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Topics addressed include: composite plates; buckling predictions; missile launch tube modeling; structural/control systems design; optimization of nonlinear R/C frames; error analysis for semi-analytic displacement; crack acoustic emission; and structural dynamics.
Methylene dianiline (MDA) and its derivatives have been used in the synthesis of polyimides to yield polymers with characteristic low-density, high tensile strength, improved solubility in organic solvents, low-melt viscosities and high thermal stability (greater than 550 F) in air. Polyimides with such properties are desirable for use in aerospace systems, e.g., jet engines, airframe, missiles, and rockets where weight is critical. Recent research at Prairie View A&M University is focused on developing monomers to generate polyimides with enhanced performance over that of NASA s PMR-15. The objective of this work is to synthesize three ring aromatic diamines which are non-toxic and when reacted with the appropriate dianhydrides will yield polyimides with lower viscosity, improve processability, good retention of mechanical properties, and oxidative stability at high environmental temperatures. Modifications of the three ring aromatic diamines include replacing the methylene linkages with aromatic ethers by nucleophilic aromatic substitution reactions and incorporating mono- and di-substituents to the center aromatic ring. An update of current reactions involved in synthesis efforts to generate three ring aromatic monomers for polyimides with methylene, carbonyl, and ether linkages separating the aromatic moieties will be displayed.
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Since September of 1956, nine Jupiter-C missiles have been launched from the firing pad at Cape Canaveral. The first Jupiter-C firing tested the propulsion system, air frame, and guidance components of the missile, and the second and third firings tested a model of the Jupiter nose cone under realistic re-entry conditions. The remaining six Jupiter-C missiles were used as the launching vehicles for EXPLORER satellites I through VI (Fig. 1). Of the six satellite firings, EXPLORERs I, III, and IV achieved satisfactory orbits. The Jupiter-C missile was designed and developed as a joint program under the technical direction of the Jet Propulsion Laboratory and the Army Ballistic Missile Agency. The Jet Propulsion Laboratory developed the three high-speed stages, and the Army Ballistic Missile Agency handled the development, construction, and operation of the first-stage booster rocket and the guidance system. Many other organizations have contributed to the success of the EXPLORER satellite program, most notably the State University of Iowa, the Air Force Cambridge Research Center, and the satellite tracking teams of the Vanguard organization.
The coherent lidar airborne shear sensor (CLASS) is an airborne CO2 lidar system being designed and developed by Lockheed Missiles and Space Company, Inc. (LMSC) under contract to NASA Langley Research Center. The goal of this program is to develop a system with a 2- to 4-kilometer range that will provide a warning time of 20 to 40 seconds, so that the pilot can avoid the hazards of low-altitude wind shear under all weather conditions. It is a predictive system which will warn the pilot about a hazard that the aircraft will experience at some later time. The ability of the system to provide predictive warnings of clear air turbulence will also be evaluated. A one-year flight evaluation program will measure the line-of-sight wind velocity from a wide variety of wind fields obtained by an airborne radar, an accelerometer-based reactive wind-sensing system, and a ground-based Doppler radar. The success of the airborne lidar system will be determined by its correlation with the windfield as indicated by the onboard reactive system, which indicates the winds actually experienced by the NASA Boeing 737 aircraft.
Control requirements were determined from calculated engine performance maps for a fixed-geometry ram jet of a configuration suitable for strategic supersonic missile propulsion. Several control schemes for attaining desired engine performance and for stabilizing missile flight velocity during cruise are presented. The advantages and disadvantages of each system are discussed.
As part of the modernization of the Acoustic Test Facility at Lockheed Missiles and Space Company, Sunnyvale, a digital acoustic control system was designed and built. The requirements imposed by Lockheed on the control system and the degree to which those requirements were met are discussed. Acceptance test results as well as some of the features of the digital control system not found in traditional manual control systems are discussed.
Topics discussed in this volume include aircraft guidance and navigation, optics for visual guidance of aircraft, spacecraft and missile guidance and navigation, lidar and ladar systems, microdevices, gyroscopes, cockpit displays, and automotive displays. Papers are presented on optical processing for range and attitude determination, aircraft collision avoidance using a statistical decision theory, a scanning laser aircraft surveillance system for carrier flight operations, star sensor simulation for astroinertial guidance and navigation, autonomous millimeter-wave radar guidance systems, and a 1.32-micron long-range solid state imaging ladar. Attention is also given to a microfabricated magnetometer using Young's modulus changes in magnetoelastic materials, an integrated microgyroscope, a pulsed diode ring laser gyroscope, self-scanned polysilicon active-matrix liquid-crystal displays, the history and development of coated contrast enhancement filters for cockpit displays, and the effect of the display configuration on the attentional sampling performance.
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.
The Balloon Launched Decelerator Test (BLDT) series conducted at White Sands Missile Range (WSMR) during July and August of 1972 flight qualified the NASA Viking '75 decelerator system at conditions bracketing those expected for Mars. This paper discusses the decelerator system design requiremnts, compares the test results with prior work, and discusses significant considerations leading to successful qualification in earth's atmosphere. The Viking decelerator system consists of a single-stage mortar-deployed 53-foot nominal diameter disk-gap-band parachute. Full-scale parachutes were deployed behind a full-scale simulated Viking vehicle at Mach numbers from 0.47 to 2.18 and dynamic pressures from 6.9 to 14.6 psf. Analyses show that the system is qualified with sufficient margin to perform successfully for the Viking mission.
NASA is planning now toward the day of long-duration flight-manned interplanetary missions for example-wherein routine health care and emergency treatment must be accomplished on-board the spacecraft over periods of months or perhaps even years. Since spacecraft design limits crew size, the medical assignment may be handled by a single astronaut-physician or by a crew member trained as a physician's assistant. In a space emergency demanding surgery, for instance, sophisticated communications equipment, backed by a computerized data processing system, would make it possible for a surgeon on Earth to "examine" the patient. He could study X-rays and other data, specify an in-flight surgical procedure, and guide the astronaut-medic step-by-step through the operation. Such a system is being evaluated now. It is called STARPAHC (Space Technology Applied to Rural Papago Health Care). NASA technology in space communications and data processing is being applied to remote health services for the Papago tribe. STARPAHC is administered by the NASA Life Sciences Directorate in the Office of Space Sciences. It is a joint program involving NASA's Johnson Space Center, the Indian Health Service of the Department of Health, Education & Welfare, and the Papago's Executive Health Council. Lockheed Missiles & Space Co. is NASA's systems support contractor.
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This paper reviews the activities at OKSI related to imaging spectroscopy presenting current and future applications of the technology. The authors discuss the development of several systems including hardware, signal processing, data classification algorithms and benchmarking techniques to determine algorithm performance. Signal processing for each application is tailored by incorporating the phenomenology appropriate to the process, into the algorithms. Pixel signatures are classified using techniques such as principal component analyses, generalized eigenvalue analysis and novel very fast neural network methods. The major hyperspectral imaging systems developed at OKSI include the Intelligent Missile Seeker (IMS) demonstration project for real-time target/decoy discrimination, and the Thermal InfraRed Imaging Spectrometer (TIRIS) for detection and tracking of toxic plumes and gases. In addition, systems for applications in medical photodiagnosis, manufacturing technology, and for crop monitoring are also under development.
Detailed measurements of the vertical profile of the wind are urgently needed f o r studies of the response of rising missiles, but conventional wind-measuring systems cannot provide the accuracy and detail required over the necessary range of altitudes. A method is presented for obtaining a detailed, accurate profile over a large altitude range. The method utilizes photogrammetric measurement of successive positions of the t rail of an ascending rocket. Construction of a rocketborne smoke generator is discussed and the photography, film reading, and data-reduction procedures are described. The accuracy of the method i s examined and error equations are derived. Finally, some examples of wind profiles measured by this method are shown, and their implications for missile response are indicated.
It is pointed out that the long-range antiship standoff missile is emerging as the foremost threat on the seas. Delivered by high speed bombers, surface ships, and submarines, a missile attack can be mounted against selected targets from any point on the compass. An investigation is conducted regarding the configuration of a system which could most efficiently identify and destroy standoff threats before they launch their weapons. It is found that by using ships for carrying and launching missiles, and employing aircraft with a powerful radar only for search and missile directing operations, aircraft cost and weight can be greatly reduced. The employment of V/STOL aircraft in preference to other types of aircraft makes it possible to use ships of smaller size for carrying the aircraft. However, in order to obtain an all-weather operational capability for the system, ships are selected which are still big enough to display the required stability in heavy seas.
An analytical study was made of an adaptive flight-control system which measures vehicle response to small-amplitude control-surface deflections produced by a sinusoidal test signal. Changes in the response to this signal are related to environmental changes,, and the system is continuously altered to maintain this response equal to a preselected value. The system is suitable for use in high-performance aircraft and missiles and requires only the addition of a signal generator and a logic circuit consisting of a filter-rectifier network and a comparator-integrator network to a basic command-control system. Thus, it presents a relatively simple approach to the problem. The effects on system performance of variation in flight condition, system-gain level, test-signal frequency, and sensor location are included in the analysis. Longitudinal control of a high-performance research aircraft over flight conditions ranging from landing approach to a Mach number of 5.8 at an altitude of 150,000 feet, and longitudinal control of a four-stage solid-fuel missile including the first bending mode over the atmospheric portion of a launch trajectory constituted the basis for the analytical study. Results of an analog-computer study using time-varying coefficients are presented to compare the control obtained with the adaptive system with-that obtained with a fixed-gain system during the atmospheric portion of a missile launch trajectory. The system has demonstrated an ability to maintain satisfactory vehicle control-system stability over wide ranges of environmental change.
Providing a program in the concept development phase with a method of determining system safety benefits of potential concepts has always been a challenge. Lockheed Martin Space and Strategic Missiles has developed a methodology for developing a relative system safety ranking using the potential hazards of each concept. The resulting output supports program decisions with system safety as an evaluation criterion with supporting data for evaluation. This approach begins with a generic hazards list that has been tailored for the program being studied and augmented with an initial hazard analysis. Each proposed concept is assessed against the list of program hazards and ranked in three derived areas. The hazards can be weighted to show those that are of more concern to the program. Sensitivities can be also be determined to test the robustness of the conclusions
The NCOREL full-potential method with an entropy correction is presently applied to supersonic missile flowfield problems. After defining the salient characteristics of the method, a combination of linear theory with NCOREL and experimental data is used to isolate the nonlinear features of the supersonic flow so that the influence of geometry and flow conditions on the development of such flow nonlinearities can be appreciated. Comparisons of experimental longitudinal force and moment data with NCOREL and various linear theory predictions are presented for several generic missile airframe configurations of circular and elliptic cross section. The NCOREL code solves the nonconservative full potential equation in a spherical coordinate system; exact boundary conditions are defined on the missile surface.