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NASA NTRS1976

Oblique-wing supersonic aircraft

An aircraft including a single fuselage having a main wing and a horizontal stabilizer airfoil pivotally attached at their centers to the fuselage is described. The pivotal attachments allow the airfoils to be yawed relative to the fuselage for high speed flight, and to be positioned at right angles with respect to the fuselage during takeoff, landing, and low speed flight. The main wing and the horizontal stabilizer are upwardly curved from their center pivotal connections towards their ends to form curvilinear dihedrals.

Jones, R. T.↗

NASA NTRS1976

Application of the nonlinear vortex-lattice concept to aircraft-interference problems

A discrete-vortex model was developed to account for the hazardous effects of the vortex trail issued from the edges of separation of a large leading wing on a small trailing wing. The model is divided into three main parts: the leading wing and its near wake, the near and far wakes of the leading wing, and the trailing wing and the portion of the far wake in its vicinity. The normal force, pitching moment, and rolling moment coefficients for the trailing wing are calculated. The circulation distribution in the vortex trail is calculated in the first part of the model where the leading wing is far upstream and hence is considered isolated. A numerical example is solved to demonstrate the feasibility of using this method to study interference between aircraft. The numerical results show the correct trends: The following wing experiences a loss in lift between the wing-tip vortex systems of the leading wing, a gain outside this region, and strong rolling moments which can change sign as the lateral relative position changes. All the results are strongly dependent on the vertical relative position.

Kandil, O. A.↗

NASA NTRS1981

Predictor symbology in computer-generated perspective displays

An advanced display format for the four dimensional commercial aircraft approach-to-landing is evaluated. The desired curved and descending approach path is presented by displaying the perspective image of a tunnel. Attention is focussed on the predictor symbology, superimposed on the tunnel image. A perspective three dimensional predictor symbol, providing future position, as well as future attitude information, is compared with a flat two dimensional version, which only provides the future position. In addition to this, the predictor displays the actual airspeed as well as the desired airspeed, prescribed by the four dimensional path. Results show that the three dimensional predictor symbol outperforms the two dimensional predictor in following the trajectory in a moderate-to-heavy turbulent environment, which is manifested in accurate manual true airspeed control was obtained without affecting the main task performance significantly.

Grunwald, A. J.↗

NASA NTRS1990

In situ measurements of NO(x) in the Airborne Arctic Stratospheric Expedition

In situ measurements of NO and NO2 were made simultaneously from the NASA DC-8 aircraft as part of the Airborne Arctic Stratospheric Expedition. Mixing ratios of NO(x) (NO + NO2) were typically higher in the arctic troposphere than in the stratosphere, with median values of 59 and 40 pptv, respectively. In the stratosphere, there tended to be a positive correlation between NO(x) and water vapor and negative correlations between NO(x) and ozone and between NO(x) and total reactive odd-nitrogen, NO(y). The ratio of NO(x) to NO(y), in conjunction with NO(y), appears to be an excellent tracer of tropospheric or stratospheric air at northern latitudes during winter. Tropospheric NO(x) was typically 10 to 50 percent of gas-phase NO(y), while in the stratosphere, NO(x) was typically less than 10 percent, and frequently less than 5 percent of gas-phase NO(y).

Carroll, Mary Anne↗

NASA NTRS1948

Effect of Centrifugal Force on the Elastic Curve of a Vibrating Cantilever Beam

A study was made to determine the effect of rotation on the dynamic-stress distribution in vibrating cantilever beams. The results of a mathematical analysis are presented together with experimental results obtained by means of stroboscopic photographs and strain gages. The theoretical analysis was confined to uniform cantilever beams; the experimental work was extended to include a tapered cantilever beam to simulate an aircraft propeller blade. Calculations were made on nondimensional basis for second and third mode vibration; the experiments were conducted on beams of various lengths, materials, and cross sections for second-mode vibration. From this investigation it was concluded that high vibratory-stress positions are unaffected by the addition of centrifugal force. Nonrotating vibration surveys of blades therefore are valuable in predicting high vibratory-stress locations under operating conditions.

Simpkinson, Scott H↗

NASA NTRS2005

Space-Based Range Safety and Future Space Range Applications

The National Aeronautics and Space Administration Space-Based Telemetry and Range Safety study is a multiphase project to demonstrate the performance, flexibility and cost savings that can be realized by using space-based assets for the Range Safety (global positioning system metric tracking data, flight termination command and range safety data relay) and Range User (telemetry) functions during vehicle launches and landings. Phase 1 included flight testing S-band Range Safety and Range User hardware in 2003 onboard a high-dynamic aircraft platform at Dryden Flight Research Center (Edwards, California) using the NASA Tracking and Data Relay Satellite System as the communications link. The current effort, Phase 2, includes hardware and packaging upgrades to the S-band Range Safety system and development of a high data rate Ku-band Range User system. The enhanced Phase 2 Range Safety Unit provided real-time video for three days during the historic GlobalFlyer (Scaled Composites, Mojave, California) flight in March, 2005. Additional Phase 2 testing will include a sounding rocket test of the Range Safety system and aircraft flight testing of both systems. Future testing will include a flight test on a launch vehicle platform. This report discusses both Range Safety and Range User developments and testing with emphasis on the Range Safety system. The operational concept of a future space-based range is also discussed.

Whiteman, Donald E.↗

NASA NTRS2006

Aerobots as a Ubiquitous Part of Society

Small autonomous aerial robots (aerobots) have the potential to make significant positive contributions to modern society. Aerobots of various vehicle-types - CTOL, STOL, VTOL, and even possibly LTA - will be a part of a new paradigm for the distribution of goods and services. Aerobots as a class of vehicles may test the boundaries of aircraft design. New system analysis and design tools will be required in order to account for the new technologies and design parameters/constraints for such vehicles. The analysis tools also provide new approaches to defining/assessing technology goals and objectives and the technology portfolio necessary to accomplish those goals and objectives. Using the aerobot concept as an illustrative test case, key attributes of these analysis tools are discussed.

Young, Larry A.↗

NASA NTRS2012

High-Altitude MMIC Sounding Radiometer for the Global Hawk Unmanned Aerial Vehicle

Microwave imaging radiometers operating in the 50-183 GHz range for retrieving atmospheric temperature and water vapor profiles from airborne platforms have been limited in the spatial scales of atmospheric structures that are resolved not because of antenna aperture size, but because of high receiver noise masking the small variations that occur on small spatial scales. Atmospheric variability on short spatial and temporal scales (second/ km scale) is completely unresolved by existing microwave profilers. The solution was to integrate JPL-designed, high-frequency, low-noise-amplifier (LNA) technology into the High-Altitude MMIC Sounding Radiometer (HAMSR), which is an airborne microwave sounding radiometer, to lower the system noise by an order of magnitude to enable the instrument to resolve atmospheric variability on small spatial and temporal scales. HAMSR has eight sounding channels near the 60-GHz oxygen line complex, ten channels near the 118.75-GHz oxygen line, and seven channels near the 183.31-GHz water vapor line. The HAMSR receiver system consists of three heterodyne spectrometers covering the three bands. The antenna system consists of two back-to-back reflectors that rotate together at a programmable scan rate via a stepper motor. A single full rotation includes the swath below the aircraft followed by observations of ambient (roughly 0 C in flight) and heated (70 C) blackbody calibration targets located at the top of the rotation. A field-programmable gate array (FPGA) is used to read the digitized radiometer counts and receive the reflector position from the scan motor encoder, which are then sent to a microprocessor and packed into data files. The microprocessor additionally reads telemetry data from 40 onboard housekeeping channels (containing instrument temperatures), and receives packets from an onboard navigation unit, which provides GPS time and position as well as independent attitude information (e.g., heading, roll, pitch, and yaw). The raw data files are accessed through an Ethernet port. The HAMSR data rate is relatively low at 75 kbps, allowing for real-time access over the Global Hawk high-data-rate downlink. Once on the ground, the raw data are unpacked and processed through two levels of processing. The Level 1 product contains geo-located, time-stamped, calibrated brightness temperatures for the Earth scan. These data are then input to a lD variational retrieval algorithm to produce temperature, water vapor, and cloud liquid water profiles, as well as several derived products such as potential temperature and relative humidity.

Brown, Shannon T.↗

NASA NTRSDate not supplied

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↗

NASA NTRSDate not supplied

Advanced Capabilities for Emergency Response Operations (ACERO)

The Advanced Capabilities for Emergency Response Operations (ACERO) project is expected to develop, integrate, demonstrate, and transition to operations, evolving aviation technologies from NASA and industry to identify, monitor, and suppress wildland fires as a means to enhance safety, improve operational efficiency, and prevent economic loss. Some of the concepts ACERO explores are: wildfire airspace mangement to improve safety and resource utilization during a disaster, applying new aviation technologies to improve safety and demonstrate new mission-support capabilities, second-shift operations to enable progress towards 24/7 aerial response, and the integration of capabilities across NASA's Aeronautics Research, Science, and Space Technology mission directorates to enable expanded and scalable operations. Realizing this vision is expected to bring positive impact to such areas as: consistency of technology adoption through a unified concept of operations, airspace coordination and deconfliction that integrates portable solutions and enables diverse operations, remote sensing and data fusion for modeling and predictions that support in-time decision making, aircraft technologies for hazard avoidance and state management, and increased response capabilities through persistent communications and surveillance. ACERO continues the research begun under the Scalable Traffic Management for Emergency Response Operations (STEReO) activity, which brings together several technologies in Unmanned Aircraft Systems (UAS) Traffic Management (UTM), Autonomy, Communications, Human Factors, and Domain Expertise & Tools, aimed at providing scalability and flexibility, as well as operational resiliency to dynamic changes during a disaster event. Some of the concepts STEReO explores are: collaborative tools to ingest remote sensing information and distribute a common mission operating picture, apply ad-hoc communication networks to facilitate timely information sharing and communication of changes, vehicle-to-vehicle and onboard autonomy technologies ensure the safety and resiliency of operations, and apply NASA’s UAS traffic management system (UTM) as a public safety UAS Service Supplier (USS) to access and coordinate use of the airspace by both manned and unmanned operations. The potential benefits of STEReO include: standardized, cross-platform communication means increased interoperability and ease of cooperation/collaboration, increased situation awareness and common operating picture allow for earlier detection and decision making, and scalable to size and complexity of environment, operations, and mission objectives. This presentation gives an informational overview of the ACERO and STEReO projects to the Council of Western State Foresters (CWSF) Western State Fire Managers (WSFM) Committee.

emergency response operations↗

NASA NTRS2017

Educational Projects in Unmanned Aerial Systems at the NASA Ames Research Center

Unmanned aerial systems (UAS), autonomy and robotics technology have been fertile ground for developing a wide variety of interdisciplinary student learning opportunities. In this talk, several projects will be described that leverage small fixed-wing UAS that have been modified to carry science payloads. These aircraft provide a unique hands-on experience for a wide range of students from college juniors to graduate students pursuing degrees in electrical engineering, aeronautical engineering, mechanical engineering, applied mathematics, physics, structural engineering and other majors. By combining rapid prototyping, design reuse and open-source philosophies, a sustainable educational program has been organized structured as full-time internships during the summer, part-time internships during the school year, short details for military cadets, and paid positions. As part of this program, every summer one or more UAS is developed from concept through design, build and test phases using the tools and facilities at the NASA Ames Research Center, ultimately obtaining statements of airworthiness and flight release from the Agency before test flights are performed. In 2016 and 2017 student projects focused on the theme of 3D printed modular airframes that may be optimized for a given mission and payload. Now in its fifth year this program has served over 35 students, and has provided a rich learning experience as they learn to rapidly develop new aircraft concepts in a highly regulated environment, on systems that will support principal investigators at university, NASA, and other US federal agencies.

UA↗

NASA NTRS1976

Characteristics of wake vortex generated by a Boeing 727 jet transport during two-segment and normal ILS approach flight paths

A series of flight tests was conducted to evaluate the vortex wake characteristics of a Boeing 727 (B727-200) aircraft during conventional and two-segment ILS approaches. Twelve flights of the B727, which was equipped with smoke generators for vortex marking, were flown and its vortex wake was intentionally encountered by a Lear Jet model 23 (LR-23) and a Piper Twin Comanche (PA-30). Location of the B727 vortex during landing approach was measured using a system of photo-theodolites. The tests showed that at a given separation distance there were no readily apparent differences in the upsets resulting from deliberate vortex encounters during the two types of approaches. Timed mappings of the position of the landing configuration vortices showed that they tended to descend approximately 91 m(300 ft) below the flight path of the B727. The flaps of the B727 have a dominant effect on the character of the trailed wake vortex. The clean wing produces a strong, concentrated vortex but as the flaps are lowered, the vortex system becomes more diffuse. Pilot opinion and roll acceleration data indicate that 4.5 n.mi. would be a minimum separation distance at which roll control of light aircraft (less than 5,670 kg (12,500 lb) could be maintained during parallel encounters of the B727's landing configuration wake. This minimum separation distance is generally in scale with results determined from previous tests of other aircraft using the small roll control criteria.

Kurkowski, R. L.↗

NASA NTRS1972

Acoustic results obtained with upper-surface-blowing lift augmentation systems

The noise caused by the interaction of the jet exhaust and a wing was measured under static conditions for several versions of a small-scale STOL engine-over-the-wing configuration. Three basic nozzles were used in the tests; a circular nozzle, a 5:1 aspect ratio slot nozzle and a 10:1 aspect ratio slot nozzle. Various flow attachment devices were included in the study. The wing included a flap that could be positioned for nominal takeoff or approach flap settings. Far field noise data are presented for the flyover mode. The data are discussed in terms of sound power and sound pressure spectra. Implications of extending the small-scale model acoustic data to full-scale aircraft are discussed briefly and indicate a sizeable flyover noise attenuation may be achieved due to shielding by the wing.

Vonglahn, U. H.↗

NASA NTRS1980

Physiological response to hyper- and hypogravity during rollercoaster flight

Twenty-six healthy male subjects were flown in a Lear jet aircraft through rollercoaster and parabolic weightlessness flight. Eye movements, respiration, and blood volume pulse were recorded on magnetic tape. The same subjects underwent a battery of five vestibular tests in the laboratory on the ground. One subject in each flight was flown in an upright position, the other in a 90 deg forward tilted head position. The forward tilted subjects always reported motion sickness earlier and after fewer rollercoaster maneuvers than the upright-sitting subjects. It is concluded that the susceptibility to changes of X-axis acceleration is higher than to changes of Z-axis acceleration. Correlation was found between the ability to estimate the subjective vertical (modified Mueller-Aubert-test), optokinetic nystagmus asymmetries, and susceptibility to rollercoaster flight sickness.

Von Baumgarten, R. J.↗

NASA NTRS1981

A head-up display format for transport aircraft approach and landing

An electronic flight-guidance display format was designed for use in evaluations of the collimated head-up display concept applied to transport aircraft landing. In the design process of iterative evaluation and modification, some general principles, or guidelines, applicable to electronic flight displays were suggested. The usefulness of an indication of instantaneous inertial flightpath was clearly demonstrated. Evaluator pilot acceptance of the unfamiliar display concepts was very positive when careful attention was given to indoctrination and training.

Bray, R. S.↗

NASA NTRS1982

Aerodynamic characteristics of a large-scale, twin tilt-nacelle V/STOL model

A subsonic tilt-nacelle V/STOL aircraft configuration is described which is powered by two turbofan engines, mounted on a single carry-through structure that is designed to maintain the thrust axis close to the center of gravity at nacelle incidences of 5-95 deg. Control during V/STOL operation, often from small ship platforms, is achieved by means of a vane assembly that is immersed in each turbofan's exhaust. Wind tunnel test data have been obtained with an 11.2-m wing span model for the vertical-to-horizontal flight transition capability of the concept. It is found that the aircraft can operate over a broad transition corridor, with sufficient maneuver capability about the trim points. The control vane exhibited linear response characteristics over a large deflection range, with little influence from power, angle of attack or ground proximity in hover. The model induced a positive ground effect in hover that increased as wheel height was approached and strake angle increased.

Falarski, M. D.↗

NASA NTRS1983

Design and flight testing of a digital landing approach autopilot

An important feature in General Aviation (GA) autopilots is the ability to intercept and hold the glideslope and localizer during a landing approach. Most General Aviation landing approach autopilots available today use analog systems. This paper presents the designs of digital landing approach autopilots for a General Aviation (NAVION) aircraft using modern linear quadratic control theory. Each constant gain, direct digitally designed autopilot operates synchronously at a slow rate (10 samples per second) and has modest memory requirements, i.e., a full state Kalman filter is not used. The autopilot is designed to track desired position trajectories constructed in an ILS or MLS terminal area using command generators. Alternative command errors for intercepting and holding the localizer beam centerline are investigated. Linear simulations and flight test results are presented demonstrating the successful application of the linear quadratic regulator approach.

Broussard, J. R.↗

NASA NTRS2005

Space-Based Range Safety and Future Space Range Applications

The National Aeronautics and Space Administration (NASA) Space-Based Telemetry and Range Safety (STARS) study is a multiphase project to demonstrate the performance, flexibility and cost savings that can be realized by using space-based assets for the Range Safety [global positioning system (GPS) metric tracking data, flight termination command and range safety data relay] and Range User (telemetry) functions during vehicle launches and landings. Phase 1 included flight testing S-band Range Safety and Range User hardware in 2003 onboard a high-dynamic aircraft platform at Dryden Flight Research Center (Edwards, California, USA) using the NASA Tracking and Data Relay Satellite System (TDRSS) as the communications link. The current effort, Phase 2, includes hardware and packaging upgrades to the S-band Range Safety system and development of a high data rate Ku-band Range User system. The enhanced Phase 2 Range Safety Unit (RSU) provided real-time video for three days during the historic Global Flyer (Scaled Composites, Mojave, California, USA) flight in March, 2005. Additional Phase 2 testing will include a sounding rocket test of the Range Safety system and aircraft flight testing of both systems. Future testing will include a flight test on a launch vehicle platform. This paper discusses both Range Safety and Range User developments and testing with emphasis on the Range Safety system. The operational concept of a future space-based range is also discussed.

Whiteman, Donald E.↗