Sceptron vibration spectrum sensor, improved Sceptron/TM/ Final study report, 6 Jun. - 6 Oct. 1966
Fiber optic device for measuring missile vibration spectrum
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Fiber optic device for measuring missile vibration spectrum
Reliability of sergeant missile assemblies - application of test-to-failure program
Digital random vibration analysis of Saturn vehicle flight and booster static test data
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An approach to defining and evaluating three-dimensional vibration test requirements is discussed. The approach is used to develop the three-dimensional space random-vibration test requirements for missile components subjected to truck transportation environments. One-dimensional testing parameters such as power spectral density and overall g rms values for three mutually perpendicular directions represent the test requirements. The coherence characteristics between each input axis were established and adjusted empirically in an attempt to simulate the cross-correlation in three-dimensional random vibration excitation.
Presented is a limited review of some experiences in flight testing of missiles and of wing flutter investigations that may be of interest in missile design. Several types of flutter of concern in missile studies are briefly described. Crude criteria are presented for two of the most common types of flutter to permit a rapid estimate to be made of the probability of the occurrence of flutter. Many of the details of the flutter problem have been omitted, and only the broader elements have been retained so as to give the designer an overall view of the subject.
Under the ARPA SMS Partnership Program for Synthesis and Processing of Smart Materials, Lockheed Missiles and Space company, Inc. has developed a demonstration prototype vibration cancelling mount using electrostrictive ceramic and shape-memory alloy actuators. Shape-memory actuators provide an adaptive-passive, self-damping support for isolation, while the electrostrictive actuators are employed to provide force and position control. The demonstration device was designed to address generic requirements for vibration stabilization of precision spacecraft instruments. It is reconfigurable to operate in any of four modes; passive isolation, active-passive isolation using force cancellation, active precision positioning, and active disturbance rejection. The presentation summarizes design of the device design and results of experimental evaluations of the device in isolation (active and passive) and positioning modes. Rejection of payload-borne disturbances is also discussed with reference to predictions from experimentally calibrated simulations. Finally, avenues for further development and refinement of the device are discussed.
Selected research and technology activities at NASA Dryden Flight Research Center are summarized. These following activities exemplify the Center's varied and productive research efforts: Developing a Requirements Development Guide for an Automatic Ground Collision Avoidance System; Digital Terrain Data Compression and Rendering for Automatic Ground Collision Avoidance Systems; Nonlinear Flutter/Limit Cycle Oscillations Prediction Tool; Nonlinear System Identification Using Orthonormal Bases: Application to Aeroelastic/Aeroservoelastic Systems; Critical Aerodynamic Flow Feature Indicators: Towards Application with the Aerostructures Test Wing; Multidisciplinary Design, Analysis, and Optimization Tool Development Using a Genetic Algorithm; Structural Model Tuning Capability in an Object-Oriented Multidisciplinary Design, Analysis, and Optimization Tool; Extension of Ko Straight-Beam Displacement Theory to the Deformed Shape Predictions of Curved Structures; F-15B with Phoenix Missile and Pylon Assembly--Drag Force Estimation; Mass Property Testing of Phoenix Missile Hypersonic Testbed Hardware; ARMD Hypersonics Project Materials and Structures: Testing of Scramjet Thermal Protection System Concepts; High-Temperature Modal Survey of the Ruddervator Subcomponent Test Article; ARMD Hypersonics Project Materials and Structures: C/SiC Ruddervator Subcomponent Test and Analysis Task; Ground Vibration Testing and Model Correlation of the Phoenix Missile Hypersonic Testbed; Phoenix Missile Hypersonic Testbed: Performance Design and Analysis; Crew Exploration Vehicle Launch Abort System-Pad Abort-1 (PA-1) Flight Test; Testing the Orion (Crew Exploration Vehicle) Launch Abort System-Ascent Abort-1 (AA-1) Flight Test; SOFIA Flight-Test Flutter Prediction Methodology; SOFIA Closed-Door Aerodynamic Analyses; SOFIA Handling Qualities Evaluation for Closed-Door Operations; C-17 Support of IRAC Engine Model Development; Current Capabilities and Future Upgrade Plans of the C-17 Data Rack; Intelligent Data Mining Capabilities as Applied to Integrated Vehicle Health Management; STARS Flight Demonstration No. 2 IP Data Formatter; Space-Based Telemetry and Range Safety (STARS) Flight Demonstration No. 2 Range User Flight Test Results; Aerodynamic Effects of the Quiet Spike(tm) on an F-15B Aircraft; F-15 Intelligent Flight Controls-Increased Destabilization Failure; F-15 Integrated Resilient Aircraft Control (IRAC) Improved Adaptive Controller; Aeroelastic Analysis of the Ikhana/Fire Pod System; Ikhana: Western States Fire Missions Utilizing the Ames Research Center Fire Sensor; Ikhana: Fiber-Optic Wing Shape Sensors; Ikhana: ARTS III; SOFIA Closed-Door Flutter Envelope Flight Testing; F-15B Quiet Spike(TM) Aeroservoelastic Flight Test Data Analysis; and UAVSAR Platform Precision Autopilot Flight Results.
An experimental investigation was conducted to gain some understanding of the character of the free vibration modes of liquids In oblate spheroidal tanks applicable in missile and space vehicle systems, Measured natural frequencies were obtained for the lowest three or four, antisymmetric modes of oscillation as a function of the liquid depth for three orientations of each of several such tanks of different size and oblateness. The orientations considered were such that: (a) the equator of the spheroid was horizontal and oscillations were along a diameter of the circular liquid surface; (b) the equator of the spheroid was vertical and the oscillations were along the minor axis of the elliptical liquid surface; and (c) the equator of the spheroid was vertical and the oscillations were along the major axis of the elliptical liquid surface; The frequency data are presented as dimensionless parameters developed for each orientation to permit the application of the experimental results to the prediction of the natural frequencies of tanks of different size and oblateness. Photographs we re made of representative surface wave or mode, shapes for each orientation.
This report presents the results of work completed during the period of 1 July 1961 through 30 September 1961 on the studies of vibrations of flexible tanks containing a liquid with a free surface. The coupling between free surface motion and tank bending is dis- cussed in some detail and preliminary experimental results are given which tend to collaborate the theoretical analysis. Experimental results for the effect of an internal fluid on the breathing frequencies of a circular cylindrical shell are also given. apparently new type of free surface sloshing motion induced by high frequency breathing vibrations is reported.
Computer program calculations of upper and lower bounds to nonzero bending frequencies of missiles
Many near-term and future space-instrument programs within NASA and the Ballistic Missile Defense Organization (BMDO) depend on the successful development of long-life, low-vibration space cryocoolers. The most demanding near-term programs include a number of science instruments selected for NASA's Earth Observing System (Eos) program, and a number of space reconnaissance instruments associated with the BMDO's Brilliant Eyes program; both of these programs require delivery of similar types of flight coolers in the next few years. To help ensure the success of these cooler commitments, JPL has implemented an extensive cryocooler program in support of the NASA/JPL AIRS project, the Air Force Phillips Laboratory (AFPL), and the Air Force Space and Missiles Systems Division (SMC). This program is directed at assisting industry in developing advanced cryocoolers that successfully address the broad array of complex performance requirements needed for NASA and BMDO long-life space instruments. The JPL cryocooler program includes extensive characterization and life testing of industry-developed cryocoolers, development and flight testing of advanced sorption cooler systems for detector cooling to 10 K , development of mechanical cryocooler enhancement technologies, and flight tests of advanced low-vibration Stirling-cooler systems.
Two low-acceleration transonic-flutter vehicles were launched and flown. The first carried two test wings, one of which fluttered at M = 0.92 at a frequency of 61.4 cycles per second. The reference flutter speed determined from two-dimensional theory for an unswept wing in incompressible flow is conservative when compared to the experimental flutter speed. The second vehicle carried two test wings, one of which failed at M = 0.71 because of low-frequency divergent oscillation. Since this failure was not caused by conventional flexure-torsion flutter, no comparison with a reference flutter speed can be made.
In the 1998 timeframe increasing numbers of proposed space-instrument programs within NASA and the Balistic Missile Defense Organization (BMDO) were in need of high-reliablility, long-life, low-vibration space cryocoolers.
A 325-page Guidelines document [1], whose objectives are to increase the accuracy and reduce the errors and variability commonly found in the measurement of structural shock and vibration and of acoustic and aerodynamic noise, wea recently submitted to the Air Force Space and Missile Systems Center.
An observation of the UV nightglow between 2670 and 3040 A was conducted over White Sands Missile Range on October 22, 1984. A 1/4-m spectrometer operating at 3.5-A resolution viewed the earth's limb at tangent heights between 90 and 110 km for 120 sec. A total of 41 spectral scans of the nightglow were obtained with the brightest feature being the O2 Herzberg I bands. The data were sorted into two groups, one from the top side of the layer and one containing the emission peak, and compared with synthetic spectra. The deduced vibrational distributions indicate that, at low altitudes, the higher vibrational levels (v-prime greater than 6) were relatively depleted; however, the magnitude of the vibrational shift is much less than that predicted from theories of vibrational relaxation. It is shown that increasing the electronic quenching with respect to the vibrational quenching can reduce the vibrational shift in the model and qualitatively explain the observations; however, several details of the vibrational distribution are not well reproduced.
A data base management and prediction system called vibroacoustic payload environment prediction system (VAPEPS) was developed to serve as a repository for shuttle or extendable booster payload component flight and ground test data. This system is to be made available to the aerospace community for multiple uses including that of establishing the vibroacoustic environment for new payload components. The VAPEPS data includes that spectral information normally processed from vibration and acoustic measurements (e.g., power spectra, sound pressure level spectra, etc.). Results of development to provide this capability by NASA Goddard Space Flight Center and Lockheed Missiles and Space Company are described.
One presumption of scientific microgravity research is that while in space disturbances are minimized and experiments can be conducted in the absence of gravity. The problem with this assumption is that numerous disturbances actually occur in the space environment. Scientists must consider all disturbances when planning microgravity experiments. Although small disturbances, such as a human sneeze, do not cause most researchers on earth much concern, in space, these minuscule disturbances can be detrimental to the success or failure of an experiment. Therefore, a need exists to isolate experiments and provide a quiescent microgravity environment. The objective of microgravity isolation is to quantify all possible disturbances or vibrations and then attenuate the transmission of the disturbance to the experiment. Some well-defined vibration sources are: experiment operations, pumps, fans, antenna movements, ventilation systems and robotic manipulators. In some cases, it is possible to isolate the source using simple vibration dampers, shock absorbers and other isolation devices. The problem with simple isolation systems is that not all vibration frequencies are attenuated, especially frequencies less than 0.1 Hz. Therefore, some disturbances are actually emitted into the environment. Sometimes vibration sources are not well defined, or cannot be controlled. These include thermal "creak," random acoustic vibrations, aerodynamic drag, crew activities, and other similar disturbances. On some "microgravity missions," such as the United States Microgravity Laboratory (USML) and the International Microgravity Laboratory (IML) missions, the goal was to create extended quiescent times and limit crew activity during these times. This might be possible for short periods, but for extended durations it is impossible due to the nature of the space environment. On the International Space Station (ISS), vehicle attitude readjustments are required to keep the vehicle in a minimum torque orientation and other experimental activities will occur continually, both inside and outside the station. Since all vibration sources cannot be controlled, the task of attenuating the disturbances is the only realistic alternative. Several groups have independently developed technology to isolate payloads from the space environment. Since 1970, Honeywell's Satellite Systems Division has designed several payload isolation systems and vibration attenuators. From 1987 to 1992, NASA's Lewis Research Center (LeRC) performed research on isolation technology and developed a 6 degree-of-freedom (DOF) isolator and tested the system during 70 low gravity aircraft flight trajectories. Beginning in early 1995, NASA's Marshall Space Flight Center (MSFC) and McDonnell Douglas Aerospace (MDA) jointly developed the STABLE (Suppression of Transient Accelerations By Levitation Evaluation) isolation system. This 5 month accelerated effort produced the first flight of an active microgravity vibration isolation system on STS-73/USML-02 in late October 1995. The Canadian Space Agency developed the Microgravity Vibration Isolation Mount (MIM) for isolating microgravity payloads and this system began operating on the Russian Mir Space Station in May 1996. The Boeing Defense & Space Group, Missiles & Space Division developed the Active Rack Isolation System (ARIS) for isolating payloads in a standard payload rack. ARIS was tested in September 1996 during the STS-79 mission to Mir. Although these isolation systems differ in their technological approach, the objective is to isolate payloads from disturbances. The following sections describe the technologies behind these systems and the different types of hardware used to perform isolation. The purpose of these descriptions is not to detail the inner workings of the hardware but to give the reader an idea of the technology and uses of the hardware components. Also included in the component descriptions is a paragraph detailing some of the advances in isolation technology for that particular component. The final section presents some concluding thoughts and a summary of anticipated advances in research and development for isolating microgravity experiments.