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NASA NTRS2019

Physics-Based Modeling and Simulation of Emerging Battery Technologies for Aerospace

Recently there is a growing interest in the aviation sector to reduce air and noise pollution. Electrochemical energy storage devices such as batteries coupled with a distributed electric propulsion system can reduce noise concerns as well as emissions and allow the concept of Urban Air Mobility to come to fruition. The battery performance needs to improve considerably compared from current state-of-art Li-ion battery (about 200Wh/Kg) to realize all-electric passenger jet for short flights (up to 690 miles). NASA is exploring lithium-oxygen battery chemistry to power hybrid (battery powered electrical system) and all-electric aircraft for short distance and long-distance flights. Li-O2 is one of the advanced Li-ion technologies that promise to provide specific energy of more than 750Wh/Kg. For this presentation, we present our work on improving power density of Li-O2 batteries through the use of multiphysics simulations. Next, a path is outlined to port these model to simulate performance for a new battery chemistry for space application, Li-CO2. Li-CO2 uses carbon dioxide as the active material instead of oxygen. Although this technology is in its early development, the offers two benefits: it can be used as a CO2 scrubber, as oxygen is one of the by-products on charging, and as a backup or a standalone battery for various Mars or Venus missions, where the carbon dioxide content in the atmosphere is high and need battery to operate at higher temperatures.

Mehta, Mohit↗
NASA NTRS2019

Reliability Requirements and Research Strategies for Urban Air Mobility Propulsion

An emerging new mission for aeronautics is Urban Air Mobility (UAM), a concept for air transportation around metropolitan areas with passenger-carrying operations. UAM vehicles must be capable of vertical take-off and landing, and this requirement presents unique technical challenges for electric and hybrid-based vertical take-off and landing (eVTOL). A critical challenge for UAM market growth is to gain public acceptance for being as safe as - or safer than - commercial air travel and automotive transportation. There is a lack of data for propulsion systems, components, and the associated thermal management systems for UAM eVTOL propulsion systems. The new mission, new propulsion system concepts, safety criticality of propulsion component performance during vertical take-off and lift operations, and lack of data presents many research challenges and opportunities. NASA has developed and published UAM vehicle concept studies. For a subset of the said concept vehicles, NASA has contracted for a study to identify failure modes and hazards associated with the propulsion systems of the concept vehicles and to perform functional hazard analyses (FHA) and failure modes and effects criticality analyses (FMECA) for each. From the completed study results, it was recommended for NASA to support research toward developing electric/hybrid-electric propulsion components with improved reliability and to explore powertrain architectures that can take advantage of higher reliability components to achieve inherent air-vehicle safety. NASA has started a research effort for UAM propulsion with a focus toward improving safety and reliability. Recent results and research strategy will be discussed toward the goals by means of: 1) improving individual component reliability through advanced materials and design methods, 2) improving the thermal management system, and 3) designing propulsion system architectures to provide inherent UAM vehicle safety.

Krantz, Timothy↗
NASA NTRS2019

Workload Considerations in Urban Air Mobility

Urban air mobility (UAM) is receiving increased attention in aviation as a system for passenger and cargo-carrying new entrants in urban airspace. In order to develop a safe and efficient system, numerous possible concepts of operation for UAM are being explored throughout industry and research domains, the features and assumptions of which may differ according to near, medium and far term operations. Much of the current research into the development of UAM has dominantly focused on technological and engineering capabilities, such as vehicle development. Although these areas of research are essential to furthering UAM, research into the role of the human operator in UAM is limited. The research described in this paper aims to begin to address this gap by investigating the capabilities and implications of human operators as traffic managers in the UAM system, focusing on near-term UAM operations. A human in the loop air traffic control simulation was used to investigate the effect of UAM traffic density, airspace routes and communication procedures on subjective workload and efficiency-related task performance. Findings indicate that medium and high-density operations were associated with high workload. A reduction in verbal communications through a letter of agreement, and optimized routes, were associated with reduced workload and increased performance efficiency. However, even with these adjustments, reported workload remained high, particularly during the high-density scenario. Future research should focus on the human operator roles and responsibilities, and the amount of involvement, in UAM system management. Particular focus should be directed on the impact of reduced human operator involvement and increased automation, on the safety and efficiency of UAM operations and the integration of UAM with traditional air traffic management.

Edwards, Tamsyn↗
NASA NTRS2019

Key Technologies, Systems, and Infrastructure Enabling the Commercialization and Human Settlement of the Moon and Cislunar Space

Over 50 years have passed since 2001: A Space Odyssey debuted in April 1968. In the film, Dr. Heywood Floydflies to a large artificial gravity space station orbiting Earth aboard a commercial space plane. He then embarks on acommuter flight to the Moon arriving there 25 hours later. Today, in this the 50th anniversary year of the Apollo 11lunar landing, the images portrayed in 2001 still remain well beyond our capabilities. This paper examines keytechnologies and systems (e.g., in-situ resource utilization, fission power, advanced chemical and nuclearpropulsion), and supporting orbital infrastructure (providing a propellant and cargo transfer function), that could bedeveloped by NASA and industry over the next 30 years allowing the operational capabilities presented in 2001 to beachieved, albeit on a more spartan scale. Lunar-derived propellants (LDPs) will be essential to developing a reusablelunar transportation system that can allow initial outposts to evolve into settlements supporting a variety ofcommercial activities. Deposits of icy regolith discovered at the lunar poles can supply the feedstock material neededto produce liquid oxygen (LO2) and hydrogen (LH2) propellants. On the lunar nearside, near the equator, iron oxiderichvolcanic glass beads from vast pyroclastic deposits, together with mare regolith, can provide the feedstockmaterials to produce lunar-derived LO2 plus other important solar wind implanted (SWI) volatiles, including H2and helium-3. Megawatt-class fission power systems will be essential for providing continuous "24/7" power toprocessing plants, human settlements and commercial enterprises that develop on the Moon and in orbit. Reusablelunar landing vehicles will provide cargo and passenger "orbit-to-surface" access and will also transport LDP toSpace Transportation Nodes (STNs) located in lunar polar (LPO) and equatorial orbits (LLO). Reusable space-based,lunar transfer vehicles (LTVs), operating between STNs in low Earth orbit, LLO, and LPO, and able to refuel withLDPs, offer unique mission capabilities including short transit time crewed cargo transports. Even commuter flightssimilar to that portrayed in 2001 appear possible, allowing 1-way trip times to and from the Moon as short as 24hours. The performance of LTVs using both RL10B-2 chemical rockets, and a variant of the nuclear thermal rocket(NTR), the LO2-Augmented NTR (LANTR), are examined and compared. If only 1% of the LDP obtained from icyregolith, volcanic glass, and SWI volatile deposits were available for use in lunar orbit, such a supply could supportroutine commuter flights to the Moon for many thousands of years. This paper provides a look ahead at what mightbe possible in the not too distant future, quantifies the operational characteristics of key in-space and surfacetechnologies and systems, and provides conceptual designs for the various architectural elements discussed.

Borowski, Stanley K.↗
NASA NTRS2020

Computational Study of NASA's Quadrotor Urban Air Taxi Concept

High-fidelity computational fluid dynamics simulations have been carried out in order to analyze NASA's quadrotor urban air taxi concept for urban air mobility, also know as on-demand mobility applications. High-order accurate schemes, dual-time stepping, and the delayed detached-eddy simulation model have been employed. The ow solver has been loosely coupled with a rotorcraft comprehensive analysis code. The vehicle simulated is a six-passenger quadrotor for air taxi operations. A study of power reduction as a function of the rear-rotor to front-rotors vertical separation has been performed, for a quad-rotor without the airframe, in cruise flight conditions. Then, the quadrotor without the airframe has been simulated in hover. The airloads and wake geometries are analyzed. To finish the study the complete quadrotor vehicle is presented. NASA's quadrotor air taxi concept is one of the many concepts being developed by NASA in support of aircraft development for vertical take-o and landing air taxi operations.

Ventura Diaz, Patricia↗
NASA NTRS2019

Key Technologies, Systems, and Infrastructure Enabling the Commercialization and Human Settlement of the Moon and Cislunar Space

Over 50 years have passed since 2001: A Space Odyssey debuted in April 1968. In the film, Dr. Heywood Floydflies to a large artificial gravity space station orbiting Earth aboard a commercial space plane. He then embarks on acommuter flight to the Moon arriving there 25 hours later. Today, in this the 50th anniversary year of the Apollo 11lunar landing, the images portrayed in 2001 still remain well beyond our capabilities. This paper examines keytechnologies and systems (e.g., in-situ resource utilization, fission power, advanced chemical and nuclearpropulsion), and supporting orbital infrastructure (providing a propellant and cargo transfer function), that could bedeveloped by NASA and industry over the next 30 years allowing the operational capabilities presented in 2001 to beachieved, albeit on a more spartan scale. Lunar-derived propellants (LDPs) will be essential to developing a reusablelunar transportation system that can allow initial outposts to evolve into settlements supporting a variety ofcommercial activities. Deposits of icy regolith discovered at the lunar poles can supply the feedstock material neededto produce liquid oxygen (LO2) and hydrogen (LH2) propellants. On the lunar nearside, near the equator, iron oxiderichvolcanic glass beads from vast pyroclastic deposits, together with mare regolith, can provide the feedstockmaterials to produce lunar-derived LO2 plus other important solar wind implanted (SWI) volatiles, including H2and helium-3. Megawatt-class fission power systems will be essential for providing continuous "24/7" power toprocessing plants, human settlements and commercial enterprises that develop on the Moon and in orbit. Reusablelunar landing vehicles will provide cargo and passenger "orbit-to-surface" access and will also transport LDP to Space Transportation Nodes (STNs) located in lunar polar (LPO) and equatorial orbits (LLO). Reusable space-based,lunar transfer vehicles (LTVs), operating between STNs in low Earth orbit, LLO, and LPO, and able to refuel with LDPs, offer unique mission capabilities including short transit time crewed cargo transports. Even commuter flights similar to that portrayed in 2001 appear possible, allowing 1-way trip times to and from the Moon as short as 24hours. The performance of LTVs using both RL10B-2 chemical rockets, and a variant of the nuclear thermal rocket(NTR), the LO2-Augmented NTR (LANTR), are examined and compared. If only 1% of the LDP obtained from icyregolith, volcanic glass, and SWI volatile deposits were available for use in lunar orbit, such a supply could support routine commuter flights to the Moon for many thousands of years. This paper provides a look ahead at what might be possible in the not too distant future, quantifies the operational characteristics of key in-space and surface technologies and systems, and provides conceptual designs for the various architectural elements discussed.

Borowski, Stanley K.↗
NASA NTRS2020

Accessibility Design and Operational Considerations in the Development of Urban Aerial Mobility Vehicles and Networks

Urban aerial mobility vehicles and networks have recently gained considerable interest in the aviation community. These small, short-range vehicles with all-electric or hybrid-electric propulsion systems, tailored to metropolitan aerial transportation needs, promise to radically change passenger mobility and cargo distribution in cities. Accessibility issues have not been a major consideration in UAM vehicle and network discussions to date. This paper seeks to help change that.

Young, Larry A.↗
NASA NTRS2019

Towards Urban Air Mobility: NASA’s Quadcopter Air Taxi Concept

Urban Air Mobility (UAM) is envisioned to be the future air transportation system over populated areas, where everything from small package delivery drones to passenger-carrying air taxis are able to interact safely and efficiently. The capacity of multi-rotor vehicles to perform vertical takeoff and landing (VTOL), together with their great maneuverability, make them an excellent choice for UAM aircraft. The accurate prediction of multirotor vehicles performance and acoustics is very challenging due to the unsteady and complex flows, as well as the aerodynamic interactions. By running high-fidelity computational fluid dynamics simulations on NASA supercomputers, researchers model the complex aerodynamics of multi-rotor flows, getting us closer to making UAM a reality.

Ventura Diaz, Patricia↗
NASA NTRS2020

Architecture and Information Requirements to Assess and Predict Flight Safety Risks During Highly Autonomous Urban Flight Operations

As aviation adopts new and increasingly complex operational paradigms, vehicle types, and technologies to broaden airspace capability and efficiency, maintaining a safe system will require recognition and timely mitigation of new safety issues as they emerge and before significant consequences occur. A shift toward a more predictive risk mitigation capability becomes critical to meet this challenge. In-time safety assurance comprises monitoring, assessment, and mitigation functions that proactively reduce risk in complex operational environments where the interplay of hazards may not be known (and therefore not accounted for) during design. These functions can also help to understand and predict emergent effects caused by the increased use of automation or autonomous functions that may exhibit unexpected non-deterministic behaviors. The envisioned monitoring and assessment functions can look for precursors, anomalies, and trends (PATs) by applying model-based and data-driven methods. Outputs would then drive downstream mitigation(s) if needed to reduce risk. These mitigations may be accomplished using traditional design revision processes or via operational (and sometimes automated) mechanisms. The latter refers to the ‘in-time’ aspect of the system concept. This report comprises architecture and information requirements and considerations toward enabling such a capability within the domain of low altitude highly autonomous urban flight operations. This domain may span, for example, public-use surveillance missions flown by small unmanned aircraft (e.g., infrastructure inspection, facility management, emergency response, law enforcement, and/or security) to transportation missions flown by larger aircraft that may carry passengers or deliver products. Caveat: Any stated requirements in this report should be considered initial requirements that are intended to drive research and development (R&D). These initial requirements are likely to evolve based on R&D findings, refinement of operational concepts, industry advances, and new industry or regulatory policies or standards related to safety assurance.

Young, Steven↗
NASA NTRS2019

Commercialization and Human Settlement of the Moon and Cislunar Space – A Look Ahead at the Possibilities over the Next 50 Years

Over 50 years have passed since the movie 2001: A Space Odyssey debuted in April 1968. In the film, Dr. Heywood Floyd flies to a large artificial gravity space station orbiting Earth aboard a commercial space plane. He then embarks on a commuter flight to the Moon arriving there 25hours later. Today, on the 50th anniversary of the Apollo 11 lunar landing, the images portrayed in 2001 still remain well beyond our capabilities. This paper examines key technologies and systems (in-situ resource utilization, fission power, advanced chemical and nuclear propulsion),and orbiting infrastructure elements (providing a propellant depot and cargo transfer function),that could be developed by NASA and the private sector in future decades allowing the operational capabilities presented in 2001 to be achieved, albeit on a more spartan scale. Lunar derived propellants (LDPs) will be essential to reducing the launch mass requirements from Earth and developing a reusable lunar transportation system (LTS) that can allow initial outposts to evolve into settlements supporting a variety of commercial activities like in-situ propellant production. Deposits of icy regolith found within permanently shadowed craters at the lunar pole scan supply the feedstock material to produce liquid oxygen (LO2) and hydrogen (LH2) propellan tneeded by surface-based lunar landing vehicles (LLVs) using chemical rocket engines. Along the Moon's nearside equatorial corridor, iron oxide-rich volcanic glass beads from vast pyroclasticdeposits, together with mare regolith, can provide the materials to produce lunar-derived LO2plus other important solar wind implanted (SWI) volatiles, including H2 and helium-3. Mega watt classfission power systems will be essential for providing continuous "24/7" power to LLVs will provide cargo and passenger "orbit-to-surface" access and willalso be used to transport LDP to Space Transportation Nodes (STNs) located in lunar polar(LPO) and equatorial orbits (LLO). Spaced-based, reusable lunar transfer vehicles (LTVs),operating between STNs in low Earth orbit (LEO), LLO, and LPO, and able to refuel with LDPs,can offer unique mission capabilities including short transit time crewed cargo transports. Even acommuter shuttle service similar to that portrayed in 2001 appears possible, allowing 1-way trip times to and from the Moon as short as 24 hours. The performance of LTVs using both RL10B-2chemical rockets, and a variant of the nuclear thermal rocket (NTR), the LO2-Augmented NTR(LANTR), are examined and compared. The bipropellant LANTR engine utilizes its divergent nozzle section as an afterburner into which oxygen is injected and supersonically combusted with reactor-heated hydrogen emerging from the engine's sonic throat. If only 1% of the LDP obtained from icy regolith, volcanic glass, and SWI volatile deposits were available for use in lunar orbit,such a supply could support routine commuter flights to the Moon for many thousands of years!This paper provides a look ahead at what might be possible in the not too distant future,quantifies the operational characteristics of key in-space and surface technologies and systems,and provides conceptual designs for the various architectural elements discussed.

Borowski, Stanley K.↗
NASA NTRS2019

Commercial and Human Settlement of the Moon and Cislunar Space – A Look Ahead at the Possibilities over the Next 50 Years

Over 50 years have passed since the movie 2001: A Space Odyssey debuted in April 1968. In the film, Dr. Heywood Floyd flies to a large artificial gravity space station orbiting Earth aboard a commercial space plane. He then embarks on a commuter flight to the Moon arriving there 25 hours later. Today, on the 50th anniversary of the Apollo 11 lunar landing, the images portrayed in 2001 still remain well beyond our capabilities. This paper examines key technologies and systems (in-situ resource utilization, fission power, advanced chemical and nuclear propulsion), and orbiting infrastructure elements (providing a propellant depot and cargo transfer function), that could be developed by NASA and the private sector in future decades allowing the operational capabilities presented in 2001 to be achieved, albeit on a more spartan scale. Lunar-derived propellants (LDPs) will be essential to reducing the launch mass requirements from Earth and developing a reusable lunar transportation system (LTS) that can allow initial outposts to evolve into settlements supporting a variety of commercial activities like in-situ propellant production. Deposits of icy regolith found within permanently shadowed craters at the lunar poles can supply the feedstock material to produce liquid oxygen (LO2) and hydrogen (LH2) propellant needed by surface-based lunar landing vehicles (LLVs) using chemical rocket engines. Along the Moon’s nearside equatorial corridor, iron oxide-rich volcanic glass beads from vast pyroclastic deposits, together with mare regolith, can provide the materials to produce lunar-derived LO2 plus other important solar wind implanted (SWI) volatiles, including H2 and helium-3. Megawatt-class fission power systems will be essential for providing continuous “24/7” power to processing plants, evolving human settlements, and other commercial activities that develop on the Moon and in orbit. Reusable LLVs will provide cargo and passenger “orbit-to-surface” access and will also be used to transport LDP to Space Transportation Nodes (STNs) located in lunar polar (LPO) and equatorial orbits (LLO). Spaced-based, reusable lunar transfer vehicles (LTVs), operating between STNs in low Earth orbit (LEO), LLO, and LPO, and able to refuel with LDPs, can offer unique mission capabilities including short transit time crewed cargo transports. Even a commuter shuttle service similar to that portrayed in 2001 appears possible, allowing 1-way trip times to and from the Moon as short as 24 hours. The performance of LTVs using both RL10B-2 chemical rockets, and a variant of the nuclear thermal rocket (NTR), the LO2-Augmented NTR (LANTR), are examined and compared. The bipropellant LANTR engine utilizes its divergent nozzle section as an afterburner into which oxygen is injected and supersonically combusted with reactor-heated hydrogen emerging from the engine’s sonic throat. If only 1% of the LDP obtained from icy regolith, volcanic glass, and SWI volatile deposits were available for use in lunar orbit, such a supply could support routine commuter flights to the Moon for many thousands of years! This paper provides a look ahead at what might be possible in the not too distant future, quantifies the operational characteristics of key in-space and surface technologies and systems, and provides conceptual designs for the various architectural elements discussed.

Borowski, Stanley K.↗
NASA NTRS2020

Airspace Operations: Vision for 2045 and Beyond

We are seeing interesting changes in airspace operations. We are experiencing growth in global aviation for passenger and cargo travel. At the same time, drones of all sizes, urban air mobility, electric aircraft, commercial space transportation, supersonics, hypersonics, and increasingly autonomous vehicles will continue to mature. These operations along with current aviation will require access to airspace operations. Such access and scalability needs will only continue to increase in the future. Given that systems and procedures that will enable and support the future density and diversity takes a considerable amount of time to build and harmonize across the globe, it is appropriate that research efforts to enable 2045 operations begin now. A perfect storm is brewing as a number of factors are coming together, including: anticipated growth in diversity and density; limitations of our current system to support the growth and diversity; lack of utilization of latest technologies in an increasingly digitized world to support air traffic management; and a long lead time to conduct research, develop requirements, and built and deploy air traffic management systems. All these factors indicate that now is the time to start thinking about the needs of 2045 and beyond. In a limited manner, Unmanned Aircraft System Traffic Management (UTM) has shown that new thinking and implementation paths for airspace operations is possible. The current system as it exists is based on many assumptions and limitations of technologies (e.g., radar, human-centered voice communications) which may not be true moving forward given the technologies around us are changing. The panel will discuss the following and related topics: 1. Expected growth in density, diversity, and needed scalability, 2. Likely requirements of air traffic management system to enable and support 2045 and beyond operations, 3. Assumptions related to air traffic management and operations that need to reevaluated based on technology trends, 4. Identification of research priorities and harmonization of research across the globe, and 5. Transition approaches from current air traffic operations to new vision 2045. The panel discussion will be useful for global air traffic management researchers, managers, strategists, airspace users, air traffic management system developers and integrators, and academic researchers.

Kopardekar, Parimal H.↗
NASA NTRS2019

Interference Drag Associated with Engine Locations for Multidisciplinary Design Optimization

This research aims to quantify the interference drag for various engine locations on a traditional “tube and wing,” 150-passenger commercial aircraft flying at 35,000 ft and Mach 0.8. Engine locations are varied in the chord wise, span wise, and vertical directions near the wing, both under and above the wing, as well as along the fuselage. Euler simulations are performed with representative powered modern engines. The results are intended to supplement empirical drag estimates suitable for multidisciplinary design environments. Large interference drag increases, as compared to the isolated air frame and engine geometry, are found to occur when the engine is placed directly above or below the wing. Interference effects are significantly reduced, and in some instances result in benefits compared to the isolated bodies, when the engines are placed fore or aft of the wing. Interference drag increases are partially explained by flow channels leading to choked flow and shock interactions between bodies.

Blaesser, Nathaniel J.↗
NASA NTRS2019

The Evaluation of Composite Energy Absorbers for Use in UAM EVTOL Vehicle Impact Attenuation

The demand for new personal air-taxi services is leading to the development of lightweight Vertical Take-off and Landing (eVTOL) vehicles with electric propulsion for the Urban Air Mobility (UAM) industry. Manufacturers (OEMs) are considering many different designs to develop a vehicle that is able to take-off, cruise, and land autonomously with seating arrangements ranging between 2 and 15 passengers. It is unclear at present how the eventual market will mature; however, one of the common design characteristics noted by many of the OEMs is the use of advanced materials such as composites. A test and analysis program was initiated at NASA Langley Research Center (LaRC) in 2018 to evaluate the impact attenuation capabilities of various composite material systems with the goal of eventual implementation into an eVTOL vehicle. A series of 3-inch diameter by 6-inch length tubular specimens were fabricated from different material systems which included both traditional carbon and hybrid woven layers of fibers. Additionally, a subset of specimens were filled with closed-cell polyisocyanurate foam to help both with stabilization and crush response. The ultimate goal of the test program was to design a specimen capable of limiting the sustained crush acceleration to 20 g through a stable crush progression. After a series of material tests, these specimens were evaluated under both static and dynamic conditions for impact energy attenuation characteristics and crush stability. Additionally, a series of simulation models were developed in parallel to the test efforts. It is anticipated that the models developed using the component level test efforts can be used to help guide the development of a design for use in full-scale eVTOL vehicle applications.

Littell, Justin↗
NASA NTRS2019

Evaluation of Impact Energy Attenuators and Composite Material Designs of a UAM VTOL Concept Vehicle

The development of Vertical Take-off and Landing (VTOL) vehicles for the Urban Air Mobility (UAM) markets presents a need for light weight vehicle structures with effective occupant protection capabilities. The National Aeronautics and Space Administration (NASA) has been working to fill that need, recently developing a cadre of concept vehicles to help characterize UAM design feasibility. This paper describes a study, using these concept vehicles, to evaluate the use of advanced composite structure and energy attenuating designs in the UAM vehicle design space. A finite element model (FEM) of a single passenger quadrotor concept vehicle was developed in LS-Dyna® and simulated under nominal and off-nominal vertical impact conditions. A variety of energy attenuating design mechanisms were implemented within this model to quantify their effectiveness in improving occupant safety. The use of carbon composites in both the energy attenuation mechanisms and vehicle structure was evaluated. The results of this study found significant reduction in occupant injury risk with the implementation of energy absorbing composite crush tubes and landing gear within the vehicle design. Additionally the use of a carbon fiber as a structural material was found to provide significant weight reduction while maintaining similar occupant loads to that predicted with an aluminum structure. This work provides a preliminary evaluation of design mechanisms and materials that may be used to optimize occupant protection capabilities within the UAM market.

Putnam, Jacob↗
NASA NTRS2019

Far Term Noise Reduction Roadmap for the NASA D8 and Single-Aisle Tube-And-Wing Aircraft Concepts

A portfolio of noise reduction technologies is applied to two advanced single-aisle class vehicle concepts in order to evaluate the prospects for these aircraft to meet the NASA Far Term noise goals, beyond 2035. TheNASAD8 (ND8) aircraft is an unconventional configuration with boundary-layer ingesting engines mounted in the aft dorsal location. The 160-passenger tube-and-wing (TW160) aircraft is a conventional configuration with podded engines located under the wing, which represents an incremental evolution of current design philosophies. The noise reduction technologies were chosen to be compatible with each aircraft’s specific configuration requirements. The acoustic effects were predicted based on experimental and numerical studies, andwere incorporated into the prediction of total system noise usingNASA’s research-level Aircraft NOise Prediction Program (ANOPP-Research). Results suggest that the unfavorable Propulsion Airframe Aeroacoustic (PAA) effects of the two aircraft considered here significantly limit their prospects of meeting NASA’s Far Term noise goal, and that further development of the technology portfolio is key to ensuring future success in addressing the noise challenges for single-aisle class vehicles.

Clark, Ian A.↗
NASA NTRS2019

Mission Planner Algorithm for Urban Air Mobility – Initial Performance Characterization

In this paper, an initial characterization was performed of the Mission Planner algorithm developed by NASA for Urban Air Mobility (UAM) operations research. The algorithm plans conflict-free trajectories for flights to support a given set of UAM passenger trips. The UAM trips are planned in an on-demand, first-come, first-served manner, such that any given trip is subject to the constraints imposed by previously planned trips. For this analysis, the mission planning algorithm considered only the trajectory constraints from previously-planned trips in one test condition and added vertiport constraints for the second test condition. The conflict and constraint resolution strategies used by the Mission Planner were characterized by their percentage contribution to planning iterations, their percentage effectiveness in those iterations, and their contributions to the departure delay applied to each UAM trip’s flight. With the exception of the climb and descent vertical speed strategies, most strategies showed reasonable or good performance in all test scenarios. In the test condition with vertipad constraints enabled, both the total number of iterations executed, and the number of flights that required planning iterations, was reduced for all scenarios. This was the result of the natural conditioning of the traffic achieved with scheduling and the additional information available to the Mission Planner from the vertiport scheduler. The next steps for this work will include improvements to the mission planning strategies and analyses with additional constraints and under other demand scenarios.

Guerreiro, Nelson M.↗
NASA NTRS2019

Far-Term Exploration of Advanced Single-Aisle Subsonic Transport Aircraft Concepts

Far-term single-aisle class aircraft concepts for potential entry-into-service of 2045 were investigated using an Interactive Reconfigurable Matrix of Alternatives (IRMA) approach. The configurations identified through this design space exploration were then distilled into three advanced aircraft concepts best characterizing the prominent features identified through the IRMA exploration. These three aircraft concepts were then configured and sized for a 150-passenger capacity and a 3,500 nautical mile design mission. Mission block fuel burn was estimated and compared to a far-term conventional configuration baseline concept and a 2005 l. These comparisons suggest considerable potential improvements in fuel efficiency from the investigated advanced concepts.

Quinlan, Jesse R.↗