Mechanical Components

Blended Wing Body Aircraft

Scientists from Boeing Phantom Works, the National Aeronautics and Space Administration (NASA), and AFRL are testing a new aircraft with the potential to realize up to 30% better fuel efficiency because of its unique "flying-wing" shape. The prototype blended wing body, or BWB, aircraft is a modified, triangular-shaped aircraft configuration with 20 control surfaces along its trailing edge. Researchers believe the BWB configuration will produce better fuel efficiency because a greater portion of the aircraft is involved in producing lift. The additional lift stems from the replacement of the conventional tube-shaped aircraft fuselage with the more aerodynamically efficient wing centerbody.

Posted in: Briefs, Mechanical Components
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Improved Accuracy of Computational Fluid Dynamics Calculations

Understanding how air flows over the surfaces of an air vehicle can help AFRL designers maximize the vehicle's performance and minimize its cost. AFRL scientists recently developed a tool that improves the accuracy of airflow simulations that result from computational fluid dynamics (CFD) calculations. As part of a Small Business Innovation Research effort, AFRL collaborated with Combustion Research and Flow Technology (CRAFT), Inc., to develop the tool for use with unstructured CFD programs. The new tool uses the solver's initial solution to determine where grid points should be added or removed within the CFD mesh, a process which then improves the solver's solution in a second—and any subsequent—iteration. This enhanced accuracy improves AFRL's ability to support the warfighter with lower-cost, higher-value designs.

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Remote-Controlled Aerial Vehicle for Application of Pesticides

AFRL demonstrated its Remotely Controlled Aerial Vehicle for Application of Pesticides (RCAVAP) at the Force Protection Equipment Demonstration (FPED) conducted at Quantico Marine Corps Base, Virginia. During times of war, disease has historically caused more deaths than bullets, far outnumbering any other cause. Consider, for example, the Mexican-American war. Over 1,000 soldiers were killed in action, 529 died of wounds sustained on the battlefield, 362 suffered accidental death, and 11,155 perished from disease— mostly yellow fever, a viral illness transmitted by the Aedes aegypti mosquito. During World War II, malaria ravaged the troops. Spread by the female anopheline mosquito, the disease affected thousands of American soldiers. More recently, a single 2-week period in Baqubah, Iraq, saw 250 cases of cutaneous leishmaniasis, a disfiguring parasitic disease spread by the female sandfly.

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AFRL Proves Feasibility of Plasma Actuators

AFRL is laying the groundwork for the development of revolutionary hypersonic aerospace vehicles (see Figure 1). Accordingly, AFRL engineers are examining the feasibility of replacing an air vehicle's traditional, mechanically or electrically actuated flight control surfaces (e.g., wing flaps) with plasma actuators that require no moving parts and are therefore potentially less expensive and more reliable. As part of the laboratory's Boundary Layers and Hypersonics program, the engineers conducted a wind tunnel test to evaluate the feasibility of using plasma actuators for airframe flight control.

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Unmanned SkyTote Demonstrates Capabilities

AFRL scientists are working on SkyTote, a novel unmanned air vehicle (UAV) that will take off and land vertically like a helicopter (see figure) but also transition into horizontal flight like a conventional aircraft. SkyTote's primary mission is to deliver a payload to a specific point within a tactically relevant range and time. AeroVironment, Inc., of Monrovia, California, developed the vehicle under a Small Business Innovation Research effort for AFRL.

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The Propulsion - Safety, Affordability, and Readiness Program

Propulsion - Safety, Affordability, and Readiness (P-SAR) is a new and unique program effort intended to achieve common engine sustainment goals across the Army, Navy, and Air Force aircraft fleets (see figure). Originally conceived as a follow-on to the highly successful High-Cycle Fatigue (HCF) program, P-SAR is evolving into a benchmark collaboration initiative that includes all Department of Defense (DoD) propulsion organizations, as well as National Aeronautics and Space Administration representatives and turbine engine original equipment manufacturers.

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Film Cooling Using Pulsed Coolant

Turbine engine designers routinely use film cooling to cool engine components in the hot-gas flowpath. Film cooling is the process of injecting coolant fluid at one or more discrete locations along a surface exposed to a harsh, high-temperature environment. The film cools and thus protects turbine engine components, enabling the engine's operation at higher turbine inlet temperatures and increasing its thermal efficiency. Current turbine engine designs employ a continuous coolant flow, typically diverting 20%- 25% of the compressor's high-pressure air to cool turbine airfoils. By reducing the volume of high-pressure air needed for turbine blade cooling, designers can proportionately increase the flow available for combustion and thus increase thrust. Therefore, coolant flow reduction is an important design goal in the development of advanced turbine engines.

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AFRL Finding Ways to Decrease Unmanned Air Vehicle Costs

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.

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AFRL Supports Desert Hawk Program

AFRL aeronautical engineers collaborated with the Electronic Systems Center's (ESC) Force Protection Program Office, Hanscom Air Force Base (AFB), Massachusetts, to conduct an in-house effort assessing the Desert Hawk small unmanned air vehicle's (SUAV) performance and exploring potential improvements to that performance. Desert Hawk, also known as the Force Protection Airborne Surveillance System (FPASS), performs air base perimeter defense and other intelligence, surveillance, and reconnaissance tasks.

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Microelectromechanical Systems Inertial Measurement Unit Flight Test

AFRL and Boeing engineers conducted successful flight tests of microelectromechanical systems (MEMS) inertial measurement units (IMU) on the Joint Direct Attack Munition (JDAM). They collected flight data and validated the MEMS IMU technology's capability to provide stable navigation performance and accurate weapon guidance, both with and without Global Positioning System (GPS) updates. Researchers will use this flight data to further refine MEMS IMU technology to enhance future capabilities of air-launched munitions.

Posted in: Briefs, Mechanical Components, Microelectricmechanical device, Navigation and guidance systems, Flight tests
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