Download or read book Effects of the Reentry Plasma Sheath on Microwave Antenna Performance written by J. Leon Poirier and published by . This book was released on 1969 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Trailblazer II rocket was launched on 18 June 1967 from the NASA wallops Island (Va.) Rocket Test Facility to study the properties of the reentry plasma sheath and its effects on microwave antenna performance. The reentry payload consisted of three major subsystems: a plasma diagnostic system, an S- band transponder system, and an X-band telemetry system. The flight data yielded (1) measurements of the influence of the plasma on the radiation pattern distortion, signal attenuation, and impedance mismatch for an S-band slot antenna located at the stagnation point of the nose cone; (2) measurements of the plasma sheath effects on the interantenna coupling between two S-band antennas on the nose cone; and (3) determinations of the electron density profile and gradients in the boundary layer about the nose cone.
Download or read book Interpretation of Microwave Antenna Results from a Reentry Flight Test written by John F. Lennon and published by . This book was released on 1974 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is one of a series of reports on the Trailblazer II program. The particular aspect treated here involves the unmodified expansion-region plasma and its effect on an antenna located on the vehicle shoulder. This report describes some of the theoretical approaches used, discusses the levels of approximation involved, and shows the agreement between these various methods and the test data. The failure of a single set of assumptions to yield consistent agreement over a range of altitudes confirms the need to adopt flow models appropriate to the changing regimes encountered during reentry. One significant conclusion is that performance characteristics such as reflection and interantenna coupling which depend mostly on the level of peak electron density can be represented by simple plane wave, as well as by the more sophisticated slot antenna models. The latter approach, however, is necessary to describe propagation across the entire plasma sheath.
Download or read book Performance of a Microwave Antenna System in the Shoulder Region of a Blunt Reentry Nose Cone written by J. Leon Poirier and published by . This book was released on 1973 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of the third AFCRL Trailblazer II reentry vehicle flight was to study the effects of shock ionized air on the performance of a microwave antenna system located in the expansion region of the nose cone. The system consisted of a pair of cavity-backed circumferential slot antennas mounted one behind the other on the conical afterbody of the reentry vehicle. During reentry, measurements of antenna impedance mismatch, interantenna coupling, signal attenuation and antenna pattern distortion were made. The data have been compared with computed values and found to be in good agreement. This experiment thus establishes the validity of the various microwave and flow field models and calculations used to obtain the theoretical values in the shoulder region of the reentry body. These results will now serve as a standard against which to compare the properties of various chemical alleviants which are being studied in other flights. (Author).
Download or read book An Ablation Technique for Enhancing Reentry Antenna Performance Flight Test Results written by Dallas T. Hayes and published by . This book was released on 1974 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: To develop alternative solutions to Air Force problems relating to signal transmission in the presence of ionization, AFCRL undertook an extensive investigation of techniques for modifying reentry plasmas. The program included laboratory tests and a series of reentry flight experiments. This report describes the flight test of one successful technique, Teflon ablation, a passive approach that requires no internal support systems. A reentry vehicle fitted with a Teflon-coated nosecap was instrumented to measure antenna impedance mismatch, interantenna coupling, signal attenuation, and charged-particle density. The probe data showed that the local boundary-layer electron density decreased by as much as a factor of 200. The Teflon coating effected a 25-dB decrease in S-band signal attenuation. High-power antenna breakdown was modified by the presence of the ablation products. Details of the vehicle design, flight dynamics, and ablation, are presented, and the results of the Teflon-ablation technique are contrasted with those of a successful liquid-injection technique that was tested on a previous flight.
Download or read book A Simple Method of Simulating Motion and Plasma Induced Variations in the Attenuation of Signals Transmitted from Reentry Vehicles written by J. L. Poirier and published by . This book was released on 1973 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A simple method of simulating the variation in the amplitude of microwave signals from rocket-borne transmitters is presented. The technique reproduces signal changes caused by vehicle motion as well as those induced by plasma effects. The simulator uses a voltage controlled attenuator which is programmed to vary the output power of a test transmitter to produce the variations in signal amplitude which would be observed during a flight. An analog system which is suitable for variations of simple cyclical shape and a digital simulator which can reproduce changes of any complexity are presented. Use of the simulator before flight allows the dynamic behavior of a microwave link to be determined, permits optimum receiver and recorder parameters to be selected, increases operator confidence, and enhances flight test reliability. (Author).
Download or read book Instrumentation Papers written by and published by . This book was released on with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laboratory and Flight Results of the Microstrip Plasma Probe written by Nicholas V. Karas and published by . This book was released on 1974 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: The microstrip plasma probe, a new diagnostic tool for use in the investigation of ionized media, has been developed and successfully tested both in the laboratory and in an actual flight. It is flush mounted (therefore causes no aerodynamic disturbances); simple in geometric shape (therefore can be modified to fit curved surfaces and ruggedized to withstand shock and vibration); only a fraction of the operating wavelength in length (therefore saves on payload space); and operates with low power (therefore does not disturb the plasma which it is measuring). Experimental results, obtained from both the laboratory and from an actual flight, have been compared to theory and to experimental data from other probes. In both instances the results are close.
Download or read book Report on Research at AFCRL written by Air Force Cambridge Research Laboratories (U.S.) and published by . This book was released on 1972 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design and Testing of a Chemical Injection System for Reentry Plasma Alleviation written by John F. Lennon and published by . This book was released on 1974 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of injecting an electrophilic liquid into the ionized flow field surrounding a reentry vehicle was observed during the flight of a trailblazer 2 on 28 July 1972. The report describes the rationale used to initially screen candidate additives and the experimental evaluation that finally resulted in the selection of Freon 114B2 for operational use. Injection system design and preliminary testing are discussed, and the predicted and actual performance during flight are compared. Data from on-board antennas and electrostatic probes confirmed that the additive reduced the electron density and improved transmission. A number of factors characterizing the injection are presented as a basis for analyzing the flow-additive interaction. (Author).
Download or read book The Entry Plasma Sheath and Its Effects on Space Vehicle Electromagnetic Systems Volume 1 written by and published by . This book was released on 1971 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electroacoustic Probe Results Obtained in an Argon Afterglow Plasma for a Planar Geometry written by Nicholas V. Karas and published by . This book was released on 1973 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental data resulting from an investigation of the electroacoustic probe in an argon afterglow plasma for a planar geometry indicates the value of the probe as a diagnostic tool. It is suited to airborne payloads because of its small size and rugged construction. In carrying out the study, some of the parameters that were varied were the pressure (range = 100 to 1000 micro m), input power to the probe (range = 40 dB), and frequency of input signal (350 to 600 MHz). The effect of changing physical dimensions of the probe was also considered. Electroacoustic probe predictions of the electron density gradients close to a surface were found to compare closely with the electron density gradients obtained with a floating double Langmuir probe. Treating the electroacoustic probe as similar to a resonant circuit produced some preliminary results that show up as familiar Q values. Both linear and nonlinear responses of the electroacoustic probe are illustrated. One nonlinear phenomenon--induced oscillations in sections of the resonance curve--is discussed in detail. (Author).
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1986 with total page 1160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bibliography with Abstracts of AFCRL Publications from 1 July to 30 September 1972 written by Air Force Cambridge Research Laboratories (U.S.) and published by . This book was released on 1972 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: This bibliography lists all AFCRL in-house reports, journal articles, and contractor reports issued during the reporting period. The DD Form 1473 (Document Control Data - R & D) for each publication is included. In Part I, the 1473's for in-house reports are arranged numerically by the series in which they were issued: in Part II, the 1473's for journal articles are arranged alphabetically by author; in Part III, the 1473's for contractor reports are arranged alphabetically by corporate author. For cross-reference purposes, an index is included, listing the publications numerically by the AFCRL document number.
Download or read book Technical Abstract Bulletin written by and published by . This book was released on with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA 73 659 AIAA 73 705 With omissions in numbering written by and published by . This book was released on 1973 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Air Force Research Resum s written by and published by . This book was released on with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Systems Analysis A Functional Organization A Customer Users Library CUL written by Eunice C. Cronin and published by . This book was released on 1972 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt: A systems analysis technique is applied to the scientific problem solving requirements of a major Air Force research organization to establish: The functional organization of a research support group; A valuable data base for a Customer User Library (CUL); and A Management Information System for scheduling, reporting and control. The report summarizes the functional organization of the Analysis and Simulation Branch of the Computation Center at AFCRL as derived from an analysis of the spectrum of analytical and computational problems originating in the Laboratories. A detailed description the structure and mode of operation of the Customer User Library is provided, together with a discussion of the associated Management Information System. An extensive listing of scientific problem abstracts is provided in the Appendices.
