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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Sustainable Aviation Fuel (SAF) State-of-Industry Report: State of SAF Production Process

GHG emissions related to commercial air travel were already significant, at 10% of the domestic transportation emissions and 3% of the global greenhouse gas emissions prior to the pandemic, and are expected to double by 2050, even with modest projected growth in air travel. Since Sustainable Aviation Fuel (SAF) is the only way that medium to long haul commercial aviation can be decarbonized, a US government wide "SAF Grand Challenge" was issued to encourage industry to develop capabilities to produce SAF, to reduce cost, improve sustainability, build value chains, and to scale production capabilities (1). The targets are to expand current domestic SAF 2022 production by 200X to 3 billion gallons per year by 2030, and then further by 12X to 35 billion gallons by 2050, while achieving life cycle GHG reduction of 50% relative to fossil Jet A. Following the SAF Grand Challenge, the DOE, USDA, EPA and FAA collaboratively developed a comprehensive strategy, outlined in the "SAF Grand Challenge Roadmap" (2), to inform stakeholders of the actions necessary to achieve the above volumetric targets. The purpose of this study is to provide an assessment of the current state of the SAF production industry and identify challenges and hurdles that industry may face in delivering the 2030 goals. This assessment is for the potential feedstocks and conversion pathways expected to contribute to 2030 goals and will generally follow action areas in the SAF Grand Challenge: feedstocks, conversion technology, supply chain, and policy & valuation.

09 BIOMASS FUELS↗
NASA NTRS2018

High-Fidelity Computational Methodology for Stitched Composite Aerospace Structures

Due to the high demands for energy efficient commercial transportation, the aviation industry has taken a leading role in the integration of composite structures. Among the leading concepts to develop lighter, more fuel-efficient commercial transport is the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept, an enabling technology for hybrid wing bodies. Many proof-of-concept tests have been performed to demonstrate that the use of PRSEUS has improved the residual strength of damaged structures compared to conventional composite structures, but efficient computational tools must be developed before the concept can be commercially certified and implemented. In an attempt to address the need for efficient computational tools, a comprehensive modeling approach is developed and applied to investigate applications of PRSEUS at multiple scales. Therefore, a computational methodology has been progressively developed based on physically realistic concepts. The focus of the work described herein is to define the modeling characteristics required to accurately simulate the damage progression and failure of PRSEUS at the coupon scale. The work herein is focused on the development and analysis of a PRSEUS stringer, the methodology for which may be extended to other PRSEUS coupons and components.

Brandon Horton↗
NASA NTRS1991

General aviation - Transportation in transition

An overview is presented of the current status of general aviation and some of the problems that it faces. Of some 220,000 active general aviation aircraft in the U.S., 195,000 are piston engine powered single- or twin-engine aircraft, that conflict with the large high-speed commercial jet transports throughout the operating spectrum. The access to airport conflict shows that the limiting factor is not airspace or airport size, but rather airway structures and airport systems that have failed to keep pace with demand. Design and development of an aircraft that can routinely fly a 150 mph approach, achieve rapid but controlled deceleration to touchdown speed, and turn off at an early exit is required. GPS satellites could provide precision approach capability to all airports and runways for commercial and general aviation aircraft.

Stickle, Joseph W.↗
NASA NTRS1980

Current and projected use of carbon composites in United States aircraft

It is noted that carbon composite materials are beginning to be used in commercial transports, general aviation aircraft, military fighter aircraft and helicopters due to demonstrated weight savings and potential manufacturing cost savings. Attention is given to current production applications of carbon composites which range from the secondary structures of new commercial transports to wing primary structures of fighters. Current development efforts are discussed that will lead to their future application to fuselages, as well as whole airframes. Finally, laminate constructions which vary widely, and may be relevant to avionics system design, are examined.

Leonard, R. W.↗
NASA NTRSDate not supplied

Multiclass Flight Anomaly Detection Using Sensor Fusion Based on Dempster-Shafer Theory

As aviation systems in commercial operations continue to grow in complexity, the anomalies exhibited by these systems become more elaborate and difficult to detect. To address the challenge of detecting these complex anomalies, deep learning models have been used extensively in aviation anomaly detection studies, at the expense of end-user interpretability. Aiming to maintain the same level of interpretability as traditional threshold-exceedance methods, we continue our development of prediction models using ordinal patterns and their distributions throughout the flight. Specifically, this study extends our work into multiclass anomaly detection using sensor fusion based on Dempster-Shafer theory (DST), a second-order probability theory used to combine information from different sources of evidence. Our approach uses DST to reduce the uncertainty in the class predictions of an ensemble of classifiers. These classifiers rely on the similarity between flight data and class templates to make a prediction of the state of the aircraft. Our approach aims to take advantage of simple models trained on interpretable features (ordinal patterns) to correctly predict an anomaly and identify the flight dynamics linked to the anomaly. Our results show an improvement when using DST-based sensor fusion over simple majority voting. Additionally, our results provide insight into aircraft states linked to rare high-risk anomalies.

Risk detection↗
NASA NTRSDate not supplied

Multiclass Flight Anomaly Detection Using Sensor Fusion Based on Dempster-Shafer Theory

As aviation systems in commercial operations continue to grow in complexity, the anomalies exhibited by these systems become more elaborate and difficult to detect. To address the challenge of detecting these complex anomalies, deep learning models have been used extensively in aviation anomaly detection studies, at the expense of end-user interpretability. Aiming to maintain the same level of interpretability as traditional threshold-exceedance methods, we continue our development of prediction models using ordinal patterns and their distributions throughout the flight. Specifically, this study extends our work into multiclass anomaly detection using sensor fusion based on Dempster-Shafer theory (DST), a second-order probability theory used to combine information from different sources of evidence. Our approach uses DST toreduce the uncertainty in the class predictions of an ensemble of classifiers. These classifiers rely on the similarity between flight data and class templates to make a prediction of the state of the aircraft. Our approach aims to take advantage of simple models trained on interpretable features (ordinal patterns) to correctly predict an anomaly and identify the flight dynamics linked to the anomaly. Our results show an improvement when using DST-based sensor fusion over simple majority voting. Additionally, our results provide insight into aircraft states linked to rare high-risk anomalies.

Risk detection↗
NASA NTRS1975

Optically coupled digital altitude encoder for general aviation altimeters

An optically coupled pressure altitude encoder which can be incorporated into commercially available inexpensive general aviation altimeters was successfully developed. The encoding of pressure altitude is accomplished in 100-ft (30.48-m) increments from -1000 to 20,000ft (-304.8 to 6096 m). The prototype encoders were retrofitted into two different internal altimeter configurations. A prototype encoder was checked for accuracy of transition points and environmental effects. Each altimeter configuration, with the encoder incorporated, was laboratory tested for performance and was subsequently flight-tested over the specified altitude range. With few exceptions, the assembled altimeter-encoder met aeronautical standards for altimeters and encoders. Design changes are suggested to improve performance to meet required standards consistently.

Bryant, F. R.↗
NASA NTRSDate not supplied

Impact of General Aviation Operations on Airport Performance Through Fast-Time Simulations at Charlotte Douglas International Airport

NASA, in partnership with the Federal Aviation Administration and commercial airlines, deployed the Integrated Arrival, Departure, and Surface (IADS) traffic management system at Charlotte Douglas International Airport (CLT) in 2017 for field evaluation. The system features new capabilities of data exchange and integration, collaborative surface metering and scheduling, which has demonstrated operational benefits of reducing delay time and fuel consumption. General Aviation flights, however, are not currently included in the surface metering programs because of their different operational procedures and lack of reliable predictability in departure time. Thus, their impact on the system performance is not well understood. This paper presents a study of the impact of General Aviation traffic at CLT using fast-time simulations.

General Aviation↗
NASA NTRS2021

Commercial Hypersonic Transportation Market Study

In support of NASA’s evaluation of its future research thrusts for its hypersonics program, NASA commissioned independent studies of the market for commercial hypersonic transportation. SAIC and BryceTech (formerly Bryce Space and Technology) were awarded one of these independent studies to assist NASA in better understanding: (1) the passenger demand for high-speed aviation travel; (2) the pressures on the business case for developing and operating a hypersonic aircraft for the commercial aviation market; and (3) the non-technical (i.e., societal) barriers and challenges, including the steps NASA and the Government could take to overcome those barriers and challenges. Our approach to addressing these three tasks for NASA included modeling future demand and future business operations, considering global air transportation at speeds of Mach 2 to Mach 7. The team forecast premium air travel demand through 2060 and assessed the willingness of passengers of different income and wealth levels to pay to save time on flights between 800 city pairs. With the total addressable market defined, we examined industry-level business case viability for several aircraft speed and range cases. Considering operating and manufacturing costs for routes that could be serviced profitably, as well as typical profitability targets for the aviation industry, we quantified the level of RDT&E funding available to support each business case.

hypersonic aircraft↗
NASA NTRS2021

Independent Market Study: Commercial Hypersonic Transportation

In support of NASA’s evaluation of its future research thrusts for its hypersonics program, NASA commissioned independent studies of the market for commercial hypersonic transportation. SAIC and BryceTech (formerly Bryce Space and Technology) were awarded one of these independent studies to assist NASA in better understanding: (1) the passenger demand for high-speed aviation travel; (2) the pressures on the business case for developing and operating a hypersonic aircraft for the commercial aviation market; and (3) the non-technical (i.e., societal) barriers and challenges, including the steps NASA and the Government could take to overcome those barriers and challenges. Our approach to addressing these three tasks for NASA included modeling future demand and future business operations, considering global air transportation at speeds of Mach 2 to Mach 7. The team forecast premium air travel demand through 2060 and assessed the willingness of passengers of different income and wealth levels to pay to save time on flights between 800 city pairs. With the total addressable market defined, we examined industry-level business case viability for several aircraft speed and range cases. Considering operating and manufacturing costs for routes that could be serviced profitably, as well as typical profitability targets for the aviation industry, we quantified the level of RDT&E funding available to support each business case.

hypersonic aircraft↗
NASA NTRS1972

Broadcast control of air traffic

Applications of wide range broadcast procedures to improve air traffic control and make more airspace available are discussed. A combination of the Omega navigation system and the very high frequency omnirange (VOR) is recommended as a means for accomplishing improved air traffic control. The benefits to be derived by commercial and general aviation are described. The air/ground communications aspects of the improved air traffic control system are explained. Research and development programs for implementing the broadcast concept are recommended.

Litchford, G. B.↗
NASA NTRS1977

Methods of reducing low frequency cabin noise and sonically induced stresses, based on the intrinsic structural tuning concept

Control of low frequency interior noise has been difficult in all commercial and general aviation aircraft, since the existing sound attenuation techniques are less effective at these frequencies. Therefore low frequency cabin noise and sonically induced stresses can be reduced mainly by a proper design of the fuselage structure. For this purpose, a concept based on intrinsic tuning and damping of fuselage structural elements has been under development at Boeing for the past three years. This paper describes the results of some laboratory and field tests that were conducted for evaluation of the concept.

Sengupta, G.↗
NASA NTRS1979

Analytical evaluation of the impact of broad specification fuels on high bypass turbofan engine combustors

Six conceptual combustor designs for the CF6-50 high bypass turbofan engine and six conceptual combustor designs for the NASA/GE E3 high bypass turbofan engine were analyzed to provide an assessment of the major problems anticipated in using broad specification fuels in these aircraft engine combustion systems. Each of the conceptual combustor designs, which are representative of both state-of-the-art and advanced state-of-the-art combustion systems, was analyzed to estimate combustor performance, durability, and pollutant emissions when using commercial Jet A aviation fuel and when using experimental referee board specification fuel. Results indicate that lean burning, low emissions double annular combustor concepts can accommodate a wide range of fuel properties without a serious deterioration of performance or durability. However, rich burning, single annular concepts would be less tolerant to a relaxation of fuel properties. As the fuel specifications are relaxed, autoignition delay time becomes much smaller which presents a serious design and development problem for premixing-prevaporizing combustion system concepts.

Taylor, J. R.↗
NASA NTRS1981

The future of aeronautical propulsion

This keynote address discusses some of the future challenges and opportunities confronting aeronautics where propulsion is a key factor. The discussion covers various aircraft types including commercial transports, general aviation and military aircraft and identifies propulsion technology required to accommodate further advancements in these types of aircraft. This is then followed by a discussion of some of the emerging technologies that, if properly exploited, will have significant effect on the engines of the '90's. Some comments on further advancements in the traditional technologies are also included.

Stewart, W. L.↗
NASA NTRS1980

Recommendations for the NASA Avionics program for the 1980's

NASA is examining the merits of a significant expansion of its avionics, controls, and human factors technology program for the 1980's. The rationale for an expanded program is related to two factors. One factor is related to a utilization of recent and anticipated significant advances in microelectronics. The second factor is the need to develop new concepts in avionics and control systems for more efficient aircraft operation and better utilization of extremely limited airport capacity. Substantial benefits could be realized in three major categories, including improved aircraft efficiency, improved flight operations, and improved/extended operational capability. The NASA Avionics, Controls, and Human Factors Technology Plan is the report of a task force of agency personnel working in close cooperation with industry, DOD, and FAA. Attention is given to the NASA role, aircraft controls, crew station technology, flight management, integration and interfacing, commercial transports, general aviation, rotorcraft, V/STOL, and high performance aircraft.

Spitzer, C. R.↗
NASA NTRS1983

Flight test validation of a design procedure for digital autopilots

Commercially available general aviation autopilots are currently in transition from an analogue circuit system to a computer implemented digital flight control system. Well known advantages of the digital autopilot include enhanced modes, self-test capacity, fault detection, and greater computational capacity. A digital autopilot's computational capacity can be used to full advantage by increasing the sophistication of the digital autopilot's chief function, stability and control. NASA's Langley Research Center has been pursuing the development of direct digital design tools for aircraft stabilization systems for several years. This effort has most recently been directed towards the development and realization of multi-mode digital autopilots for GA aircraft, conducted under a SPIFR-related program called the General Aviation Terminal Operations Research (GATOR) Program. This presentation focuses on the implementation and testing of a candidate multi-mode autopilot designed using these newly developed tools.

Bryant, W. H.↗