SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 13 - JULY 5, 2006
05 AIRCRAFT DESIGN, TESTING AND PERFORMANCE
Includes all stages of design of aircraft and aircraft structures and systems.
Also includes aircraft testing, performance and evaluation, and aircraft and flight simulation technology.
For related information see also 18 Spacecraft Design, Testing and Performance and 39 Structural Mechanics.
For land transportation vehicles see 85 Technology Utilization and Surface Transportation.
20060016449 Army Research Lab., Aberdeen Proving Ground, MD USA A Shadow Unmanned Aerial Vehicle (UAV) Improved Performance Research Integration Tool (IMPRINT) Model Supporting Future Combat Systems
Hunn, Bruce P; Heuckeroth, Otto H; Feb 2006; 40 pp.; In English; Original contains color illustrations Report No.(s): AD-A443567; ARL-TR-3731; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443567; Avail.: CASI: A03, Hardcopy
This study describes the creation of an IMPRINT (Improved Performance Research Integration Tool) model to describe crew workload levels in the Shadow unmanned aerial vehicle (UAV). Field data were collected for tasks performed by Shadow UAV crews. This model was developed to support the Army's Future Combat System, human robotics interaction Army Technology Objective. The design and operation of this model are discussed, along with several workload conclusions based on the model's operation. Workload for individual crew members and as a crew entity is discussed. DTIC
Combat; Crews; Drone Vehicles; Military Operations; Models; Pilotless Aircraft; Workloads (Psychophysiology)
20060016523 Defence Science and Technology Organisation, Edinburgh, Australia
Auditory Warnings in the Military Cockpit: A Preliminary Evaluation of Potential Sound Types
Smith, Sean E; Stephan, Karen L; Parker,, Simon P; Sep 2004; 28 pp.; In English; Original contains color illustrations Report No.(s): AD-A444013; DSTO-TR-1615; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444013; Avail.: CASI: A03, Hardcopy
This document reports the results of two experiments assessing the viability of speech, auditory icons (environmental sounds) and abstract sounds (complex tones) for use as auditory warnings in military cockpits. Experiment One evaluated the comparative ease of learning and retention of these three sound types, with the results demonstrating that speech warnings and auditory icons were learnt and trained with equal ease, while abstract-sound warnings were found to be learnt and retained with far greater difficulty. Experiment Two examined a user's ability to respond to speech, icon and abstract auditory warnings under varying degrees of workload. The results of this experiment show that speech warnings provide and advantage in reaction time and response accuracy over auditory icon warnings, which in turn hold an advantage over abstract sounds. The results of these two experiments indicated that, under low levels of workload, speech warnings may prove to be an effective supplement to traditional visual warnings, while icons also warrant further investigation. DTIC
Acuity; Auditory Perception; Cockpits; Warning Systems
20060016584 Smart Information Flow Technologies, Minneapolis, MN USA
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The Playbook (Trademark) Approach to Adaptive Automation
Miller, Christopher; Funk, Harry; Wu, Peggy; Goldman, Robert; Meisner, John; Chapman, Marc; Jan 2005; 6 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): DAAH01-03-C-R177 Report No.(s): AD-A444096; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444096; Avail.: CASI: A02, Hardcopy
SIFT has pioneered a human-automation integration architecture, called Playbook(TM), based on a shared model of the tasks in the domain. This shared task model provides a means of human-automation communication about plans, goals, methods and resource usage a process akin to referencing plays in a sports team's playbook. The Playbook enables human operators to interact with subordinate systems with the same flexibility as with well-trained human subordinates, thus allowing for adaptive automation. We describe this approach and its application in an ongoing project called Playbook-enhanced Variable Autonomy Control System(TM) (P-VACS). DTIC
Adaptation; Man Machine Systems
20060016599 Lambda Research, Inc., Cincinnati, OH USA
Mitigation of SCC and Corrosion Fatigue Failures in 300M Landing Gear Steel Using Mechanical Suppression
Prevey, Paul S; Jayaraman, N; Ontko, Neal; Shepard, Michael; Ware, Robert; Coate, Jack; Aug 2004; 13 pp.; In English; Original contains color illustrations Report No.(s): AD-A444124; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444124; Avail.: CASI: A03, Hardcopy
300M steel is widely used in landing gear because of its unique combination of ultrahigh strength with high fracture toughness. However, 300M is vulnerable to both corrosion fatigue and stress corrosion cracking (SCC) failures with catastrophic consequences for aircraft landing gear. Plating and shot peening surface treatments currently used to extend life are only partly effective. A surface treatment is needed that will mitigate foreign object damage (FOD), corrosion fatigue and stress corrosion cracking. This paper describes the use of low plasticity burnishing (LPB) to mechanically suppress stress sensitive corrosion failure mechanisms in 3.5% salt solution. The fatigue and corrosion fatigue performance of LPB processed 300M steel was compared with shot peened (SP) and low stress ground (LSG) conditions. LPB produced residual compression to a depth of 1.27 mm (0.050 in.), and shot peening only 0.127 mm (0.005 in.), an order of magnitude less. LPB treatment dramatically improved both the HCF performance and corrosion fatigue strength, with and without simulated FOD. The corrosion fatigue strengths of LSG and SP surfaces decreased dramatically, to only 20% and 50%, respectively, of the baseline strength, with no discernible endurance limit behavior under corrosion fatigue conditions. The fatigue behavior was even worse with FOD, simulated with a 0.5 mm (0.020 in.) deep EDM notch, both in air and exposed to salt. In contrast, LPB treated specimens with FOD exhibited a definite endurance limit of 1035 MPa (150 ksi) even under corrosion fatigue conditions. SCC testing of LPB treated landing gear sections at 1030 to 2270 MPa (150 to 180 ksi) static loads was terminated after 1500 hrs without failure, compared to failure in as little as 13 hours without treatment. DTIC
Corrosion; Failure; Landing Gear; Metal Fatigue; Steels; Stress Corrosion
20060016626 Metron, Inc., Reston, VA USA
Multi-Agent Framework for the Fair Division of Resources and Tasks
Godfrey, Gregory A; Jan 2006; 183 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): F30602-00-C-0175; DARPA ORDER K543; Proj-TASK Report No.(s): AD-A444182; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444182; Avail.: CASI: A09, Hardcopy
Under this contract, we developed technology that addresses the dynamic problem of autonomous, competitive agents negotiating over the fair division of resources and tasks.We have applied this multi-agent technology to two military domains: commercial airlift procurement for large contingencies; and unmanned aerial vehicle (UAV) coordinated search and surveillance. The collaborative auction and mission exchange approach that we developed makes planning more flexible, missions more reliable, and leverages commercial operational best practices without having to integrate those practices into military systems or to make the expertise available to competitors. The UAV challenge is achieving real-time, effective coordination of a fleet of autonomous UAVs performing intelligence, surveillance and reconnaissance tasks. The focus is on coordinated target search (detection) and surveillance (monitoring) tasks. The developed technologies demonstrate how UAVs can plan missions collaboratively and re-plan adaptively based on realtime changes in UAV availability, pop-up targets and sensor capabilities. Metron has transitioned this UAV search technology to a NAVAIR Phase II SBIR contract to provide a new real-time search mission planning capability. DTIC
Drone Vehicles; Game Theory; Surveillance
20060016627 Dayton Univ. Research Inst., OH USA
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User Feedback on RFID and Integrated Flightline Data for Maintenance Decisions
Gallimore, Jennie J; Quill, Laurie; Cagle, Ron; Gruenke, Jessica; Hosman, Chris; Matthews, Elizabeth; Faas, Paul; Seyba, Jason; Young, Ian; Jan 2006; 8 pp.; In English Contract(s)/Grant(s): FA8650-04-C-6404 Report No.(s): AD-A444185; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444185; Avail.: CASI: A02, Hardcopy
Creating Agile Combat Support (ACS) requires real time integrated information systems to support human decision making. Real time sensing technologies are being investigated to improve logistics support.
The purpose of this study was to investigate integrated Radio Frequency Identification/Real Time Location System (RFID/RTLS) technology with flightline information for improved decision making for flightline maintenance operations.
A simulation was developed that ntegrated information related to the flightline with RFID location information (Smart Systems).
A simulated field test was conducted to compare the Smart Systems integrated condition with an off-the- shelf RFID technology and a baseline condition for providing support for the fix or swap decision. DTIC
Feedback; Information Systems; Maintenance
20060016642 Army Aeromedical Research Lab., Fort Rucker, AL USA
The Head Posture of Helicopter Pilots During Visual Flight: A New Hypothesis for the Head Tilt Associated With Banking Aircraft
Temme, Leonard A; Still, David L; Jan 2006; 97 pp.; In English Report No.(s): AD-A444218; USAARL-2006-05; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444218; Avail.: CASI: A05, Hardcopy
Head azimuth, pitch, and lateral tilt of four pilots controlling a Lynx helicopter through multiple slalom maneuvers under visual flight conditions are reported and analyzed. PilotAperformed the maneuver ii times, Pilot B performed it 12 times, Pilot C performed it 8 times, and Pilot D performed it 12 times. The specifics of the slalom maneuver, two 900 right turns followed by two 900 left turns, are unambiguously reflected in the head motions. As the aircraft turned twice to the right then twice to the left, the head turned twice to the right then twice to the left, presumably to enable the pilot to see where the aircraft was going. Head azimuth was highly correlated with head tilt: When the head turned to the right, it tilted to the left; and when the head turned to the left, it tilted to the right. Furthermore, the correlation between head tilt and pitch was highly reliable: When the head tilted either to the left or to the right, it pitched up. On the other hand, the correlation between azimuth and pitch was inconsistent and variable. The pattern of reliable correlations among head posture suggests mechanisms that might help explain the opto-kinetic cervical reflex. DTIC
Attitude (Inclination); Helicopters; Hypotheses; Pilots; Posture; Reflexes; Visual Flight Rules; Visual Perception
20060016666 Air Command and Staff Coll., Maxwell AFB, AL USA
Microsoft, Al-Jazeera, and the Predator: The Challenge of Effects-Based Operations in the Global War on Terrorism
Kumashiro, David J; Dec 2005; 34 pp.; In English Report No.(s): AD-A444256; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444256; Avail.: CASI: A03, Hardcopy
Acomplex and interdependent environment in the global war on terrorism (GWOT) highlights the challenge of translating the theory of effects-based operations (EBO) into practice, particularly with respect to influencing the will of the people and achieving a desired end state. The following paper seeks to illustrate the conditions and challenges surrounding the translation of current effects-based theory into operational practice in the GWOT by using three conceptual constructs. First, the Microsoft Corporation, its connectivity to the Internet, and the persistent attacks by computer hackers on Microsoft products help frame the adversary and the complex environment and conditions surrounding the GWOT. Second, the Al-Jazeera satellite news network serves as an anecdotal backdrop for the challenges Military planners face in managing EBO assessment and controlling the 'effects' in EBO. Third, the versatility of both the MQ-1B Predator unmanned aerial vehicle and Special Operations Forces illustrates the importance of developing and maintaining collective knowledge, technological relevance, and doctrinal adaptability in an ever-changing GWOT environment. Military planners who follow an effects-based strategy should recognize EBO's inherent limitations and plan for its characteristic uncertainty and uncontrollability. In the end, the ability to manage the constructive and destructive strategic effects required to achieve a desired end state as complex as that found in the GWOT requires a holistic perspective that is, at its heart, more art than science. DTIC
Drone Vehicles; Terrorism; Warfare
20060016735 Carnegie-Mellon Univ., Pittsburgh, PA USA
The U.S. Army's Common Avionics Architecture System (CAAS) Product Line: A Case Study
Clemente, Paul; Bergey, John; Sep 2005; 62 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): FA8721-05-C-0003 Report No.(s): AD-A444361; CMU/SEI-2005-TR-019; No Copyright; ONLINE: ttp://hdl.handle.net/100.2/ADA444361; Avail.: CASI: A04, Hardcopy
This report is one in a series of Carnegie Mellon Software Engineering Institute case studies of organizations that have adopted a software product line approach for developing a family of software-intensive systems. The U.S. Army's Technical Applications Program Office (TAPO) has adopted a product line approach for the avionics software used for the Army's special operations helicopters. That software is based on Rockwell Collins Common Avionics Architecture System (CAAS). he product line has evolved beyond its original scope and is now being adopted to include other Army aviation platforms such as cargo and utility helicopters. This case study describes the acquisition context and organizations involved in The product line, the history behind the development and evolution of the product line, its application to the mission of the Army's special operations helicopters, the Army's motivation for adopting a product line, specifics of the product line approach, and the underlying CAAS system and software architecture. The case study also highlights the software product line accomplishments, examines the results and lessons learned from TAPO's and Rockwell Collins perspective, and discusses future considerations. DTIC
Avionics; Computer Programming; Software Engineering
20060016747 Air Command and Staff Coll., Maxwell AFB, AL USA
Back to the Basics: An Aviation Solution to Counterinsurgent Warfare
Davis, Arthur D; Dec 2005; 35 pp.; In English Report No.(s): AD-A444383; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444383; Avail.: CASI: A03, Hardcopy
This study focuses on the current global war on terrorism as a conflict against insurgents who attack U.S. power through asymmetric means. Of late, these individuals have selected as a primary target the military and civilian convoy operations in Iraq and, to some extent, Afghanistan. By examining past examples of the use of air power in counterinsurgent warfare, this study sheds light on the USA' current failings in both equipment and doctrine as it wages this type of war. The French used low-technology aircraft --WorldWar II-vintage A-1 and T-6 fighters -- in Algeria to attack insurgent forces and defend ground troops.Well adapted to the environment as well as effectively deployed and employed, these aircraft helped contain and defeat the insurgents. In Vietnam, the USA employed A-1s and T-28s -- aircraft with a proven track record in this type of war and ideally suited to training the South Vietnamese air force. The USA should rethink its inventory of aircraft devoted to counterinsurgent war by considering possible replacements for the A-1. It should also reevaluate the manner of employing these assets by locating them with the ground forces they support. The technology that would meet the needs of future limited conflicts would have the following characteristics: (1) off-the-shelf technology, (2) long-range and loiter capability, (3) short takeoff and landing (STOL) capability, (4) ability to operate from austere airfields, (5) diverse weapons-carrying capability, (6) good navigation and fire-control systems, (7) good pilot visibility, (8) speed and maneuverability at low-to-medium altitudes, and (9) the ability to absorb ground fire with a high degree of survivability. DTIC
Aircraft; Algeria; Propellers; Vietnam; Warfare
20060016928 Naval Research Advisory Committee, Arlington, VA USA
Lighter-Than-Air Systems for Future Naval Missions
Oct 4, 2005; 52 pp.; In English; Original contains color illustrations Report No.(s): AD-A444479; No Copyright; Avail.: CASI: A04, Hardcopy
Outline of presentation: Panel Membership; Terms of Reference; Categories of LTAVehicles; Executive Summary; Study Flow; Briefings Received; LTA vehicles and characteristics; Missions; LTA Categories vs Missions Matrix; Study Findings- Aerostat and Low Altitude Airship, High Altitude Airship, Heavy-Lift Hybrid Airship; Conclusions; Summary Recommendations. DTIC
Airships; Balloons; Navy
20060016939 Lambda Research, Inc., Cincinnati, OH USA
Improved Damage Tolerance of Ti-6Al-4V Aero Engine Blades and Vanes Using Residual Compression by Design
Jayaraman, N; Prevey, P S; Ravindranath, R; Jan 2005; 11 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): N68335-01-C-0274 Report No.(s): AD-A444511; No Copyright; Avail.: CASI: A03, Hardcopy
The deep stable layer of compressive residual stress produced by low plasticity burnishing (LPB) has been demonstrated in laboratory testing to improve damage tolerance in engine alloys IN718, Ti-6Al-4V, Ti-6-2-4-6, and 17-4PH. This paper describes the fatigue and FOD tolerance benefits afforded by LPB treatment of a Ti-6Al-4V first stage fan blade and vane. FOD sensitive blades and vanes removed from fielded engines were LPB processed to protect the leading edge of the blade and the trailing edge of the vane. Both components were fatigue tested in cantilever bending mode at R\g0 using specially designed test fixtures. FOD was simulated with machined notches for the blade and electrical discharge machined (EDM) notches for the vane. Residual stress and cold work distributions were measured using x-ray diffraction mapping techniques. DTIC
Aircraft Engines; Aluminum Alloys; Damage; Fan Blades; Jet Vanes; Titanium Alloys; Tolerances (Mechanics); Vanadium Alloys; Vanes
20060016966 Naval Surface Warfare Center, Bethesda, MD USA
NATO HLA Federation for Study of Air Vehicle Landings on Ships
Hurwitz, Myles M; Reading, Richard A; Jan 2006; 6 pp.; In English; Original contains color illustrations Report No.(s): AD-A444553; 00S-SIW-126; No Copyright; Avail.: CASI: A02, Hardcopy
In November 1997, the NATO Naval Armaments Group on Ship Design (NG/6) established a Specialist Team on Simulation Based Design and Virtual Prototyping (ST-SBDVP). The purpose of the Team is to share information on the benefits, risks, and costs of instituting the technologies and processes of SBDVP applied to the acquisition of naval warships. A specific challenge undertaken by the Team is an experience-based study of international simulation interoperability, by applying the NATO-recommended High Level Architecture (HLA) to a military operations problem with significance to ship design. The Team has chosen to focus on vertical landings on warships by helicopters and unmanned aerial vehicles (UAVs), an peration of national interest to each of the Team nations. This problem incorporates daunting physics and military operations issues, which are dependent on understanding system interoperability between the ship, air vehicle, air vehicle control, and the landing system. Further, sufficient understanding of interoperability early in the system design process can be leveraged to optimize the ship/aircraft design in consideration of landing operations. This problem is therefore particularly conducive to examination via interoperable modeling and simulation. Three objectives the ST has in undertaking its study are: (1) to identify and correct any interoperability (technical, process, or culture) deficiencies in the conduct of a joint, allied nation federated simulation; (2) to introduce ST member nations to the development and execution of a simulation federation using HLA; and (3) to make advances, via international cooperation, toward a validated simulation of an important and potentially dangerous military operation, which encompasses very complex physics. DTIC
North Atlantic Treaty Organization (NATO); Vertical Landing
20060016982 Air Force Research Lab., Wright-Patterson AFB, OH USA A Dynamic Mission Replanning Testbed for Supervisory Control of Multiple Unmanned Aerial Vehicles
Nelson, Jeremy; Calhoun, Gloria; Draper, Mark; Mar 2006; 7 pp.; In English Contract(s)/Grant(s): Proj-7184 Report No.(s): AD-A444586; AFRL-HE-WP-TP-2006-0051; No Copyright; Avail.: CASI: A02, Hardcopy
As unmanned aerial vehicles (UAVs) increase in autonomy, operators will be increasing their span of control. Most UAV systems require two or more operators to fly and operate payloads, but systems are being developed with the concept of a single operator monitoring multiple UAVs. This supervisory control of multiple UAVs raises many issues concerning the balance of system autonomy with human interaction to keep the operator in-the-loop. Testbeds are needed that specifically address multi-UAV supervisory control, replicating the complex automation algorithms and allowing operator initiation and inspection into these systems. There is currently an effort underway to develop a dynamic mission replanning testbed for human factors research on supervisory control of multiple UAVs. This testbed utilizes Air Force certified autorouting study is being performed with this still developing testbed and results will be presented. DTIC
Drone Vehicles; Pilotless Aircraft
20060017044 Library of Congress, Washington, DC USA
Tactical Aircraft Modernization: Issues for Congress
Bolkcom, Christopher; Oct 7, 2005; 19 pp.; In English Report No.(s): AD-A443898; CRS/DC-10-07-05; No Copyright; Avail.: ASI: A03, Hardcopy
This Issue Brief examines DOD's four largest tactical aircraft modernization programs. The background section provides a brief description of each program, and a discussion of how tactical aircraft fit into military air operations: the missions they typically perform and how they contrast to longer-range combat aircraft. The Analysis section examines a number of policy issues including affordability, capability required, force structure, service roles and missions, industrial base, and transformation. The paper concludes with a synopsis of recent congressional action on these programs. The Defense Department plans to buy the F/A-22 fighter for the Air Force, the F/A-18E- /F fighter/attack plane for the Navy, and the V-22 tilt-rotor aircraft for the Marines and Air Force special operations, as well as pursue a joint-service program to develop a multirole Joint Strike Fighter (JSF) aircraft in three variants, some of which might be operational around 2012. Decisions in Congress and the Defense Department regarding these aircraft programsmay have important long-term implications. The F/A-18E/F is in full-rate production. The V-22, and the F/A-22 are now in transition from research-development (R&D) to procurement and could remain in production for decades. The next-generation combat aircraft that are expected to result from joint-service efforts now getting underway through the Joint Strike Fighter (JSF) program might be in production through the 2020s. Decisions about the funding of these programs will influence which U.S. aircraft manufacturers survive in the aviationindustry, and may well affect the division of combat roles and missions among the services in the next century. DTIC
Budgeting; Military Operations; Fighter Aircraft; V-22 Aircraft; Aircraft Industry; Tilt Rotor Aircraft
20060017052 Naval Postgraduate School, Monterey, CA USA
The Fast Theater Model (FATHM): Optimization of Air-to-Ground Engagements as a Defender-Attacker Model
Seichter, Stephan; Dec 2005; 79 pp.; In English; Original contains color illustrations Report No.(s): AD-A443395; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443395; Avail.: CASI: A05, Hardcopy
The FAst THeater Model (FATHM) is a joint theater-level attrition model that combines a Lanchester ground combat model with a linear program, hereafter the Air model, that determines the optimal allocation of air strikes against ground forces. FATHM models time phased ground battles between two forces BLUE and RED, and calls the Air model based on the outcomes of the most recent ground battle, assuming BLUE air supremacy. This thesis develops an enhanced Air model that endows RED with the ability to actively prepare for BLUE air attacks by deploying dummy targets and anti-aircraft artillery as two augmenting defense plans with the goal to more realistically reduce BLUE effectiveness in killing RED targets and simultaneously increase attrition to attacking BLUE aircraft. This Air model is a mixed integer program (MIP), a defender-attacker model, with RED as the defender and BLUE as the attacker. The MIP is a cost- and resource-interdicted model, combining interdiction-induced costs with restrictions on resources for some constraints. This new defender-attacker model provides an optimal defense plan by RED in anticipation of optimized BLUE air attacks without changing FATHM's basic concept or structure. We demonstrate defensive actions by RED that can significantly reduce the BLUE attacker's effectiveness. DTIC
Attack Aircraft; Optimization; Combat; Targets
20060017059 NASA Glenn Research Center, Cleveland, OH, USA
Dynamic Wind-Tunnel Testing of a Sub-Scale Iced Business Jet
Lee, Sam; Barnhart, Billy P.; Ratvasky, Thomas P.; Dickes, Edward; Thacker, Michael; May 2006; 21 pp.; In English; AIAA 44th Aerospace Sciences Meeting and Exhibit, 9-12 Jan. 2006, Reno, NV, USA; Original contains color illustrations Contract(s)/Grant(s): 280.02.07.03.02 Report No.(s): NASA/TM-2006-21468; AIAA Paper 2006-0261; Copyright; Avail.: CASI: A03, Hardcopy
The effect of ice accretion on a 1/12-scale complete aircraft model of a business jet was studied in a rotary-balance wind tunnel. Three types of ice accretions were considered: ice protection system failure shape, pre-activation roughness, and runback shapes that form downstream of the thermal ice protection system. The results were compared with those from a 1/12-scale semi-span wing of the same aircraft at similar Reynolds number. The data showed that the full aircraft and the semi-span wing models showed similar characteristics, especially post stall behavior under iced configuration. However, there were also some discrepancies, such as the magnitude in the reductions in the maximum lift coefficient. Most of the ice-induced effects were limited to longitudinal forces. Rotational and forced oscillation studies showed that the effects of ice on lateral forces were relatively minor. Author
Ice Formation; Wind Tunnel Tests; Aerodynamic Coefficients; Dynamic Tests; Reynolds Number; Surface Roughness; System
Failures; Thermal Protection; Deicing; Ice Prevention
20060017065 NASA Langley Research Center, Hampton, VA, USA
Equivalent Plate Analysis of Aircraft Wing with Discrete Source Damage
Krishnamurthy, T.; Mason, Brian H.; [2006]; 21 pp.; In English; 47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 1-4 May 2006, Newport, RI, USA; Original contains color illustrations Contract(s)/Grant(s): 23-076-40-01 Report No.(s): AIAA Paper 2006-2218; No Copyright; Avail.: CASI: A03, Hardcopy
An equivalent plate procedure is developed to provide a computationally efficient means of matching the stiffness and frequencies of flight vehicle wing structures for prescribed loading conditions. First, the equivalent plate is used to match the stiffness of a stiffened panel without damage and the stiffness of a stiffened panel with damage. For both stiffened panels, the equivalent plate models reproduce the deformation of a corresponding detailed model exactly for the given loading conditions. Once the stiffness was matched, the equivalent plate models were then used to predict the frequencies of the panels. Two analytical procedures using the lumped-mass matrix were used to match the first five frequencies of the corresponding detailed model. In both the procedures, the lumped-mass matrix for the equivalent plate is constructed by multiplying the diagonal terms of the consistent-mass matrix by a proportionality constant. In the first procedure, the proportionality constant is selected such that the total mass of the equivalent plate is equal to that of the detailed model. In the second method, the proportionalityconstant is selected to minimize the sum of the squares of the errors in a set of pre-selected frequencies between the equivalent plate model and the detailed model. The equivalent plate models reproduced the fundamental first frequency accurately in both the methods. It is observed that changing only the mass distribution in the equivalent plate model did not provide enough flexibility to match all of the frequencies. Author
Wing Loading; Damage; Mass Distribution; Wings; Flexibility; Deformation
20060017080 Air Force Research Lab., Wright-Patterson AFB, OH USA
Advanced UMV Operator Interfaces
Nelson, Jeremy; Jan 2006; 7 pp.; In English Contract(s)/Grant(s): Proj-7184 Report No.(s): AD-A444168; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444168; Avail.: CASI: A02, Hardcopy
In man portable platforms, the UMV is ideally very small, lightweight, rugged, and easy to operate [1]. It is essential that this platform meet these characteristics because a typical operator will be transporting the entire UMV system along with other mission critical These UMVs are usually used for 'what's over the hill' type missions; requiring fairly autonomous operation to gain time critical, nearby information. The control stations for man portable UMVs will typically be no larger than a laptop and can be made to fit on smaller devices such as a PDA or head-mounted displays. For example, the Pointer UAV, developed by AeroVironment Corporation, is operated by the user through a large tablet-like PDA [2] (Figure 1). Another example of this can be seen in the work of Goodrich and Quigley (2004) [3]. However, ruggedization of this equipment will generally increase weight and size. DTIC
Remotely Piloted Vehicles; Operators (Personnel)
20060017258 Air Force Research Lab., Wright-Patterson AFB, OH USA
State-Space Search for Improved Autonomous UAVs Assignment Algorithm
Rasmussen, S J; Shima, T; Mitchell, J W; Sparks, A G; Chandler, P; Dec 2004; 7 pp.; In English; Original contains color illustrations Report No.(s): AD-A444705; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444705; Avail.: CASI: A02, Hardcopy
This paper describes an algorithm that generates vehicle task assignments for autonomous uninhabited air vehicles in cooperative missions. The algorithm uses a state- space best-first search of a tree that incorporates all of the onstraints of the assignment problem. Using this algorithm a feasible solution is generated immediately, that monotonically improves and eventually converges to the optimal solution. Using Monte Carlo simulations the performance of the search algorithm is analyzed and compared to the desirable assignment algorithm attributes. It is shown that the proposed deterministic searchmethod can be implemented for given run times, providing good feasible solutions. DTIC
Algorithms; Autonomy; Monte Carlo Method
20060017259 QinetiQ Ltd., Kent, UK
Defining the Cockpit Noise Hazard, Aircrew Hearing Damage Risk and the Benefits Active Noise Reduction Headsets Can Provide
James, S; Jun 1, 2005; 25 pp.; In English; Original contains color illustrations Report No.(s): AD-A444706; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444706; Avail.: CASI: A03, Hardcopy
No abstract available
Active Control; Auditory Defects; Cockpits; Damage; Earphones; Flight Crews; Hazards; Hearing; Military Technology; Noise (Sound); Noise Reduction; Risk
20060017288 Military Academy, West Point, NY USA
A Preliminary Analysis of Loitering Aircraft as a Capability Added to Anti-Ballistic Missile Systems
Boylan, Gregory L; Foote, Bobbie L; Burk, Roger; Dec 3, 2005; 13 pp.; In English Report No.(s): AD-A444769; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444769; Avail.: CASI: A03, Hardcopy
Since the end of the Cold War, a considerable cause for concern has been the potential loss of accountability of nuclear/chemical weapons, missiles, and associated technologies and materials in former Soviet states. This state of affairs has induced a reevaluation of the strategic, operational, and tactical postures of the armed forces to deal with the broad array of threats to our security. Of these threats, the possibility of a large-scale conventional bomb/missile, nuclear, or chemical/ biological attack on the homeland, our national interests abroad, or deployed forces rank high. Ultimately, this is because 1)such weapons have the potential to inflict mass destruction on several levels; 2) obtaining these weapons, or the materials necessary to fabricate them, has become relatively easy; and 3) the asymmetric nature and radical idealism of the enemies who oppose our interests increases the level of uncertainty. - A critical aspect of these threats is the manner in which our enemies could employ them. One that interests the Army's Aviation & Missile Research, Development, and Engineering Center (AMRDEC) is the use of ballistic missiles as a delivery platform. Accordingly, this organization has expanded its research of ballistic missile defense to include analysis of emerging technologies as viable military options. Pursuant to that end, AMRDEC chartered the Department of Systems Engineering at West Point to conduct a feasibility study of the use of SCRAMJET and other kinetic energy-based technologies for military purposes, with a particular emphasis on missile defense. DTIC
Antimissile Defense; Ballistic Missiles; Integral Rocket Ramjets; Kinetic Energy; Missile Systems; Projectiles; upersonic Combustion Ramjet Engines
20060017492 Army Research Lab., Aberdeen Proving Ground, MD USA
Examination of Human Factors in Networked Sensors in Live and Virtual Environments
Sterling, Bruce S; Jacobson, Catherine N; Mar 2006; 113 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): Proj-62716AH70 Report No.(s): AD-A444767; ARL-TR-3734; No Copyright; Avail.: CASI: A06, Hardcopy
A demonstration was held with Soldiers operating robotic networked sensors in an actual mock-up of a reconnaissance and surveillance vehicle (HMMWV [high mobility, multipurpose wheeled vehicle]) in the field and in virtual reality simulators. The crew in the live re-supply vehicle (RSV) and the two crews in the virtual simulators consisted of three Soldiers each. The allocation of personnel in both environments was the same: (a) one Soldier served as the vehicle commander and operated the unmanned ground sensors (UGS); (b) one Soldier operated unmanned aerial vehicles (UAVs), and (c) one Soldier operated an unmanned ground vehicle (UGV). Data from surveys and interviews revealed insights into the interface design, sensor and software capabilities, workload, and skills and abilities required of robotic operators. The interface (maneuver command and control [MC2]) was judged as very good for mission planning, but re-tasking sensors to different routes was difficult and time consuming, which resulted in the inability to identify previously detected targets. The imagery on the infrared (IR) UAV sensor, unlike the daylight camera, was not good enough for target identification. The imagery and interface in the virtual simulators was not as those on the live vehicle, resulting in higher workload and stress in the virtual simulators. Situational awareness was equal but low in both the live and virtual environments, probably because of technical difficulties,especially in the live RSV. Skills needed in both environments tended to be those necessary to receive information from andsend information to higher (communication), identify and solve problems concerning sensor coverage (conceptual), and recognize targets quickly (speed loaded). Visual skills were also needed to interpret sensor feeds and track the sensor on the MC2, especially on the virtual simulators. DTIC
Education; Human Factors Engineering; Remotely Piloted Vehicles; Robotics; Situational Awareness; Virtual Reality; Workloads (Psychophysiology)
20060017497 Ohio State Univ., Columbus, OH USA
Approximate Feedback Linearization of an Air-Breathing Hypersonic Vehicle (PREPRINT)
Parker, Jason T; Serrani, Andrea; Yurkovieh, Stephen; Bolender, Michael A; Doman, David B; Dec 2005; 20 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): F33615-01-C-3154; Proj-A02D Report No.(s): AD-A444874; No Copyright; Avail.: CASI: A03, Hardcopy
This paper describes the design of a nonlinear control law for an air-breathing hypersonic vehicle. The model of interest includes flexibility effects and intricate couplings between the engine dynamics and flight dynamics. To overcome the analytical intractability of this model, a nominal control-oriented model is constructed for the purpose of feedback control design. Analysis performed on the nominal model reveals the presence of unstable zero dynamics with respect to the output to be controlled, namely altitude and velocity. By neglecting certain weaker couplings and resorting to dynamic extension at the input side, a simplified nominal model with full vector relative degree with respect to the regulated output is obtained. Standard dynamic inversion can then be applied to the simplified nominal model, and this results in approximate lineariation of the nominal model. Finally, a robust outer loop control is designed using LQR with integral augmentation in a model reference scheme. Simulation results are provided to demonstrate that the approximate feedback linearization approach achieves excellent tracking performance on the truth model for two choices of the system output. Finally, a brief case study is presented to qualitatively demonstrate the robustness of the design to parameter variations. DTIC
Control Theory; Feedback; Hypersonic Vehicles; Linearization
20060017524 Air Force Systems Command, Brooks AFB, TX USA
Human Factors Considerations in Migration of Unmanned Aircraft System (UAS) Operator Control
Tvaryanas, Anthony P; Feb 2006; 31 pp.; In English Report No.(s): AD-A444925; HSW-PE-BR-TR-2006-0002; XC-311TH HSW; No Copyright; Avail.: CASI: A03, Hardcopy
Unmanned aircraft system (UAS) operator control can be migrated within temporal, physical, and functional domains. Although such control migrations occur in current UAS operations, there are no human factors studies specifically addressing this issue in UASs. This work sought to identify reasons for migrating UAS operator control and summarize the human factors literature with inferential bearing on this topic. Migration of UAS operator control is necessary to overcome limitations of the human operator, current technology, or both. There are potential advantages to control migration to include mitigating operator vigilance decrements and fatigue, facilitating operator task specialization, and optimizing workload during multi-aircraft and payload control tasks. However, there are also significant disadvantages to include transient degraded operator situational and systems awareness and more complex and potentially distributed teams of operators. Future work should focus on improving the empirical knowledge base on UAS human factors so evidence-based recommendations can be made when incorporating control migration in UAS design and operations. DTIC
Aircraft Control; Control; Drone Vehicles; Human Factors Engineering; Migration; Pilotless Aircraft
20060017536 Army Aeromedical Research Lab., Fort Rucker, AL USA
Airsickness Prevention in Helicopter Passengers: A Comparison of Four Countermeasures
Estrada, Arthur; LeDuc, Patricia A; Curry, Ian P; Persson, James L; Phelps, Shean E; Parrado, Carlos M; McGhee, James S; Fuller, Daniel R; Alderman, Shawn M; Watto, Michael B; Mar 2006; 32 pp.; In English Contract(s)/Grant(s): Proj-878 Report No.(s): AD-A444947; USAARL-2006-07; No Copyright; Avail.: CASI: A03, Hardcopy
Despite many existing treatments, airsickness remains an issue of concern in today's military. This study used a double-blind, between groups, placebo-controlled design to compare the effectiveness of four airsickness countermeasures: three pharmacological and one non-pharmacological. All flights were conducted in an actual UH-60 Black Hawk helicopter. Sixty-four, male, non-aviator subjects (ages 18 to 34) were recruited from Fort Benning, Georgia. Sixteen subjects were randomly assigned to each of four groups: 1) promethazine (25 mg)-caffeine (200 mg), 2) meclizine (25 mg), 3) scopolamine (1.5 mg), and 4) ReliefBand. Each individual participated twice, once with the treatment and once with placebo. The finding indicate that only the combination of promethazine-caffeine produced a statistically significant reduction in nausea and motion sickness severity, and improvement in reaction time when compared to its placebo control and the other countermeasures. Data from this study indicated that of the countermeasures tested, promethazine-caffeine is the most effective at reducing airsickness with the least adverse side effects. DTIC
Countermeasures; Health; Helicopters; Motion Sickness; Passengers; Prevention
20060017557 Ohio State Univ., Columbus, OH USA
Anti-Windup Control for an Air-Breathing Hypersonic Vehicle Model
Groves, Kevin P; Serrani, Andrea; Yurkovich, Stephen; Bolender, Michael A; Doman, David B; Dec 2005; 17 pp.; In English Contract(s)/Grant(s): F33615-01-C-3154; Proj-A02D Report No.(s): AD-A444973; No Copyright; Avail.: Defense Technical Information Center (DTIC)
An anti-windup controller modification is implemented in control system design for a model of the longitudinal dynamics of an air-breathing hypersonic vehicle. Anti-windup control allows the input constraints to be considered explicitly in the design of linear controllers to track a reference trajectory for the vehicle velocity, altitude, and angle of attack. The presence of anti-windup alleviates the need of keeping large penalties on the magnitude of the control input to avoid the occurrence of saturation. This, in turn, allows tighter tuning of the controller gains to obtain faster and more accurate trajectory tracking.The paper employs recent developments in anti-windup design to deal with the presence of exponentially unstable dynamics,which are typically encountered in air-breathing vehicle models. Simulation results on a fully nonlinear model are presented to validate the controller design. DTIC
Air Breathing Engines; Flight Control; Hypersonic Aircraft; Hypersonic Vehicles
20060017558 Air Force Research Lab., Wright-Patterson AFB, OH USA
Flight Path Angle Dynamics of Air-Breathing Hypersonic Vehicles
Bolender, Michael A; Doman, David B; Dec 2005; 37 pp.; In English Report No.(s): AD-A444974; AFRL-VA-WP-TP-2006-301; No Copyright; Avail.: Defense Technical Information Center (DTIC)
The flight path dynamics of aircraft are often characterized by the presence of a right-half plane zero in the elevator-to-flight path angle transfer function. For most aircraft, the frequency of this zero is high enough that it does not limit the bandwidth of the flight control system. This is not the case, however, with air-breathing hypersonic aircraft. This class of aircraft is characterized by unstable longitudinal dynamics, strong loop interactions, and the presence of non-minimum phase transmission zeros. In the case of flight-path angle and velocity control, the presence of a low frequency transmission zeroseverely limits the achievable bandwidth. We show that the frequency of the zero is related to the instantaneous center-of-rotation of the aircraft, which is dependent upon the amount of lift produced by the longitudinal control effectors. In order to improve flight-path control, we investigate the feasibility of an aircraft configured with redundant pitch control effectors. The additional effector moves the instantaneous center-of-rotation, and as a result, the location of the zero. The trade-off is that the path-attitude decoupling inherent in hypersonic aircraft becomes more pronounced. Results are given for both a rigid hypersonic aircraft model and a model that includes the effects of the first fuselage bending mode. DTIC
Air Breathing Engines; Angles (Geometry); Flight Paths; Hypersonic Aircraft; Hypersonic Vehicles
20060017565 Air Force Research Lab., Wright-Patterson AFB, OH USA
Cooperative Electronic Attack using Unmanned Air Vehicles
Mears, Mark J; Jan 2006; 10 pp.; In English; Original contains color illustrations Report No.(s): AD-A444985; No Copyright; Avail.: CASI: A02, Hardcopy
In this paper, an attempt is made to define electronic attack of integrated air defenses using multiple unmanned air vehicles acting in a coordinated fashion, and to define features of the problem that are salient in the context of cooperative control. The utility of electronic attack is described in the context of integrated air defense systems that rely on RADAR sites that act as a network to gather information about potential airborne threats. General concepts for the use of multiple vehicles against RADAR systems are described and formulated in terms of cooperative path planning and resource allocation. Then some approaches to solving the technical problems are described. Although the interests expressed in this paper are motivated by capabilities that might be afforded by many unmanned autonomous vehicles, the concepts are relevant for manned aircraft working in concert with groups of air vehicles. DTIC
Air Defense; Control; Drone Vehicles; Electronic Warfare; Radar
20060017604 Ohio State Univ., Columbus, OH USA
Coordinating Networked Uninhabited Air Vehicles for Persistent Area Denial
Liu, Yong; Cruz, Jr , Jose B; Sparks, Andrew G; Dec 17, 2004; 7 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): F33615-01-2-3154 Report No.(s): AD-A445060; No Copyright; Avail.: CASI: A02, Hardcopy
This paper explores the problem of cooperative control among multiple networked unmanned air vehicles (UAVs) for a persistent area denial (PAD) mission. An adaptive Markov chain model is used to predict the locations of pop-up threats. the mixed information of predicted pop-up threats and actual pop-up targets is utilized to develop cooperative strategies for networked UAVs. The approach is illustrated by use of a simulation test bed for multiple networked UAVs and Monte Carlo simulation runs to evaluate the cooperative strategy set forth here. Both theoretical analysis and simulation results are presented to demonstrate the effectiveness of using predicted pop-up information in improving the overall PAD mission performance. DTIC
Control; Drone Vehicles; Markov Processes; Networks; Position Sensing; Surveillance
20060017605 Ohio State Univ., Columbus, OH USA
General Markov Modeling of Pop-Up Threats with Applications to Persistent Area Denial
Liu, Yong; Cruz, Jr , Jose B; Schumacher, Corey J; Jan 2006; 32 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): F33615-01-2-3154 Report No.(s): AD-A445061; No Copyright; Avail.: CASI: A03, Hardcopy
Pop-up threats usually appear or disappear randomly in a battlefield. If the next pop-up threat locations could be predicted, it would assist a search or attack team in getting a team of unmanned air vehicles (UAVs) to the threats sooner, such as in the case of a Persistent Area Denial (PAD) mission. The authors present a Markov model for predicting pop-up ground threats in military operations. They first introduce a general Markov chain of order 'n' to capture the dependence of the appearance of pop-up threats on previous locations of the pop-up threats over time. Then they present an adaptive approach to estimating the stationary transition probabilities of the 'nth' order Markov models. To choose the order of the Markov chain model for a specific application, they also discuss hypothesis tests from statistical inference on historical data of pop-up threat locations. Anticipating intelligent responses from an adversary, which might change its pop-up threat deployment strategy upon observing UAV movements, the authors present adaptive Markov chain models using a moving horizon approach to estimate possibly abrupt changes in transition probabilities. They consider the problem of cooperative control among multiple networked UAVs for the PAD mission. The combined information of predicted and actual pop-up target locations is utilized to develop efficient cooperative strategies for networked UAVs. Both a theoretical analysis and simulation results are presented to evaluate the Markov model used for predicting pop-up threats. These results demonstrate the effectiveness of cooperative strategies using the combined information of threats and predicted threats in improving overall mission performance. Index terms: Pop-up threats; Markov chain model; Model order test; Cooperative strategies. DTIC
Control; Drone Vehicles; Markov Processes; Networks; Position Sensing; Surveillance
20060017606 Air Force Research Lab., Wright-Patterson AFB, OH USA
Effects of Target Arrival Rate on Mission Performance of Cooperatively Controlled UAVs with Comunication Constraints
Mitchell, Jason W; Rasmussen, Steven J; Sparks, Andrew G; Dec 17, 2004; 7 pp.; In English; Original contains color illustrations Report No.(s): AD-A445062; No Copyright; Avail.: CASI: A02, Hardcopy
The authors investigate the effects of target arrival rate on the communication and mission performance of cooperatively controlled uninhabited aerial vehicles (UAVs) with task allocation performed by iterative network flow. Specifically, they quantify the effect of arrival rate on observed statistics of communication and mission performance. The statistics of interest are peak communication data rate and execution defects. The effects are seen in a series of vehicle-target scenarios simulated in the U.S. Air Force Research Laboratory's MultiUAV environment. DTIC
Algorithms; Computerized Simulation; Control; Drone Vehicles; Message Processing; Rates (Per Time); Targets
20060017642 Air Force Research Lab., Wright-Patterson AFB, OH USA
Assignment of Cooperating UAVs to Simultaneous Tasks using Genetic Algorithms
Shima, Tal; Schumacher, Corey; Aug 18, 2005; 15 pp.; In English; Original contains color illustrations Report No.(s): AD-A445125; No Copyright; Avail.: CASI: A03, Hardcopy
A problem of assigning multiple unmanned aerial vehicles (UAVs) to simultaneously perform cooperative tasks on consecutive targets is posed as a new NP-hard combinatorial optimization problem. The investigated scenario consists of multiple ground moving targets prosecuted by a team of heterogeneous UAVs carrying designated sensors and/or weapons. To successfully prosecute each target it first needs to be simultaneously tracked by multiple UAVs, from significantly different line of sight angles to reduce the position estimate errors, and then attacked by a different UAV carrying a weapon. Even for small sized scenarios, the problem has prohibitive computational complexity for classical combinatorial optimization methods due to timing constraints on the simultaneous tasks and the coupling between task assignment and path planning for each UAV. A genetic algorithm (GA) is proposed for efficiently searching the space of feasible solutions. A matrix representation of the GA chromosomes simplifies the encoding process and the application of the genetic operators. To further simplify the encoding, the chromosome is composed of sets of multiple genes, each corresponding to the entire set of assignments on each target. Simulation results conform the viability of the proposed assignment algorithm for different sized scenarios. The sensitivity of the performance to variations in GA tuning parameters is also investigated. DTIC
Algorithms; Drone Vehicles; Genetic Algorithms; Planning; Stochastic Processes; Trajectory Planning
20060017649 Air Force Research Lab., Wright-Patterson AFB, OH USA
Path Planning by Unmanned Air Vehicles for Engaging an Integrated Radar Network
Larson, Reid A; Pachter, Meir; Mears, Mark J; Aug 2005; 17 pp.; In English; Original contains color illustrations Report No.(s): AD-A445137; No Copyright; Avail.: CASI: A03, Hardcopy
A growing concept in the field of unmanned air vehicles (UAVs) is the idea of using a team of cooperating vehicles to participate in electronic countermeasures, defined here as jamming or deception techniques. A UAV may be tasked to engagea radar using noise jamming to mask its radar return or that of another vehicle. Similarly, a UAV may be assigned to deceive a radar by directing a delayed signal toward the victim radar, which has the effect of producing a radar phantom perceived by the radar as an object at a false range and/or bearing. Previous work focused on generating a set of waypoints for the UAV to follow in order the countermeasures to be successful. This paper addresses the path planning required to meet the temporal, spatial, and UAV flight dynamics constraints associated with employing these electronic countermeasures, especially between jamming and deception activities. The UAVs are assigned simplified flight dynamics and performance constraints in two-dimensions, assuming constant altitude flight over a flat-surfaced earth. All tracking radars are given simplified detection properties. A single UAV is provided a pre-determined series of 'goal positions.' The goal positions may lie along a countermeasure's pre-planned course or they may be established such that the UAV moves from the final waypoint of one countermeasure to the starting point of the next countermeasure. Therefore the UAV must autonomously navigate to a given goal position, subsequently perform a simple, associated task (countermeasure, if required), then navigate the next goal position in the series. The will be required to arrive at these waypoints with a specific state, depending on the task at hand. Algorithms for optimal autonomous navigation of this nature were formulated to effectively guide the UAVs to their goal positions to meet the necessary temporal and spatial requirements. DTIC
Computerized Simulation; Drone Vehicles; Networks; Radar Networks; Radar Tracking; Systems Integration; Trajectory Planning
0060017650 Air Force Research Lab., Wright-Patterson AFB, OH USA
Optimum Cooperative UAV Sensing Based on Cramer-Rao Bound
Gu, G; Chandler, P R; Schumacher, C J; Sparks, A; Pachter, M; Jun 2005; 7 pp.; In English Report No.(s): AD-A445138; No Copyright; Avail.: CASI: A02, Hardcopy
We investigate optimal estimation for both the position and the velocity of the ground moving target (GMT) by employing sensors composed of unmanned aerial vehicles (UAVs). The problem is the cooperative sensing by the UAVs, in terms of their location geometries to achieve optimal estimation of the GMT. Based on the Cramer-Rao bound, we are able to derive the minimum achievable error variance in estimation of the position and the velocity of the GMT, and obtain the optimal geometries of the UAV sensors via minimization of the minimum achievable error variance for unbiased estimation commanded by the Cramer-Rao bound. Our solution is complete that encompasses various situations for the GMT, and the number of UAV sensors. DTIC
Cramer-Rao Bounds; Detection; Drone Vehicles; Error Analysis; Maximum Likelihood Estimates
20060017651 Air Force Research Lab., Wright-Patterson AFB, OH USA
Optimization of Air Vehicle Operations Using Mixed-Integer Linear Programming
Schumacher, Corey; Chandler, Phillip R; Pachter, Meir; Pachter, Lior S; Jan 2006; 21 pp.; In English Report No.(s): AD-A445142; No Copyright; Avail.: CASI: A03, Hardcopy
A scenario where multiple air vehicles are required to prosecute geographically dispersed targets is considered. Furthermore, multiple tasks are to be successively performed on each target, i.e. the targets must be classified, attacked, and verified as destroyed. The optimal, e.g. minimum time, performance of these tasks requires cooperation amongst the vehicles such that critical timing constraints are satisfied, that is, a target must be classified before it can be attacked, and an air vehicle is sent to a target area to verify its destruction only after the target has been attacked. In this paper, the optimal task assignment/scheduling problem is posed as a mixed integer linear program (MILP). The solution of the MILP assigns all tasks to the vehicles and performs the scheduling in an optimal manner, including staged departure times. Coupled tasks involving timing and task order constraints are automatically addressed. When the air vehicles have sufficient endurance. the existence of a solution is guaranteed. DTIC
Classifications; Damage Assessment; Drone Vehicles; Integers; Linear Programming; Optimization; Pilotless Aircraft; Targets
20060017652 Brigham Young Univ., Provo, UT USA
Time-Dependent Cooperative Assignment
Kingston, Derek B; Schumacher, Corey J; Jun 2005; 7 pp.; In English; Original contains color illustrations Report No.(s): AD-A445144; No Copyright; Avail.: CASI: A02, Hardcopy
The problem of assigning multiple agents to time- dependent cooperative tasks is addressed using a Mixed- Integer Linear Program. A time-dependent cooperative task is a task requiring multiple agents to perform separate subtasks simultaneously or within some predetermined margin where agent availability to perform a subtask is limited to specific intervals in time. By separating the underlying calculation of agent availability and cost from the mechanism of assignment, a method to solve complex cooperative assignment problems can be formulated. A cooperative UAV target tracking/target prosecution scenario is presented to illustrate the assignment method. DTIC
Computer Programming; Drone Vehicles; Targets; Time Dependence
20060017657 Air Force Research Lab., Wright-Patterson AFB, OH USA
UAV Cooperative Multiple Task Assignments using Genetic Algorithms
Shima, Tal; Rasmussen, Steven J; Sparks, Andrew G; Jun 2005; 7 pp.; In English; Original contains color illustrations Report No.(s): AD-A445154; No Copyright; Avail.: CASI: A02, Hardcopy
A multiple task assignment problem for cooperating uninhabited aerial vehicles is posed as a combinatorial optimization problem. A genetic algorithm for assigning the multiple agents to perform multiple tasks on multiple targets is proposed. The algorithm allows efficiently solving this NP- hard problem that has prohibitive computational complexity for classical combinatorial optimization methods. It also allows taking into account the unique requirements of the scenario such as task precedence and coordination, timing constraints, and flyable trajectories. The performance of the algorithm is compared to that of deterministic branch and bound search and stochastic random search methods. Monte Carlo simulations demonstrate the viability of the genetic algorithm, providing good feasible solutions quickly. Moreover, it converges near to the optimal solution considerably faster than the other methods for some test cases. This makes real time implementation for high dimensional problems feasible. DTIC
Algorithms; Combinatorial Analysis; Drone Vehicles; Genetic Algorithms; Stochastic Processes; Surveillance; Targets
20060018301 NASA Dryden Flight Research Center, Edwards, CA, USA
Reconfigurable Control with Neural Network Augmentation for a Modified F-15 Aircraft
Burken, John J.; Williams-Hayes, Peggy; Kaneshige, John T.; Stachowiak, Susan J.; April 2006; 29 pp.; In English; Original contains black and white illustrations Report No.(s): NASA/TM-2006-213678; No Copyright; Avail.: CASI: A03, Hardcopy
Description of the performance of a simplified dynamic inversion controller with neural network augmentation follows. Simulation studies focus on the results with and without neural network adaptation through the use of an F-15 aircraft simulator that has been modified to include canards. Simulated control law performance with a surface failure, in addition to an aerodynamic failure, is presented. The aircraft, with adaptation, attempts to minimize the inertial cross-coupling effect of the failure (a control derivative anomaly associated with a jammed control surface). The dynamic inversion controller calculates necessary surface commands to achieve desired rates. The dynamic inversion controller uses approximate short period and roll axis dynamics. The yaw axis controller is a sideslip rate command system. Methods are described to reduce the cross-coupling effect and maintain adequate tracking errors for control surface failures. The aerodynamic failure destabilizes the pitching moment due to angle of attack. The results show that control of the aircraft with the neural networks is easier (more damped) than without the neural networks. Simulation results show neural network augmentation of the controller improves performance with aerodynamic and control surface failures in terms of tracking error and cross-coupling reduction. Author
Augmentation; Controllers; F-15 Aircraft; Neural Nets
20060018357 NASA Langley Research Center, Hampton, VA, USA
An MDOE Assessment of Nozzle Vanes for High Bypass Ratio Jet Noise Reduction
Henderson, Brenda; Norum, Thomas; Bridges, James; [2006]; 10 pp.; In English; 12th AIAA/CEAS Aeroacoustics Conference, 8-10 May 2006, Cambridge, MA, USA; Original contains color and black and white illustrations Contract(s)/Grant(s): 23-781-30-12 Report No.(s): AIAA Paper 2006-2543; No Copyright; Avail.: CASI: A02, Hardcopy
The effect of airfoil-shaped vanes placed in the fan stream of a BPR 8 coannular nozzle model system on the resulting jet noise was investigated. The experiments used a Modern Design of Experiments approach to investigate the impact of a range of vane parameters on the noise reduction achieved at representative takeoff conditions. The experimental results showed that the installation of the vanes decreased low frequency noise radiation in the downstream peak-noise direction and increased high frequency noise in the upstream direction. Results also showed that improper selection of the vane configuration resulted in increased low frequency noise radiation in the upstream direction. Large angles of attack are shownto reduce noise near the peak jet noise angle and increase noise in the upstream direction. The MDOE analysis yields an optimum design that minimizes perceived noise levels. Limited data taken with a BPR 5 nozzle system showed that the vanes result in better effective perceived noise reduction for lower bypass ratio nozzles than for the BPR 8 model. Author
Bypass Ratio; Experiment Design; Jet Aircraft Noise; Noise Reduction; Vanes; Nozzle Design
20060018360 NASA Langley Research Center, Hampton, VA, USA
Assessment of Bulk Absorber Properties for Multi-Layer Perforates in Porous Honeycomb Liners
Jones, Michael G.; Parrott, Tony L.; [2006]; 21 pp.; In English; 12th AIAA/CEAS Aeroacoustics Conference, 8-10 May 2006, Cambridge, MA, USA; Original contains color illustrations Contract(s)/Grant(s): 23-781-30-14 Report No.(s): AIAA Paper 2006-2403; No Copyright; Avail.: CASI: A03, Hardcopy
CONTINUING progress in materials technology provides potential for improved acoustic liners for attenuating broadband fan noise emissions from aircraft engine nacelles. Conventional liners (local-reacting perforate-over-honeycomb structures) provide significant narrow-band attenuation, but limited attenuation over wide bandwidths. Two approaches for increasing attenuation bandwidth are to (1) replace the honeycomb structure with bulk material, or (2) cascade multiple layers of perforate/honeycomb structures. Usage of the first approach is limited because of mechanical and maintenance reasons, while multi-layer liners are limited to about three layers because of their additional mechanical complexity, depth and weight. The current research concerns a novel approach reported by the University of Cincinnati, in which a single-layer conventional liner is converted into an extended-reaction, broadband absorber by making the honeycomb core structure porous. This modified single-layer liner requires no increase in depth and weight, and minimal increase in mechanical complexity. Langley has initiated research to identify potential benefits of liner structures with porous cell walls. This research has two complementary goals: (1) develop and validate experimental techniques for treating multi-layer perforates (representative of the internal cells of a liner with porous cell walls) as 1-D bulk materials, and (2) develop analytical approaches to validate this bulk material assumption. If successful, the resultant model can then be used to design optimized porous honeycomb liners. The feasibility of treating an N-layer perforate system (N porous plates separated by uniform air gaps) as a one-dimensional bulk absorber is assessed using the Two-Thickness Method (TTM), which is commonly used to educe bulk material intrinsic acoustic parameters. Tests are conducted with discrete tone and random noise sources, over an SPL range sufficient to determine the nonlinearity of the test specimens, for test specimens consisting of 5, 10 and 15% porous plates. Measured impedances for two liner thicknesses (e.g., 12 and 24 layers) are used as input to the TTM to determine the characteristic impedance and propagation constant that characterize these liners as bulk absorbers. These parameters are then used to calculate the predicted impedance of liners with different thicknesses (e.g., 36 layers), and a comparison of predicted and measured impedances for these other thicknesses is used to determine the efficacy of this approach. Finally, an independent method is used to educe the propagation constant for a single representative sample, and excellent comparison between the results for this method and those for the TTM provides increased confidence in the results achieved with the TTM. In general, the results demonstrate these multi-layer perforates can be acceptably treated as bulk absorbers. Author
Honeycomb Cores; Linings; Absorbers (Materials); Perforated Plates; Porous Plates
20060018361 NASA Langley Research Center, Hampton, VA, USA
Development of Aeroservoelastic Analytical Models and Gust Load Alleviation Control Laws of a SensorCraft Wind-Tunnel Model Using Measured Data
Silva, Walter A.; Shimko, Anthony; Kvaternik, Raymond G.; Eure, Kenneth W.; Scott, Robert C.; [2006]; 17 pp.; In English; 47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 1-4 May 2006, Newport, RI, USA; Original contains color illustrations Contract(s)/Grant(s): 754-02-07-07; Copyright; Avail.: CASI: A03, Hardcopy
Aeroservoelastic (ASE) analytical models of a SensorCraft wind-tunnel model are generated using measured data. The data was acquired during the ASE wind-tunnel test of the HiLDA (High Lift-to-Drag Active)Wing model, tested in the NASA Langley Transonic Dynamics Tunnel (TDT) in late 2004. Two time-domain system identification techniques are applied to the development of the ASE analytical models: impulse response (IR) method and the Generalized Predictive Control (GPC) method. Using measured control surface inputs (frequency sweeps) and associated sensor responses, the IR method is used to extract corresponding input/output impulse response pairs. These impulse responses are then transformed into state-space models for use in ASE analyses. Similarly, the GPC method transforms measured random control surface inputs and associated sensor responses into an AutoRegressive with eXogenous input (ARX) model. The ARX model is then used to develop the gust load alleviation (GLA) control law. For the IR method, comparison of measured with simulated responses are presented to investigate the accuracy of the ASE analytical models developed. For the GPC method, comparison of simulated open-loop and closed-loop (GLA) time histories are presented. Author
Aeroservoelasticity; Gust Loads; Mathematical Models; Wind Tunnel Models; Sensors; Wind Tunnel Tests; Control Theory
20060018401 Government Accountability Office, Washington, DC, USA
Electronic Warfare: Option of Upgrading Additional EA-6Bs Could Reduce Risk in Development of EA-18G
Apr. 2006; 34 pp.; In English Report No.(s): PB2006-109739; GAO-06-446; No Copyright; Avail.: CASI: A03, Hardcopy
The EA-6B has conducted airborne electronic attack for all services since 1996. In 2002, the Department of Defense (DOD) completed an analysis of alternatives for the EA-6B that concluded the inventory would be insufficient to meet the DOD's needs beyond 2009. Since then, the services have embarked on separate acquisition efforts to develop airborne electronic attack assets. In 2003, the Navy started development of the EA-18G aircraft to replace the EA-6B. This report wasdone under the Comptroller General's authority and assesses if (1) DOD's 2002 conclusion that the EA-6B inventory would be insufficient beyond 2009 remains valid for assessing the Navy's future needs, and (2) the acquisition approach used to develop the EA-18G is knowledge-based and might mitigate future risks. NTIS
Electronic Warfare; Inventory Controls; Risk
20060018453 Air Force Research Lab., Wright-Patterson AFB, OH USA
A Non-Linear Model for the Longitudinal Dynamics of a Hypersonic Air-breathing Vehicle
Bolender, Michael A; Doman, David B; Jan 2006; 23 pp.; In English; Original contains color illustrations Report No.(s): AD-A445058; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA445058; Avail.: Defense Technical Information Center (DTIC)
A non-linear, physics-based model of the longitudinal dynamics for an air-breathing hypersonic vehicle is developed. The model is derived from first principles and captures the complex interactions between the propulsion system, aerodynamics, and structural dynamics. Unlike conventional aircraft, hypersonic vehicles require that the propulsion system be highly integratedinto the airframe. Furthermore, hypersonic aircraft tend to have very lightweight, flexible structures that have low natural frequencies. Therefore, the first bending mode of the fuselage is important as its deflection affects the amount of airflow entering the engine, thus influencing the performance of the propulsion system. The equations of motion for the flexible aircraft are derived using Lagrange's Equations. The equations-of-motion capture inertial coupling effects between the pitch and normal accelerations of the aircraft and the structural dynamics. The linearized aircraft dynamics are shown to be unstable, and in most cases, exhibit non-minimum, phase behavior. The linearized model also indicates that there is an aeroelastic mode that has a natural frequency more than twice the frequency of the fuselage bending mode. Furthermore, the short-period mode is very strongly coupled with the bending mode of the fuselage. DTIC
Hypersonic Vehicles; Lagrangian Function; Nonlinearity
20060018460 Air Force Inst. of Tech., Wright-Patterson AFB, OH USA
Modeling, Stability, and Control of a Rotatable Tail on a Micro Air Vehicle
Higgs, Travis J; Dec 2005; 131 pp.; In English; Original contains color illustrations Report No.(s): AD-A445217; AFIT/GAE/ENY/06-05; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA445217; Avail.: Defense Technical Information Center (DTIC)
This research uses existing experimental wind tunnel data to develop a non-linear model that is used to characterize the stability of a flexible wing Micro Air Vehicle (MAV) with a rotatable tail. The experimental data are curve fit based on either angle of attack or angle of sideslip, and the coupled effect of tail rotation and tail deflection on the force and moment coefficients. Static optimization trims the input and state variables for Steady Level Unaccelerated Flight (SLUF). The resulting initial conditions are fed to an open loop non-linear Simulink/Matlab simulation. The study found that the bare MAV design is unstable, but parametric studies identified practical modifications that could be made to the MAV to improve its open loop stability characteristics. The study found that the coupling effect due to the dihedreal derivative played a large role in destabilizing the lateral-directional dynamics and a feedback Stability Augmentation System is required for flight. DTIC
Drone Vehicles; Rotation; Stability
20060018474 Naval Postgraduate School, Monterey, CA USA
Impact of GFO Satellite and Ocean Nowcast/Forecast Systems on Naval Antisubmarine Warfare (ASW)
Amezaga, Guillermo R; Mar 2006; 154 pp.; In English; Original contains color illustrations Report No.(s): AD-A445285; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA445285; Avail.: CASI: A08, Hardcopy
The purpose of this thesis is to investigate the value-added of the Navy's nowcast/forecast and GFO satellite to the naval antisubmarine warfare (ASW) and anti-surface warfare. For the former, the nowcast/forecast versus observational fields were used by the WAPP to determine the suggested presets for MK 48 variant torpedo. The metric used to compare the two setsof outputs is the relative difference in acoustic coverage area generated by WAPP. Output presets are created for five different scenarios, two anti-surface warfare scenarios and three ASW scenarios, in each of two regions: the East China Sea and South China Sea. Analysis of the output reveals that POM outperforms MODAS in all tactic scenarios. For the latter, the MODAS (T, S) profiles were used by the WAPP to determine suggested presets for Mk 48 variant torpedo. The only difference in the MODAS fields was the altimeter used to initialize the respective MODAS fields. The same metrics used in the nowcast/forecast case were used to generate and compare the acoustic coverages. Analysis of the output reveals that, in most situations, WAPP output is not very sensitive to the difference in altimeter orbit. DTIC
Antisubmarine Warfare; Design Analysis; Extraterrestrial Oceans; Forecasting; Models; Navy; Ocean Data Acquisitions
Systems; Optical Equipment; Torpedoes; Warfare; Warheads
20060018533 Instituto Superior Tecnico, Lisbon, Portugal
Research and Development of a Scaled Joined-Wing Flight Vehicle
Suleman, Afzal; Apr 2005; 25 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): FA8655-04-1-3006 Report No.(s): AD-A445389; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA445389; Avail.: CASI: A03, Hardcopy
This report results from a contract tasking Instituto Superior Tecnico as follows: The Grantee will investigate the aeroelastic performance of the joined-wing concept. Dr. Suleman and his research team have proposed to investigate the aeroelastic performance of the joined-wing concept by analyzing, designing, manufacturing, and wind tunnel testing aeroelastically scaled models. The first step will include designing a test assembly to conduct aeroelastic flutter and gust response tests. A fairly flexible wing with low bending and torsion mode frequencies is envisioned in order to study the aeroelastic phenomena in a low subsonic regime. The structure of the joined wing will be analyzed in order to determine its vibrational behavior. Design aspects to be considered include the spanwise loadings and the design of wing camber and twist. A comparison of experimental and computational results will be conducted. Nonlinear structural issues will also be addressed. In order to predict the post-buckling behavior of the joined-wing structure, this task will concentrate on the development of higher-order geometric nonlinearity models for the joined-wing concept. Appropriate criteria will be determined for (a) stiffness and weight effects on vehicle handling and flutter; (b) ultimate strength and stability; (c) skin postbuckling and stringer column buckling of skin/stringer configurations; and (d) critical damage conditions associated with ultimate strength. DTIC
Aeroelasticity; Research Aircraft; Wings
20060018543 Naval Postgraduate School, Monterey, CA USA
Study of Micro-Sized Technology, Micro Air Vehicles, and Design of a Payload Carrying Flapping Wing Micro Air Vehicle
Kinkaid, Timothy; Mar 2006; 66 pp.; In English; Original contains color illustrations Report No.(s): AD-A445409; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA445409; Avail.: CASI: A04, Hardcopy
There has been recent interest by the military to have platforms capable of operating close to a point of interest without being detected while providing critical surveillance. By providing information that is not readily available, these platforms could provide a useful tool for small unit commanders in potentially life-threatening situations. Highly maneuverable, slow-flying micro air vehicles could fly under canopies, through alleys, or indoors to provide such intelligence. This study consists of a survey of current micro-sized technologies and commercially available components. The findings are presented and used in the design process of a larger payload-carrying variant of the NPS flapping wing micro air vehicle. The intent is to develop a readily deployable, backpackable, slow-flying micro air vehicle that can be used by smaller-size ground units in theatre for urban reconnaissance. DTIC
Drone Vehicles; Flapping; Payloads; Wings
20060018555 Naval Postgraduate School, Monterey, CA USA.
Using Integrated Mechanical Diagnostics Health and Usage Management System (IMD-HUMS) Data to Predict UH-60L Electrical Generator Condition
Willard, Lee; Klesch, Greg; Mar 2006; 122 pp.; In English; Original contains color illustrations Report No.(s): AD-A445430; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA445430; Avail.: CASI: A06, Hardcopy
Military aircraft maintenance methods are moving from practices based on hard-time inspection and replacement intervals to one of Condition Based Maintenance (CBM). Benefits of CBM are the minimization of maintenance efforts and component replacement along with an increase in readiness and safety. Goodrich has developed the Integrated Mechanical Diagnostics Health and Usage Management System (IMD-HUMS) for the practices of CBM in helicopters. Great benefits have been realized with the IMD-HUMS system in regards to several maintenance practices, readiness, and safety. However, the total potential of the system in regards to these benefits for the multiple components observed by the IMDHUMS is not yet achieved. The IMD-HUMS gathers a great deal of pertinent, important data on the condition of multiple components and systems, but the meaning and full potential of all this data is not yet fully realized. The purpose of this research is to conduct and document a statistical analysis of IMD-HUMS produced data. Statistical applications of data mining, regression and classification trees are explored. The approaches used in the exploration of the IMD-HUMS acquired data sets are based on six electrical generators which displayed degradation or failure and hence required maintenance actions compared with sixty others which did not. DTIC
Diagnosis; Health; Maintenance; Management Systems
20060018601 North Carolina State Univ., Raleigh, NC USA
Evaluation of Material Integrity Using Reduced Order Computational Methodology
Banks, H T; Joyner, Michele L; Wincheski, Buzz; Winfree, William P; Jan 1999; 59 pp.; In English Contract(s)/Grant(s): F49620-91-1-0180 Report No.(s): AD-A445500; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA445500; Avail.: CASI: A04, Hardcopy
This paper explores the feasibility of detecting damage within structures such as air foils by application of eddy current based techniques and reduced order modeling. To identify the geometry of a damage, an optimization algorithm is employed which requires solving the forward problem numerous tin%s. Therefore, the forward algorithm must be solved with extremely fast and accurate solution methods. In constructing these forward methods, we employ reduced order Proper orthogonal Decomposition (P()D) techniques. The P()D technique is a method which creates all 'optimal' ordered basis in the sense that information captured in the first few basis elements is maximized. ()ne then uses a fixed number (based on a quantitative formula for percentage energy captured) of the first few basis elen%nts, called the reduced PC)D basis, in the forward algorithm. Since one uses only a small number of basis elen%nts, one is able to create a fast forward algorithm that accurately represents the relevant information. In this paper, for illustrative purposes and proo%ofconcept, we consider rectangular 'cracks' parameterized by a vector parameter q representing the length, thickness, depth, center, etc. of the damage.We attempt to recap- ture the parameters of a damage assuming we have access to the magnetic vector potential A (which is not pratical experimentally) or the magnetic flux density B. ()ur analysis uses simuhted data A or B with normally dis- tributed noise to represent corrupted experimental data. When recapturing the length or thickness of a damage using the component of the magnetic flux density orthogonal to the eddy current flow in the sample, the methods are shown to be efficient and robust even with data containing 10% relative noise. DTIC
Airfoils; Damage
20060018761 European Office of Aerospace Research and Development, FPO New York, NY USA
Flow Structure Interaction on Flexible UCAV Wing Platforms
Gursul, Ismet; Jun 2005; 51 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): F61775-02-C-4024 Report No.(s): AD-A445564; No Copyright; Avail.: Defense Technical Information Center (DTIC)
This report results from a contract tasking University of Bath as follows: The next generation of unpiloted combat air vehicles (UCAV's) will likely have flexible delta wings and will likely need the capability to perform extreme maneuvers at high g's. Vortical flows over delta wings produce periodic aerodynamic excitation which may cause unacceptable buffeting of a flexible wing structure. In this effort the contractor will investigate unsteady vortex flows over flexible delta wings, theirinteraction with the wing, and possibility of flow control by structural tuning. Basic research issues related to fluid/structure interactions for vortical flows will be addressed in analytical modeling, water tunnel testing, and wind tunnel testing. Wingtip accelerations will be measured using multiple accelerometers. PIV and LDV measurements will be used to capture the steady and unsteady phenomena in the wing flow field. The model geometry of the delta wing is simple, hence the experimental results may serve as benchmark tests for computational simulations. DTIC
Delta Wings; Drone Vehicles; Flexible Wings; Wind Tunnel Tests; Wing Tips
20060018794 Air Force Research Lab., Wright-Patterson AFB, OH USA
Position-Adaptive UAV Radar for Urban Environments
Mitra, Atindra K; Apr 14, 2005; 7 pp.; In English Report No.(s): AD-A445684; No Copyright; Avail.: CASI: A02, Hardcopy
A bistatic radar concept is presented where a low-altitude UAV (Unmanned Aerial Vehicle) 'position-adaptively' converges to line-of-sight (LOS) locations for objects that are embedded between buildings. The concept is developed by deriving approximate electromagnetic signal models based on the uniform theory of diffraction (UTD). In addition, a new signature exploitation technique is formulated that allows for the estimation of target parameters in cases when neither the transmitting nor the receiving platform is in LOS with an embedded target or object. This technique is denoted as exploitation of leakage signals via path trajectory diversity (E-LS-PTD). Additional areas for further research are cited. DTIC
Adaptation; Cities; Multistatic Radar; Pilotless Aircraft; Remotely Piloted Vehicles
20060018832 Brigham Young Univ., Provo, UT USA
Path Planning for Sensing Multiple Targets from an Aircraft
Howlett, Jason K; Apr 2003; 138 pp.; In English; Original contains color illustrations Report No.(s): AD-A445771; No Copyright; Avail.: CASI: A07, Hardcopy
To generate an assignment of tasks that best utilizes a team's resources, it is necessary to know the costs incurred by a team member for doing those tasks. In a cooperative search and destroy scenario, tasks generally require that the vehicle's sensor pass over specific known target points, which, to produce the associated costs, requires calculating the path the vehicle will take to sense the various targets. When the targets are far apart, the path-planning problem is trivial. For targets that are closely spaced, however, the problem is much more difficult, and thus is needed the ability to plan paths that sense multiple, closely-spaced targets. Traditional path-planning methods are not well suited for generating paths that sense multiple, closely-spaced targets. Traditional methods focus on connecting some starting point and ending point with a feasible, minimum length path segment. Because an end point must be specified, these methods require too much information about how the path should accomplish its objectives, and hence the complexity of the associated problem is too great for real-time path-planning applications. This thesis introduces the discrete-step path tree, and several methods for finding paths from the tree that accomplish the desired objectives, as solutions to the multiple-target sensing problem. Two of these methods use potential fields to guide the movement of the vehicle through the path tree. However, these methods are problematic and do not produce very good paths. Augmenting the potential-field methods by randomly branching to different parts of the path tree improves the path-length performance, but still not to completely satisfactory levels. The final two methods are based on the path-length performance. DTIC
Aircraft; Algorithms; Detection; Targets; Trajectory Planning
20060018838 Naval Postgraduate School, Monterey, CA USA
Determination of Changes in the State of the Arctic Ice Pack Using the NPS Pan-Arctic Coupled Ice-Ocean Model McNamara,
Terry; Mar 2006; 75 pp.; In English; Original contains color illustrations Report No.(s): AD-A445788; No Copyright; Avail.: CASI: A04, Hardcopy
This thesis provides an analysis of the diminishing sea ice trend in the Arctic Ocean by examining the NPS 1/12-degree pan-Arctic coupled ice-ocean model. While many previous studies have analyzed changes in ice extent and concentration, this research focuses on ice thickness as it gives a better indication of ice volume variability. The skill of the model is examined by comparing its output to sea ice thickness data gathered during the last two decades. The first dataset used is the collection of draft measurements conducted by U.S. Navy submarines between 1986 and 1999. The second is electromagnetic (EM) induction ice thickness measurements gathered using a helicopter by the Alfred Wegener Institute in April 2003. Last, model output is compared with data collected by NASA's ICESat program using a laser altimeter mounted on a satellite of the same name. The NPS model indicates an accelerated thinning trend in Arctic sea ice during the last decade. The validation of model output with submarine, EM and ICESat data supports this result. This lends credence to the postulation that the Arctic not only might, but is likely to be ice-free during the summer in the near future. DTIC
Arctic Ocean; Arctic Regions; Helicopters; Ice; Ocean Models; Sea Ice
20060018942 Carnegie-Mellon Univ., Pittsburgh, PA USA
Mixed-Initiative Control of Autonomous Unmanned Units Under Uncertainty
Thrun, Sebvastian; Gordon, Geoffrey; Burstein, Mark; Diller, David; Fox, Dieter; Feb 2006; 39 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): F30602-01-C-0219; DARPA ORDER-M421; Proj-M421 Report No.(s): AD-A446039; No Copyright; Avail.: CASI: A03, Hardcopy
The MICA program focused on changing the control and coordination of unmanned aerial vehicles from a need for two to four persons per vehicle to one person controlling five or more vehicles. This program developed techniques for hierarchical control using mixed-initiative planning guidance and control taking a number of kinds of uncertainty into account at a fundamental level. These techniques focused on reasoning about uncertainty, including planning, belief tracking and communications with both human and automation. We developed this control model using Partially Observable Markov Decision Processes. The mixed-initiative interactions enabled users to describe constraints at multiple levels of the planning hierarchy. Techniques include visualization of the environment and optional speech input. The capabilities were demonstrated in a laboratory environment and on the program's Open Experimental Platform. DTIC
Aircraft; Autonomy; Command and Control; Markov Processes
20060019037 Swedish Defence Research Establishment, Linkoeping, Sweden
Information-Theoretic Approach for Concurrent Path and Sensor Planning for a UAV with EO/IR Sensors )
Skoglsar, P.; Bjoerstroem, R.; Nygards, J.; Ulvklo, M.; May 2005; 78 pp.; In English Report No.(s): PB2006-112058; FOI-R-1685-SE; Copyright; Avail.: National Technical Information Service (NTIS)
This report presents an information-theoretic approach to concurrent path and sensor planning for a UAV equipped with gimbaled EO/IR sensors. The goal is autonomous UAV surveillance, i.e.search for objects along a road or in a certain area and localization of discovered targets. The work is inspired by research in optimal observer trajectory computations for bearings-only tracking. NTIS
Information Theory; Infrared Detectors; Infrared Radiation; Pilotless Aircraft; Surveillance; Trajectory Planning
20060019060 Quebec Univ., Chicoutimi, Quebec, Canada
Indoor Snow Testing of Aircraft Ground Anti-Icing Fluids
Apr. 2006; 52 pp.; In English ontract(s)/Grant(s): DTFACT-04-P-00023 Report No.(s): PB2006-111449; No Copyright; Avail.: National Technical Information Service (NTIS)
Currently, holdover time performance for aircraft deicing and anti-icing fluids under snow conditions are determined from outdoor tests on flat plates in natural snow. The Federal Aviation Administration Airport and Aircraft Safety Research and Development Division has sponsored research to do similar tests under indoor laboratory conditions. Such indoor tests would lead to a more timely and improved assessment of a new fluid's performance without relying on outdoor snow conditions. During past investigations, when similar tests were conducted in laboratory cold rooms, the resulting holdover times were significantly different (typically shorter) from those produced outdoors in natural snow conditions. This difference was attributed to the effects of wind. Recent research at the National Center for Atmospheric Research has produced indoor procedures using temperature-controlled test plates that accounted for the effects of wind and produced holdover time results that more closely matched those obtained from outdoor snow tests. NTIS
Deicers; Deicing; Ice Prevention; Snow
Source: NASA
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