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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Cooperative Upper Class E Airspace: Concept of Operations and Simulation Development for Operational Feasibility Assessment

Upper Class E Traffic Management (ETM) is a novel community-based traffic management concept incorporating the FAA, NASA, and industry’s collaborative efforts to support safe, efficient, and scalable future operations in the airspace near and above 60,000 ft. The concept complements Air Traffic Control (ATC) infrastructure and Air Traffic Management (ATM) services by facilitating cooperative operations with ETM provided services. This paper presents an initial Cooperative Separation Management (CSM) concept for High Altitude Long Endurance (HALE) vehicles’ conflict detection and resolution during their extended operations. A prototype simulation platform has been developed to visualize and assess the concept during demonstrations to stakeholders. Further development plans for simulations and the CSM concept are discussed.

upper Class E airspace↗
NASA NTRSDate not supplied

Initial Regulatory and Certification Approach for the SUSAN Electrofan Concept

New aircraft concepts and associated technologies are required to meet emerging environ-mental impact goals, while still meeting established airworthiness certification standards and regulations. The SUbsonic Single Aft eNgine (SUSAN) Electrofan is one of these concepts, utilizing a single aft-mounted engine, electrified aircraft propulsion, and an emergency backup battery. This paper explores the current certification and regulatory barriers to this novel aircraft design and the potential methods for adapting certification and regulatory requirements for the SUSAN Electrofan concept. Although some certification requirements, such as the Extended Operations regulations for continued operation after the loss of an engine, can be met with only minor changes, other requirements require modifications to the regulations or the aircraft concept for compliance. Early insight to the certification approach for the SUSAN concept, while the design is still undergoing trade space exploration, allows the development of the aircraft alongside any modifications to certification standards.

SUSAN Electrofan↗
NASA NTRSDate not supplied

Design Concepts to Meet EASA SC-VTOL-01 Single Failure Criteria

The objective of the current work is to discuss European Union Aviation Safety Agency (EASA) SC-VTOL-01 single failure criteria, VTOL.2250(c). Prior studies have developed concept distributed propulsion and flight control (DPFC) system architectures and found they comply with EASA SC-VTOL-01 probabilistic failure criteria, VTOL.2510(a). Prior work developed two all-electric DPFC systems utilized in a quadrotor concept aircraft developed by the National Aeronautics and Space Administration (NASA); one uses interconnecting shafts and gearboxes to interconnect redundant motors with each rotor system and the other uses gearboxes to connect redundant motors locally, near each rotor. Common between the two electric DPFC systems were rotor shafts, epicyclic systems, and motors. The current work explores Category I failures in drive systems, relevant research to support fail-safe design practices for gear systems, research and adjacent industry trends in motor fail-safety and reliability, and proposed design concepts to comply with VTOL.2250(c). Continued research in fail-safe design concepts and design guidance will benefit eVTOL and conventional rotorcraft, alike. Continued research in these areas will benefit eVTOL certification against SC-VTOL-01, and could optimistically translate to more widespread adoption of similar fail-safe design concepts into new rotorcraft designs certified against CS-29.

Rotorcraft↗
NASA NTRS2022

PAAV Concept Document

The Pathfinding for Airspace with Autonomous Vehicles (PAAV) Concept Document, version 1.0, lays out the key challenges and potential solutions for the use of uncrewed aircraft (UA) technology for future regional air cargo operations. The challenges and solutions described in this document were informed by communications with the UA industry community (e.g., RTCA, the Federal Aviation Administration, and regional air cargo business operators), as well as the PAAV team’s research activities during the last two years including four tabletop exercises, a human-in-the-loop simulation study, a numerical simulation study, a functional allocation study, and flight data analysis (Appendix A). This document first describes the expected operational context of PAAV (Section 2), such as the flight mission, baseline UAS components, nominal operations, m:N operations (i.e., "m" remote pilots per "N" aircraft), and off-nominal operations. This context sets the scope for the PAAV concept development work. PAAV concept development assumes that UA operations will be increasingly autonomous. Thus, near- and far-term assumptions are defined (Section 3). PAAV identified seven key challenges for UA operations (Section 4): - Flight route planning - Separation and flow management - Traffic pattern integration - Contingency management - Taxi, takeoff, and landing - m:N operations - Communications operations The following 13 potential solutions to these challenges are then described (Section 5): - Scalable communications architecture - Data link - Designated UAS corridors - Crew planning for m:N operations - Flight route optimization - Traffic load-level control - Trajectory solutions with data link - Automated hazard avoidance for m:N operations - Traffic pattern integration (TPI) tool - Standard lost command and control (C2) link (LC2L) procedures - Automated hazard avoidance under LC2L - Auto-taxi, auto-takeoff, and auto-land - Ground control station (GCS) user interface for m:N operations The document attempts to link each of these solutions to one or more of the challenge areas. Novel solutions involving numerous automation technologies are needed to mitigate traffic and airspace management challenges, especially for realizing m:N operations and ensuring safety under LC2L conditions. The purpose of this document is to help understand alternatives and tradeoffs among potential solutions and provide a foundation for a cohesive PAAV concept that will be described and refined in subsequent concept versions.

Unmanned aircraft, uncrewed aircraft, regional air↗
NASA NTRS2022

A Model-Based Approach for Europa Lander Mission Concept Exploration

This study investigates the usage of a system model as a means to capture concept formulation for a potentialmission. Efforts are underway at JPL to explore thearchitectural and system concepts for a lander on Europa.Executing a mission on the surface of Europa poses uniquechallenges that will require the lander to operate with onboardautonomy that is more sophisticated than systems previouslyoperated by JPL. Current tasks to explore surface missionconcepts intend to identify concepts that enable a high degree ofonboard autonomy as well as identify the issues and technicallimitations that restrict autonomy. The Europa lander missionconcept team is developing a system model to support thisexploration.The results of this study highlight how executable systemmodeling and the associated engineering environment may beapplied to pre-project conceptual exploration. The applicationof system modeling has resulted in a central system model thatprecisely describes the concepts formulated by the EuropaLander Mission Concept Team. Documentation in the form ofdiagrams and narrative has been directly generated from thesystem model and accessible by team members in a webapplication. The executability of the system model enablesvarious analyses such as simulation of interactions betweencomponents and evaluating system behavior againstrequirements. Execution of the system model has produced statetimelines, plots of system variables, and simulation traces basedon input scenarios. The executable system model enables therapid and repeatable production of these artifacts.

Reeves, Glenn↗
NASA NTRSDate not supplied

Design Exploration of a Mild Hybrid Electrified Aircraft Propulsion Concept

NASA has performed in-depth research and analysis into hybrid-electric aircraft concepts featuring high levels of electrification. Many of these concepts were found to be infeasible, whereas feasible designs were significantly heavier and more costly compared to conventional concepts. This study presents the development and analysis of an alternative mild hybrid concept that uses relatively low levels of stored electric energy applied strategically throughout the mission. The team researched several mild hybrid technologies, developed integrated aircraft models, and then evaluated the effects of these technologies on vehicle level performance metrics. Technologies explored in this study include the Turbine Electrified Energy Management system, electric taxi, electric climb assist, and replacing the auxiliary power unit with on-board electric energy storage. Key enabling technologies were energy storage devices that prioritized high power output over energy capacity and integrating electric motors with the shafts of the gas turbine engines. Significant performance improvements were observed when applying multiple technologies separately and in combination, with the most promising configuration incorporating all of them at once. Results for the mild hybrid configuration indicate an 8.2% reduction in block fuel, a 7.7% reduction in equivalent CO2 emissions, and a 3.5% increase in gross takeoff weight compared to a conventional baseline. Results of a cost analysis suggest the mild hybrid slightly reduces direct operating cost plus interest, which demonstrates that aircraft emissions can be significantly reduced without the cost increases associated with highly electrified concepts.

Turbine Electrified Energy Managment↗
NASA NTRS2023

Concept Design for a 5 MW Partially Superconducting Generator

This paper presents a concept design for the 5 MW generators on NASA’s SUSAN hybrid electric flight concept. The performance targets for this machine are 25 kW/kg and 99% efficiency. The concept design is a partially superconducting machine that builds on NASA’s past work on its High Efficiency Megawatt Motor (HEMM). A partially superconducting machine design tool is used to create a preliminary concept design capable of achieving the target specifications for the SUSAN generator. Higher fidelity design and analysis is applied to the preliminary design. After high fidelity analysis the machine is predicted to achieve 22.3 kW/kg and 99.1% efficiency. Lessons learned from this concept design will be incorporated in the next iteration of the machine.

Thomas Tallerico↗
NASA NTRS2023

Concept Design of a 5 MW Partially Superconducting Generator

This paper presents a concept design for the 5 MW generators on NASA’s SUSAN electric flight demonstrator concept vehicle. The performance targets for this machine are 25 kW/kg and 99% efficiency. The concept design is a partially superconducting machine that builds on NASA’s past work on its High Efficiency Megawatt Motor(HEMM). A partially superconducting machine design tool is used to create a preliminary concept design capable of achieving the target specifications for the SUSAN generator. Higher fidelity design and analysis is applied to the preliminary design. After high fidelity analysis the machine is predicted to achieve 22.3 kW/kg and 99.1% efficiency. Lessons learned from this concept design will be incorporated in the next iteration of the machine.

Thomas Tallerico↗
NASA NTRS2021

Mission Concept Design for Autonomous Space Missions using Mission-Level Modeling and Simulation

NASA’s Europa Lander mission is to search for biosignatures on Europa based on in-situ science using a lander architecture. This mission presents a set of challenges that requires a high level of autonomy on the lander system, leading to the need for a new operational paradigm that supports better collaboration and coordination between the lander and the ground operations team. M\&S is used for both designing the onboard system-level autonomy and the ground operations paradigm that allows effective and efficient collaboration and coordination between the lander and the ground operations team. In this paper, M\&S as applied to the design of new mission and operational concepts will be discussed. At its current early stage of the mission development for Europa Lander, the M\&S is used to explore different mission concepts and gain insights for design (formative) rather than to verify and validate fully designed mission concepts quantitatively (summative). Organically, we established a new approach to mission and operational concept exploration using high-fidelity modeling and simulation. M\&S has been an integral part of the approach of defining constraints and assertions, designing mission concepts, assessing (i.e., simulating them), and discovering insights, which feeds back to the definition an design steps. This organically-established approach provided important benefits to the project at its early phase of the development by enabling the project team to be able to build shared understanding of impacts from design characteristics, constraints, and their interactions on the mission performance.

Ye, Sean↗
NASA NTRSDate not supplied

Simplified Vehicle Control Concept for a Lift Plus Cruise eVTOL Vehicle

Electric Vertical Takeoff and Landing (eVTOL) vehicles have the potential to enable cost effective Urban Air Mobility (UAM) applications. These concepts may also pose several challenging handling and control problems, which must be addressed prior to safe and reliable urban operations. This paper investigates a simplified vehicle control concept that is designed to address some of these challenges for a conceptual Lift Plus Cruise vehicle designed by NASA’s Revolutionary Vertical Lift Technology (RVLT) project. The command and control architecture for this concept is presented along with preliminary findings. Initial results explore the vehicle performance in an approach to hover transition scenario, designed to explore the challenge of dissipating energy across all flight regimes. Operational concepts with varying aggressiveness are evaluated through changing glideslope and deceleration rates. Preliminary results show that the simplified control concept is effective over these operational conditions, with control strategies and envelope protection limits able to maintain control though aggressive operations despite saturation at steeper slopes with higher deceleration rates. Final results will show piloted simulation evaluations in the the Aerospace Cognitive Engineering Lab – Rapid Automation Test Environment (ACEL-RATE) laboratory at NASA Ames Research Center. The planned tests will build on these operations with additional test cases exploring variations in wind conditions as well as transition-to-hover automation strategies and display information.

simplified vehicle control↗
NASA NTRSDate not supplied

Simplified Vehicle Control Concept for a Lift Plus Cruise eVTOL Vehicle

Electric Vertical Takeoff and Landing (eVTOL) vehicles have the potential to enable cost effective Urban Air Mobility (UAM) applications. These concepts may also pose several challenging handling and control problems, which must be addressed prior to safe and efficient urban operations. This paper investigates a simplified vehicle control concept that is designed to address some of these challenges for a conceptual Lift Plus Cruise vehicle. This concept also includes several variations of a transition-to-hover function, designed to assist pilots in capturing and maintaining a stabilized hover prior to landing. The different simplified control architectures for this concept are presented along with preliminary findings. Preliminary results show that the simplified control concept can be effective in assisting pilots to achieve safe and reliable hover landings, and that transition-to-hover functions have the potential of reducing workload while increasing accuracy. A follow on evaluation will be performed in the Vertical Motion Simulator (VMS) at NASA Ames Research Center. The planned tests will focus on more operationally representative scenarios, while building upon these operations with additional test cases exploring variations in glidepath angles and wind conditions.

simplified vehicle control↗
NASA NTRS2024

NASA Engineering and Safety Center Lunar Rover Design Concepts Assessments

Mass is a significant risk to programs and projects as they transition from formulation to implementation, especially in larger human space systems where delivery mass or volume can be a constrained commodity. • Concepts developed without an adequate systems-engineering basis, including design and operations experience, may miss significant functionality and subsequent mass required for integration or operations. • Further uncertainty can be associated with not fully understanding design best practices and standards that drive mass, such as design for minimum risk or fault tolerance.1 • Finally, the appropriate systems engineering mass properties management rigor and technical discipline insight are required to set the mass baseline, including appropriate mass growth allowance (MGA) to ensure program success. Mass is a key quantity that should be constantly monitored by the systems engineer and the program/project management stakeholder to ensure mission compatibility throughout the project life cycle. In addition, mass is a key programmatic performance metric monitored by the NASA Chief Financial Officer for current and future program cost estimating. NASA Exploration Systems sought an assessment of reasonableness with respect to different potential rover concepts that balances mass needs and human-class cargo lander capabilities. Appropriate systems engineering mass properties management rigor and technical discipline insight were used, and are required to set the mass baseline, including appropriate MGA to ensure program success. Two independent Lunar rover concepts were evaluated, with a goal to understand concept credibility and the Lunar rover designs potential extensibility for Mars surface operations. A notional generic rover concept is shown in Figure 1.

Systems Engineering↗
NASA NTRSDate not supplied

NTP Demonstration Vehicles and Mission Concepts for Generation 1

Nuclear thermal propulsion (NTP) maintains continued interest in support of NASA’s goal to produce a human rated spacecraft for Mars exploration. The NASA/DARPA DRACO effort aims to demonstrate the first nuclear thermal rocket through a flight in 2027. This paper considers the option of a follow-on in-space demonstration supported by a more extensive pre-flight ground test campaign. A concept of operations to accomplish the objectives is outlined and figures of merit for selection of a spacecraft concept are defined. Conceptual designs of various nuclear thermal propulsion demonstration vehicles are presented, spanning a wide trade space. Each concept differently balances performance capability and extensibility to operational missions with schedule, risk, cost of the ground and flight demonstration. Key attributes of notable concepts are provided, with these demonstrating the degree to which each concept can accomplish the objectives considered.

NTP↗
NASA NTRS1972

Vehicle performance impact on space shuttle design and concept evaluation

The continuing examination of widely varied space shuttle concepts makes an understanding of concept interaction with vehicle performance imperative. The estimation of vehicle performance is highly appurtenant to all aspects of shuttle design and hence performance has classically been a key indicator of overall concept desirability and potential. Vehicle performance assumes the added role of defining interactions between specific design characteristics, the sum total of which define a specific concept. Special attention is given to external tank effects.

Craig, M. K.↗
NASA NTRS1972

Comparison of advanced propulsion concepts for deep space exploration

Equations and charts are presented that permit rapid estimation of propulsion-system performance requirements for some typical deep-space missions. A number of advanced propulsion concepts for which performance estimates are available are compared with respect to their capability for flyby, rendezvous, and roundtrip planetary missions. Based on these estimates, the gas-core nuclear fission rocket and the pulsed fusion rocket yield the fastest trip times to the near planets. For round trips to Jupiter and beyond, the controlled fusion rocket shows progressively superior capabilities. Several propulsion concepts based on use of impinging laser beams are found to be noncompetitive with the other advanced concepts for deep space missions. Requirements for attainment of interstellar distances within a human lifetime are found to be some orders of magnitude beyond the capabilities of any propulsion concepts for which performance estimates are now possible.

Moeckel, W. E.↗
NASA NTRS1972

Study of aircraft centered navigation, guidance, and traffic situation system concept for terminal area operation

A concept for automating the control of air traffic in the terminal area in which the primary man-machine interface is the cockpit is described. The ground and airborne inputs required for implementing this concept are discussed. Digital data link requirements of 10,000 bits per second are explained. A particular implementation of this concept including a sequencing and separation algorithm which generates flight paths and implements a natural order landing sequence is presented. Onboard computer/display avionics utilizing a traffic situation display is described. A preliminary simulation of this concept has been developed which includes a simple, efficient sequencing algorithm and a complete aircraft dynamics model. This simulated jet transport was flown through automated terminal-area traffic situations by pilots using relatively sophisticated displays, and pilot performance and observations are discussed.

Anderson, W. W.↗
NASA NTRS1973

Photoheliograph thermal concepts study. Volume 1: Summary

The performances of thermal subsystem concepts for each of three photoheliograph designs oriented toward unique solar observation missions are defined. These designs and missions may be categorized as: (1) A 150-centimeter photoheliograph for large Solar Observatory (LSO) missions; (2) a 100-centimeter photoheliograph for shuttle sorties; and (3) a 100-centimeter photoheliograph for balloon missions. For each of these photoheliograph designs are the basic thermal environments, boundary conditions, and applicable thermal control concepts defined, the interactions between concepts and environments determined, and a baseline thermal control concept for the three classes of photoheliographs selected. A set of experimental work plans describing the major efforts required to further the detailed design and to confirm analytical performance predictions is included.

Source record↗
NASA NTRS1971

Study of alternate space shuttle concepts

A study of alternate space shuttle concepts was conducted to examine the stage-and-one-half concept and its potential for later conversion and use in the two stage reusable shuttle system. A study of external hydrogen tank concepts was conducted to determine the issues involved in the design and production of a low-cost expendable tank system. The major objectives of the study were to determine: (1) realistic drop tank program cost estimates, (2) estimated drop tank program cost for selected specific designs, and (3) change in program cost due to variations in design and manufacturing concepts and changes in program assumptions.

Source record↗