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Nimbus Meta-plane, a New Aerodynamic Concept for Unmanned Hybrid Aerial Vehicle Application

Nimbus S.r.l. (Italy)-A. Capuani, A. Mercalli, S. Fantino
Politecnico di Torino (Italy)-E. Cafaro, L. Stantero, R. Taurino
Published 2008-08-19 by SAE International in United States
The work attains a new hybrid concept of a light unmanned aerial vehicle, called “Nimbus”, based on an inflatable lifting body which combines the characteristics and the performances of Lighter-Than-Air and Heavy-Than-Air platforms. This hybrid design allows short take off and landing (STOL) capability due to its low wing loading, absolute stability reference, good employable payload capacity, high endurance, no runway or ground handling system requirements and easy piloting. The inflatable wing is a cylindrical pneumatic chamber, light weight, V shaped and filled with helium. The main aim of the paper is to describe the approach followed in the preliminary design of the Nimbus platform supported by evidences provided by both CFD simulations and experimental trials of a model prototype. The numerical simulations are performed in order to characterize the near flow field on the blimp lifting body balloon and to estimate the main performances of the aerial vehicle. Flight tests are performed by a model prototype demonstrating the goodness of the preliminary theoretical analysis. A complete system performance overview is reported, covering all main…
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Are the New Ones Really Better? An Inquiry About Sporty Looking Airplanes of All Ages

Retired-Harry R. Clements
Published 2008-08-19 by SAE International in United States
This abstract and the following paper are written in conversational, rather than technical, language. The only technical element of the paper is the statistical analysis of the information collected, thoroughly but informally, from Reference 1, Jane's “All the World's Aircraft.” It started as a personal curiosity on my part, but when I had the statistical results I thought they would be of interest to aircraft buffs of all ages, not just old codgers like me. I was curious if the sporty looking new personal airplanes really are better performing than the groovy (is that term used anymore?) looking airplanes of my youth. I divided old and new by the year 1970, giving plenty of candidates in both groups (about one hundred in total) and compared their max cruising speeds for the horsepower installed. The groups include two and four place models, each with a logical subcategory of fixed or retractable gear. Do the new ones get more speed for the horsepower they carry? The results are in - and displayed below.
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Aerodynamic Comparison of Tilt-Rotor, -Wing and -Body Concept for Multi Task MAVs

Institute Supérieur de I'Aéronautique et de I'Espace-Chinnapat Thipyopas
Published 2008-08-19 by SAE International in United States
Multi task Micro Air Vehicles (MAVs) have been interested in last few years. VTOL and hovering capacities are required in case of flying in very confined zone and to enter into the building. In this paper, the VTOL concepts including tilt-wing, tilt-body, and tilt rotor had been studied. Analytical study and wind tunnel test have been done to compare different configurations by using the same power system. Since MAVs have been limited by size, the result concludes that tilt-body concept seems to be most appropriate for MAV application.
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Going Green: What's in it for General Aviation?

Cessna Aircraft Company-Ahmed S. Mohamed
Wichita State University-William H. Wentz
Published 2008-08-19 by SAE International in United States
Global warming concerns have prompted actions to restrict carbon dioxide emissions by a rapidly growing number of nations throughout the world. The aviation community can expect emission limits in the near future, and should become pro-active in this arena. Rapid advances are being made in the automobile industry to research and develop more efficient vehicles. The very successful introduction of gasoline-electric hybrid automobiles has spawned intense research and development of advanced batteries, ultra-capacitors, electric motors and controls. Opportunities for adapting automobile technologies to small general aviation airplanes should be exploited. Over the past few years, several groups have successfully flown experimental airplanes powered by ground-rechargeable batteries. Performance studies of small single-engine battery-powered airplanes show that performance is severely restricted because of low specific energy values (kWh/kg) of chemical batteries compared to traditional fossil fuels. However, advantages of zero in-flight emissions, high reliability, and fuel cost of only $1/gallon of avgas equivalent make the battery-powered airplane increasingly attractive. An airplane with minimum power lift-to-drag ratio (L/D) of 17 and battery with specific energy of 0.250 kWh/kg…
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Ensuring VLJ Operational Safety: Learning to Ask the Right Questions

Robert B Barnes Associates, Inc.-Robert Barnes
Published 2008-08-19 by SAE International in United States
Very Light Jets (VLJ)1 could very well revolutionize regional air travel around the world for both business and pleasure by providing an affordable alternative for thousands of owner/pilots, small companies, and potential customers of on-demand air services. Unfortunately, there are also concerns that the VLJ may experience a surge of early deliveries and rapid growth followed by a series of tragic and preventable human-caused accidents. Many international aviation professionals feel that, in order to ensure VLJ operational safety, stakeholders must cause manufacturers, insurers, and regulators to address key questions about proposed VLJ training programs and their related human factors issues.
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The Art of Conducting a Safety Risk Analysis on In-Service Problems

Pratt & Whitney Fellow for Product Safety Risk Analysis-Robert Mattern
Published 2008-08-19 by SAE International in United States
This technical paper presents the author’s recommended approach to one aspect of managing flight safety - conducting Safety Risk Analyses (SRA) on in-service problems that may threaten flight safety. The author did not develop this statistically based approach for assessing the risk of future events, but has helped to improve it and highly endorses it. In conducting a safety risk analysis, the analyst might decide to perform a “quick” SRA and will need a minimal amount of information that will show the relative level of flight safety risk. When the analyst decides a complete safety risk analysis is needed, the possible approaches and level of details included in the SRA can vary greatly from company to company.Knowing what specific information is needed for the inputs and assumptions, how best to use that information, what missing data needs to be estimated, selecting the most appropriate estimation technique, is what makes conducting a Safety Risk Analysis an Art, as well as a science. Process knowledge is not enough. It takes creativity, foresight and experience. The analyst must…
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Using Synthetic Kerosene in Civil Jet Aircraft

Delft University of Technology-T. A. Snijders, J. A. Melkert
Published 2008-08-19 by SAE International in United States
TU Delft in the Netherlands is performing research into the effects of the use of synthetic kerosene in aircraft. The research program consists of both desk research and tests. In the desk research gas turbine simulations will be combined with payload range performance calculations to show engine effects and fuel consumption changes. Ground and flight tests will be performed to show safe operation on synthetic fuel and to validate the calculations. Measurements during the ground tests will show the changed emissions as a result of the synthetic fuel.
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Model-Driven Architecture for Platform and Store Design

Lockheed Martin - Missiles and Fire Control-Robert M. Boman
Published 2008-08-19 by SAE International in United States
The high cost, lengthy time, and lack of synergistic integration activities between aircraft based on the current aircraft/store integration process have driven domestic and foreign militaries to search for a plug-and-play approach for aircraft/store integration. In order to integrate the increasingly complex, software-intensive systems that are currently being designed, streamlined processes must be developed to facilitate their timely adoption. One of the most promising approaches is Model-Driven Engineering (MDE) and Model Driven Architecture (MDA). MDE allows designers to use high-level models to solve particular design problems. With MDE, the systems architecture can be analyzed through many different views and then MDA can be used to transform these high-level models to usable software through an automatic code generation process. The following discusses the current state of aircraft/store integration and how MDA can be used in the integration process to achieve a higher degree of interoperability and move towards true plug-and-play systems.
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Numerical Investigation of Transitional Flows over a NACA0012 Airfoil

North Dakota State University-Mohammad Alam, Yildirim B. Suzen
Published 2008-08-19 by SAE International in United States
A computational study of separated flows over a NACA 0012 airfoil at transitional Reynolds numbers is performed. The transitional nature of the flowfield is incorporated into the computations through γ-Reθ transition model based on local variables. Fully turbulent and transitional computations are performed for steady airfoil flowfields and computed results are compared against experiments. The γ-Reθ transition model, in association with Menter’s SST turbulence model is used for the transitional solutions while, SST turbulence model alone is used for the fully turbulent solutions. Both steady and unsteady compressible flow analysis for transition onset prediction and flow separation characterization has been performed. Effects of free stream flow conditions on flow transition are examined.
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Active Vortex Generators Using Jet Vectoring Plasma Actuators

SAE International Journal of Aerospace

Oklahoma State University-Michael Bolitho, Jamey Jacob
  • Journal Article
  • 2008-01-2234
Published 2008-08-19 by SAE International in United States
Vortex generators, both active and passive, have been shown to be useful flow control devices on aircraft for both separation control and to maintain uniform flow over sections of the wing by energizing the boundary layer, particularly control surfaces. Meanwhile, plasma actuators have been used to delay separation by adding momentum to the boundary layer. Linear plasma actuators have been shown to be an effective arrangement of the plasma actuator for several applications of aerodynamic flow control, primarily separation. The annular plasma actuator, or plasma synthetic jet actuator (PSJA), has also been shown to be effective as a zero net mass flux jet. Similar to the annular plasma actuator, the linear thrust vectoring plasma actuator can be used to create a wall-normal jet, but with vectoring capability. It is shown that by varying parameters of the input signal, the strength of the dielectric barrier discharge, as well as the direction of the jet produced, can be controlled. The type of jet produced by unsteady actuation is shown to be affected by the pulsing frequency, and…
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