Some recent results in aerospace vehicle trajectory optimization techniques
Algorithms and computation techniques for solving trajectory optimization problems
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Algorithms and computation techniques for solving trajectory optimization problems
Polymeric fuel tank sealants incorporating fluorine atoms for hypersonic aircraft
This publication consists of a series of lectures prepared by personnel of the NASA Langley Research Center. Collectively, they were presented as a graduate seminar at Rensselaer Polytechnic Institute, Troy, New York, under the auspices of Professor Robert E. Duffy. The lectures summarize theoretical and experimental work in a number of areas of current interest in the design of aeronautical and space vehicles and were intended as an extension of general academic studies toward applications to solutions of practical problems. The material presented is not intended to be a comprehensive survey of the state of the art but rather a series of resumes of work in several areas, some of which represent fairly recent developments and others in which the significant contributions are distributed in various publications. The material covered reflects the specialties and viewpoints of the individual lecturers and little effort has been made to provide continuity between the different papers. The topics are, nevertheless, grouped under three general headings, as follows: 1. Aerodynamics of vehicles in various speed ranges 2. Problems involving aeroelasticity and unsteady aerodynamics 3. Methods and application of analytical techniques in dynamic stability problems The material is considered suitable for providing aeronautical engineering students with background information and working knowledge in a number of specialized fields which are usually omitted or discussed only briefly in an undergraduate curriculum.
Statistical analysis of atmospheric turbulence at Cape Kennedy Launch Complex for spacecraft design
The principal types of separation systems and mechanisms used in spacecraft are described and compared. Important parameters to be considered in tradeoff studies are discussed. Several examples of successful applications and failures and the lessons learned from them are discussed.
Guidelines are presented on probable precipitation extremes and characteristics, applicable for NASA space vehicles and associated equipment development. Information is provided on probability of rainfall rates, drop size, drop rate of fall, associated wind speeds with rainfall, snow loads, hail, laboratory test simulation, and rain erosion.
The problems of estimation and control of discrete, linear, time-varying systems are considered. Previous solutions to these problems involved either approximate techniques, open-loop control solutions, or results which required excessive computation. The estimation problem is solved by two different methods, both of which yield the identical algorithm for determining the optimal filter. The partitioned results achieve a substantial reduction in computation time and storage requirements over the expanded solution, however. The results reduce to the Kalman filter when no delays are present in the system. The control problem is also solved by two different methods, both of which yield identical algorithms for determining the optimal control gains. The stochastic control is shown to be identical to the deterministic control, thus extending the separation principle to time delay systems. The results obtained reduce to the familiar optimal control solution when no time delays are present in the system.
The selection of an estimator which is unbiased when applied to structural parameter estimation is discussed. The mathematical relationships for structural parameter estimation are defined. It is shown that a conventional weighted least squares (CWLS) estimate is biased when applied to structural parameter estimation. Two approaches to bias removal are suggested: (1) change the CWLS estimator or (2) change the objective function. The advantages of each approach are analyzed.
Rawinsonde wind profile data provide adequate wind shear information for vertical height intervals greater than 1 km. To specify wind shears for intervals below 1 km for space vehicle design, detailed wind-profile information like that provided by the FPS-16 Radar/Jimsphere system or an extrapolation procedure is required. This paper is concerned with the latter alternative. It is assumed that any realization from an ensemble of wind profiles can be represented in terms of a Fourier integral. This permits the calculation of the ensemble standard deviation and mean of the corresponding shear ensemble for any altitude and shear interval in terms of the power spectrum of the ensemble of wind profiles. The results of these calculations show that the mean and standard deviation of the wind shear ensemble, as well as the wind shear for any percentile, asymptotically behave like the vertical interval to the 0.7 power. This result is in excellent agreement with shear data from Cape Kennedy, Fla.
The collection and disposal of human wastes, such as urine and feces, in a spacecraft environment are performed in an aesthetic and reliable manner to prevent degradation of crew performance. The waste management system controls, transfers, and processes materials such as feces, emesis, food residues, used expendables, and other wastes. The requirements, collection, transport, and waste processing are described.
A summary of selected atmospheric conditions observed near launch time for 155 NASA-Marshall Space Flight Center and Army Ballistic Missile Agency related vehicles, launched primarilv from Cape Kennedy, Florida, between August 20, 1953, and November 16, 1963, is presented. Values of ambient pressure, temperature, relative humidity, ground winds, visual observations, density aloft, and wind/wind shear aloft are included. The extremes of these parameters are listed for each type of launch vehicle.
Guidelines are provided on probable climatic extremes and terrestrial environment data applicable to space vehicle and associated equipment design and development. Operational criteria for ground support sites are emphasized.
An independent geometry display program called IMAGE is presented. The use of the program permits the editing of geometric configurations and the monitoring of geometric perturbations.
The ODIN system is a new design synthesis procedure for solving multiple discipline design problems. In ODIN an unlimited number of independent technology codes can be linked together in the computer in any desired sequence. This paper describes the ODIN system, the executive program DIALOG, the data management technique, and the program library. The use of ODIN is illustrated with an application drawn from space system studies.
An implicit numerical procedure is developed to solve the full three-dimensional laminar, boundary layer equations over realistic aircraft and spacecraft configurations. This procedure utilizes splined functions in the direction normal to the surface and finite differences in the cross flow direction. Calculation of off-pitch plane attachment and detachment lines can be calculated. The solution procedure permits the incorporation of a wide variety of turbulent models and boundary conditions including; entropy layer procedures, specified surface temperatures or heat flux distributions, surface catalysis, mass addition, and the coupling to both three-dimensional inviscid codes and surface ablation codes. In addition, reasonable computing times are obtained.
Results are presented from a two-dimensional model of the stratosphere that simulates the seasonal movement of ozone by both wind and eddy transport, and contains all the chemistry known to be important. The calculated reductions in ozone due to NO2 injection from a fleet of supersonic transports are compared with the zonally averaged results of a three-dimensional model for a similar episode of injection. The agreement is good in the northern hemisphere, but is not as good in the southern hemisphere. Both sets of calculations show a strong corridor effect in that the predicted ozone depletions are largest to the north of the flight corridor for aircraft operating in the northern hemisphere.
An overview is provided of the Ipad System, including its goals and objectives, organization, capabilities and future usefulness. The systems implementation is also presented with operational cost summaries.
The aircraft design process is discussed along with the degree of participation of the various engineering disciplines considered in this feasibility study.