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AFRL Finding Ways to Decrease Unmanned Air Vehicle Costs

Testing confirms the research theory that tolerances can be relaxed on surfaces with favorable pressure gradients.

In support of the Aeronautical Systems Center’s (ASC) Global Hawk Systems Group, AFRL has undertaken a program to study manufacturing tolerances for laminar flow on aircraft wings. On the drawing board, air vehicle designs have perfectly smooth aerodynamic surfaces, yet it is nearly impossible for manufacturers to fabricate those surfaces without some imperfections. Any surface imperfection, no matter how slight, can affect the properties of the boundary layer— the air flowing nearest an air vehicle’s body during flight. In turn, this airflow dramatically impacts the amount of drag an air vehicle experiences. When the boundary layer is smooth, or laminar, drag is minimal; as the boundary layer becomes more turbulent, drag increases. Nonetheless, decreasing the amount of surface imperfection is not always a practical solution, because as the manufacturing processes become more stringent, they also become increasingly expensive and time-consuming endeavors. It is therefore vitally important to determine the relationship between the height, shape, and location of surface imperfections and the resulting performance degradation.

Posted in: Briefs, Mechanical Components
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Cyberspace Security via Quantum Encryption

Quantum fluctuations at the physical layer of encryption enable ultrasecure communications with highly competitive performance metrics.

Perfect information- theoretical security requires that the meaning of an encrypted message transmitted from point A to point B be statistically independent of the ciphertext in which that message is embedded. In other words, possession and analysis of the ciphertext must yield no information about the message sent. This article briefly describes cryptographic protocols exhibiting perfect, or nearperfect, security before addressing a new quantum data encryption protocol that employs quantum noise of light at the physical layer to buttress security based on mathematical complexity. This new protocol is called Keyed Communication in Quantum Noise, or KCQ. KCQ does not presently guarantee flawless informationtheoretical security; however, because of KCQ’s physical-layer encryption in the quantum noise of light, some scientists believe that it enables better security than current secure communications systems based solely on mathematical complexity.

Posted in: Briefs, Photonics
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Unified Flow Solver

The Unified Flow Solver enables accurate and efficient simulation of gas flows for the entire range of Knudsen numbers.

A variety of gas flow problems are characterized by the presence of rarefied and continuum domains. In a rarefied domain, the mean free path of gas molecules is comparable to (or larger than) a characteristic scale of the system. The rarefied domains are best described by particle models such as Direct Simulation Monte Carlo (DSMC); or, they involve solution of the Boltzmann kinetic equation for the particle distribution function. The continuum flows are best described by Euler or Navier-Stokes equations in terms of average flow velocity, gas density, and temperature and are solved by computational fluid dynamics (CFD) codes. The development of hybrid solvers combining kinetic and continuum models has been an important area of research over the last decade. Potential applications of such solvers range from high-altitude flight to gas flow in microsystems.

Posted in: Briefs, Software
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A Concept for Information Extraction From Remote Wireless Sensor Networks

AFRL engineers develop advanced information management capabilities to monitor wireless sensor networks.

Recent advances in the development of microsensors, microprocessors, information fusion algorithms, and ad hoc networking have led to increasingly capable wireless sensor networks. These networks, when deployed to monitor an urban area, show great promise in enhancing warfighter situational awareness. However, delivering the sensor network’s collected information back to the proper decision makers is one network capability that still requires improvement. To bridge this gap between the tactical operations center and multiple wireless sensor networks distributed across a city, engineers must create a system-of-systems architecture. This architecture must permit a warfighter to receive near-real-time sensor information from an out-of-theater operating post, whether a mile or an ocean away. Research accomplished in efforts such as the Defense Advanced Research Projects Agency’s (DARPA) Information Exploitation Officesponsored Networked Embedded Systems Technology (NEST) program has provided information gathering algorithms for wireless sensor networks that are independent of the hardware platform on which they run. Nevertheless, these networks have no means for publishing the massive amounts of information to the Global Information Grid (GIG). To address this publication requirement, AFRL engineers have begun integrating NEST technologies with the Joint Battlespace Infosphere (JBI).1, 2 They recently developed a proof-of-concept demonstration of this idea for Scientific Advisory Board (SAB) review. In this demonstration, they integrated a tracking application developed for the NEST program with the AFRLdeveloped JBI Reference Implementation and showcased the resultant capability to connect low-level information gatherers to high-level information distributors.

Posted in: Briefs, Information Sciences
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Rapid Model Fabrication for Responsive Aerodynamic Experimental Research

Researchers are exploring rapid prototyping methods and materials for wind tunnel models.

Technicians machine traditional metal wind tunnel models in a process that can span months. Although these models are highly precise, the meticulously slow manufacturing process precludes a quick assessment regarding a new design’s feasibility and thus impedes the ever-increasing need to help today’s warfighter address constantly changing warfare threats. In support of the Integrated Rapid Aerodynamics Assessment program, AFRL has been exploring the impact of rapid prototyping (RP) technology in meeting this escalating need. According to AFRL’s Mr. Gary Dale, an originator of this experimental research effort, “We were looking for a way to quickly generate experimental data that we could use to verify computational fluid dynamics (CFD) results. The CFD researchers were generating solutions in a matter of days or even hours, and they wanted to verify their solutions with [wind tunnel] experimental data.” By producing a model in days—or possibly hours, depending upon model complexity—RP technology enables this concurrent study of air vehicle concepts via computer simulation and wind tunnel results.

Posted in: Briefs, Manufacturing & Prototyping
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Collapsing and Closing Unmanned Air Vehicle Swarms

A unique design methodology for advanced sensor design applications

AFRL researchers are exploring an adaptive and reconfigurable unmanned air vehicle (UAV) swarm configuration known as “collapsing and closing UAV swarms.” This approach to developing UAV swarms is suitable for a number of multifunction radio frequency (RF) applications in challenging environments such as urban and mountainous regions. Figures 1a-1c illustrate the basic approach. In Figure 1a, a long-range search UAV swarm collectively forms a scanning RF aperture. The swarm’s scanning RF aperture interrogates a region of interest to detect high-clutter, discrete objects such as buildings or mountains. As depicted in Figure 1b, once the swarm detects these large, obscuring objects, it “collapses and closes” in on the region between the objects. This allows the swarm configuration to interrogate the embedded channels between the buildings or mountains to look for signal leakage points within these large objects, and once detected, these leakage points facilitate cavity interrogation.1 After the swarm has finished interrogating the embedded channels and cavities, it reconfigures itself for RF long-range remote sensing with regard to the next region of interest, as illustrated by Figure 1c.

Posted in: Briefs, Electronics & Computers
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Eddy Current Inspection System

Engineers deliver major throughput enhancement to Air Force engine maintenance depot.

AFRL manufacturing technology engineers, working with personnel from the 76th Maintenance Wing’s Software and Propulsion Maintenance Groups at the Oklahoma City Air Logistics Center (OC-ALC) and Wyle Laboratories (formerly Veridian Engineering), delivered a major configuration upgrade and improved the inspection process for the Air Force (AF) Eddy Current Inspection System (ECIS) at OC-ALC, Tinker Air Force Base (AFB), Oklahoma. These ECIS improvements are part of AFRL’s Engine Rotor Life Extension program. With investments exceeding $80 million, the ECIS program addresses an AFRL initiative to extend the useful life of turbine engine components and reduce the cost of replacing aging engine components in the AF’s fighter and bomber fleets.

Posted in: Briefs, Electronics & Computers
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Super-High-Strength Aluminum Alloy

Researchers develop a novel alloy for use in aerospace cryogenic applications.

AFRL researchers developed a superhigh- strength aluminum alloy that engineers can use to improve the capability and performance of aerospace components—cryogenic rocket engine components, in particular. They created an aluminum alloy with specific strength and ductility characteristics surpassing those of the alpha titanium alloy currently used in rocket engine turbopumps. The aluminum alloy also demonstrates less sensitivity to hydrogen embrittlement, is lighter weight, and is potentially less costly to manufacture than the titanium alloy.

Posted in: Briefs, Materials
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Recent Advances in Insensitive Munitions

A new explosive formulation improves insensitive munitions characteristics without affecting production processes.

AFRL scientists from the High Explosives Research and Development facility successfully developed, demonstrated, and transitioned a nextgeneration melt-castable explosive formulation. The new formulation, MNX-795, exhibits significantly improved insensitive munitions (IM) characteristics—a requirement for the formulation’s intended use in the MK- 84 bomb.

Posted in: Briefs, Materials
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Geopolymers

AFRL scientists are developing a new class of inexpensive ceramic-like materials.

The use of ceramics in an ancient culture is one measure of that society’s overall technical sophistication. Combining the study of ancient ceramics with modern science and technology has led to the creation of new ceramics with superior properties. Victor Glukhovsky, a scientist working in the Ukraine half a century ago, researched differences in the durability of ancient cements and more modern concretes. His work ultimately led to the synthesis of various aluminosilicate binders from clays, feldspars, volcanic ashes, and slags. These binders exhibited properties superior to those of the cementitious materials in common use at that time. Decades after Glukhovsky’s discoveries, Ukrainian builders continued to employ aluminosilicate binders in construction applications, confirming their outstanding durability.

Posted in: Briefs, Materials
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