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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Progress towards extreme attitude testing with Magnetic Suspension and Balance Systems

Progress is reported in a research effort aimed towards demonstration of the feasibility of suspension and aerodynamic testing of models at high angles of attack in wind tunnel Magnetic Suspension and Balance Systems. Extensive modifications, described in this paper, have been made to the Southampton University suspension system in order to facilitate this work. They include revision of electromagnet configuration, installation of all-new position sensors and expansion of control system programs. An angle of attack range of 0 to 90 deg is expected for axisymmetric models. To date, suspension up to 80 deg angle of attack has been achieved.

Britcher, Colin P.↗
NASA NTRS1994

Large angle magnetic suspension test fixture

Over the past few decades, research has proven the feasibility of the concept of noncontacting magnetic bearing systems which operate with no wear or vibration. As a result, magnetic bearing systems are beginning to emerge as integral parts of modern industrial and aerospace systems. Further applications research is still required. NASA has loaned an existing magnetic bearing device, the Annular Suspension and Pointing System (ASPS), to ODU to permit student design teams the opportunity to pursue some of these studies. The ASPS is a protoype for a high-accuracy space payload pointing and vibration isolation system. The project objectives are to carry out modifications and improvements to the ASPS hardware to permit recommissioning in a 1-g (ground-based) environment. Following recommissioning, new applications will be studied and demonstrated, including a rotary joint for solar panels. The first teams designed and manufactured pole shims to reduce the air-gaps and raise the vertical force capability as well as on control system studies. The most recent team concentrated on the operation of a single bearing station, which was successfully accomplished with a PC-based digital controller. The paper will review the history and technical background of the ASPS hardware, followed by presentation of the progress made and the current status of the project.

Britcher, Colin P.↗
NASA NTRS1992

The large-angle magnetic suspension test fixture

As part of a NASA effort to develop the technology and techniques required to demonstrate the magnetic suspension of objects over wide ranges of attitudes, a small-scale demonstration project was undertaken. The objectives here are to suspend a cylindrical element containing a permanent magnet core, to demonstrate stability and control in five degrees-of-freedom, and to permit controlled rotation of the model in one degree-of-freedom over the full range of 360 deg. Further constraints are that all suspension and control electromagnets are to be behind a flat plane, located some distance from the model. Since this is a ground-based experiment and in order to maintain generality, the plane is chosen to be horizontal with the model levitated above the plane by repulsive forces.

Britcher, Colin P.↗
NASA NTRS1997

Large Angle Magnetic Suspension Test Fixture

Progress in the areas of eddy current computations, modelling and analysis, design optimization methods, wind tunnel Magnetic Suspension and Balance Systems (MSBS), payload pointing and vibration isolation systems, and system identification is reported. Research accomplishments facilitated the demonstration of several new developments in the field of magnetic suspension technology.

Britcher, Colin P.↗
NASA NTRS1996

Large angle magnetic suspension test fixture

Good progress is being made in several major areas. These include eddy current modelling and analysis, design optimization methods, wind tunnel Magnetic Suspension and Balance Systems (MSBS), payload pointing and vibration isolation systems, and system identification. In addition, another successful International Symposium has been completed, with the Proceedings being printed at the time of writing. These activities continue current work under this Grant and extend previous work on magnetic suspension systems and devices in the Guidance and Control Branch and will permit the demonstration of several new developments in the field of magnetic suspension technology.

Britcher, Colin P.↗
NASA NTRS1980

Electromagnet configurations for extreme attitude testing in magnetic suspension and balance systems

The inclusion of adequate versatility into the electromagnet array configuration requires sizing the electromagnets to satisfy particular absolute force and moment requirements. Magnetic performance of a permanent magnet model core, air cored electromagnet may easily and reliably be computed by using the FORCE program which calculates model forces and moments via representations of the model as an assembly of dipoles and the electromagnets as an assembly of line currents. Some aspects of the performance of an ellipsoidal iron cored model may be inferred from the above under certain circumstances.

Britcher, C. P.↗
NASA NTRS1989

A test of magnetic field draping induced Bz perturbations ahead of fast coronal mass ejecta

ICE plasma and magnetic field data are examined to look for observational evidence of IMF draping ahead of fast coronal mass ejections (CMEs). The utility of the draping model for predicting the Bz perturbations and hence geomagnetic activity associated with the sheath regions ahead of such CMEs is also examined. A simple prediction scheme based on the upstream radial field component is developed and a set of interplanetary shock events previously associated with interplanetary type II bursts, and hence solar source locations, is used. Of 17 events the radial component predictor developed here correctly predicts the direction considered of the Bz perturbations for 13 events (76 percent). While this result is certainly not conclusive, it is considered to be supportive of the draping scenario.

Mccomas, D. J.↗
NASA NTRS2000

Failure Accommodation Tested in Magnetic Suspension Systems for Rotating Machinery

The NASA Glenn Research Center at Lewis Field and Texas A&M University are developing techniques for accommodating certain types of failures in magnetic suspension systems used in rotating machinery. In recent years, magnetic bearings have become a viable alternative to rolling element bearings for many applications. For example, industrial machinery such as machine tool spindles and turbomolecular pumps can today be bought off the shelf with magnetically supported rotating components. Nova Gas Transmission Ltd. has large gas compressors in Canada that have been running flawlessly for years on magnetic bearings. To help mature this technology and quiet concerns over the reliability of magnetic bearings, NASA researchers have been investigating ways of making the bearing system tolerant to faults. Since the potential benefits from an oil-free, actively controlled bearing system are so attractive, research that is focused on assuring system reliability and safety is justifiable. With support from the Fast Quiet Engine program, Glenn's Structural Mechanics and Dynamics Branch is working to demonstrate fault-tolerant magnetic suspension systems targeted for aerospace engine applications. The Flywheel Energy Storage Program is also helping to fund this research.

Provenza, Andy J.↗
NASA NTRSDate not supplied

Comparison of Dynamic Stability Testing Techniques with Magnetic Suspension Wind Tunnel

Dynamic stability testing techniques currently utilized at NASA Langley Research Center (LaRC) are conducted in multiple facilities and consists of free flight, forced oscillation, and free-to-oscillate tests. The MIT/NASA/ODU Magnetic Suspension and Balance System (MSBS) has been recommissioned to explore its utility as an additional facility to expand the dynamic stability test capabilities currently available at NASA LaRC. Simulations were created to replicate each current test facility and method as closely as possible. Data collected from the simulated environments was corrupted with replicated noise sources of the different testing environments and then compared to real data collected during tests when such data was available. The corrupted data was then passed through data reduction and System Identification (SID) to estimate the accuracy of the results with the known aerodynamic model that was utilized within the simulation to generate the original data. Magnitudes of noise were varied utilizing Monte Carlo analysis to perform sensitivity analysis of each noise source on the extracted dynamic stability coefficients. Some preliminary results will be presented.

Otoniel Ramirez↗
NASA NTRSDate not supplied

Comparison of Dynamic Stability Testing Techniques with Magnetic Suspension Wind Tunnel

Dynamic stability testing techniques currently utilized at NASA Langley Research Center (LaRC) are conducted in multiple facilities and consists of free flight, forced oscillation, and free-to-oscillate tests. The MIT/NASA/ODU Magnetic Suspension and Balance System (MSBS) has been recommissioned to explore its utility as an additional facility to expand the dynamic stability test capabilities currently available at NASA LaRC. Simulations were created to replicate each current test facility and method as closely as possible. Data collected from the simulated environments was corrupted with replicated noise sources of the different testing environments and then compared to real data collected during tests when such data was available. The corrupted data was then passed through data reduction and System Identification (SID) to estimate the accuracy of the results with the known aerodynamic model that was utilized within the simulation to generate the original data. Magnitudes of noise were varied utilizing Monte Carlo analysis to perform sensitivity analysis of each noise source on the extracted dynamic stability coefficients. Some preliminary results will be presented.

Otoniel Ramirez↗
NASA NTRS1980

Magnetic field satellite /MAGSAT/ spacecraft vector magnetometer calibration

The low-flying MAGSAT spacecraft, launched October 30, 1979, included a Vector Magnetometer to accurately map the magnitude and direction of the magnetic field of the earth. Calibration of the magnetometer included arc-second precision determination of the relative orientations of the three sensor axes in a coordinate system defined by optical references. This determination began with laboratory measurements of the relative alignments of optical components mounted with the magnetometer. The actual calibration procedure then consisted basically of accurate and repeatable positioning of the Vector Magnetometer within a unique magnetic test facility which nulls the earth's magnetic field, then generates magnetic fields of various orientations and strengths. Analysis of the magnetometer sensor outputs together with the position and alignment data then gave the axes orientations. We used precision theodolites and methods related to surveying techniques to achieve the accurate positioning and optical component alignment measurements. The final calibration accuracy exceeded results previously achieved in the facility.

Hinkal, S. W.↗