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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Feasibility of a Networked Air Traffic Infrastructure Validation Environment for Advanced NextGen Concepts

Abstract-Next Generation Air Transportation System (NextGen) applications reliant upon aircraft data links such as Automatic Dependent Surveillance-Broadcast (ADS-B) offer a sweeping modernization of the National Airspace System (NAS), but the aviation stakeholder community has not yet established a positive business case for equipage and message content standards remain in flux. It is necessary to transition promising Air Traffic Management (ATM) Concepts of Operations (ConOps) from simulation environments to full-scale flight tests in order to validate user benefits and solidify message standards. However, flight tests are prohibitively expensive and message standards for Commercial-off-the-Shelf (COTS) systems cannot support many advanced ConOps. It is therefore proposed to simulate future aircraft surveillance and communications equipage and employ an existing commercial data link to exchange data during dedicated flight tests. This capability, referred to as the Networked Air Traffic Infrastructure Validation Environment (NATIVE), would emulate aircraft data links such as ADS-B using in-flight Internet and easily-installed test equipment. By utilizing low-cost equipment that is easy to install and certify for testing, advanced ATM ConOps can be validated, message content standards can be solidified, and new standards can be established through full-scale flight trials without necessary or expensive equipage or extensive flight test preparation. This paper presents results of a feasibility study of the NATIVE concept. To determine requirements, six NATIVE design configurations were developed for two NASA ConOps that rely on ADS-B. The performance characteristics of three existing in-flight Internet services were investigated to determine whether performance is adequate to support the concept. Next, a study of requisite hardware and software was conducted to examine whether and how the NATIVE concept might be realized. Finally, to determine a business case, economic factors were evaluated and a preliminary cost-benefit analysis was performed.

McCormack, Michael J.↗
DOE OSTI2021

Joint CO 2 Mole Fraction and Flux Analysis Confirms Missing Processes in CASA Terrestrial Carbon Uptake Over North America

Terrestrial biosphere models (TBMs) play a key role in the detection and attribution of carbon cycle processes at local to global scales and in projections of the coupled carbon-climate system. TBM evaluation commonly involves direct comparison to eddy-covariance flux measurements. This study uses atmospheric CO 2 mole fraction ([CO 2 ]) measured in situ from aircraft and tower, in addition to flux-measurements from summer 2016 to evaluate the CASA TBM. WRF-Chem is used to simulate [CO 2 ] using biogenic CO 2 fluxes from a CASA parameter-based ensemble and CarbonTracker version 2017 (CT2017) in addition to transport and CO 2 boundary condition ensembles. The resulting “super ensemble” of modeled [CO 2 ] demonstrates that the biosphere introduces the majority of uncertainty to the simulations. Both aircraft and tower [CO 2 ] data show that the CASA ensemble net ecosystem exchange (NEE) of CO 2 is biased high (NEE too positive) and identify the maximum light use efficiency E max a key parameter that drives the spread of the CASA ensemble in summer 2016. These findings are verified with flux-measurements. The direct comparison of the CASA flux ensemble with flux-measurements confirms missing sink processes in CASA. Separating the daytime and nighttime flux, we discover that the underestimated net uptake results from missing sink processes that result in overestimation of respiration. NEE biases are smaller in the CT2017 posterior biogenic fluxes, which assimilates observed [CO 2 ]. Flux tower analyses, however, reveal an unrealistic overestimation of nighttime respiration in CT2017 due to the limitation of inversion strategy.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1971

Flight investigation of airframe installation effects on an auxiliary inlet ejector nozzle on an underwing engine nacelle

The local flow field approaching an installed nozzle may vary from isolated test conditions, thereby affecting exhausting nozzle performance. An installation of general interest is a podded engine mounted near the aft lower surface of the wing. The effect of this installation on the performance of an auxiliary inlet ejector nozzle was investigated over a Mach number range of 0.7 to 1.3 by using a modified F-106B aircraft. Both floating and fixed-open door configurations were examined. The ejector nozzle trailing-edge flaps were simulated in the closed position with rigid structure which provided a boattail angle of 15 deg. Primary nozzle area was varied as exhaust gas temperature was varied between 982.2 and 2003.3 K.

Burley, R. R.↗
NASA NTRS1973

Navigation, guidance, and control systems for V/STOL aircraft.

The development of digital autopilots and integrated avionics systems, applicable to many classes of vehicles and missions, was undertaken by Sperry Flight Systems in the mid-sixties. The first application of the system was planned for automatic flight control in the U.S. supersonic transport; the termination of that program, however, thwarted any flight experience. The second application, which has additional navigation and energy management functions, is an airborne simulator of the space shuttle vehicle. The latter system underwent a series of successful flight tests in a CV-990 aircraft under contract with NASA. The third application, which has new electronic displays, air data computation, and time-constrained guidance (i.e., specified position and altitude at a specified time), is in the DOT/NASA STOLAND test program. The STOLAND system is described specifically in this paper.

Osder, S. S.↗
NASA NTRS1973

High temperature lubricant screening and systems studies

Four candidate lubricants for next generation aircraft gas turbine application were tested under open atmosphere conditions in a rig simulating an advanced engine 125 mm bore mainshaft thrust bearing position. Testing was conducted at speeds to 24,000 rpm (3,000,000 bearing DN), bearing ring temperature of 500 F, and with 1200 F air and 100 psi differential pressure across the seals installed in a dual tandem arrangement. Test bearing was a 125 mm bore split inner ring, outer race riding angular contact ball bearing under a 3280 lb. thrust load. One lubricant, a type 2 ester, performed extremely well. The mainshaft seal limited the performance. Numerous design improvements for this seal were indicated.

Jones, D. A.↗
NASA NTRS1977

Surface fluctuating pressure measurements on a 1/4-scale YC-14 boilerplate model

A research program is conducted for the study of the fluctuating loads imposed on both upper-surface blown-flap and externally blown-flap powered-lift STOL aircraft configurations by the impingement of the jet engine exhaust flow. Attention is given to the measurement of the unsteady pressures at 30 positions in the vicinity of the jet exhaust on the surface of a NASA 1/4-scale YC-14 boilerplate wing and fuselage section.

Pappa, R. S.↗
NASA NTRS1979

A simulation investigation of cockpit display of aircraft traffic during curved, descending, decelerating approaches

The results of a simulation experiment involving the evaluation of cockpit display of aircraft traffic information are presented. The experiment was conducted using taped time dependent, noninteractive traffic in an approach to landing situation and two levels of pilot control models: 3-D automatic and computer augmented control. The tests involved two cases: the simulation aircraft flew approach paths which (1) followed another aircraft in between two other aircraft, and (2) merged between two other aircraft. Speed control via manual throttles was used in all tests (path stretching was not allowed for maintaining separation between aircraft). The approaches were conducted while the simulation aircraft was conducting a curved, descending, decelerating approach to landing. Performance data sets were examined, and subjective opinions regarding workload were gathered. Traffic positioning was varied to further evaluate the test subjects' monitoring performance.

Steinmetz, G. G.↗
NASA NTRS1983

Miniature Two-Axis Joystick Controller

Novel movable-button-actuated self-centering controller uses optoelectronics to produce X and Y signals for aircraft control. In addition to be extremely compact, device puts our voltages having high signal-to-noise ratio, especially at critical center position where in many controllers this ratio is poorest. Combination of new saddle-shaped button and positive centering gives "feel" and "breakout" met with pilot approval.

Hollow, R.↗
NASA NTRS1982

QCSEE Over-the-Wing Engine Acoustic Data

The over the wing (OTW) Quiet, Clean, Short Haul Experimental Engine (QCSEE) was tested at the NASA Lewis Engine Noise Test Facility. A boilerplate (nonflight weight), high throat Mach number, acoustically treated inlet and a D shaped OTW exhaust nozzle with variable position side doors were used in the tests along with wing and flap segments to simulate an installation on a short haul transport aircraft. All of the acoustic test data from 10 configurations are documented in tabular form. Some selected narrowband and 1/3 octave band plots of sound pressure level are presented.

Bloomer, H. E.↗
NASA NTRS1981

Exploration for fractured petroleum reservoirs using radar/Landsat merge combinations

Since fractures are commonly propagated upward and reflected at the earth's surface as subtle linears, detection of these surface features is extremely important in many phases of petroleum exploration and development. To document the usefulness of microwave analysis for petroleum exploration, the Arkansas part of the Arkoma basin is selected as a prime test site. The research plan involves comparing the aircraft microwave imagery and Landsat imagery in an area where significant subsurface borehole geophysical data are available. In the northern Arkoma basin, a positive correlation between the number of linears in a given area and production from cherty carbonate strata is found. In the southern part of the basin, little relationship is discernible between surface structure and gas production, and no correlation is found between gas productivity and linear proximity or linear density as determined from remote sensor data.

Macdonald, H.↗
NASA NTRS1990

Array Of Rockets For Multicrewmember Evacuation

Emergency egress system undergoing development for aircraft and aerospace vehicles uses fixed array of tractor rockets to eject crewmembers. Crewmembers hook up to tractor rockets and fire them unaided. Positioned as unit in ready-to-use orientation during flight operations. On ground, swung out of way. Rocket array also mounts under exit hatch, serving as egress ramp.

Allen, Margaret A.↗
NASA NTRS1992

Appraisal of digital terrain elevation data for low-altitude flight

The use of terrain elevation databases in advanced guidance and navigation systems has greatly expanded. However, the limitations and accuracies of these databases must be considered and established prior to safe system flight evaluation. A simple approach to quantify reasonable flight limits is presented and evaluated for a helicopter guidance system dependent on a terrain database. The flight test evaluated involved a helicopter equipped with a Global Positioning System (GPS) receiver and radar altimeter, and a ground station GPS receiver which provided improved helicopter positioning. The precision navigation and radar altimeter data was acquired while flying low-altitude missions in south-central Pennsylvania. The aircraft-determined terrain elevations were compared with the terrain predicted by the Defense Mapping Agency (DMA) Level 1 terrain elevation data for the same area. The results suggest a safe set clearance altitude of 220 ft for flight testing of a DMA-based guidance avionic in the same area.

Zelenka, Richard E.↗
NASA NTRS1992

Appraisal of digital terrain elevation data for low-altitude flight

The use of terrain elevation databases in advanced guidance and navigation systems has greatly expanded. However, the limitations and accuracies of these databases must be considered and established prior to safe system flight evaluation. A simple approach to quantify reasonable flight limits is presented and evaluated for a helicopter guidance system dependent on a terrain database. The flight test evaluated involved a helicopter equipped with a Global Positioning System (GPS) receiver and radar altimeter, and a ground station GPS receiver which provided improved helicopter positioning. The precision navigation and radar altimeter data was acquired while flying low-altitude missions in south-central Pennsylvania. The aircraft-determined terrain elevations were compared with the terrain predicted by the Defense Mapping Agency (DMA) Level 1 terrain elevation data for the same area. The results suggest a safe set clearance altitude of 220 ft for flight testing of a DMA-based guidance avionic in the same area.

Zelenka, Richard E.↗
NASA NTRS1992

Helicopter precision approach capability using the Global Positioning System

The period between 1 July and 31 December, 1992, was spent developing a research plan as well as a navigation system document and flight test plan to investigate helicopter precision approach capability using the Global Positioning System (GPS). In addition, all hardware and software required for the research was acquired, developed, installed, and verified on both the test aircraft and the ground-based reference station.

Kaufmann, David N.↗
NASA NTRS1995

Acoustic flight tests of rotorcraft noise-abatement approaches using local differential GPS guidance

This paper presents the test design, instrumentation set-up, data acquisition, and the results of an acoustic flight experiment to study how noise due to blade-vortex interaction (BVI) may be alleviated. The flight experiment was conducted using the NASA/Army Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) research helicopter. A Local Differential Global Positioning System (LDGPS) was used for precision navigation and cockpit display guidance. A laser-based rotor state measurement system on board the aircraft was used to measure the main rotor tip-path-plane angle-of-attack. Tests were performed at Crows Landing Airfield in northern California with an array of microphones similar to that used in the standard ICAO/FAA noise certification test. The methodology used in the design of a RASCAL-specific, multi-segment, decelerating approach profile for BVI noise abatement is described, and the flight data pertaining to the flight technical errors and the acoustic data for assessing the noise reduction effectiveness are reported.

Chen, Robert T. N.↗
NASA NTRS1995

Weather Information System

WxLink is an aviation weather system based on advanced airborne sensors, precise positioning available from the satellite-based Global Positioning System, cockpit graphics and a low-cost datalink. It is a two-way system that uplinks weather information to the aircraft and downlinks automatic pilot reports of weather conditions aloft. Manufactured by ARNAV Systems, Inc., the original technology came from Langley Research Center's cockpit weather information system, CWIN (Cockpit Weather INformation). The system creates radar maps of storms, lightning and reports of surface observations, offering improved safety, better weather monitoring and substantial fuel savings.

Source record↗
NASA NTRS2011

High-Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement

One of key NASA goals is to develop and integrate noise reduction technology to enable unrestricted air transportation service to all communities. One of the technical priorities of this activity has been to account for and reduce noise via propulsion/airframe interactions, identifying advanced concepts to be integrated with the airframe to mitigate these noise-producing mechanisms. An adaptive geometry chevron using embedded smart structures technology offers the possibility of maximizing engine performance while retaining and possibly enhancing the favorable noise characteristics of current designs. New high-temperature shape memory alloy (HTSMA) materials technology enables the devices to operate in both low-temperature (fan) and high-temperature (core) exhaust flows. Chevron-equipped engines have demonstrated reduced noise in testing and operational use. It is desirable to have the noise benefits of chevrons in takeoff/landing conditions, but have them deployed into a minimum drag position for cruise flight. The central feature of the innovation was building on rapidly maturing HTSMA technology to implement a next-generation aircraft noise mitigation system centered on adaptive chevron flow control surfaces. In general, SMA-actuated devices have the potential to enhance the demonstrated noise reduction effectiveness of chevron systems while eliminating the associated performance penalty. The use of structurally integrated smart devices will minimize the mechanical and subsystem complexity of this implementation. The central innovations of the effort entail the modification of prior chevron designs to include a small cut that relaxes structural stiffness without compromising the desired flow characteristics over the surface; the reorientation of SMA actuation devices to apply forces to deflect the chevron tip, exploiting this relaxed stiffness; and the use of high-temperature SMA (HTSMA) materials to enable operation in the demanding core chevron environment. The overall conclusion of these design studies was that the cut chevron concept is a critical enabling step in bringing the variable geometry core chevron within reach. The presence of the cut may be aerodynamically undesirable in some respects, but it is present only when the chevron is not immersed in the core jet exhaust. When deployed, the gap closes as the chevron tip enters the high-speed, high-temperature core stream. Aeroacoustic testing and flow visualization support the contention that this cut is inconsequential to chevron performance.

Quackenbush, Todd R.↗
NASA NTRS2017

Methods and Apparatus for Deployable Swirl Vanes

An aircraft control structure for drag management includes a nozzle structure configured to exhaust a swirling fluid stream. A plurality of swirl vanes are positioned within the nozzle structure, and an actuation subsystem is configured to cause the plurality of swirl vanes to move from a deployed state to a non-deployed state. In the non-deployed state, the plurality of swirl vanes are substantially flush with the inner surface of the nozzle structure. In the deployed state, the plurality of swirl vanes produce the swirling fluid stream.

Shah, Parthiv N.↗