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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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A high-level description of NASA GRC research in electrical materials is presented with a brief description of the AATTHGEP funding project. To be presented at the Interagency Advanced Power Group Electrical Materials panel session.
This presentation delves into a recent evaluation conducted at NASA-Ames on the Vertical Motion Simulator, focusing on the handling qualities of Distributed Electric Propulsion VTOL (eVTOL) aircraft, specifically tailored for Urban Air Mobility (UAM) applications. The presentation will focus on the recent effort to adapt and refine use of the Aeronautical Design Standard -33 (ADS-33) rotorcraft handling qualities developed by the U.S. Army and NASA to meet the diverse needs of civilian (eVTOL) concept evaluation. A brief discussion of the author’s personal test pilot insights in the early development of military Fly-By-Wire evaluation methods will also be provided. The emergence of innovative eVTOL designs with unique lift capabilities and flight control systems, present both opportunities and challenges, particularly in ensuring safety amidst technological complexity. To navigate these challenges, our investigation examined evaluation criteria designed to accommodate the varied configurations and advanced automation systems inherent in modern eVTOL aircraft. By establishing a standardized approach to evaluation, our research not only fosters innovation but also upholds safety standards in the dynamic landscape of urban air mobility. Through this endeavor, we help to facilitate the seamless integration of novel aircraft capabilities into new operations, contributing to a new era of safe and efficient aerial transportation.
This presentation delves into a recent evaluation conducted at NASA-Ames on the Vertical Motion Simulator, focusing on the handling qualities of Distributed Electric Propulsion VTOL (eVTOL) aircraft, specifically tailored for Urban Air Mobility (UAM) applications. The presentation will focus on the recent effort to adapt and refine use of the Aeronautical Design Standard -33 (ADS-33) rotorcraft handling qualities developed by the U.S. Army and NASA to meet the diverse needs of civilian (eVTOL) concept evaluation. A brief discussion of the author’s personal test pilot insights in the early development of military Fly-By-Wire evaluation methods will also be provided. The emergence of innovative eVTOL designs with unique lift capabilities and flight control systems, present both opportunities and challenges, particularly in ensuring safety amidst technological complexity. To navigate these challenges, our investigation examined evaluation criteria designed to accommodate the varied configurations and advanced automation systems inherent in modern eVTOL aircraft. By establishing a standardized approach to evaluation, our research not only fosters innovation but also upholds safety standards in the dynamic landscape of urban air mobility. Through this endeavor, we help to facilitate the seamless integration of novel aircraft capabilities into new operations, contributing to a new era of safe and efficient aerial transportation.
Electrified aircraft have the potential to provide significant benefits for efficiency and emissions reductions. To assess these potential benefits, modeling tools are needed to provide rapid evaluation of diverse concepts and to ensure safe operability and peak performance over the mission. The modeling challenge for these vehicles is the ability to show significant benefits over the current highly refined aircraft systems. The STARC-ABL (single-aisle turbo-electric aircraft with an aft boundary layer propulsor) is a new test proposal that builds upon previous N3-X team hybrid designs. This presentation describes the STARC-ABL concept, the NASA Electric Aircraft Testbed (NEAT) which will allow testing of the STARC-ABL powertrain, and the related modeling and simulation efforts to date. Modeling and simulation includes a turbofan simulation, Numeric Propulsion System Simulation (NPSS), which has been integrated with NEAT; and a power systems and control model for predicting testbed performance and evaluating control schemes. Model predictions provide good comparisons with testbed data for an NPSS-integrated test of the single-string configuration of NEAT.
Small-scale aircraft are being electrified with small e-aircraft already certified to fly and with test flights underway for retrofits of existing aircraft focused on near-term deployment. Internationally, from 2018 to 2020, the number of electric aircraft projects underway increased 50%. These technologies are projected to increase operational efficiency and reduce emissions and noise from a growing aviation sector. This emerging interest in aviation electrification includes aircraft, energy supply equipment, and battery storage manufacturers. Federal agencies are currently funding a variety of efforts including technology research as well as forecasting demand and environmental impacts and state governments have also begun pushing for further investigation in this area. This paper provides an overview of the current state and potential future development of aviation electrification. To understand the types of research questions around current and future challenges for this emerging sector, we consider a case study of the potential deployment of small commercial electric aircraft for existing, under-served markets and consider operational requirements and technical challenges as well as the range of questions that will need to be addressed around charging infrastructure, grid integration, policy and regulatory requirements, and emissions impacts. This case study also outlines potential nearer-term solutions and research areas of interest that will need to be addressed in the longer term at much larger scales and highlights NREL capabilities for addressing these challenges.
High voltage hybrid electric propulsion systems are now pushing new technology development efforts for air transportation. A key challenge in hybrid electric aircraft is safe high voltage distribution and transmission of megawatts of power (>20 MW). For the past two years, a multidisciplinary materials research team at NASA Glenn Research Center has investigated the feasibility of distributing high voltage power on future hybrid electric aircraft. This presentation describes the team's approach to addressing this challenge, significant technical findings, and next steps in GRC's materials research effort for MW power distribution on aircraft.
High specific power density, megawatt-scale electric machines (motors and generators) are needed to enable megawatt-scale electric aircraft propulsion systems for single isle aircraft. Thermally insulating electrical insulation materials in the stator windings limits the ability to thermally manage the heat produced in these machines. Polymer-ceramic composites along with novel processing techniques offer viable options to improve the thermal conductivity of the electrical insulation system. This paper outlines current National Aeronautics and Space Administration’s Glenn Research Center efforts of developing several polymer-ceramic systems and processing techniques as they relate to electric machine insulation (including potting). There is also analysis of how these factors relate to machine performance.
Electric aircraft applications require electric motors with increased specific power and efficiency. Composite structural components in motors are a potential solution for reducing motor mass, reducing magnetic losses, and limiting undesired conduction paths for fault, electromagnetic interference, or common-mode currents. In this report, manufacturing trials for a high-speed carbon fiber reinforced polymer composite motor shaft are presented. Four prototype shafts were produced using a hybrid biaxial/triaxial fabric that was circumferentially wrapped onto an additively manufactured high-temperature washout mandrel. An additional traditional overbraid approach was also evaluated and shows promise for high-rate, high-performance parts using automated manufacturing. This paper discusses the shaft design, manufacturing methods explored, material selection, the manufacturing trials, and the lessons learned. The results of this manufacturing investigation show feasibility for manufacturing composite shafts for electric motors.
This presentation provides the NASA perspective for government and industry technology developers world-wide who are exploring the potential for hydrogen (H2) in aviation applications including electric aircraft, airport vehicles, and airport related equipment. NASA’s H2 interest has been related to vehicle-level technology development and integration only, but NASA is keenly aware of the necessity of work focused on solving the challenges of H2 airport infrastructure. Some historical perspectives are provided on NASA efforts in H2 fuel cell development for space and aeronautics applications. NASA’s current research portfolio includes some investigation of H2 energy storage and hydrocarbon conversion for fuel cells on electric aircraft. There is no current emphasis on the other H2-related challenges. Over the years NASA has conducted research into “Quiet Green Transport” with a H2 fuel cell powered aircraft, an Emissionless Aircraft Study with Non Flow Through – Regenerative Fuel Cell (NFT-RFC) technology which captures the water, and an H2 fuel cell powered Unmanned Aerial Vehicle (UAV) study. NASA has flown a long endurance UAV using a RFC in the Low Emissions Alternative Power (LEAP) program. Recently, NASA conducted feasibility studies on hybrid SOFC with onboard hydrocarbon fuel reformation for aircraft primary propulsive power and secondary power under the Fostering Ultra-Efficient, Low-Emitting Aviation Power (FUELEAP) program. NASA currently has a multiyear program with the Center for Cryogenic High-Efficiency Electrical Technologies for Aircraft (CHEETA) to explore the benefits of using cryogenic H2 on aircraft for fuel cell propulsion and to provide superconductivity in electrical power management on the aircraft.
Hydrogen has gained significant traction in research as a potential carbon-neutral fuel for future aircraft propulsion. The focus of this paper is on the hydrogen-electric aircraft (HEA) propulsion system which is a highly integrated network of high-power electrical, mechanical, fluidic, cryogenic, and thermal management components. These systems require careful analysis to determine the most efficient and light-weight design that ultimately reduces carbon emissions and operating cost. Fuel cell and energy storage sizing and optimization will be major factors that contribute to the aircraft feasibility independent of hydrogen storage. This paper describes the framework and modeling approach for the analysis of hydrogen-electric aircraft (HEA) propulsion systems for a under the National Aeronautics and Space Administration (NASA) Commercially-viable Hydrogen Aircraft for Reduction of Greenhouse Emissions (CH 2 ARGE) Project. For the first time, the Electrical Power System – Sizing and Analysis Tool (EPS-SAT) is used to conduct the sizing and trade studies on the hydrogen-electric aircraft propulsion system.
A variety of tools, from fundamental to high order, have been used to better understand applications of distributed electric propulsion to aid the wing and propulsion system design of the Leading Edge Asynchronous Propulsion Technology (LEAPTech) project and the X-57 Maxwell airplane. Three high-fidelity, Navier-Stokes computational fluid dynamics codes used during the project with results presented here are FUN3D, STAR-CCM+, and OVERFLOW. These codes employ various turbulence models to predict fully turbulent and transitional flow. Results from these codes are compared for two distributed electric propulsion configurations: the wing tested at NASA Armstrong on the Hybrid-Electric Integrated Systems Testbed truck, and the wing designed for the X-57 Maxwell airplane. Results from these computational tools for the high-lift wing tested on the Hybrid-Electric Integrated Systems Testbed truck and the X-57 high-lift wing presented compare reasonably well. The goal of the X-57 wing and distributed electric propulsion system design achieving or exceeding the required 𝐶 (sub L) = 3.95 for stall speed was confirmed with all of the computational codes.
A gas turbine engine is anywhere from 40-50% efficient. A large amount of energy is wasted as heat. Some of this heat is recoverable through the use of energy harvesting and can be used for powering on-board systems or for storing energy in batteries to replace auxiliary power units (APUs). As hybrid electric aircraft become more common, the use of energy harvesting will see increasingly more benefit and become commonplace in gas turbine engines. For electric aircraft with motors, TEGs would be beneficial for reclaiming waste heat from electric motors. The primary focus of this work was to evaluate the feasibility of harvesting energy from the hot section of a gas turbine engine (for a single aisle Boeing 737 thrust class) using thermoelectric generators (TEGs). The resulting heat could be used to power on-board actuation mechanisms such as plasma actuators and piezoelectric actuators. The work is a result of a two year NASA Center Innovation Fund from 2009 to 2011. The trade-off between thermoelectric harvesting and blade surface temperature were studied to ensure that blade durability is not adversely impacted by embedding a low thermal conductivity TEG. Calculations show that.5-10 Watts can be harvested per blade depending on flow conditions and on the thermoelectric material chosen. BiTe and SiGe were used for this analysis and future thermoelectric generators or multiferroic alloys could considerably improve power output.
The physical design and operation of electric aircraft like NASA Maxwell X-57 are significantly different than conventionally fueled aircraft. Operational optimization will require close coupling of aerodynamics, propulsion, and power. To address the uncertainty of electric aircraft operation, a system level Mission Planning Tool is developed to simulate all aircraft trajectory phases: taxi, motor run-up, takeoff, climb, cruise, and descent. The Mission Planning Tool captures performance parameters at each point of the trajectory including battery state of charge, the temperatures of components in the electrical system, and propulsion system thrust. This work describes the modeling of each mission phase, and compares the results of simulating a user-specified trajectory, and using a collocated optimal control approach to determine an optimal trajectory. The results show that optimization of the mission show a significant increase in the final battery state of charge over the user- specified simulation strategy. These results will inform the operation of the NASA Maxwell X-57 test flights that will take place this year.
A hybrid-electric aircraft flying testbed was developed in this program with the intent to serve as a dedicated, enduring testbed to test and evaluate ARPA-e CIRCUITS Program and other electrified aviation technologies in relevant flight environments. This testbed enabled rapid development cycles of novel and innovative technologies in the electrified aviation space, maturing them from a research lab environment to flying in an aircraft. By providing research groups with the means to test their transformative technologies in a real-world, aircraft environment, the path to validating the safety and reliability of their technologies for future commercial opportunities was greatly accelerated. Three core technologies were integrated and tested: an inverter/motor drive built by the University of Arkansas, a solid-state circuit breaker (iBreaker) built by the Illinois Institute of Technology, and a Flying Capacitor Multi-level (FCML) DC/DC converter built by the University of California, Berkeley. In each of these cases, the requirements established for safety of flight resulted in a holistic approach to the designs, evoking a deeper understanding of the potential failure modes and mitigations necessary to build a robust and flightworthy system. Further, the integration into a hybrid-electric aircraft de-risked the potential electrical and mechanical issues that cannot easily be experienced or replicated in a lab environment. The experiments were also required to undergo representative temperature, shock, and vibration testing as the FAA prescribes for this category of aircraft, facilitating familiarity with the relevant design and test guidelines necessary to commercialize the technologies. This testbed unlocks the massive potential of core power electronics technologies necessary for a safe, robust, and efficient electric aviation future. With quick iterative design, test, and flight cycles, these core technologies are on a quicker path to technology readiness level maturity and commercialization, enabling a more sustainable future for the aviation industry.
NASA is developing a new hybrid-electric aircraft concept called the SUbsonic Single Aft eNgine (SUSAN) Electrofan. The SUSAN airplane is being designed as a 180-passenger commercial regional jet and is expected to fly in the 2040 time frame. The flight deck of the SUSAN airplane is expected to resemble a typical two flightcrew transport. Research issues include pilot control and the display elements needed for the hybrid-electric propulsion system. This paper describes a research study conducted in a high-fidelity simulator where 14 commercial pilots evaluated throttle controls and engine display concepts for a proposed SUSAN flight deck. The results showed that the number of throttle levers did not affect pilot’s situation awareness, workload, or speed control.
Aircraft measurement of electric fields is difficult as the electrically conducting surface of the aircraft distorts the electric field. Calibration requires determining the relations between the undistorted electric field in the absence of the vehicle and the signals from electric field meters that sense the local distorted fields in their immediate vicinity. This paper describes a generalization of a calibration method which uses pitch and roll maneuvers. The technique determines both the calibration coefficients and the direction of the electric vector. The calibration of individual electric field meters and the elimination of the aircraft's self-charge are described. Linear combinations of field mill signals are examined and absolute calibration and error analysis are discussed. The calibration method was applied to data obtained during a flight near thunderstorms.
Among the potential future technologies for low-carbon transport aircraft, all-electric concepts stand out environmentally, yet their feasibility and cost-effectiveness at scale remain uncertain. This paper examines the conceptual design of an all-electric 150-passenger aircraft with a range of 840 NM based on assumed future battery cell-level specific energy of1620Wh/kg. The tube and wing design is propelled by open rotors driven by four electric motors per nacelle and utilizes advanced structural materials for weight reduction. Powertrain technology gaps are identified. The conceptual design shows that all-electric aviation could supplant about 30% of current fossil fuel use by transport aircraft and potentially more with air-traffic-control modifications.
The basic purpose of this paper is to provide some information regarding bidirectional four quadrant resonant power conversion and describe possible applications to aircraft electrical systems. As this technology has been developed sufficiently to demonstrate its feasibility, this is an appropriate time to evaluate the benefits of its application to aircraft electrical systems.