SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 18 - SEPTEMBER 09, 2005

04 AIRCRAFT COMMUNICATIONS AND NAVIGATION
Includes all modes of communication with and between aircraft; air navigation systems (satellite and ground based); and air traffic control.

For related information see also 06 Avionics and Aircraft Instrumentation, 17 Space Communications, Spacecraft Communications, Command and Tracking, and 32 Communications and Radar.

20050207427 Tethers Unltd., Inc., Bothell, WA, USA

Analysis of The Interaction of Space Tethers with Catalogued Space Objects

Bonometti, Joseph, Technical Monitor; Hoyt, Robert; Buller, Jason; March 23, 2005; 5 pp.; In English; 41st AIAA Joint Propulsion Conference, 10-13 Jul. 2005, Tucson, AZ, USA Contract(s)/Grant(s): NNM04AAlOC; No Copyright; Avail: CASI; A01, Hardcopy

The potential for collisions or close passes with other space objects presents a significant issue for many space tether applications, representing a potential risk both to the integrity of the tether system and t o the safety of other spacecraft. Potential collisions between tethers and other space objects may be possible to avoid if close encounters can be predicted with sufficient precision and advance notice. In order to provide a method for predicting the frequency with which a tether must be maneuvered to avoid collisions, and to provide a resource for accurate close-encounter prediction during tether flight experiments, we have developed a software tool that compares the trajectory of a tether object with that of all of the objects in the NORAD space catalogue. In this paper we describe the models and algorithms used in this tool, and discuss results of test cases conducted to predict the close-encounter frequency of a tether systems ranging from a short nanosatellite-based tether experiment to a hundred-kilometer long MXER tether system. Author

Tethering; Collisions; Safety; Risk; Predictions

20050209972 Air Force Flight Test Center, Edwards AFB, CA, USA

Flight Test Instrumentation, Chapter 6

Crounse, David R.; Introduction to Flight Test Engineering, Volume 14; July 2005, pp. 6-1 - 6-12; In English; See also 20050209967; Copyright; Avail: CASI; A03, Hardcopy; Available from CASI on CD-ROM only as part of the entire parent document

The purpose of a flight test instrumentation system is to acquire data about the operation of the test vehicle and provide the data to the data processing group. As a flight test engineer (FTE), no matter what discipline, the FTE needs to define the measurands needed for the assigned tasks to the instrumentation engineer. In general, a test article will support multiple discipline testing. Many measurands are requested by more than one user and the FTE needs to coordinate with engineers from other disciplines to define those measurands. Other measurands are exclusively the lead FTE’s. All must be defined in detail. A great deal of detailed information is required to prepare and implement an adequate instrumentation specification. This section will provide some general information on the elements that make up an instrumentation system and provide guidance on where to find additional information. AGARDograph 160, the Flight Test Instrumentation Series of volumes, provides a wealth of information equally useful to the neophyte or journeyman engineer. Derived from text

Flight Test Instruments; Flight Tests; User Requirements; Engineers

20050209975 Sparta, Inc., Lancaster, CA, USA

Radar Cross Section, Chapter 19A

Borek, Robert W.; Introduction to Flight Test Engineering, Volume 14; July 2005, pp. 19A - 13; In English; See also 20050209967; Original contains black and white illustrations; Copyright; Avail: CASI; A03, Hardcopy; Available from CASI on CD-ROM only as part of the entire parent document

The material in this Section will provide the novice Flight Test Engineer (FTE) with a brief overview of the radar cross section (RCS) concept. Brief details of radar range descriptions, operations, target calibrations, and data reduction are included. It is noted that these range operations concentrate on the ‘static’ test range rather than the much more sophisticated ‘dynamic’ test range. The dynamic test range is what the FTE will probably work with. Radar reflectivity measurement has developed over the last two decades from a relatively simple endeavor involving the measurement of target RCS amplitude statistics to involving wide band, coherent systems that can measure high resolution images of targets as well as, in many cases, the polarization and phasing properties. This rapid growth in RCS technology has occurred because of the increased use of radar in today’s commercial and military systems. In general, the goal for commercial systems is to enhance radar reflectivity, whereas the military goal is to reduce radar reflectivity. Also, classification and identification are important for military purposes because in adverse weather radar may be the only system that may be capable of separating enemy targets from friendly ones. This Section will discuss the fundamentals of RCS. Since the flight test techniques associated with RCS measurements are very similar to those of antenna pattern measurements, both will be presented at the same time in Section 19B Antenna Radiation Pattern Measurements. Author

Antenna Radiation Patterns; Radar Cross Sections; Radar Measurement; Flight Tests

Source: NASA.