) 4 Jason Watson has moved to Fort Drum and is deploying to OEF as part of a Brigade Aviation Element imbedded in one of the 10th Mountain Divisions ground combat brigades. On the plus side, JCAT has gained two assessors with recent deployment experience. Both CW3 Brian Bartee, an Apache pilot, and CW3 Rob Olson, a Kiowa Warrior pilot, come to JCAT from the 82d CAB. The biggest transition JCAT faces is the loss of CW5 Bobby Sebren. CW5 Sebren is the only two-time offender, having been the JCAT-Army components OIC twice. He split this unique qualication with his deployment to OEF with the 10th Mountain Division in 2011. After over 30 years of service to our nation, CW5 Sebren is retiring; his leadership and technical expertise in everything Army Aviation will be missed. The Army has provided a tting replacement in CW5 Mike Apple, who comes to us from the 12th CAB, where he was the Brigades Command Warrant Ofcer. JCAT-Navy CDR Dave Storr reported back for duty as the Navy JCAT Liason Ofcer to 3d MAW, MCAS Miramar, CA after a successful second combat tour in OEF. CDR Storr will resume his duties maintain ing the JCAT-Navy mission forward, supporting projects at NAWC China Lake and assisting other NAVAIR Reserve Program units with pre-deployment training, logistics, and seamless integra tion with 2d and 3d MAW. Welcome home Dave and job well done. Figure 2. LCDR(S) Martin performs forensic testing during a JCAT assessment at Camp Leatherneck

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 6 COMPUTER-AIDED DESIGN GEOMETRIES AND BALLISTIC VULNERABILITY ANALYSESCOVER STORYby Rod Stewart

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7 http://jaspo.csd.disa.mil AS Journal 13 / FALLThe availability of improved computing capabilities, however, has increased the chances of introducing unintended errors. With the ability to handle vast amounts of data, analysts have been progressively increasing the precision of their inputs, especially with respect to geometric models. While models are becoming more exact, the amount of information needed to capture the extra complexity in the associated geometry makes it harder for the analyst to manipulate, which may lead to a situation where the model lies outside the theoretical and practical limits of the tools conducting the analysis. A quick comparison of the technological capabilities between aircraft design and ballistic vulnerability tools reveals this risk. Advances in CAD have greatly reduced the burden of designing aircraft, and the state-of-the-art of these tools progresses rapidly. Companies release updates for their CAD applications ( e.g., AutoCAD, CATIA/SolidWorks, and PTC Creo) yearly, providing additional features to facilitate geometry creation and taking advantage of recent improvements in computing technology. Many designers use these tools for visualization and production purposes, so the resulting models tend to be elaborate and include many geometric features, such as rivets, holes, llets, bevels, ribbing, etc. In contrast, the ballistic vulnerability community has not developed their toolset to the point where it can effec tively utilize intricate, CAD-derived, target models. While the level of detail found in such models generates excellent graphics, their complexity can overwhelm the abilities of community ballistic vulnerability tools ( i.e., Advanced Joint Effectiveness Model [AJEM], Computation of Vulnerable Area Tool [COVART], Endgame Framework, etc. ) to effectively handle them. In other words, using CAD-derived models in a ballistic vulnerability analysis may not t the conceptual and processing domains available within these tools.CONCEPTUAL LIMITATIONSWhen examining the current community toolset for ballistic vulnerability analyses, two major limitations are readily apparent: 1) the penetration data backing these tools reference far simpler geometries than that which exist on actual aircraft, and 2) these tools depend on ray tracing to interrogate the target. The rst limitation on the ability of ballistic vulnerability codes to handle complex models lies in the conceptual domain of the penetration methodolo gies. The basis of our current ability to assess penetration is test data. While a vast amount of test data is available after years of ballistic testing, most of these tests have one major limitation: nearly all of the targets were large, at, uniform plates. The community has done little penetration testing against curved surfaces or surfaces with various features ( e.g., ribs, bevels) to better develop existing penetration methodolo gies. As a result, the current community penetration toolset is best suited when assessing plate-like geometries. Seeing that most CAD-generated models are not typically plate-like, the risk for incorrect penetration assessment increases when using these models. Beyond the limitations in penetration test data, the communitys use of ray tracinga common method for interro gating target modelscan further lead to errors in penetration assessment. In ballistic vulnerability applications, rays represent the assumed paths of a threat through a target. Most codes use one ray to represent the path of one threat object ( e.g., intact missile, projectile, fragment) and assume that intersections with the target model along this ray are locations where the threat will strike target components. This approach inherently limits the understanding of the interac tions between target and threat to one dimension. As a result, applications using ray tracing have to make assumptions regarding the surface associated with the intersection. These assumptions are acceptable when the model is relatively simple, but conceptual problems arise as the complexity of the model ( i.e., the number of features/elements) increases. Figure 1 demonstrates how adding complexity to a model may have a substantial impact on penetration assessments. The left side of the plate in the gure is simplistic with no additional features, while the right side of the plate has a sinusoidal tread. If the red and blue rays through the geometry represent threat shotlines, it is evident that threat penetration estimated for the red shotline will differ vastly from that estimated for the blue shotline. The red shotline will Ballistic vulnerability analyses are highly complicated endeavors that utilize and create voluminous amounts of data. As computing technology has progressed over the years, our ability to handle this type of analysis has improved exponentially. Todays computers complete these studies, once performed by hand many years ago, more quickly than ever before with an ever-increasing degree of precision.

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 8 have a single, solid line of sight that will correspond well with the assumptions behind the penetration methodologies. On the other hand, the blue shotline will have multiple smaller lines of sight with higher obliquities that may lie outside the conceptual domain of the penetration methodology employed. Having geometry like that associated with the blue shotline may also have unanticipated negative impacts on other methodologies used within the tools. One example would be the AIRGAP re assessment methodology in COVART, where the number of intersec tions between a function and a ammable material are important for re initiation.PROCESSING LIMITATIONSBeyond conceptual issues, using CAD-derived geometry models in ballistic vulnerability analyses may exceed the capabilities of the toolset to process them efciently. The current trend in the community involves converting geometry models, initially in a proprietary CAD format, into code inputs using the bag of triangles (BoTs) approach. Undertaking this approach, the analyst exports CAD-derived parts in some non-proprie tary intermediate format and then converts the resulting geometry into the input format of the ballistic vulnerability code of interest (typically the Fast Shotline Generator [FASTGEN] or BRL-CAD format). Some of the more popular intermediate formats include the stereolithography (STL), standard for the exchange of product model data (STEP), virtual reality modeling language (VRML), initial graphics exchange specication (IGES), and Wavefront technologies object le formats. While exporting into this intermediate format, the converter redenes the part as a mesh of triangular elements. The number of triangles in this mesh can be quite large (from hundreds to millions of elements), depending on the complexity of the part and desired precision as opposed to the relatively small number of elements (from tens to hundreds) that generally result when recreating the part outside of CAD. Millions of triangles in meshes can have two major drawbacks in a ballistic vulnerability analysis: 1) the amount of time needed to process the geometry increases, and 2) much of the geometric information in the target will not be sampled during the analysis due to gridded ray approach typically employed, resulting in space wasted to hold unused information. As an example, Figure 2 reports COVART runtimes for three simple geometric shapes dened using varying numbers of elements. These shapes, as shown in Figure 3, included a cube, a cylinder, and a sphere. The number of elements used to represent each shape ranged from one primitive representing the geometry to as high as 6.3 million triangular elements. The Survivability/Vulnerability Information Analysis Center (SURVIAC) ran all of the geometry models with Figure 1 Two Shotlines, Different Penetration Figure 2 FASTGEN Runtimes for Simple Geometric Shapes Represented with Varying Numbers of Elements

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9 http://jaspo.csd.disa.mil AS Journal 13 / FALL COVART using the FASTGEN legacy feature to create shotline output les for a grid of parallel rays with 2-inch spacing. The data points in the gure reect the clock time necessary for a Windows 7, 64-bit laptop with 2.80 GHz processors and 4 Gb of RAM to process each model. After creating the shotline les for each model, SURVIAC checked to ensure that these results were similar across all models of the same shape. Figure 2 clearly demonstrates that the runtime of FASTGEN increases as the number of elements increases, with runtimes growing more dramatically as this number exceeds 10,000. Since the triangular elements typically generated with the BoTs approach are small, the likelihood of creating element information that will never be intersected during an analysis increases. In the above example, the box and cylindrical targets resulted in 49 shotlines while the sphere only resulted in 41. Seeing that there could only be two element intersections per shotline, it remains that a maximum of 98 of these elements would have any utility in this analysis. Comparing this number to the maximum number of 6.3 million elements demonstrates that these higher delity shape denitions unneces sarily hinder the processing of these geometries from a runtime perspective. Even with its shortfalls, the BoTs methodology tends to be the favored approach for analysts in the community due to how cost-effective it appears to be for generating geometry for ballistic vulnerability analyses. The less-obvious drawback is that simple parts like fuel lines now require a vast amount of information due to the number and size of elements used. This results in large geometric model sizes that were unanticipated during the creation of the current ballistic vulnerability toolset. No more than a few decades ago, the community would deem a model in the multiple-megabyte range as too large. Now, FASTGEN models have sizes approaching a gigabyte in size with some of the newest models, like that for the KC-46A tanker, reaching the multiple-gigabyte range. The effort that goes into manipulating or maintaining these large les can quickly evaporate any potential cost savings realized in their development.ADDRESSING THESE LIMITATIONSWith this noticeable gap between our ability to design aircraft and our capabili ties to assess ballistic vulnerability, the need exists to do one of two things: 1) improve existing tools so that they can effectively handle increasingly complex geometries, or 2) simplify geometries to t within the domain of the current toolset. To follow the rst approach, the commu nity will need to conduct additional penetration testing against complex geometries as well as build methodolo gies that can better interpret the geometry impacted on a shotline. As to testing, the feasibility of using curved and complex surfaces is uncertain, and it appears that there are other priorities ( e.g., improving existing data sets, increasing materials tested) ahead of moving into this realm. On the methodol ogy side, initial capabilities exist that use multiple rays to account for long or large threats (AJEM and Uncontained Engine Debris Damage Assessment Model), but more work should be done on these methodologies to ensure they are robust and conceptually valid. Since tools better capable of handling CAD-derived models have not yet arrived, the only recourse in the near-term is to adopt the second approach and simplify geometry inputs to t the tools. In recent work for various xed-wing platforms, SURVIAC has determined that a geom etry simplication process has three major facets: Figure 3 FASTGEN Models of Geometric Shapes Using Varying Numbers of Elements continued on page 13

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 10 DEVELOPMENT OF MULTIPLE IMPACT TRANSPARENT ARMOR SYSTEMSby Dr. Marc A. Portanova, Richard M. Delmont, and Michael C. BreslinOver the past several decades, signicant improvements in small arms protection have provided increased protection levels to virtually all Department of Defense (DoD) rotary wing aircraft. Unlike ground vehicles, where the application of high-hard or rolled homogeneous armor (RHA) steel plate is often an acceptable solution, the obvious weight sensitivity of aircraft platforms prohibit such a simple approach. Instead, the use of advanced composite systems have seen widespread application on the DoD helicopter eet, employing a multitude of materials including ceramics ( e.g., silicon carbide, boron carbide, etc. ), para-aramids ( e.g., Kevlar), and most recently ultra-high molecular weight polyethylenes (UHMWPEs) ( e.g., Spectra Shield II). Regardless of construct, these composite armor systems have one thing in common: they are opaque. This simple fact often limits the use of armor to opaque areas on a given platform ( e.g., seat, oor, etc. ). Opaque armor panels have been effectively used inboard of transparent materials ( e.g., chin bubbles, down-look windows, etc.); however, they are used at the expense of situational awareness. The obvious solution to the above dilemma is the use of bullet resistant (BR) glass. Shown schematically in Figure 1(a), BR glass is comprised of numerous layers of conventional glass (oat glass) laminated together with polymer interlayer (polyvinyl buterol/ PVB) and backed with a polycarbonate spall shield. While effective at providing small arms protection, BR glass is typically too heavy and too thick for any practical application on most (if not all) rotary wing aircraft. Much like the weight sensitivity issue for opaque armor (described above), the most practical and efcient solution to the transparent problem lies in the use of composite materials. NEW TRANSPARENT ARMOR TECHNOLOGIESRecent developments in materials technology have provided a multitude of transparent materials (other than glass) for use in a transparent armor system. Of particular interest are transparent ceramics ( e.g., synthetic sapphire, magnesium aluminate spinel, and aluminum oxynitride) [1], and several advanced polymers ( e.g., polyurethanes, polycarbonates, etc. ). These materials can be combined in a manner analogous to BR glass systems, resulting in higher performing, lighter weight transparent armor systems. Standard (a) (b)Advanced Ceramic Strike Face Advanced Interlayer Alternative Midlayer Advanced PolyurethaneAdvanced Float Glass Float Glass Float Glass Float Glass Float Glass PVB PVB PVB PVB Polycarbonate Figure 1. Schematic Representation of (a) BR Glass and (b) Transparent Armor

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11 http://jaspo.csd.disa.mil AS Journal 13 / FALL Under a recent Aviation Applied Technology Directorate (AATD)managed and Joint Aircraft Survivability Program Ofce (JASPO)-funded Technology Investment Agreement (TIA), the above concepts were explored towards the development of an advanced ballistic transparency, capable of sustaining multiple impacts. Working closely with the Department of Energys Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, The Protective Group (TPG), located in Miami Lakes, FL, designed and devel oped a transparent armor system specically for rotary wing aviation platforms. Described as a Multiple Impact Transparent Armor System (MITAS), the system was optimized not only for weight, but for post-impact visibility. As is the case for any rotary wing application, weight is the dominant design factor. For MITAS, weight reduction was derived from technology initially developed by LLNL under a contract from the Defense Advanced Research Projects Agency. The LLNL design was based on a different approach than most contemporary transparent armor/BR glass systems. Rather than using numerous layers of glass, where the ballistic threat is literally overcome by the mass of the laminate sheets, an approach more in line with opaque armor design was used. Three primary materials were employed, each of which played a different role in the defeat of the projectile (Figure 1[b]). First, an advanced ceramic strikeface is utilized, which is typically selected from one of the three ceramic materials identied above. The role of this material is to blunt and/or shatter the incoming threat. Following the hard ceramic strikeface is an alternate material mid-layer, which is typically a thick layer of glass or an advanced polymer ( e.g., polyurethane). The function of this layer is to effectively erode and slow down the core frag ments and ceramic shard generated from the impact. Finally, much like the BR glass system, a spall shield material is used at the rear of the laminate to prevent fragments from exiting the armor system. While the same polycar bonate used in the BR glass can function adequately for this purpose, materials ( e.g., polymethyl methacrylate or polyurethane) may offer some weight savings.POST-STRIKE VISIBILITYGiven the reduced weight architecture, the next objective in designing MITAS was the ability to maintain visibility following a ballistic impact. In tradi tional glass systems (both BR and non-BR), a catastrophic impact will result in spider web cracking through out the entire window, rendering limited (if any) residual visibility (Figure 2[a]). For MITAS, an engineered mosaic approach was employed. Shown in Figure 2[b]), the strikeface of the window is actually comprised of individual ceramic tiles arranged in a mosaic grid. As can be seen, the effect of this architecture allows for the damage to be contained within the tile that is impacted. Further careful attention is paid to the tile seams and triple points during production, so that damage resulting from impacts to these regions is contained within adjacent cells. The end result is a transparent armor window capable of defeating multiple threats, minimizing collateral damage to the window, and providing the operator situational awareness after the ballistic event. Given the performance exhibited by MITAS during the course of this effort, AATD/JASPO recommended the MITAS technology to the Department of Defense Research and Engineering Helicopter Survivability Task Force (HSTF) for consideration. The HSTF was established in 2009 as a means of addressing hostile re threats to rotorcraft, particularly in Afghanistan. Concurrent with HSTF reviewing the MITAS technology, TPG prepared a H-47 down-look window technology demon strator capable of defeating armor piercing threats (Figure 3). The MITAS technology demonstrator window offered 300% the viewing area and substantially improved multi-hit threat protection (Figure 2) at a 17% weight reduction as compared to the legacy system own on current Army H-47 models. Figure 2. (a) Monolithic Transparent Armor Showing Extensive Damage and Spider Web Cracking Due to a Single Shot, and (b) MITAS Showing Reduced Level of Damage after Five Shots (Wwo (2) in the Strikeface Tiles, One at a Tile-Tile Seam, and Two at Tile Triple Point SeamsA B

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 12 MITAS was briefed to both the 160th Special Operations Aviation Regiment and PMO Cargo Helicopter. Both expressed interest and became the initial customers for the transparent armor technology. A focused engineer ing and manufacturing development effort, funded by the HSTF, was awarded as an extension to the existing effort with the intent of providing MITAS windows for the H-47 and H-60 platforms. The MITAS windows would not only be required to meet a revised ballistic specication, but all require ments for an airworthiness release. Examples of the resultant windows are shown in Figure 4 and 5. The H-47 window features a modular A-kit/B-kit conguration, where the A-kit is installed on the aircraft to allow rapid removal/installation of the armored B-kit (less than 10 minutes based on eld trials). The H-60 window is a direct replacement for the current opaque panel and is installed using existing hard-points on the airframe. Windows for all three aircraft platforms were recently displayed at the Army Aviation Association of America Professional Forum and Exposition. Following the meeting, the Air Force expressed interest in the H-60 MITAS window for their H-60 CSAR (Combat Search and Rescue) eet.MITAS FIELDINGIn late 2012, MITAS Low Rate Initial Production (LRIP) was completed for the CH-47, followed by H-60 LRIP for the Air Force CSAR aircraft. To date, 100 MITAS shipsets have been procured for the Army, Air Force, and Special Operations rotary wing aircraft. This technology provides the soldier Theater relevant, armor piercing, and sniper protection Multi-hit performance with excellent post-strike visibility Improved NVG compatibility (versus legacy systems) Greater than 45% weight reduction (versus H-47 variant) Increased situational awareness and mission endurance Field installability/ airframe swappingACKNOWLEDGEMENTSThe authors would like thank the following individuals and their teams, all of whom were instrumental in the success of the MITAS program: Bob Hood, AATD; Ken Branham, JASPO; Dennis Lindell, JASPO; George Chinea, Cargo Helicopter Modernization Program Ofce; Army Lieutenant Colonel James J.T. Naylor, Technology Applications Program Ofce; Richard Landingham, LLNL; Joshua Kuntz, LLNL; Parimal Patel, Army Research Laboratory; George Hart, AesirFletching; Tony Moffatt, Aesir-Fletching; and TPG MITAS Development Team lead by Dave Sparks. References[1] Patel, P.J., Gilde, G. A., Dehmer, P.G., and McCauley, J.W., Transparent Armor, The AMPTIAC Newsletter Fall 2000. Figure 3. (a) MITAS Armor Piercing Technology Demonstration Window for the H-47 Chinook and (b) Legacy BR Glass Window from H-47 Chinook. Note: Legacy window does not offer armor piercing protection, is heavier, and has a substantially reduced viewing area when compared to the MITAS window.A B Figure 4. MITAS H-47 Down-Look Window Figure 5. MITAS H-60 Wing Armor

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13 http://jaspo.csd.disa.mil AS Journal 13 / FALL Conversion Transforming geometry data from one format to another Optimization Simplifying complex geometries and reducing the number of elements Verication Identifying that optimized/converted geometries are adequate reections of the original SURVIAC has identied or developed initial capabilities for each of these facets and used them to support a ballistic vulnerability study of the HC/MC-130J aircraft. The starting point of this effort was an existing FASTGEN model of the C-130H with an initial le size of 681 MB. While modifying the model to reect the HC/MC-130J, SURVIAC simplied the geometry, reducing the nal target size to approximately 525 MB. This roughly 23 percent reduction in le size led to a 23 percent reduction in FASTGEN processing time, enabling this model to be processed faster than the older C-130H model. Future efforts to develop geometric simplication capabilities will focus on expanding the current toolset and making the process less expensive and analystintensive through automation. These plans also include incorporating geometry simplication tools into future releases of the vulnerability toolkit. In conclusion, while the community attempts to bridge the gap between the complexities of CAD-derived geometry models and the capabilities of existing ballistic vulnerability tools, it should remain mindful of the potential risks of using CAD-derived geometries in ballistic vulnerability studies. While CAD technology creates beautiful pictures, the resulting complexity and volume of data can easily, while unintentionally, exceed the conceptual limitations of the communitys penetration methodologies as well as needlessly slow the analysis process down. Without using simplica tion in the near-term and expanding our testing and tools to handle increased complexity in the long-term, these complicated endeavors called ballistic vulnerability analyses may unintentionally be providing misleading results. References[1] Smith, J. K. & Stewart, R. K. (2011). HC/ MC-130J Vulnerability analysis, volume 1: Analysis overview (SURVIAC TR-11-2465). Dayton, OH: SURVIAC. [2] Stewart, R. K. (2013). Improving ballistic vulnerability analyses through geometry simplica tion. SURVIAC Bulletin, (1), 8-10.COMPUTER-AIDED DESIGN GEOMETRIEScontinued from page 9

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 14 INTEGRATED BATTLEFORCE SURVIVABILITY: BUILDING A BETTER MOUSETRAPby Lee Venturino, David Black, and William DooleyThe concept of integrated aircraft survivability equipment needs to be expanded to the entire Battleforce structure. In addition to individual platform survivability, the entire strike package must maintain the ability to execute the complete kill chain of detect, track, ID, target, engage, and assess. Survivability becomes even more critical when fth generation aircraft are operating with their fourth generation cousins and may be called upon to provide an overarching Battleforce protection role. Advanced threats will attempt to disrupt our integrated capability by jamming our global positioning system and Link-16 sensors. Both the US Air Force and US Navy have realized the importance of ensuring critical tactical information be readily accessible across the Battleforce, regardless of which platform is collect ing the information. Both fourth and fth generation aircraft operating together ensures that threat electronic attack capabilities do not negate our ability to generate a common operating picture for situational awareness, and they prevent targeting information from being shared across the Battleforce. The older fourth generation radars are more susceptible to advanced digital radio frequency memory (DRFM) jamming techniques since, in many cases, they were designed before the threat-jamming techniques were fully developed or known. As more advanced platforms and radar systems are elded, the Battleforce must strive to stay ahead of the threat ability to adapt and reprogram their jamming capabilities. Critical nodes in our kill/effects chain can be broken by threat-jamming in certain access denied scenarios. By maintaining an integrated Battleforce survivability posture through the more jam-resistant fth generation platforms, the Battleforce can maintain our air superiority and dominance. The challenge is to dene potential solutions to the threat-jamming waveforms before they have actually been elded. The F-35 took on this challenge as it developed a process to design elec tronic protection (EP) features into its active electronically scanned array (AESA) radar. This development activity led to a very robust EP capability that provides a better mousetrap to defend against an ever-increasing, threatjamming capability. OVERVIEWOccasionally, over the course of many attempts, a better mousetrap will come along in the acquisition of advanced aircraft capabilities. The mouse, in the form of airborne enemy jammers, must compete to avoid the cheesy kill after navigating through the new radar EP trap. To build the better mousetrap, one must start with a well-dened set of requirements. The clear starting point is to dene the mouse; however, there are over 50 different species of mice in the world, and we still do not have full knowledge of all their individual attributes. The enemy jammer operates in exactly the same manner. For self-preservation reasons, enemy jammer designers do not populate their specications in open literature or Internet accessible sources; therefore, it is nearly impossible to design an EP specication without knowing what the jammers whiskers, nose, and tail are about. The Joint Strike Fighter (JSF) Program Ofce took a different approach to specifying the threat by providing a comprehensive set of design-driving characteristics and asked the contractors to put their best effort in defeating this trap.THE JSF APPROACHThe F-35 Radar EP team has successfully demonstrated a quantum leap in performance against enemy jammers using a novel acquisition approach designed to meet an advanced threat, while transitioning the most effective techniques to other advanced US radars.

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15 http://jaspo.csd.disa.mil AS Journal 13 / FALLThe historical approach has been to design EP systems to defeat hardwarespecic threats; however, with the proliferation of DRFMs, jamming waveforms can be changed rapidly and arbitrarily. The historical acquisition process was not agile enough to react to changes and updates to softwarebased systems. The result typically involved a laundry list of individual jammer waveform reactions, which is a specic response to a specic technique ( aka Pavlovs dogs). Once the jammer changed small parameters on the next sortie due to the full reprogrammability of the pods, the original reaction was made obsolete. The innovative process for setting requirements was to take a capabilitiesbased approach to solving the agility issue. The approach was to address the challenge in a holistic manner. This effective holistic approach was the result of a joint government and industry team applying a disciplined system engineering process to dening an effective and affordable EP specication for the APG-81 Radar. This process required prognosticating many years in the future to dene multiple potential jammer capabilities and to provide a specication that addresses the attributes of those systems. Unnaturally, this process meant providing a threat description not currently blessed by the intelligence community because a single threat system did not have all of the design driving characteristics. There were, however, tightly-coupled interac tions between the program ofce and the National Air and Space Intelligence Center to ensure the denition was not unobtanium. The F-35 Program Ofce did not specify a performance requirement in the tradi tional sense. To be more forward-looking and exible, they dened a potential future jamming threat with a wide range of postulated, future state-of-the-art performance characteristics. Contractors were expected to address each charac teristic, but was not strictly required to design one-for-one countermeasures for each characteristic. Instead, contractors were given exibility to balance the overall design to meet a broad set of jamming techniques. To a great extent, this approach requires a high degree of trust between the program executive ofcer (PEO), the contractors (Lockheed Martin and Northrop Grumman), and the program ofce engineers. The Joint Program Ofce (JPO) asked the contractors to put their best effort in defeating the specication with the understanding that the contract specication would not be held hostage if the EP performance was not met 100% of the time. It required trust on behalf of the PEO to accept the risk of developing a capability that has never been developed before on time and on schedule. This JSF process has worked extremely well as Block 2 has delivered much of the radar EP. RED TEAM APPROACH TO TESTINGOnce the EP team built the radar, they then deployed a wide range of indepen dent test teams to try to defeat the radar using various jamming systems. These systems included the most advanced jamming systems and jammer designers, and were tested with the F-35 radar in the lab and in ight. The EP team identied and xed radar vulner abilities, software errors, and limitations throughout system design and develop ment. Ultimately, the team ew the F-35 radar on an instrumented test-bed aircraft against a multitude of aircraft, radars, and jamming systems at Northern Edge 09 and Northern Edge 11, a joint training exercise involving hundreds of aircraft and ships in a realistic combat training environment. A comprehensive set of laboratory testing is required prior to deploying to a large force exercise like Northern Edge. Therefore, the JPO invited several jammer teams from industry, Federally Funded Research and development Centers and from international organiza tions to Red Team against the radar. The benet of a jointly developed program is attaining best-of-breed practices from other highly sophisticated jamming teams from around the world. Their different worldviews provided a unique series of test and jamming techniques allowing our designers to account for wide variations in jamming approaches. Large force exercises early in a develop ment program are anathema to most program ofces; however, they provide invaluable opportunities to take capabilities out of the lab environment and into a real-world situation that involves real world clutter, aircraft motion, multiple jammers, hostile mountainous terrain, and realistic enemy tactics. Detailed analysis of the data collected at Northern Edge was completed and indicated that the F-35 radar exceeded expectations. The cost to participate in the exercise was negligible; however, it enabled the performance to be vali dated 3 years ahead of schedule and in a far more realistic environment than what could have been achieved in a normal ight test. The radar, however, was not infallible. The radar contractor discovered several software bugs, and they were able to x them prior to delivery to the prime; therefore, by the time the APG-81 is elded on an continued on page 24

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 16 Lt Col Ryther is a combat forensics evaluator with JCAT and currently deployed from Wright-Patterson Air Force Base (AFB), OH to Kandahar, Afghanistan. There, hes supporting Army aviation operations by providing critical forensic analysis of hostile re against coalition combat aircraft. Deployed JCAT assessors work closely with the intelligence community as they collect information and contribute to a database that identies trends on the battleeld and shapes operations. Their joint status helps them interact with each service. The JCAT program selects members who have a strong background in aviation and engineering. Lt Col Rythers education and technical background in aeronautical and mechanical engineering make him an ideal candidate for this job. From science and technology in laboratory environments to full up live re test and evaluation, his career spans multiple areas of the survivability discipline. Lt Col Ryther is one of a handful of deployed JCAT assessors in Afghanistan and serves as the JCAT liaison ofcer. Together, the deployed JCAT assessors provide battleeld commanders with key information and tools to ght the enemy by evaluating combat damage and weapons effects. JCAT assessments allow rapid dissemination of threat system information and tactics, techniques, and procedures to the soldier in the area of responsibility. A nal report is published for each incident and loaded in the Combat Damage Incident Reporting System database, which is used to enhance the combat survivability of current and future aircraft. From October 2011 until now, JCAT assessors have evaluated 306 combat damage incidents; Lt Col Ryther has assessed 64 of those himself. These assessments typically entail documenting evidence, collecting and analyzing fragments, and interviewing crewmembers. All JCAT assessors must graduate from a rigorous, three phase multi-service training program funded by JASP. Phase 1, located at Ft Rucker, AL, serves as an introduction to JCAT and focuses on helicopter systems and operations, threat munitions charac teristics, and forensic analysis (photography, material failure, weapon dynamics, and physical evidence preserva tion). Phase II, located at Naval Air Weapons Station China Lake, CA, provides advanced JCAT training and focuses on munitions characteristics (fragments, incendiary, guided, unguided), wreckage EXCELLENCE IN SURVIVABILITY CHAD RYTHERby Maj Ron Pendleton The Joint Aircraft Survivability Program (JASP) is pleased to recognize Air Force Lieutenant Colonel (Lt Col) Chad Ryther, personally and as a representative of all the Joint Combat Assessment Team (JCAT) assessors that have deployed to Iraq and Afghanistan, for Excellence in Survivability. Figure 1. Lt Col Ryther, right, pieces together forensic evidence of a helicopter shot down by enemy re in Afghanistan Figure 2. Lt Col Ryther recovering evidence at a crash site in Afghanistan

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17 http://jaspo.csd.disa.mil AS Journal 13 / FALL investigation, and formal report develop ment. Phase III, located at Eglin AFB, FL, concludes the training with two important parts: hands-on investigation of live re demonstrations of various weapons and threat community interaction. Lt Col Ryther is a graduate of the 2012 JCAT training class, and he is one of roughly 40 assessors that have deployed to Iraq and Afghanistan since 2004. Lt Col Rythers career began in 1997 when he graduated from the US Air Force Academy with a BS in aeronautical engineering. After spending 4 years in the space and missile community, where he supported numerous activities including restoring mission capability to satellite vehicle failures, Lt Col Ryther began his adventure in the ight test community. In 2001, Lt Col Ryther moved to Barksdale AFB, LA, where he executed the weapon system evaluation program WSEP as a B-52 ight test engineer. This program entailed testing various munitions on the B-52H, including the joint-direct attack munition, air-launched cruise missile, conventional air-launched cruise missile, advanced cruise missile, and the joint air-to-surface standoff missile. In 2003, Lt Col Ryther moved to Nellis AFB, NV, where he was a ight test engineer on the HH-60G executing developmental, quality, and operational test and evaluation ight test missions on the Pave Hawk. He led ight tests of the upgraded Integrated Electronic Warfare Suite, infrared missile warning, and countermeasures systems. Additionally, he was the ight test engineer for the CSAR-X, replacement for HH-60G, and source selection. He also designed ight test programs to determine HH-60G mishap causes. In 2006, Lt Col Ryther moved to Edwards AFB, CA, where he became an instructor at the Air Force Test Pilot School (TPS). He taught the application of ight test theory, techniques, and procedures and developed curricula and instructed the TPS Qualitative Evaluation course. Lt Col Ryther was also instrumental in acquiring diverse aircraft from across the Department of Defense and civilian aviation community for the TPS Qualitative Evaluation program. Lt Col Ryther received his PhD in aeronau tical engineering from the Air Force Institute of Technology at WrightPatterson AFB, OH in 2011. He then became the deputy chief of the Aerospace Vehicle division in the Aerospace Systems Directorate of Air Force Research Laboratory. It was here at WrightPatterson AFB where Lt Col Ryther was introduced to JCAT, and as the saying goes...the rest is history. Figure 3. B-52 launches a joint-direct attack munition as part of a weapon systems evaluation Figure 4. HH-60G Pave Hawk landing in Afghanistan

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 18 OPERATIONAL EVALUATION OF AIR COMBAT EFFECTIVENESSby Ronald Thompson, Hugh Grifs, and Josef SeidlTo allow weapon systems to be used most effectively when elded, the Joint Anti air Combat Effectiveness (J-ACE) DVD is providing the Department of Defense (DoD) warghting community with the means for quantitative operational evaluation of air combat. J-ACE includes a suite of interfaced analysis software application packages, RED and BLUE system performance data sets, a pilot-friendly graphical user interface (GUI), various output display tools, and an analyst manual. Figure 1 displays an operational view of the J-ACE evaluation capability.J-ACE is developed by a collaborative team led by the Joint Technical Coordinating Group for Munitions Effectiveness (JTCG/ME) and the Joint Aircraft Survivability Program (JASP). Intelligence agencies and technical organizations from across the services provide active support. J-ACE builds on the investment in modeling, simulation, and data made by the acquisition community during the development of elded weapon systems. J-ACE OVERVIEWJ-ACE consists of over six million lines of code in modules that are independently designed, built, tested, documented, and maintained. Interface control and application program interface documents are available. Windows, Linux, and Sun operating systems are supported. The basic J-ACE package is classied. Special data sets which are formatted, checked, and tested for use in the Joint Anti Air Model (JAAM) can be made available as required. The primary J-ACE interface is through JAAM, which is a fast running, two-sided, M versus N simulation of RED and BLUE air-to-air missiles (AAM); RED surface-toair missiles (SAM); and, RED and BLUE aircraft aero performance. The JAAM GUI supports explicit simulation of air combat engagements. A key output is the probability of missile intercept (Pi). The Endgame Manager (EM) is a new application that adds missile lethality and target vulnerability. The EM allows explicit evaluation of weapon miss distance, fuse performance, weapon lethality, and target vulnerability. The EM provides the probability of kill given an intercept (Pk/i). Providing RED and BLUE system performance data sets for use in J-ACE is a major focus. Source information is collected and then formatted, docu mented, tested, and congured. An audit trail report is provided which documents each data element and the source. Data are coordinated with their source, which includes BLUE system program ofces. The J-ACE DVD is available to the DoD and DoD contractors. Requests can be submitted to the JTCG/ME through Tinker Air Force Base Figure 1 Operational View of J-ACE Evaluation Capability

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19 http://jaspo.csd.disa.mil AS Journal 13 / FALLKEY J-ACE APPLICATIONSThe J-ACE JAAM package is widely used across the services to develop: Air combat tactics For training range SHOT evaluation Mission planning Acquisition support. Air Combat Tactics Development: JAAM is used for US Air Force and Navy tactics and Multi-Command Manual 3-1 development. The JAAM three and pseudo six Degree of Freedom (3 & 6 DoF) kinematic simulations of aircraft and weapons are used to analyze air combat engagement maneuvering and weapons employment. Fidelity is suitable for tactical assessment of preand postmerge maneuvers, engagement geometry, effective F-pole (distance from launching aircraft to the target at missile impact) and A-pole (distance from launch aircraft to target when missile active terminal guidance begins) ranges, and engage ment outcomes. Air Combat Training Shot Evaluation: The JTCG/ME supports a direct software interface between JAAM and mission debrieng systems. The Personal Computer Debrieng System (PCDS) and the Integrated Combat Aircrew Debrieng system (ICADS) are examples which are widely used across the services. PCDS is a Windows-based mission debrieng software system in which time space position information (TSPI) from aircraft tracking is recorded and replayed to provide a comprehensive operational debrieng capability. During pilot post-ight performance evaluations, JAAM is used to evaluate the effective ness of missile launches at actual trigger points on the TSPI ight record. To improve pilot effectiveness, the JAAM simulation is also used to consider alternative engagement timing and conditions. ICADS is currently implementing the JAAM interface for air-to-air evaluation with surface-to-air capability to follow. Ongoing implementation work has the goal of allowing quantitative real-time kill removal. Mission Planning and Analysis: J-ACE performance evaluation is appropriate for use in mission planning, analysis, and rehearsal. An example is the Enhanced Air Defense Simulation, which has a J-ACE interface for on demand calculation of Pi and Pk/i. This interface supports US Strategic Command analysis of Global Strike mission planning through the evaluation of parameters such as ingress proles, risk areas, and risk avoidance. System Acquisition Support: J-ACE is being used in support of the F-35 Joint Strike Fighter (JSF). Application extends from limited support of the developmen tal test program, to operational test and evaluation (OT&E), through tactics development. Initial coordination to support JSF operations is also underway.J-ACE PRODUCT DEVELOPMENT PROCESSESFour key administrative processes are used to leverage work from across the services in J-ACE development: The user interface process bounds J-ACE development, beginning with the collection of operational capabil ity requirements and ending with support of J-ACE use when elded. Systems engineering provides a methodical process to efciently develop an effective product. Product management controls development resources, reports progress, and allows timely correc tive actions. Verication, Validation, and Accreditation (VV&A); and, Approval and Authentication (AA) processes ensure that the J-ACE product provides the best capability available from across the services. User Interface: Annual J-ACE product development is initiated by a require ments call. A formal solicitation is sent to the services and the combatant com mands for data and methodology requirements. Additionally, Operational User Working Group (OUWG) meetings are held where users of J-ACE are brought together to identify requirements. Collectively these top-down and bottom-up surveys are used to dene the operational capability that future J-ACE releases will provide. Systems Engineering (SE): Here the operational objectives dened by the user interface are developed into performance requirements and communi cated to the extended J-ACE developmental team. An appropriate functional approach to meeting those requirements is identied; and nally, the physical J-ACE product is developed. The SE process generally consists of product planning, development, test, review, and approval efforts. Each phase and associated milestone provides only what is necessary and possible at that point in development to support follow-on work. The SE process is applied both at the individual module and the overall product level. The process is tailored and scaled to the complexity and scope of each development effort, while structured to allow the right people to explicitly make necessary judgments and decisions when required.

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 20 Figure 2 displays the SE process activities and milestones. Figure 3 displays the documentation developed through the SE process. Program Management: J-ACE is released annually. This allows timely intelligence and data updates and elding of new capability. However, 2 years are required for the complete product development cycle and some complex developments require several years of phased effort. As a result, 2 versions of J-ACE are under development at any given time. Formal planning for future J-ACE development extends at least 3 years. Annual J-ACE funding is provided by the Ofce of the Secretary of Defense (OSD), Operational Test and Evaluation, Live Fire Test and Evaluation. VV&A and AA: This is the J-ACE product quality control process. Verication ensures things are correct and are working as designed. Validation conrms results reect real-world outcomes. The JTCG/ ME accreditation documentation process explains the intended applicability of the product, subject to known assumptions, limitations, or errors. Approval is a nal quality and administrative review by the Air Force, Army, and Navy JTCG/ME Service Leads, which results in formal authentication of the product for use by that service. Testing and documentation of results are critical elements of the quality control process. Software and data subject matter experts (SME) conduct develop mental testing to verify performance. Hierarchies of developmental tests, which extend from the component to the integrated product level, are conducted. Extensive, ongoing, automated regression testing is done to ensure changes made during development do not introduce errors in previously completed work. Validation testing is typically done at the performance level. J-ACE is an opera tional tool. The results of validation testing are compared against engineering level analytical models. The analytical models are in turn validated against the available set of real-world test results. Product operational testing is conducted to ensure the user interface is appropri ate, the integrated product performs as New Product Conceptualization Requirements Development A Requirements Analysis & Allocation B Product Initial Physical Design C Product Final Design D Product Development, Verification Test & Integration E Integrated System Test, Review and Approval F Product Distribution, User Interface & Support G Product Initiation Decision 0 System Requirements Review (SRR) I System Functional Review (SFR) II Preliminary Design Review (PDR) III Critical Design Review (CDR) IV Test Readiness Review (TRR) V System Verification Review (SVR) VI Planning DevelopmentTest, Review & Approval Figure 2 J-ACE SE Activities and Milestones System Performance Specification (SPS) 3 System Requirements Document (SRD) 2 Capability Development Document (CDD) 1 Requirements Verification Matrix (RVM) 4 Software Requirements Specification (SRS) 8 Interface Requirements Specification (IRS) 9 Interface Control Document (ICD) 7 Data Base Design Document (DBDD) 6 Software Design Document (SDD) 5 Software Test Plan (STP) 10 Software Test Description(STD) 11 Software Test Reports (STR) 12 Government Responsibility Developer Responsibility Model/Module Level Docs Figure 3 Documentation Developed During the J-ACE Systems Engineering Process

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21 http://jaspo.csd.disa.mil AS Journal 13 / FALLexpected, and provides reasonable results. Operational testing often includes experienced J-ACE Power Users.PLANNED J-ACE DEVELOPMENTThe following paragraphs summarize the J-ACE capability expected in annual releases over the next 3 years. JAAM and Aero Performance: Each J-ACE release provides updated missile y-out models. Historically, only elded systems have been provided, but the scope will increase to include near-term future threats. Including future threats enhances J-ACE use in system acquisi tion and operational test. Advanced pseudo six DoF BlueMax6 and Hercules aircraft aero performance models will be provided. These models will allow tactics development to take better advantage of the full aircraft capabilities. BlueMax6 and Hercules provide a large library of BLUE and RED aircraft models developed by the acquisi tion and intelligence communities. JAAM aircraft maneuver scripting using the pseudo six DoF models will be simplied. A basic suppression of enemy air defenses (SEAD) capability will be provided that allows selected BLUE air-to-surface weapon launch and y-out against a SAM threat. The PCDS user request for BLUE air-to-surface weapon assessment capability in JAAM will be addressed. Target Vulnerability, Weapon Lethality, and Endgame Manager (EM): Initial EM capability has been elded. The November 2013 J-ACE version 5.2 release includes data adequate for the evaluation of hundreds of weapon target pairings. Additional weapon and target data will continue to be provided and updated. The following list describes key ongoing developments: Near eld blast damage evaluation that does not assume spherical blast propagation Legacy pseudo-empirical methodol ogy for evaluation of continuous and discrete rod threats Advanced optical, passive InfraRed (IR) and semi-active Radio Frequency (RF) missile fusing Providing this capability will complete major EM development. Electronic Counter Measures (ECM): Evaluation of ECM is an important part of air warfare which has been beyond the capability of a fast-running operational tool. However, signicant capability is now available and annual J-ACE releases of increasing capability will be provided. The focus is self-protection ECM. Development will leverage available methodologies and empirical data. The initial scope includes BLUE ECM effects on RED RF and IR AAM and SAM. Follow-on capability will be the evalua tion of RED ECM on BLUE RF and IR AAM effectiveness. Dynamic visualization of an aircrafts ECM systems zones of coverage will allow pilots, while developing threat engagement or evasive maneuvers, to consider ECM protection with respect to the threat position. When more explicit effectiveness evaluation is required, the Enhanced Surface to Air Missile Simulation (ESAMS) and MOSAIC legacy engineering tools (respectively for RF and IR systems), along with the necessary performance data sets, will be called directly from the JAAM user interface. SUMMARYWith annual OSD funding, the J-ACE development team is methodically integrating work and leveraging expertise from across the DoD to provide the quantitative tools required by the warghting community for optimal application of elded air combat systems.

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 22 PHYSICS-BASED MODELS FOR INFRARED (IR) COUNTERMEASURESby Caroline Wilharm and Brent WaggonerModeling and simulation is an important component in the development and employment of airborne expendable infrared countermeasures (IRCM) to protect military aircraft from hostile missiles. As more sophisticated threats emerge, new countermeasures and techniques are needed to defeat these threats. To support the development of these items, more sophisticated, higher delity models are required.Current models rely on empirical inputs from look-up tables constructed from measured data at limited test conditions ( i.e., aspects, speeds, and altitudes). Countermeasures are sometimes represented as spherical sources with time-varying intensities. More sophisti cated representations may include multiple spherical sources per expend able that change in size and intensity dynamically. To add detail to these representations, data from high resolution IR cameras SuperFrame or Duochrome imagers, which are state-of-the-art for measuring IR eventscould be analyzed to develop more sophisticated look-up tables, but these would still be based on empirical data; therefore, they would have no predictive capabilities. Alternately, a physics-based approach can be used to generate imagery for any given set of conditions. Physics-based modeling is a cross-disciplinary eld that includes elements of applied mathematics, numerical analysis, computational physics, and computer graphics. This technique enables the development of computationally-based visual models for complex objects based on their inherent physical characteristics. [1] There are several types of IRCM devices. All such devices function by presenting an additional source of IR radiation to the missile seeker. Each IRCM device type has unique performance character istics, stemming from different underlying physical phenomena. This Joint Aircraft Survivability Program project addressed two IRCM types: conventional pyrotechnic decoy ares and pyrophoric decoy devices.CONVENTIONAL PYROTECHNIC DECOY FLARESThe payload of a conventional pyrotech nic decoy are is a are grain made from magnesium, Teon, and Viton (MTV). This material is ignited as it is dispensed from the aircraft, resulting in a burning, high-intensity IR source. Flare grain material undergoes combustion in two stages. The condensed phase compo nents at the surface of the grain react to form initial gaseous and ne particulate products that rapidly expand into a reball. The particulates are carried in the expanding gas that mixes with surrounding air to further react, liberating additional energy. The dynamic motion of the grain through space shapes the plume. Many efforts have been made in the past to model MTV, particularly its reaction chemistry, at varying levels of detail. [2, 3] To model this type of device, the following characteristics must be described mathematically: Reaction Chemistry What reactions occur, the heat generated by the reactions, what products are formed along with their concentra tions and phases, and the kinetics or rate of the reaction Mass Transfer The physical interaction of the reaction products with the surroundings to form the are plume Heat Transfer The conduction of heat into the are grain to propagate combustion into the are, and convection and radiation of heat from the reaction zone to the surroundings The result is a large, highly coupled set of partial differential equations (PDEs). COMSOL Multiphysics is a customiz able, module-based PDE solver. To use COMSOL, the problem geometry must be dened, a variable resolution meshing must be applied, the physics of the system must be specied, and material properties, source terms, and boundary conditions must also be applied. COMSOL

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23 http://jaspo.csd.disa.mil AS Journal 13 / FALLthen solves the oweld and provides a visualization of the resultsa detailed spatial map of species, temperature, and velocity as a function of time for the burning are grain. The temperature map shown in Figure 1 illustrates the level of detail that can be generated using such modeling techniques.PYROPHORIC DECOY DEVICESA pyrophoric decoy device contains pyrophoric metal. The material reacts very quickly with air, liberating large quantities of heat, which gives an IR signature. To model this type of device, two main events must be described: the dispersion of the material into the air and the heating that occurs. To model the heating of the material, the physical properties of the material must be dened, including macroscopic dimensions, a mathematical description of the porous structure, and the physico chemical properties of the metal. Mass and energy balance equations must be established to describe the interaction of the material with its surrounding environment. Numerical methods must be used to solve this set of coupled differential equations, yielding the temperature of the material as a function of time, for a given set of conditions at the time of dispense. The material can then be given a trajectory. Naval Surface Warfare Center Crane is working with aerodynamics teams from the US Army Aviation and Missile Research Development and Engineering Center (AMRDEC) Aeroightdynamics Directorate (AFDD) and Naval Air Systems Command Naval Air Station Patuxent River to develop detailed aircraft ow elds using computational uid dynamics. These ow elds are being used to create highdelity models of the spatial distribution of the material. Figure 2 shows a sample ow eld.IMAGERY GENERATIONThe IR scenes needed for missile-are engagement models must contain detailed representations of the aircraft, backgrounds, and countermeasures. Most Department of Defense activities doing missile effectiveness studies are migrating to the Fast Line-of-Sight Imagery for Target and Exhaust Signatures (FLITES) software, produced by Kinetics, Inc. Figure 3 shows a sample image from a FLITES run with a detailed aircraft and pyrotechnic countermeasures.SUMMARYThis effort is the rst integration of countermeasure combustion, thermody namics, spectral emission, and trajectory programs to render a representative scene. It will provide a new class of models for expendable IRCM to be used in both current simulations and those being derived for advanced seekers. This new class of physics-based countermea sure models will have the ability to predict the behavior and performance of countermeasures that have not yet been fabricated. This effort will greatly reduce both countermeasure design optimization Figure 1. Simulated Pyrotechnic Decoy from COMSOL Multiphysics Figure 2. Sample Flow Field (courtesy of Army AMRDEC AFDD) Figure 3. Sample Aircraft and Flare Image from FLITES (photo courtesy Kinetics, Inc.)

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 24 cost and time. Increasing model delity has the potential to reduce or eliminate a signicant portion of ight testing for countermeasure development. Ultimately, these increased delity models have great potential to improve countermea sure effectiveness, which will better protecting our soldiers. References[1] Kakadiaris, Ioannis A., Physics-Based Modeling, Analysis and Animation, MS-CIS-93-45, GRASP LAB 346, Computer & Information Science Department, University of Pennsylvania, April 1993. [2] deYong, L.V. and K.J. Smit, A Theoretical Study of the Combustion of Magnesium/Teon/ Viton Pyrotechnic Compositions, MRL-TR-91-25, Materials Research Labs, Ascot Vale, Australia, August 1991. [3] Magalhaes, L.B. and F.D.P. Alves, Estimation of Radiant Intensity and Average Emissivity of Magnesium/Teon/Viton (MTV) Flares, Proc. of SPIE Vol. 7662 766218, 2010.operational F-35 (a process that has already started with the Marines at Yuma), the radar has been tested, xed, and tested again to verify its excep tional performance. As a result of the Northern Edge testing and all of the testing before, the F-35 Radar Program is now in the condent position that it will be operationally effective in a dense and advanced electronic attack environment with its Block II conguration. This productivity will lead to a tremendous increase in the F-35 lethality and survivability. AWARD WINNING RESULTSThe F-35 Radar EP team won the David Packard Excellence in Acquisition award in 2010 for its novel approach to acquisition. The F-35 sensor-fused radar environment will provide US and coalition soldiers with a distinct advantage over enemy aircraft for the foreseeable future. The denition of the mousetrap was initially fraught with problems, but at the end of the day, the trap once again ensnared the cheeseseeking jammer. INTEGRATED BATTLEFORCE SURVIVABILITYcontinued from page 15

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25 http://jaspo.csd.disa.mil AS Journal 13 / FALL A POTENTIAL AIRCRAFT CASUALTY EVALUATION APPROACH FOR LIVE FIRE TEST AND EVALUATION (LFT&E)by Joel Williamsen, James Rhoads, and Mark CouchTraditional approaches to aircraft casualty evaluation within aircraft LFT&E programs have focused on direct threat effects on pilots, treating them as just one of many critical components that could lead to aircraft attrition or mission loss. In 2007, Director, Operational Test and Evaluations (DOT&Es) of LFT&E directed the Joint Aircraft Survivability Program (JASP) to develop and expand tools to predict casualties from all potential casualty sources and identify casualty reduction features. In the intervening years, JASP developed Crew and Passenger Survivability (CAPS) casualty assessment methodologies, and demonstrated the CAPS methodology in part for H-60 and C-130 (although additional renement is needed). An FY14 JASP Roadmap task is planned to outline test data and model development needs for evaluation of personnel casualties.Table 1 shows the number of casualties (fatalities and injuries) from Department of Defense (DoD) rotorcraft combat damage incidents from October 2001 through August 2012. The fatalities were grouped in four broad categories: 1. Those that were a result of threat effects directly hitting the person 2. Those that were a result of a catastrophic crash 3. Those that were a result of a survivable crash 4. Those where the cause of the fatality is attributed to both threat impacts and crash effects Although more detailed causes for fatalities are possible, they were not seen in the available post-crash evidence. Examples include cascading effects from secondary res aboard the aircraft (leading to casualties before a crash occurs) and a failure to egress the aircraft following a crash. This article outlines a standardized casualty assessment approach for rotary and xed wing aircraft that supports the development of the JASP casualty assessment roadmap; with terminology and metrics that are consistent with combat data such as that shown above; already existing aircraft vulnerability data Table 1 DoD Rotorcraft Fatality and Injury Data (October 2001 to December 31, 2012) Cause of Casualty Combat Hostile Action Fatalities Combat Hostile Action Injuries Pilot Pax/Crew Unknown Total Pilot Pax/Crew Unknown Total Threat Directly Hitting Person 23 45 0 68 67 99 17 183 Catastrophic Crash* 26 58 0 84 0 0 0 0 Survivable Crash** 12 17 0 29 16 17 8 41 Threat and Crash 2 15 0 17 0 19 0 19 Unknown 0 4 0 4 2 4 0 6 Total 63 139 0 202 85 139 25 249 A catastrophic crash is dened as one where the aircraft impacts the surface (land or water) under conditions of attitude and velocity that do not permit the survival of any of the crew members, even when considering all available crashworthiness features that help lessen the impact forces (e.g., hitting the surface at severe pitch or roll attitudes or at high speed such as in controlled ight into terrain). ** A survivable crash is dened as one where the aircraft impacts the surface (land or water) under conditions of attitude and velocity that allow crashworthiness features to help lessen the impact forces, and other damage cascading effects, to the extent where at least one crew member might survive. A threat and crash is dened as one where the occupants have both threat and crash injuries to them and the cause of the casualty is both.

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 26 and models; the JASP CAPS methodol ogy; and the Armys Full Spectrum Crashworthiness criteria. DEFINITIONSCasualty is broad term that can include both fatalities and injuries. At a minimum, an aircraft crew casualty assessment should include fatalities and use methodologies that adequately predict fatalities so that suitable casualty reduction techniques can be applied. Assessing the extent of injuries may vary signicantly from aircraft to aircraft, depending on the mission, the number of crew and passengers, and their seating locations in the aircraft. The extent of injury assessment will be dened for individual programs in cooperation with DOT&E; however, considering the potential for aircraft res shortly following crash landings or landings where fuel is leaking (near hot engines), casualty evaluations should include any injuries that lead to an inability to safely egress the aircraft following landing. The possibility of casualties is greatly affected by the end state of the aircraft. Consequently, the proposed approach denes three possible outcomes of the aircraft: Outcome I: Immediate Loss/No ControlThe aircraft has a total loss of control and will crash catastrophi cally with the loss of all crew and passengers. Outcome II: Degraded Capability Includes crashes, forced landings, or air egress Outcome III: Return to BaseA crash does not occur, but other casualties are possible nonetheless. Within each of the se out comes, up to four casualty categories should be determined: Direct casualties from threat effects impacting occupants Cascading casualties from indirect explosions, cabin res while in the air, or other delayed effects prior to a landing attempt Crash-related casualties from structural deformation of the aircraft or from seat failure Egress casualties due to the inability to egress following landing, ditching, or ejection/bailout (includes postcrash re effects). Mapping of the three possible outcomes to the four casualty categories is shown pictorially in Figure 1. Within the outcomes, t refers to time, and tcrit is dened as the time at which the aircraft experiences immediate loss or total loss of control, allowing no additional time for air egress and meaning the aircraft will crash cata strophically. The term tbase refers to the time required to y back to base ( e.g., the point of departure or intended landing location) and conduct a normal landing. Direct and crash casualties can IMMEDIATE LOSS/NO CONTROL: t
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27 http://jaspo.csd.disa.mil AS Journal 13 / FALLoccur for any aircraft outcome. Cascading and egress casualties can occur for Outcomes II and III, and crash casualties are not considered in Outcome III. Outcome II is considered the most difcult outcome to assess since it includes all four casualty types. EVALUATION METHODOLOGYCasualty evaluation begins with the denition of a threat and vignette that is consistent with a larger integrated survivability assessment, which includes mission type, phase of ight ( e.g., takeoff, cruise, landing), denitions for time to a safe landing at base, ight prole ( e.g., altitude, airspeed), and ight conditions ( e.g., payload, fuel load). For selected vignettes, the program should perform a vulnerability assessment with a distinctive critical item list for each potential aircraft outcome, taking into account the individual aircraft attributes. The relative likelihood of each outcome may set the scope of the overall casualty assessment, which is a matter of negotiation between DOT&E and the program of record. For example, if the relative likelihood of Outcome II is consid ered low or is made low through vulner ability reduction or crashworthiness features, a detailed crash casualty assessment might not be required for Outcome II. Direct casualties would be assessed through the combined use of existing aircraft vulnerability models and estab lished casualty criteria. Cascading casualties would be assessed by identifying the source of casualties (usually explosive or re producing cabin materials) and developing tests and models to predict the hazard level to passengers and crew, the hazard radius (of effect from the hazard site), and the time required for critical damage thresholds to be reached com pared to the time needed to extinguish res or land the aircraft. Fire suppression systems designed into the aircraft have the potential to lower both the probability of re and the hazard level created. Personal protection equipment, such as smoke hoods and oxygen masks, that is readily available or required to be worn at all times could increase occupant survival time relative to the time needed to land the aircraft, potentially reducing cascading casualties. Crash casualties are the most difcult to assess. Such assessments require design and test data from aircraft vendors early in the program regarding the expected out-of-limit crash failure conditions (vertical and horizontal landing speeds in the selected vignette) where fuselage failures and seat failures are expected to occur. To supplement the vendor data, programs could have ight crews y simulators with various components failed (identied from the Outcome II vulnerability assessment) to compare the landing speeds and orienta tions from the simulator to the design criteria. Landing conditions could also be varied to include impacts into hard surfaces, soil, and water, which are not always listed in the design specications. Lacking detailed data, the default assumption would consider fuselage failures to cause fatalities to all passengers aboard and a seat failure to cause an individual fatality. Additionally, qualitative assessments based on comparisons of new aircraft structure and seats to the legacy aircraft could be performed if detailed data are not available. Egress casualties can include air egress (considered under Outcome III) or land/ sea egress (within Outcomes II and II). Air egress casualties are determined through examining the ejection/bailout envelope of ejection systems compared to vignettes of interest. Land egress losses are assessed by rst determining the probability and severity of postcrash res (including pool res) through exterior models or tests, then determining the time available to egress the aircraft through specialized testing, considering day/night, soldier equip ment, blockage, and presence of injuries. If egress time is greater than the critical hazard development time, a casualty can occur. The number of casualties will be related to the number of occupants failing to egress before critical hazards occur. Evaluations of casualty-reducing technologies are possible throughout the evaluation process. Aircraft solutions include traditional vulnerability reduction measures (to prevent a crash), improved crashworthiness features, cabin re suppression, cabin lighting, and improved equipment storage. Personnel solutions include hoods, oxygen masks or other breathing assists, body armor, and improved ejection systems. Improved tactics, techniques, and procedures, such as improved egress procedures and training for crash events, may also be employed to reduce casualties.POTENTIAL LIVE FIRE ISSUESThe following live re issues parallel the three outcomes and four casualty categories described above: What are the likelihoods of the following aircraft outcomes follow ing attack? Immediate loss or total loss of control Degraded capability (landing attempt short of base) Return to base/controlled landing What are the estimated casualties following attack in each of the following categories? Direct crew and passenger casualtiescontinued on page 31

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 28 CRITICAL COMPONENT PROTECTION (CCP)Increased Vulnerability Reduction for Rotorcraftby Dr. Marc A. Portanova, Nicholas C. Gramly, and Michael C. BreslinA recent article published in Aircraft Survivability [1] states that the combat hostile action loss rate for aircraft in Operation ENDURING FREEDOM and Operation IRAQI FREEDOM was 8 times lower than that seen in Vietnam. This assertion is supported by data collected in a previously released document, Study on Rotorcraft Survivability Summary Report [2], and is attributed largely to improved aircraft vulnerability design and the resulting reduction of cheap kills caused by small arms and automatic weapon threats. Further analysis of this data suggests that the number of fatalities resulting from catastrophic crashes (other than mishaps) exceeds the number of fatalities resulting from a direct hit on an aircraft occupant.Practically speaking, this data indicates a simple trend: current aircraft occupant protection systems ( e.g., Ballistic Protection System [BPS/BAPS], Enhanced Ballistic Protection System [EBPS], etc. ) are effective. The occupants of the aircraft are better protected now than in previous conicts. Crashes, however, have now become the dominant cause of fatalities for rotary wing aircraft. There are two primary means to reduce theses fatalities: 1. Improve aircraft crashworthiness 2. Reduce the effect of the aforemen tioned cheap hit on an aircrafts critical systems (in which a success ful hit would result in a downed aircraft) It is the latter that will be the focus of this article.LEGACY ROTORCRAFT PROTECTIONBPS/BAPS and EBPS have been deployed and/or are currently in use on numerous platforms, including Hueys (UH-1), Chinooks (CH-47), Blackhawk Fleets (UH-60 and MH-60), and the Super Stallion (CH-53E). These systems date back to the late 1990s/early 2000s, rst surfacing in response to the needs of the 160th Special Operations Air Regiment and as a replacement for the ill-fated BASS (Ballistic Armor Sub System). Unlike BASS, which was ceramic-based and lacked durability, the original BPS was a metallic composite capable of providing the desired level of protection and an extremely long service life. Similar to BASS, the BPS attached to the oor of the aircraft and provided bulk protection to the occupants of the cockpit and cabin. More recent versions of BPS ( e.g., AOBPS, EBPS, etc. ) feature similar levels of protection at a reduced weight due to the use of ultra-high molecular weight polyethylene (UHMWPE) ( e.g., Spectra Shield) as the core of the system. While the previously noted report conrms the effectiveness of these occupant protection systems, the data continues to indicate an unacceptable level of fatalities. This simple fact became the impetus for Army Aviation Applied Technology Directorate (AATD)-managed Joint Aircraft Survivability Program Ofce(JASPO)funded critical component protection effort described in the next section.CRITICAL COMPONENT PROTECTION (CCP)The concept of CCP is not new to aviation; however, the ability to protect critical ight systems in a weighteconomical means has been a challenge. As evidenced by the BPS family of systems, most lightweight ( i.e., compos ite) armor systems are at. This is a result of the fact that most materials used in these armor systems ( e.g., ceramics, para-aramids, UHMWPEs, etc. ) require high consolidation pres sures at some point in their manufac ture; therefore, historically, the use of at or large radii of curvature panels to protect critical components was the primary solution available, resulting in bulky, ineffective, and heavy protection.

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29 http://jaspo.csd.disa.mil AS Journal 13 / FALL As part of this effort, The Protective Group (TPG), located in Miami Lakes, FL, was tasked to demonstrate a combina tion of mature materials and manufac turing technologies which, when put together, could provide a means to produce complex shape, high degree of curvature, and high performance armor composite parts without using high pressure processing and incurring signicant cost or weight above traditional at panels. Two platforms were focused on for this effort, both of which have critical component areas of high vulnerability: AH-1 Cobra and OH-58D Kiowa Warrior. NEAR NET-SHAPE FORMING TECHNOLOGIESTo achieve the overriding goal of this effort, a number of unique, near-net shape ceramic, metallic, and polymeric rapid-fabrication technologies were investigated. While numerous technolo gies were identied that were capable of providing the necessary design and performance features, two technologies were focused on based on the require ments of the platforms: 1. Reaction bonding of complex-shaped, monolithic ceramic components 2. Direct composite integrationReaction Bonding of ComplexShaped, Monolithic Ceramic ComponentsReaction-bonded ceramic materials have been used in industrial applica tions for over 50 years. Following the attack on the US in 2001 and the subsequent wars, these materials saw a rebirth for use in body armor. M Cubed Technologies (MCT), located in Newark, DE, has become a leader in this technology, pushing the performance of reaction-bonded boron carbide (B4C) and silicon carbide (SiC) [3,4] materials well beyond that of many of their hot pressed competitors. One of the key advantages of MCTs process is their ability to fabricate complex shaped and/ or large, monolithic ceramic components. This fabrication allows large areas to be protected using a single piece of tough ceramic, rather than a tiled approach used in conventional armored designs. Direct Component IntegrationIn nearly all advanced, lightweight armor solutions available today, some form of ber-based composite material ( e.g., para-aramid, UHMWPE, etc. ) is utilized in a spall liner/backing system. The two primary methods used to process these components in hard armor systems are high-tonnage pressing and autoclave consolidation. Due to the much higher ballistic performance usually associated with high-tonnage pressing, it is the process most typically used in modern hard armor systems. Consequently, autoclave consolidation has been seldom used in these systems. It is worth noting, however, that the high-tonnage processing route requires a second process step (in an autoclave) in order to bond the strike face compo nent to the ber-based backing material. This secondary reheating of the pressed backing reduces its ultimate perfor mance, reducing the performance gap between the two processing methods. TPG, under a concurrent ONR effort [5], developed a technique whereby the ber backing system is directly integrated within the system via autoclave process ing. Through unique materials architec tures and processing techniques, the performance of the directly integrated system is virtually the same as that of the high-tonnage approach. By invoking this technology, the entire armor system can be integrally processed in a single autoclave process cycle. One of the major benets to the direct integration autoclave approach is the dramatic reduction in tooling costs. Unlike the high-tonnage approach that typically requires billet-machined aluminum or stainless steel tooling, the direct integration approach can employ the rigid system components ( e.g., structural metallics and/or strike face ceramics) as the tooling. For example, in a ceramic-based armor system (speci cally one that makes use of a reaction bonded, complex-shaped monolithic ceramic tile), the ceramic component, itself, acts as the tool. By using this methodology, the path to prototype (and then production) is signicantly shorter and less expensive (and less risky) than it would be in high-tonnage pressing.OH-58D KIOWA WARRIORFollowing the selection of the OH-58D platform for this demonstration effort, and upon further discussion with the program ofce, the engine access door was identied as a candidate compo nent (Figure 1). The current door is outtted with two at armor panels that are attached on the inboard side of the door. By combining the two materials technologies described above, these panels could be better integrated into the door structure, reducing overall weight and/or improving protection. After multiple rounds of iterative design and live re testing, a ballistic defeat solution was developed that could provide the same level of protection at a substantially reduced weight. This weight savings was applied to the area of protection, resulting in a solution that not only covered 51% more area than the legacy design (at the same weight), but

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AS Journal 13 / FALL http://jaspo.csd.disa.mil 30 also provided protection against a more aggressive range of attack angles due to the curvature of the panel (Figure 2). As a means of further enhancing the potential weight savings, it was sug gested that the aluminum door be replaced by one made from carbon ber. While outside the scope of this effort, it is estimated that an optimized door structure would reduce the component weight by approximately 15%. A rough mock-up of the door was fabricated from carbon and the actual armor panel was attached for validation testing (Figure 3). To verify that ballistic performance was maintained in the full-scale part, the prototype (while mounted to the mock-up door) was impacted twice by the OH-58 specied threat. The armor areal density was 6.3 lbs./sq. ft. (PSF), which, at this protection level, equates to a mass efciency of 3.32. The successful test concluded the CCP effort demonstration on the OH-58 platform.AH-1Z CobraAdmittedly, the OH-58D application of the CCP armor concept did not exercise the full capability of the technology. While considered a successful demon stration, the complexity of the part was minimal. Through initial discussions with Naval Air Systems Command (NAVAIR), it became apparent that the AH-1Z would be a better platform on which to demonstrate the technology. The specic area to be protected was the bell crank housing located on the starboard side of the aircraft, below and approximately between the pilot and copilot seats. The nature of this location as well as the AH-1 threat protection requirements made it necessary to design an armor system of a much higher complexity and curvature. For the sake of this effort and to reduce a number of security issues, an AH-1S was used to model the area requiring protection. Although the AH-1S is no longer own by the US military, they are readily available at the Army Research Laboratory, Survivability/Lethality Analysis Directorate (ARL/SLAD). The bell crank areas on several AH-1S models were digitally scanned as a means of creating a digital model of the CCP component. A rapid prototype was produced from the digital model and used to t-check the design. Once the CCP design was conrmed, a reaction bonded boron carbide strikeface was created and backed using the direct component integration approach. The completed system was mounted on a retired AH-1S at ARL/SLAD and subjected to live re testing (Figure 4). Results of the ballistic testing were positive, with multiple rounds being defeated in each panel. As shown in Figure 5, the back face deformation did not interfere with the control roda requirement of this system.CONCLUSIONThe prevailing benet of this effort is that it provides clear evidence that small, complex, lightweight armor components can be designed, developed, and implemented in relatively short time frames and inexpensively. It also serves as a blueprint for the execution of similar design efforts in the future. Figure 1. OH-58D Engine Access Door Figure 2. OH-58D Armor Mounted to Inside Surface of Engine Cowling Door Figure 3. (a) OH-58 Engine Cowling Door CCP Prototype Armor Panel and (b) Panel Mounted to a Carbon Fiber Mock-Up DoorA B Figure 4. (a) TPG CCP Prototype Installed on AH-1 at ARL/SLAD Prior to Ballistic Testing and (b) Side View of TPG CCP Prototype Showing 3-D CurvatureA B

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31 http://jaspo.csd.disa.mil AS Journal 13 / FALL ACKNOWLEDGEMENTSThe authors would like thank the following individuals for their efforts and support on the CCP program: Ken Branham, JASPO; Dennis Lindell, JASPO; Bob Hood, AATD; Raymond Lou Roncase, NAVAIR; Fred Marsh, ARL/SLAD; Brandon Bostwick, TPG; and Keith Funderburk, TPG. References[1] Sayre, Rick. Casualty Assessment and Reduction At the 5-year Mark. Aircraft Survivability. 13 Spring Issue 2013: 6-8, 13. Print. [2] Study on Rotorcraft Survivability Summary Report. Department of Defense, Washington, D.C., September 2009. Print. [3] M. K. Aghajanian, B. N. Morgan, J. R. Singh, J. Mears, and R. A. Wolffe. A New Family of Reaction Bonded Ceramics for Armor Applications. Ceramic Armor Materials by Design, Ceramic Transactions, 134, J. W. McCauley et al. editors, 527-40 (2002). [4] P. G. Karandikar, M. K. Aghajanian, and B. N. Morgan. Complex, Net-Shape Ceramic Composite Components for Structural, Lithography, Mirror and Armor Applications, Ceram. Eng. Sci. Proc., 24 [4] 561-6 (2003). [5] Contract No. W911QY-08-C-0092; POC: James Mackiewicz, (508) 233-5925 Figure 5. AH-1S CCP Live Fire Test Results. Note: Back face deformation did not interfere with the control rod/bell crank assembly.A B Cascading crew and passenger casualties Crash-related crew and passen ger casualties (considering hard surface, soil, and water landings) Egress crew and passenger casualtiesCONCLUSIONThis article outlines a standardized, conceptual aircraft casualty evaluation process that may be applied to existing aircraft or future programs of record. Its implementation would require the establishment of new data items to be specied in the live re strategy, including seat failure and airframe collapse data based on vertical and horizontal aircraft impact velocity into hard surfaces, soil, and water. Casualty evaluation also requires specialized testing, including ight simulations with damaged equipment, cabin interior environment following the onset of re, egress tests of equipped occupants, and the use of safety-related aircraft data. The casualty evaluation described here can be tailored by taking into account early vulnerability assessments (for aircraft Outcomes I, II, and III), and should make use of both qualitative and quantitative elements where needed. The authors look forward to participat ing with JASP and aircraft programs in further rening tools and methods for evaluating and reducing aircraft crew and passenger combat casualties. A POTENTIAL AIRCRAFT CASUALTY EVALUATIONcontinued from page 27

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