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At least 127 records · Page 7

Active Electrostatic flight for airless bodies

The environment near the surface of asteroids, comets, and the Moon is electrically charged due to the Sun’s photoelectric bombardment and lofting dust, which follows the Sun illumination as the body spins. Charged dust is ever present, in the form of dusty plasma, even at high altitudes, following the solar illumination. If a body with high surface resistivity is exposed to the solar wind and solar radiation, sunexposed areas and shadowed areas become differentially charged. The E-Glider (Electrostatic Glider) is an enabling capability for operation at airless bodies, a solution applicable to many types of in-situ missions, which leverages the natural environment. This platform directly addresses the "All Access Mobility" Challenge, one of the NASA’s Space Technology Grand Challenges. Exploration of comets, asteroids, moons and planetary bodies is limited by mobility on those bodies. The lack of an atmosphere, the low gravity levels, and the unknown surface soil properties pose a very difficult challenge for all forms of know locomotion at airless bodies. This EGlider levitates by extending thin, charged, appendages, which are also articulated to direct the levitation force in the most convenient direction for propulsion and maneuvering. The charging is maintained through continuous charge emission. It lands, wherever it is most convenient, by retracting the appendages or by firing a cold-gas thruster, or by deploying an anchor. Preliminary calculations indicate that a 1 kg mass can be electrostatically levitated in a microgravity field with a 2 m diameter electrostatically inflated ribbon structure at 19kV, hence the need for a “balloon-like” system. The wings could be made of very thin Au-coated Mylar film, which are electrostatically inflated, and would provide the lift due to electrostatic repulsion with the naturally charged asteroid surface. Since the E-glider would follow the Sun’s illumination, the solar panels on the vehicle would constantly charge a battery. Further articulation at the root of the lateral strands or inflated membrane wings, would generate a component of lift depending on the articulation angle, hence a selective maneuvering capability which, to all effects, would lead to electrostatic (rather than aerodynamic) flight.

Schaub, Hanspeter↗

Paraglider Recovery Systems

In 1945 it occurred to the writer that if we could discover how to make flexible wings that could be packaged and deployed somewhat like a parachute, such wings would have many new applications as well as replacing some parachutes and rigid wings. Previous uses of flexible materials in aerodynamic surfaces - parachutes, kites, boat sails, and wind mills - were reviewed, and some crude experiments were performed with gliders and kites. Before the end of 1948, the device now generally called a paraglider was evolved and developed sufficiently to merit a patent application. The study was continued privately as time permitted, and in 1954 a short paper on the subject was presented to an audience of about 50 Reserve Air Force officers. This paper was given rather wide distribution, although it suffers from lack of the many kite and glider demonstrations of the original presentation. Little serious interest was shown by the aeronautical community, however, until about a year after Sputnik I. In December 1958 the flexible-wing concept was presented to the Langley Committee on General Aerodynamics with the aid of the hurriedly prepared charts shown in figure 1, faithfully reproduced here for historical purposes.

Flexible wing↗

Propulsive effects due to flight through turbulence

A simple and straightforward analysis is presented for evaluating the approximate magnitude of the propulsive effect for various types of airplane (soaring glider, light airplane, fighter, and transport). The airplane, subject to vertical gust disturbances, is assumed to be constrained to fly at constant airspeed and constant pitch angle. Changes in the magnitude and direction of the lift vector are taken into account. It is shown that the thrust effects due to turbulence vary as the square of the turbulence intensity and are quite small for moderate turbulence. Only for rather severe turbulence are the effects large enough to be given any consideration. The thrust coefficient is 10-20% of the drag coefficient of a soaring glider.

Phillips, W. H.↗

Dynamics of ultralight aircraft: Motion in vertical gusts

Gust load calculations are extended to the range of conditions encountered by ultralight aircraft such as hang gliders. Having wing loadings of the order of 5 kg/sq m, these gliders acquire a substantial fraction of the motion of a gust within a distance of 1 or 2 m. Comparative loads and displacements for a small powered airplane having a wing loading of 50 kg sq m and for a commercial jet with 500 kg sq m are shown.

Jones, R. T.↗

Science and Technology of Low Speed and Motorless Flight, Part 1

The proceedings of the Third International Symposium on the Science and Technology of Low Speed and Motorless Flight are reported. Twenty-eight papers were presented in the areas of low speed aerodynamics, new materials applications and structural concepts, advanced flight instrumentation, sailplane optimal flight techniques, and self launching and ultralight glider technology. These papers are included in the document along with another paper, which was not presented, on proposed definitions for various categories of sailplanes and gliders.

Hanson, P. W.↗

Composite structural materials

The composite aircraft program component (CAPCOMP) is a graduate level project conducted in parallel with a composite structures program. The composite aircraft program glider (CAPGLIDE) is an undergraduate demonstration project which has as its objectives the design, fabrication, and testing of a foot launched ultralight glider using composite structures. The objective of the computer aided design (COMPAD) portion of the composites project is to provide computer tools for the analysis and design of composite structures. The major thrust of COMPAD is in the finite element area with effort directed at implementing finite element analysis capabilities and developing interactive graphics preprocessing and postprocessing capabilities. The criteria for selecting research projects to be conducted under the innovative and supporting research (INSURE) program are described.

Ansell, G. S.↗

Kasprzyk airfoil. The first wind-tunnel tests

The Kasprzyk slotted flap glider airfoil (the Kasper wing) enabling glider flight at 32 km/h and 0.5 m/sec descent speed was wind tunnel tested in the U.S. The test layout is described and reasons offered for discrepancies between wind tunnel results and Polish in flight data: high induced drag caused by relative size of model wing span and tunnel, by vortex attenuators on the model and their proximity to the tunnel wall, nonsimilarity between flow over a smooth wing and flow over the Kasprzyk wing with bound vortices, obstruction of the tunnel test chamber cross section by the model wing, discrepant Reynolds numbers, and model airfoil aspect ratio much smaller than the prototype. The overall results offer partial confirmation of the Kasprzyk theory, but further in tunnel and in flight studies are recommended.

Wusatowski, T.↗

Twelfth Rhon soaring contest, 1931

The crew of the "Fafnir" was given an excellent opportunity for collecting first-hand data as to the usefulness of gliders in the Alps. It is necessary to recount the remarkable glider achievements ahead of the Rhon Soaring Contest, in order to understand the tension and expectation with which the Rhon contest was anticipated.

Georgii, Walter↗

Guidance and Control of an Autonomous Soaring UAV

Thermals caused by convection in the lower atmosphere are commonly used by birds and glider pilots to extend flight duration, increase cross-country speed, improve range, or simply to conserve energy. Uninhabited Aerial Vehicles (UAVs) can also increase performance and reduce energy consumption by exploiting atmospheric convection. An autonomous soaring research project was conducted at the NASA Dryden Flight Research Center to evaluate the concept through flight test of an electric-powered motor-glider with a wingspan of 4.27 m (14 ft). The UAV's commercial autopilot software was modified to include outer-loop soaring guidance and control. The aircraft total energy state was used to detect and soar within thermals. Estimated thermal size and position were used to calculate guidance commands for soaring flight. Results from a total of 23 thermal encounters show good performance of the guidance and control algorithms to autonomously detect and exploit thermals. The UAV had an average climb of 172 m (567 ft) during these encounters.

Allen, Michael J.↗

Gliding Experiments of the Wright Brothers: The Wrights and Flight Research 1899-1908

Viewgraphs showing glider experiments of the Wright Brothers from 1899-1908 are presented. The slides review the experiments that the Wright Brothers conducted prior to their first powered flight in 1903 to developing the first practical aircraft in 1905. Many pictures of the gliders and other devices are used to illustrate the gradual development and experimentation that preceeded the first powered flight.

Bowers, Albion H.↗

Gliding Experiments of the Wright Brothers: The Wrights and Flight Research 1899-1908

This viewgraph presentation reviews the Wright Brothers's flight research during the 10 years between 1899 and 1908. The Wright Brothers began their research in flight with gliders. The presentation shows pictures, replicas and characteristics of the gliders that the Wright Brothers used. This presentation is not just a history lesson. In the end it investigates "What Does Flight Research Accomplish?" Flight research can serve many uses, such as Separates the Real from the Imagined, Uncovers the Unexpected and the Overlooked, Forces the Realistic Integration of the Pilot, Forces the Development of Reliable Prediction and Test Processes, Requires Every Problem to Be Addressed, Promotes Technology Transfer, and Builds a Core Technical Team,

Bowers, Al↗

Gliding Experiments of the Wright Brothers: Flight Research 1899-1908

Presentation showing glider experiments of the Wright Brothers from 1899-1908 are presented. The slides review the experiments that the Wright Brothers conducted prior to their first powered flight in 1903 to developing the first practical aircraft in 1905, Many pictures of the gliders and other devices are used to illustrate the gradual development and experimentation that preceeded the first powered flight.

Bowers, Albion H.↗

SCAMP: Rapid Focused Sonic Boom Waypoint Flight Planning Methods, Execution, and Results

Successful execution of the flight phase of the Superboom Caustic Analysis and Measurement Project (SCAMP) required accurate placement of focused sonic booms on an array of prepositioned ground sensors. While the array was spread over a 10,000-ft-long area, this is a relatively small region when considering the speed of a supersonic aircraft and sonic boom ray path variability due to shifting atmospheric conditions and aircraft trajectories. Another requirement of the project was to determine the proper position for a microphone-equipped motorized glider to intercept the sonic boom caustic, adding critical timing to the constraints. Variability in several inputs to these calculations caused some shifts of the focus away from the optimal location. Reports of the sonic booms heard by persons positioned amongst the array were used to shift the focus closer to the optimal location for subsequent passes. This paper describes the methods and computations used to place the focused sonic boom on the SCAMP array and gives recommendations for their accurate placement by future quiet supersonic aircraft. For the SCAMP flights, 67% of the foci were placed on the ground array with measured positions within a few thousand feet of computed positions. Among those foci with large caustic elevation angles, 96% of foci were placed on the array, and measured positions were within a few hundred feet of computed positions. The motorized glider captured sonic booms on 59% of the passes when the instrumentation was operating properly.

Haering, Edward A., Jr.↗

System and Method for Air Launch from a Towed Aircraft

The invention is a system and method of air launching a powered launch vehicle into space or high altitude. More specifically, the invention is a tow aircraft which tows an unpowered glider, with the powered launch vehicle attached thereto, to launch altitude. The powered launch vehicle is released from the unpowered glider and powered on for launch.

Budd, Gerald D↗

Free-Flight Investigation of Aerodynamic Heat Transfer to a Simulated Glide-Rocket Shape at Mach Numbers up to 10

Heat-transfer measurements were made on a simulated glide-rocket shape in free flight at Mach numbers up to 10 and free-stream Reynolds numbers of 2 x 10 based on distance along surface from apex and 3 x 10 based on nominal leading-edge diameter. The model simulated the bottom of a 75 deg delta wing at 8O deg angle of attack. The data indicated that for the test conditions a modified three-dimensional stagnation-point theory will predict to reasonable engineering accuracy the heating on a highly swept wing leading edge, the heating being reduced by sweep by the 3/2 power of the cosine of the sweep angle. The data also indicate that laminar heating rates over the windward surface of a highly swept flat glider wing at moderate angles of attack can be predicted with reasonable engineering accuracy by flat-plate theory using wedge local flow conditions and basing Reynolds numbers on lengths from the wing leading edge parallel to the surface center line.

FREE FLIGHT↗

Learning to Fly: The Wright Brothers' Adventure. A Guide for Educators and Students with Activities in Aeronautics

This guide was produced by the NASA Glenn Research Center Office of Educational Programs in Cleveland, OH, and the NASA Aerospace Educational Coordinating Committee. It includes activity modules for students, including the history of the Wright Brothers and their family in Dayton, Ohio and flight experimentation in Kitty Hawk, North Carolina. Student activities such as building models of the Wright Brothers glider and writing press releases of the initial flight are included.

WILBUR WRIGHT↗

Enhanced Tensile and Tear Toughness Properties of Thin-Wall Vacuum-Assisted High-Pressure Die-Cast Aural-5 Alloy by Friction Stir Processing

Steadily rising demand for glider weight reduction has driven the development of vacuum-assisted high-pressure die-cast (HPDC) Al-alloys for automotive structural components. Aural-5 is a strontium-modified HPDC alloy utilizing manganese (Mn) to reduce die soldering, eliminating detrimental needle-shaped Fe-bearing ß-phase intermetallic and improving ductility. HPDC Aural-5 contains shrinkage porosity, dendrites with Al-Si eutectic colonies, externally solidified crystals (ESCs), shear-band structure, and large second-phase particulates. Porosity, ESCs and large second-phase particles work as crack initiation sites, negatively impacting tensile properties. In this study, friction stir processing (FSP) is employed for microstructural modification of a thin-walled HPDC Aural-5 by eliminating porosity and breaking down dendrites, second-phase particles, eutectic colonies, ESCs and shear-band structures to create wrought microstructure with homogenized particle distribution. Mechanical property characterization indicates ~30% and ~35% enhancement in yield strength and ductility and associated marked effects on ~69% improvement in tear toughness according to the ASTM B871 test.

Friction stir processing, Aural-5, Strength, Tear ↗

Extracting energy from ocean thermal and salinity gradients to power unmanned underwater vehicles: State of the art, current limitations, and future outlook

Thermal gradient energy-generation technologies for powering unmanned underwater vehicles (UUVs) or autonomous sensing systems in the ocean are mainly in the research development phase or commercially available at a limited scale, and salinity-gradient energy-generation technologies have not been adequately researched yet. The demand for self-powered UUVs suitable for long-term deployments has been growing, and further research related to small-scale ocean gradient energy systems is needed. In this study, we conducted a comprehensive review about harvesting energy from ocean thermal or salinity gradients for powering UUVs, focusing on gliders and profiling floats. Thermal gradient energy systems for UUVs based on phase change materials (PCM) cannot provide the energy required for powering autonomous sensing systems because of the systems' low energy conversion efficiency. Besides reducing energy consumption by developing more efficient electrical-mechanical systems, enhancing the thermal conductivity of the PCMs may help address this challenge by increasing the power generation rate of the UUVs. Several other emerging technologies, such as thermoelectric generators, shape memory alloys, and small-scale thermodynamic cycle systems, have shown potential for powering UUVs, but they are still only at the laboratory testing or conceptual design phase. The most advanced power generation technologies based on salinity gradients, reverse electrodialysis and pressure-retarded osmosis, are still not economically viable for large-scale deployment, mainly because of the high cost of the components required to operate in harsh saline environments. Our feasibility evaluation showed that existing salinity gradient power generation technologies are not directly feasible for powering UUVs in the open ocean.

16 TIDAL AND WAVE POWER↗