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Of particular concern to most spacecraft programs is the verification of the finite element model used to predict launch loads. The verification process requires a test-to-model correlation of the high loads producing modes. Presently, this usually requires building/using a test fixture to simulate the spacecraft-booster interface fixity conditions. This method, usually referred to as fixed-base modal testing, introduces significant uncertainties to the test results in the form of test stand flexibility, friction at the interface, etc. To avoid this myriad of problems and possibly reduce the overall structural test program duration significantly, alternative test programs have been developed. These test programs couple a standard modal test of a freely suspended structure with modified modal tests designed to highlight the character of the payload-booster interface without the need of simultaneously constraining all the interface degrees of freedom (DOF's).

A cross modal assurance criteria which represents the degree of correlation between the analytical modes and the test modes is defined. It is used as an indicator to predict the quality of the orthogonality with respect to the dynamically or statically reduced mass matrix using test modes. The root mean square values of the cross modal assurance criteria can be used to identify whether the significant errors exist in the analytical model or the test data.

Mathematical models of structures are validated by adjusting them to match the results of static and dynamic tests. Several automated methods have been developed to aid in the test-analysis correlation process. A recent method uses design sensitivity and optimization methods to directly adjust the Finite element model. The strengths and weaknesses of this method are demonstrated by the test-analysis correlation results from several modal surveys.

This paper contains a review of the program in Hypersonics currently being carried out at the State University of New York at Buffalo (SUNY/Buffalo) in collaboration with the Calspan-UB Research Center (CUBRC). A description is given of the academic features of the program (Courses, seminars, student-selection process) and the research activities.

Hypersonic Aerodynamics has attracted outstanding graduate students and faculty at NCSU. It has grown to 6 faculty and 32 graduate students for fall, 1988. A significant feature of the program is that students and faculty spend time at government laboratories which currently include NASA Langley Research Center, Naval Surface Warfare Center at Silver Spring, and the Wright Aeronautical Laboratories. Research projects include analysis, computational and experimental aerodynamics. The combined program produces graduates with the background needed to perform aerodynamics investigations of hypersonic aircraft and spacecraft. The research performed helps advance the state of the art as well as assist government laboratories in meeting their goals.

Structural nonlinearities should be considered in the analysis and modeling of mechanical systems for accuracy in predicting dynamic behavior. Moreover, checks for nonlinearity should address the type and class of nonlinearity in the structure and identify the probable cause. A series of experimental modal survey tests were carried out to determine and characterize the structural nonlinearities of the Space shuttle Main Engine (SSME) main injector. Different excitation regimes at various amplitudes were utilized to induce vibration and strain, and acceleration measurements were taken at judiciously selected locations. The test results indicated that both stiffness and damping non-linearities were present.

At some future time, on orbit repairs will have to be made to Space Station parts that become damaged, or otherwise lose their functional capabilities. This paper is a summary of the extensive study Grumman performed to define sources of structural and mechanical damage, define tools and fabrication processes for repair, implement prototype tool development, design and construct a mock-up of a Maintenance Work Station (MWS), and perform repairs under simulated “zero G” conditions. This study program confirmed the premise that repairs must and can be made by Astronauts while in an orbital environment. Since the program only began to investigate and solve the engineering problems of performing repairs in a space environment, adequate planning for engineering design and development is required to provide safe and continued operation of the Space Station.

This paper addresses the development of new planning methodologies which will evolve to successfully serve the Space Station Freedom program for many years to come. These planning processes will focus on the complex task of effectively managing the resources provided by the Space Station Freedom. These resources will be made available to the diverse International community of space station users in support of their ongoing investigative activities. These resources will also meet the needs associated with the growth and maintenance of the Space Station Freedom itself.

Currently there is a need for strategic planning/mission management techniques that help to reduce pilot workload and enhance decision making. This need is clearly seen in rotorcraft operations, especially during NOE flight in adverse conditions. To date, decision aiding techniques have focused on the development of avionics. However, another adjunct possibility is the development of formalized training programs that help a pilot to make quick, accurate decisions under time pressure. Although formalized training exists (e.g., Line Oriented Flight Training) there has been a dearth of literature that investigates the efficacy of the decision aiding strategies and tactics that these techniques employ. One such technique is contingency planning. The present study explored the relationship of contingency planning to safety and decision performance in air transport crews.

Pilots' use of the traffic alert and collision avoidance system (TCAS II) was evaluated in simulated air carrier line operations. Sixteen three-person airline flight crews currently flying the Boeing 727 served as subjects. Each crew flew eight flights with or without TCAS as part of the full-mission simulation. Their performance of the avoidance maneuvers and evaluation of the system were measured. The crews were trained on the aircraft differences and the TCAS II. The second day consisted of a 10 hour duty day of normal line operations. All communications, navigation, and cockpit procedures were carried out according to the standards of their particular airline. The crews were under full air traffic control along with the other aircraft in the airspace. All crews were exposed to the same traffic conflicts under the same conditions of high/low traffic densities, high/low workload, high/low visibility. Pilot flying and dusk/night lighting were counterbalanced.

Gear surface fatigue endurance tests were conducted on two groups of 10 gears each of carburized and hardened AISI 9310 spur gears manufactured from the same heat of material. Both groups were manufactured with standard ground tooth surfaces. The second group was subjected to an additional shot-peening process on the gear tooth surfaces and root radius to produce a residual surface compressive stress. The gear pitch diameter was B.89 em (3.S in.). Test conditions were a gear temperature of 350 K (170 °F). a maximum Hertz stress of 1.71×l09 N/m2 (248000 psi). and a speed of 10 000 rpm. The shot-peened gears exhibited pitting fatigue lives 1.6 times the life of the standard gears without shot peening. Residual stress measurements and analysis indicate that the longer fatigue life is the result of the higher compressive stress produced by the shot peening.

A series of studies at the General Motors Research Laboratories have demonstrated the practical benefits of constructing automotive structures as three dimensional space frames with attached panels. Importantly, a metallic space frame with a plastic skin has been shown to be a highly weight-efficient passenger car structure.

The major US helicopter manufacturers were asked to support a study by the FAA to design a total FAA system for the year 2000 and beyond. Bell Helicopter Textron chaired a VSTOL committee which collectively prepared and presented the desires of the vertical lift community. A requirement was noted for the necessary infrastructure including vertiports with appropriate landing aids. The integration of emergency medical service into the system was also recommended. Some operational improvements were noted utilizing rapid computational techniques for both ground and airborne systems to reduce separation and permit joint usage of existing facilities under separate rules, maintaining at least the present level of safety. The automation of cockpits using simplified controls and advanced presentation methods to provide the pilot with similar cues under restricted visibility to those available in the real world was also suggested.

It is highly probable that the advanced air transport aircraft which will become available early in the next century will be hydrogen fueled. The use of hydrogen fuel will require designers, production personnel and aircraft operators to positively assure fuel system integrity. The safety, reliability, maintainability and quality assurance specialists in the manufacturers' organizations and in the operating air carrier organizations will be faced with unique problems in achieving fuel system integrity and assuring it throughout the operational life of the aircraft. The reasons why the use of hydrogen fuel in transport aircraft seems inevitable and some of the safety and quality problems which may be encountered, with some possible solutions, are described in this paper.

Rolls-Royce Civil Engine strategy calls for technology development for derivative engine programs and application to longer term new propulsion concepts. In the near future, further development of the turbofan for the next generation of derivative aircraft is planned. Reductions in fuel consumption, noise, weight, and cost will be achieved with engine cycles in the range currently in service and by refinements to component efficiency and application of advanced materials and manufacturing techniques. This derivative approach is likely to continue until the relationship between first and operating cost changes dramatically. As fuel prices rise, or the demand for more rapid travel develops, changes to the basic engine cycle will be necessary. For long range, high subsonic speed operation, substantial increases in turbofan bypass ratio will be needed to realize further fuel burn reductions.

On the Thermodynamic Spectrum of Airbreathing Propulsion - Insights from 1958 are valid guidelines yet in 1988 - Paul Czysz. Staff Manager, McDonnell Douglas Fellow. McDonnell Douglas Corporation

Sustained high speed flight cannot be achieved by improvements in traditional turbojet/turbofan propulsion systems. Instead, propulsion cycles optimized for high speed flight are required. These include combined cycles such as the air turboramjet for the lower speed regime, and scramjet-type cycles for the higher speed regime. Characteristics of these advanced airbreathing propulsion cycles are discussed, and propulsion-related technology issues are addressed.

Since 1982 Daimler-Benz is the first commercial vehicle and bus manufacturer to offer modern anti-lock systems (ABS). After several years of development, anti-lock systems have technically matured to be installed upon request in vehicles with air brakes. The installation rate of this safety item has been steadily increasing ever since. The fundamental design and control philosophy of 4- and 6-channel anti-lock systems will be described. Besides a global analysis regarding the failsafe quotas of digitized electronics in road vehicles, the ABS-specific components will be looked at. The gain of safety achieved by the installation of ABS in commercial vehicles and buses will be presented with the aid of computer simulation. A 40-t-truck/trailer combination, with ABS, without ABS and with a partially defect system, will serve as an example to demonstrate the dynamic behavior during “Braking in a Straight Line” and “Braking in a Turn”

NASA has determined by experimental and analytical effort that use of advanced turboprop propulsion instead of the conventional turbofans in the older narrow-body airline fleet could reduce fuel consumption for this type of aircraft by up to 50 percent. In cooperation with industry, NASA has defined and implemented an Advanced Turboprop (ATP) program to develop and validate the technology required for these new high-speed, multibladed, thin, swept propeller concepts. This paper presents an overview of the analysis, model-scale test, and large-scale flight test elements of the program together with preliminary test results, as available.

Future on-board navigation and information systems for automobiles will automatically keep the driver informed of current location, deduce best routes to specified destinations taking into account current traffic and road conditions, and provide turn-by-turn route guidance according to where the automobile is along the route. Other road transport informatics functions will include location-keyed directory services and automatic vehicle identification for toll and parking billing. These systems will be integrated with systems for automatic headway control and collision avoidance and, eventually, automatic vehicle control. Advanced on-board information systems require integration of vehicular navigation technologies such as dead reckoning, proximity beacons, and radiolocation with various other technologies including digital cartography, data processing and storage, mobile data comunications, information display, voice synthesis, etc.