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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Wind Tunnel-Based Aerodynamic Model Identification for a Tilt-Wing, Distributed Electric Propulsion Aircraft

This paper describes the methodology used to develop a high-fidelity aerodynamic model for the Langley Aerodrome No. 8 (LA-8) tandem tilt-wing, distributed electric propulsion, vertical takeoff and landing aircraft. Electric vertical takeoff and landing (eVTOL) vehicle configurations exhibit aerodynamic characteristics of both fixed-wing and rotary-wing aircraft as well as complex vehicle-specific phenomena, such as propeller-wing interactions and high incidence angle propeller aerodynamics. Consequently, conventional aircraft aerodynamic modeling strategies require modification when applied to eVTOL aircraft. Two novel system identification-based approaches are used to develop an aerodynamic model for the LA-8 aircraft configuration using wind tunnel data collected with design of experiments techniques. The modeling strategies are compared by assessing their predictive performance for validation data acquired separately from the data used to identify the model and are shown to have sufficient predictive capability. Research findings are presented with a discussion of unique eVTOL aerodynamic modeling characteristics and practical strategies to inform future aerodynamic modeling efforts for eVTOL aircraft.

Urban Air Mobility↗
NASA NTRSDate not supplied

Introduction to Aircraft Icing and NASA’s Approach to Understanding It

This presentation provides a brief introduction to aircraft icing and NASA’s approach to understanding it. Specific topics that will be discussed include ice formation on an aircraft, the different types of ice, parameters that influence icing, engine and rotorcraft icing, and NASA’s approach to understanding icing through flight tests, wind tunnels tests, and computational tools. The presentation concludes with a look into the future of aviation and how it will be affected by icing.

Icing↗
NASA NTRSDate not supplied

Impact of Technology and Mission Variations on Aircraft Designed for Advanced Air Mobiity

NASA is conducting investigations in Advanced Air Mobility (AAM) aircraft and operations, including the development of Urban Air Mobility (UAM) aircraft designs that can be used to focus and guide research activities in support of AAM. This report is an investigation of the impact of technology and mission variations on several of the NASA AAM concept aircraft: quadrotor, quiet single main rotor, side-by-side, and tiltrotor configurations, with turboshaft and electric propulsion variants for each. First, the mission and aircraft models of the baseline designs were reassessed and updated, including rotor geometry optimization, update of the rotor performance models, and disk loading optimization. For these eight designs, technology and mission excursions were performed. Relative to the calibration cases that can be considered examples of good design practice, the impact of the weight technology factors is significant. For the electric aircraft, there is a very large impact of battery specific energy (Wh/kg), and correspondingly a very large impact of mission range. The vision of Advanced Air Mobility is driven by missions that will enable new transportation capabilities. Hence it is appropriate to compare Concept Vehicles of different lift and propulsive architectures, all designed to accomplish the same UAM mission. It is also useful however to consider specific missions that can take advantage of the strengths of individual aircraft configurations. So alternate designs were also developed for the concept vehicles: for turboshaft aircraft, longer unrefueled range, including faster cruise speed for the tiltrotor; for electric aircraft, shorter range and more realistic battery weight.

Technology↗
NASA NTRS1972

Engine selection for transport and combat aircraft.

Review of the procedures used to select engines for transport and combat aircraft by illustrating the procedures for a long haul CTOL transport, a short haul VTOL transport, a long range SST, and a fighter aircraft. For the CTOL transport, it is shown that advances in noise technology and advanced turbine cooling technology will greatly reduce the airplane performance penalties associated with achieving low noise goals. A remote lift fan powered by a turbofan air generator is considered for the VTOL aircraft. In this case, the lift fan pressure ratio which maximizes payload also comes closest to meeting the noise goal. High turbine temperature in three different engines is considered for the SST. Without noise constraints it leads to an appreciable drop in DOC, but with noise constraints the reduction in DOC is very modest. For the fighter aircraft it is shown how specific excess power requirements play the same role in engine selection as noise constraints for commercial airplanes.

Dugan, J. F., Jr.↗
NASA NTRS1975

Recent NASA progress in composites

The application of composites in aerospace vehicle structures is reviewed. Research and technology program results and specific applications to space vehicles, aircraft engines, and aircraft and helicopter structures are discussed in detail. Particular emphasis is given to flight service evaluation programs that are or will be accumulating substantial experience with secondary and primary structural components on military and commercial aircraft to increase confidence in their use.

Heldenfels, R. R.↗
NASA NTRS1975

Modelling atmospheric turbulence for a motion-based simulator

The background information in establishing several proposed atmospheric turbulence models for use on motion based aircraft simulators was documented. A specific model was proposed which, in addition to varying turbulence intensity (rms velocity), varies the atmospheric turbulence scale length to achieve compatibility with real atmospheric turbulence. With a suitable combination of scale length and intensity distribution, the model will simulate various atmospheric conditions characterized by altitude, stability, and terrain. The model is mechanized to be included in a flight simulator experiment in order to determine to what extent the pilots are sensitive to changes in atmospheric conditions and the realism of the model. The following topics were covered: literature survey, presently used techniques, proposed model, and simulation details.

Jacobson, I. D.↗
NASA NTRS1976

Research requirements to reduce empty weight of helicopters by use of advanced materials

Utilization of the new, lightweight, high-strength, aerospace structural-composite (filament/matrix) materials, when specifically designed into a new aircraft, promises reductions in structural empty weight of 12 percent at recurring costs competive with metals. A program of basic and applied research and demonstration is identified with the objective of advancing the state of the art to the point where civil helicopters are confidently designed, produced, certified, and marketed by 1985. A structural empty-weight reduction of 12 percent was shown to significantly reduce energy consumption in modern high-performance helicopters.

Hoffstedt, D. J.↗
NASA NTRS1981

Composite structural materials

The development of composite materials for aircraft applications is addressed with specific consideration of physical properties, structural concepts and analysis, manufacturing, reliability, and life prediction. The design and flight testing of composite ultralight gliders is documented. Advances in computer aided design and methods for nondestructive testing are also discussed.

Ansell, G. S.↗
NASA NTRS1983

DC-link approach to constant-frequency aircraft power

This paper discusses a hybrid high-power aircraft electrical system that has very difficult and complex operating requirements. Many issues raised in selecting an approach for this application are similar to those that must eventually be addressed for a large all-electric aircraft. The requirements for this specific system are reviewed, a solution for those requirements is proposed, and some explanation is provided for the choice. Because the system requires a substantial amount of 400-Hz power, a dc-link system was selected to provide that power.

Yorksi, D. S.↗
NASA NTRS1985

Human factors in cockpit automation: A field study of flight crew transition

The factors which affected two groups of airline pilots in the transition from traditional airline cockpits to a highly automated version were studied. All pilots were highly experienced in traditional models of the McDonnell-Douglas DC-9 prior to their transition to the more automated DC-9-80. Specific features of the new aircraft, particularly the digital flight guidance system (DFGS) and other automatic features such as the autothrottle system (ATS), autobrake, and digital display were studied. Particular attention was paid to the first 200 hours of line flying experience in the new aircraft, and the difficulties that some pilots found in adapting to the new systems during this initial operating period. Efforts to prevent skill loss from automation, training methods, traditional human factors issues, and general views of the pilots toward cockpit automation are discussed.

Wiener, E. L.↗
NASA NTRS1987

Cockpit Resource Management (CRM) training in the 349th military airlift wing

CRM training can be done on a limited budget. It seems that everyone has a special name for their CRM program. A new program was created and entitled, Aircrew Resource Management (ARM) to emphasize the use of the full resources on our aircraft. That is meant to specifically include the loadmasters. The name also emphasizes the concept that all crewmembers are responsible for safe completion of the trip. The loadmasters have been the brightest students to date. They are a classic under-utilized resource. Together, their crew position has been credited with more ARM saves than the engineers and pilots. The seminar-based program is run by two seminar facilitators that is reinforced by Line Oriented Flight Training sessions run by the active-duty counterparts.

Halliday, John T.↗
NASA NTRS1992

Nozzle material requirements and the status of intermetallic matrix composites

The HSCT exhaust nozzle must manage high temperature exhaust gases and pressure gradients while meeting HSCT economic and noise goals. The important features and requirements for an HSCT exhaust nozzle are shown for a 2DCD (two-dimensional convergent-divergent) design. The same requirements would apply to an axisymmetric design. Exhaust nozzle weight has an adverse effect on the overall aircraft range, payload, and engine specific fuel consumption and is therefore the primary driver for advanced exhaust nozzle materials. Because of the large airflow and pressure gradients, exhaust nozzles are extremely large and heavy when made from current materials. The use of advanced materials with higher specific strength will reduce the weight of exhaust nozzle components. In addition to the flow of high-temperature exhaust gases into the exhaust nozzle, ambient air is entrained to reduce gas exit velocities and suppress sound. This leads to components exposed to extremely high temperature gradients and, hence, high thermal stresses. Further, exhaust gases are highly oxidizing; material environmental resistance will be an important factor for long life. Several viable concepts have been identified to reduce noise through the mixture of exhaust and ambient air. Sound can be further suppressed by acoustic panels that absorb high-frequency noise.

Johnson, Andrew M.↗
NASA NTRS1999

Determining Usability Versus Cost and Yields of a Regional Transport

Regional transports are designed to operate on air networks having the basic characteristics of short trip distances and low density passengers/cargo, i.e. small numbers of passengers per flight. Regional transports passenger capacity is from 10 to 100 seats and operate on routes from 350 to 1000 nautical miles (nm). In order to meet passenger requirements providing low fares and high or required number of frequencies, airlines must constantly monitor operational costs and keep them low. It is obvious that costs of operating aircraft must be lower than yield obtained by transporting passengers and cargo. The requirement to achieve favorable yield/cost ratio must provide the answer to the question of which aircraft will best meet a specific air network (Simpson, 1972). An air network is defined by the number of services, the trip distance of each service, and the number of flights (frequencies) per day and week.

Gvozdenovic, Slobodan↗
NASA NTRS2000

ICEG2D: An Integrated Software Package for Automated Prediction of Flow Fields for Single-Element Airfoils with Ice Accretion

An integrated software package, ICEG2D, was developed to automate computational fluid dynamics (CFD) simulations for single-element airfoils with ice accretion. ICEG2D is designed to automatically perform three primary functions: (1) generating a grid-ready, surface definition based on the geometrical characteristics of the iced airfoil surface, (2) generating a high-quality grid using the generated surface point distribution, and (3) generating the input and restart files needed to run the general purpose CFD solver NPARC. ICEG2D can be executed in batch mode using a script file or in an interactive mode by entering directives from a command line. This report summarizes activities completed in the first year of a three-year research and development program to address issues related to CFD simulations for aircraft components with ice accretion. Specifically, this document describes the technology employed in the software, the installation procedure, and a description of the operation of the software package. Validation of the geometry and grid generation modules of ICEG2D is also discussed.

Thompson, David S.↗
NASA NTRS1999

Determining Usability Versus Cost and Yields of a Regional Transport

Regional transports are designed to operate on air networks having the basic characteristics of short trip distances and low density passengers/cargo, i.e. small numbers of passengers per flight. Regional transports passenger capacity is from 10 to 100 seats and operate on routes from 350 to 1000 nautical miles (nm). An air network operated by regional transports has the following characteristics: (1) connecting regional centers; (2) operating on low density passengers/cargo flow services with minimum two frequencies per day; (3) operating on high density passengers/cargo flow with more than two frequencies per day; and (4) operating supplemental services whenever market demands in order to help bigger capacity aircraft already operating the same routes. In order to meet passenger requirements providing low fares and high or required number of frequencies, airlines must constantly monitor operational costs and keep them low. It is obvious that costs of operating aircraft must be lower than yield obtained by transporting passengers and cargo. The requirement to achieve favorable yield/cost ratio must provide the answer to the question of which aircraft will best meet a specific air network. An air network is defined by the number of services, the trip distance of each service, and the number of flights (frequencies) per day and week.

Gvozdenovic, Slobodan↗
NASA NTRS2000

Small Engine Technology (SET) Task 23 ANOPP Noise Prediction for Small Engines, Wing Reflection Code

The work performed under Task 23 consisted of the development and demonstration of improvements for the NASA Aircraft Noise Prediction Program (ANOPP), specifically targeted to the modeling of engine noise enhancement due to wing reflection. This report focuses on development of the model and procedure to predict the effects of wing reflection, and the demonstration of the procedure, using a representative wing/engine configuration.

Lieber, Lysbeth↗
NASA NTRS1991

Flight Planning

Seagull Technology, Inc., Sunnyvale, CA, produced a computer program under a Langley Research Center Small Business Innovation Research (SBIR) grant called STAFPLAN (Seagull Technology Advanced Flight Plan) that plans optimal trajectory routes for small to medium sized airlines to minimize direct operating costs while complying with various airline operating constraints. STAFPLAN incorporates four input databases, weather, route data, aircraft performance, and flight-specific information (times, payload, crew, fuel cost) to provide the correct amount of fuel optimal cruise altitude, climb and descent points, optimal cruise speed, and flight path.

Source record↗