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At least 667 records · Page 37

Procedures used in flight tests of an integrated propulsion control system on an F-111E airplane

A digital integrated propulsion control system (IPCS) was tested on an F-111E airplane. The IPCS provided full authority control of the left inlet and the TF30 afterburning engine. Supersonic test conditions were of primary interest. The operational procedures and maneuvers developed for IPCS evaluation, displays for test monitoring and data acquisition, flight safety, and problems encountered are discussed. The software refinements that made modifications to standard flight test procedures necessary are described. The flexibility of digital control and the ways software was used to overcome hardware deficiencies are discussed. Application of these procedures to a typical IPCS flight is described.

Baer, J. L.↗

Acoustic Flight Test of the Joby Aviation Advanced Air Mobility Prototype Vehicle

An extensive acoustic flight test was performed on the Joby Aviation pre-production all-electric vertical takeoff and landing prototype. With the design intent of carrying a pilot and four passengers a maximum range of 150 miles, this vehicle utilizes distributed propulsion and vectored thrust via six tilting propellers. As part of the Advanced Air Mobility (AAM) National Campaign, this is the first full-scale AAM aircraft tested by NASA over representative conditions for all phases of a typical mission profile. A 58- channel distributed microphone array was used to acquire acoustic measurements on more than 100 test points (31 unique conditions). The measurements were postprocessed with synchronously sampled vehicle position and state data to form ground noise contours of departures and approaches at various flight path angles and accelerations. Comparing ground areas of 75 dBA isolines, approaches consistently exhibit higher noise levels rela- tive to departures. Directivity maps were generated for constant airspeed level flyovers. Examples comparing the differences in a semi-thrust borne and full wing-borne mode are given, with full wing-borne mode representing the quietest phase of the flight envelope tested. Measurements for hover in and out of ground effect are given and found to have 2 to 5 dB variation over a single run, and more significant variation between back-to-back runs. Finally, initial analysis of acoustic symmetry about the longitudinal vehicle axis and repeatability over several test days are presented.

Acoustics↗

Flight Testing of the Forward Looking Infra-Red (FLIR) Sensor on the Electronic Combat and Reconnaissance (ECR) Tornado

This paper presents details of the flight testing of the Forward Looking Infra-Red (FLIR) sensor integrated into the German Electronic Combat And Reconnaissance (ECR) Tornado aircraft. A brief description of the ECR operational requirements and the key avionic equipment is given. The technical features of the FLIR system and its integration into the aircraft arc presented as are the flight test methods used in assessing its performance. Test facilities are addressed as arc test results. The FLIR system for the ECR Tornado was shown to provide a useful pilot and WSO sight/ navigation aid and to provide an assistance to reconnaissance tasks. The FLIR system has also been shown to meet its specified range-resolution requirements.

Flight Testing↗

System Identification of Flexible Aircraft: Lessons Learned from the X-56A Phase 1 Flight Tests

The X-56A Multi-Utility Technology Testbed (MUTT) is a subscale airplane that was de-signed as an experimental flight research platform for improving aeroelastic modeling and control technologies. The Phase 1 flight tests, conducted from 2017 to 2019 at the NASA Arm-strong Flight Research Center (AFRC), included 39 flights and approximately 1000 research maneuvers, some of which demonstrated stable closed-loop flight beyond the open-loop flutter speed. This paper summarizes the system identification effort to extract nondimensional stability and control derivatives from the flight test data for constructing aeroelastic models of the flight dynamics. Topics discussed include instrumentation, experiment design, model postulation and reduction, parameter estimation, and others. Throughout the paper, unique challenges for the identification of flexible aircraft, practical aspects of the analysis, and lessons learned are presented.

Jared A Grauer↗

Ares I-X Flight Test - On the Fast Track to the Future

In less than two years, the National Aeronautics and Space Administration (NASA) will launch the Ares I-X mission. This will be the first flight of the Ares I crew launch vehicle, which, together with the Ares V cargo launch vehicle, will send humans to the Moon and beyond. Personnel from the Ares I-X Mission Management Office (MMO) are finalizing designs and fabricating vehicle hardware for an April 2009 launch. Ares I-X will be a suborbital development flight test that will gather critical data about the flight dynamics of the integrated launch vehicle stack; understand how to control its roll during flight; better characterize the severe stage separation environments that the upper stage engine will experience during future flights; and demonstrate the first stage recovery system. NASA also will modify the launch infrastructure and ground and mission operations. The Ares I-X Flight Test Vehicle (FTV) will incorporate flight and mockup hardware similar in mass and weight to the operational vehicle. It will be powered by a four-segment Solid Rocket Booster (SRB), which is currently in Shuttle inventory, and will include a fifth spacer segment and new forward structures to make the booster approximately the same size and weight as the five-segment SRB. The Ares I-X flight profile will closely approximate the flight conditions that the Ares I will experience through Mach 4.5, up to approximately130,OOO feet and through maximum dynamic pressure ("Max Q") of approximately 800 pounds per square foot. Data from the Ares I-X flight will support the Ares I Critical Design Review (CDR), scheduled for 2010. Work continues on Ares I-X design and hardware fabrication. All of the individual elements are undergoing CDRs, followed by an integrated vehicle CDR in March 2008. The various hardware elements are on schedule to begin deliveries to Kennedy Space Center (KSC) in early September 2008.

Davis, Stephan R.↗

NASA test flights with increased flight stress indices

This paper presents the objectives, results, and conclusions stemming from a series of six test flights conducted for the National Aeronautics and Space Administration (NASA) by the National Scientific Balloon Facility (NSBF). Results from the test flights indicate that: (1) the current two U.S. balloon films are capable of being flown at significantly increased flight stress index values; (2) payload weights less than the design minimum payload can be reliably flown without fear of structural failure due to increased circumferential stress; and (3) large and rapid decreases in payload weight can be tolerated by current balloons without structural failure.

Smith, I. S., Jr.↗

Constellation Program Flight Test Methodology and Strategy

Main projects elements: a) Orion & Ares b) New & Modified heritage hardware. c) Shuttle retirement in 2010. Methodology: a) Flight test objectives. b) Risk reduction. Strategy a) Mapping Flight Test Objectives. b) Build incremental capability.

Vigil, Art↗

Flight test of ARINC 741 configuration low gain SATCOM system on Boeing 747-400 aircraft

The Boeing company conducted a flight test of a SATCOM system similar to the ARINC 741 configuration on a production model 747-400. A flight plan was specifically designed to test the system over a wide variety of satellite elevations and aircraft attitudes as well as over land and sea. Interface bit errors, signal quality and aircraft position and navigational inputs were all recorded as a function of time. Special aircraft maneuvers were performed to demonstrate the potential for shadowing by aircraft structures. Both a compass rose test and the flight test indicated that shadowing from the tail is insignificant for the 747-400. However, satellite elevation angles below the aircraft horizon during banking maneuvers were shown to have a significant deleterious effect on SATCOM communications.

Murphy, Timothy A.↗

International Space Station Freedom Program (SSFP) flight test demonstrations - Results and future plans

SSFP flight test demonstrations conducted to verify and quantify the performance of selected technologies needed for the development of the Space Station are described. Attention is focused on the performance of thermal systems, the effects of atomic oxygen on materials, and the difficulties of on-orbit crew mobility for assembly and operations utilizing either extravehicular robots or methods. Consideration is given to challenges in system development, a technology assessment summary for the areas of thermal systems, materials, EVA activities, and the results of flight demonstrations.

Simon, William E.↗

Postflight simulation of parachute deployment dynamics of Viking qualification flight tests

Simulation calculations of the Viking qualification flight tests are conducted by use of analytical models of the parachute deployment dynamics process. Results from the study indicate that good simulations of event times and trajectory are obtained. If the full-scale parachute drag coefficient is used, a good simulation of first opening load is obtained and the overall nature of the load history is calculated. For longitudinal motions, the two-degree-of-freedom models give good agreement with a six-degree-of-freedom model. It is believed that the analytical models used are tools which will aid in the analysis of future flight systems.

Whitlock, C. H.↗

Flight test development and evaluation of a Kalman filter state estimator for low-altitude flight

Flight operations dependent on digitized terrain elevation data for navigational reference or trajectory generation are constrained in minimum flight altitude, due to airborne navigation errors and inaccuracies of the reference terrain elevation data. This limitation is not restrictive in traditional medium-altitude implementations of such databases, such as in unmanned aerial vehicles, missiles, or high-performance, high-speed aircraft. In low-altitude, lower speed terrain hugging helicopter missions, however, such constraints on minimum flight altitudes greatly reduce the effectiveness of their missions and diminish the benefits of employing terrain elevation maps. A Kalman filter state estimator has been developed which blends airborne navigation, stored terrain elevation data, and a radar altimeter in estimating above-ground-level (AGL) altitude. This AGL state estimator was integrated in a near-terrain guidance system aboard a research helicopter and flight tested in moderately rugged terrain over a variety of flight and system conditions. The minimum operating altidude of the terrain database referenced guidance system was reduced from 300 ft to 150 ft with the addition of the Kalman filter state estimator.

Zelenka, Richard E.↗

Mars Sample Return and Flight Test of a Small Bimodal Nuclear Rocket and ISRU Plant

A combined Nuclear Thermal Rocket (NTR) flight test and Mars Sample Return mission (MSR) is explored as a means of "jump-starting" NTR development. Development of a small-scale engine with relevant fuel and performance could more affordably and quickly "pathfind" the way to larger scale engines. A flight test with subsequent inflight postirradiation evaluation may also be more affordable and expedient compared to ground testing and associated facilities and approvals. Mission trades and a reference scenario based upon a single expendable launch vehicle (ELV) are discussed. A novel "single stack" spacecraft/lander/ascent vehicle concept is described configured around a "top-mounted" downward firing NTR, reusable common tank, and "bottom-mount" bus, payload and landing gear. Requirements for a hypothetical NTR engine are described that would be capable of direct thermal propulsion with either hydrogen or methane propellant, and modest electrical power generation during cruise and Mars surface insitu resource utilization (ISRU) propellant production.

George, Jeffrey A.↗

The 1979 clear air turbulence flight test program

A clear air turbulence (CAT) flight test to evaluate and test four different sensors in the detection and measuring of CAT and other meteorological targets that relate to turbulence is discussed. The primary types of CAT investigated were mountain wave CAT, jetstream CAT, CAT in cirrus clouds, and CAT in frontal wind shears, troughs, and ridges. The sensors included the CO2 pulsed Doppler lidar and three radiometers. One of the radiometers, at a frequency of 55.5 GHz, looked at atmospheric temperature structure. Another, at a frequency of 180.1 GHz, looked at atmospheric water vapor and investigated the feasibility of measuring at the microwave frequency the turbulence features seen in the infrared (IR) frequencies. An IR radiometer at 27 to 33 microns was the fourth sensor. This last device and the temperature structure radiometer worked well at all flight levels.

Weaver, E. A.↗

Boundary layer flow visualization for flight testing

Flow visualization is used extensively in flight testing to determine aerodynamic characteristics such as surface flow direction and boundary layer state. Several visualization techniques are available to the aerodynamicist. Two of the most popular are oil flows and sublimating chemicals. Oil is used to visualize boundary layer transition, shock wave location, regions of separated flow, and surface flow direction. Boundary layer transition can also be visualized with sublimating chemicals. A summary of these two techniques is discussed, and the use of sublimating chemicals is examined in some detail. The different modes of boundary layer transition are characterized by different patterns in the sublimating chemical coating. The discussion includes interpretation of these chemical patterns and the temperature and velocity operating limitations of the chemical substances. Information for selection of appropriate chemicals for a desired set of flight conditions is provided.

Obara, Clifford J.↗

Structure Computation of Quiet Spike[Trademark] Flight-Test Data During Envelope Expansion

System identification or mathematical modeling is used in the aerospace community for development of simulation models for robust control law design. These models are often described as linear time-invariant processes. Nevertheless, it is well known that the underlying process is often nonlinear. The reason for using a linear approach has been due to the lack of a proper set of tools for the identification of nonlinear systems. Over the past several decades, the controls and biomedical communities have made great advances in developing tools for the identification of nonlinear systems. These approaches are robust and readily applicable to aerospace systems. In this paper, we show the application of one such nonlinear system identification technique, structure detection, for the analysis of F-15B Quiet Spike(TradeMark) aeroservoelastic flight-test data. Structure detection is concerned with the selection of a subset of candidate terms that best describe the observed output. This is a necessary procedure to compute an efficient system description that may afford greater insight into the functionality of the system or a simpler controller design. Structure computation as a tool for black-box modeling may be of critical importance for the development of robust parsimonious models for the flight-test community. Moreover, this approach may lead to efficient strategies for rapid envelope expansion, which may save significant development time and costs. The objectives of this study are to demonstrate via analysis of F-15B Quiet Spike aeroservoelastic flight-test data for several flight conditions that 1) linear models are inefficient for modeling aeroservoelastic data, 2) nonlinear identification provides a parsimonious model description while providing a high percent fit for cross-validated data, and 3) the model structure and parameters vary as the flight condition is altered.

Kukreja, Sunil L.↗

Feasibility Study of the Superconducting Gravity Gradiometer (SGG) Flight Test on the European Retrievable Carrier (EURECA)

A study was performed to determine the feasibility of conducting a flight test of the Superconducting Gravity Gradiometer (SGG) Experiment Module on one of the reflights of the European Retrievable Carrier (EURECA). EURECA was developed expressly to accommodate space science experimentation, while providing a high quality microgravity environment. As a retrievable carrier, it offers the ability to recover science experiments after a nominal six months of operations in orbit. The study concluded that the SGG Experiment Module can be accommodated and operated in a EURECA reflight mission. It was determined that such a flight test would enable the verification of the SGG Instrument flight performance and validate the design and operation of the Experiment Module. It was also concluded that a limited amount of scientific data could be obtained on this mission.

Source record↗

Flight test evaluation of drag effects on surface coatings on the NASA Boeing 737 TCV airplane

A flight test program was conducted in which the effects of various surface coatings on aerodynamic drag were investigated; results of this program are described in this report. The tests were conducted at NASA-Langley Research Center on the terminal configured vehicle (TCV) Boeing 737 research airplane. The Boeing Company, as contractor with NASA under the Energy Efficient Transport (EET) program, planned and evaluated the experiment. The NASA-TCV Program Office coordinated the experiment and performed the flight tests. The principal objective of the test was to evaluate the drag reduction potential of an elastomeric polyurethane surface coating, CAAPCO B-274, which also has been considered for application on transport airplanes to protect leading edges from erosion. The smooth surface achievable with this type of coating held some promise of reducing the skin friction drag as compared to conventional production type aircraft surfaces, which are usually anodized bare metal or coated with corrosion protective paint. Requirements for high precision measurements were the principal considerations in the experiment.

George-Falvy, D.↗