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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Predictive Workload Model for Air Traffic Controllers during UAM Operations

The effect of airspace factors on air traffic controller (ATC) workload has been an active area of study for almost three decades due to the importance of safety considerations necessary to design and maintain operations. Existing literature has examined several traffic-related (e.g., number of aircraft under control, loss of separation) contributors to ATC workload and proposed mathematical functions to best describe controller response. However, future air traffic continues to increase in complexity with the introduction of urban air mobility (UAM) – or the transportation of humans and cargo using electric vertical takeoff and landing (eVTOL) aircraft. UAM aims to alleviate congestion for existing ground transportation systems and improve mobility within urban centers and other high-demand locations. This shift in the traditional airspace paradigm necessitates an evolved understanding of model use and development for ATC workload prediction. This study aimed to develop an ATC workload forecasting model based on human-in-the-loop (HITL) simulation data for UAM operations at large airports. Data collected from the HITL simulation served as the training and testing data for a Long Short-Term Memory recurrent neural network and enabled time-series forecasting of ATC workload from traffic characteristics. Results demonstrated the potential of LSTM models for forecasting ATC workload 40 minutes into the future and highlighted important considerations for future development.

predictive model↗
NASA NTRSDate not supplied

Assistive Detect and Avoid Technology in Urban Air Mobility Environments

The use of Assistive Detect and Avoid (Assistive DAA or ADAA) technology in Urban Air Mobility (UAM) environments poses potential benefits as well as challenges. Assistive DAA refers to the leveraged use of DAA technology, originally developed to replace see-and-avoid capabilities for remotely piloted aircraft, in onboard-piloted aircraft to augment (rather than replace) pilots’ see-and-avoid abilities and thus enhance the safety and efficiency of visual flight operations. ADAA is anticipated to be especially safety-enhancing in airspace where traffic density is high or traditional air traffic services are limited, such as in future UAM environments. ADAA may also enable higher-tempo UAM operations than with only see-and-avoid capabilities, while still maintaining acceptable levels of safety. UAM concepts under development by the FAA, NASA, and industry focus on operations moving people and cargo in urban and suburban areas using innovative technologies, operations, and aircraft, including electric vertical takeoff and landing (eVTOL) aircraft. Researchers at NASA Langley Research Center, in collaboration with FAA researchers at the William J. Hughes Technical Center in Atlantic City, NJ, have conducted a series of medium-fidelity, human-in-the-loop research simulations of potential future UAM operations and concepts in both Class C and Class B airspace environments. These simulations have included use of a Langley-developed ADAA research tool called DANTi, which enables configurable ADAA displays to be presented to pilots of simulated eVTOL aircraft participating in higher-density and higher-tempo UAM operations. Experience and observations made during testing of the NASA-developed DANTi ADAA capability in the UAM NFLITE simulation environment will be reported in this paper together with a discussion of airspace integration and regulatory topics.

Detect and Avoid↗
NASA NTRSDate not supplied

Training the Powered-Lift Evaluation Pilot

This presentation focuses on the preparation and training of evaluation pilots during the second of two research studies: Automation Enabled Pilot studies 1 and 2 (AEP-1 and AEP-2). These studies are intended to assess novel aircraft automation concepts for electric powered aircraft equipped with Indirect Flight Control Systems (IFCS) capable of Vertical Takeoff and Landing (eVTOL). The AEP-1 study importantly introduced the concept of future evaluation methods used in the AEP-1 study for eVTOL equipped with IFCS that are agnostic and cut cross both airworthiness and operational requirements. The AEP-2 study utilized an updated Lift Plus Cruise aircraft model and examined pilot interaction with novel procedures and interfaces. Specifically, it explored challenges related to transitioning from forward flight to landing with an industry representative Urban Air Mobility (UAM) approach procedure, establishing baselines for future automation studies.

AAM↗
NASA NTRSDate not supplied

A Call To Action To Engage The Community To Meet The Challenges That Must Be Tackled To Make Electrified Aircraft Propulsion Real

Technology risk reduction is essential, as it is necessary to demonstrate the potential of Electrified Aircraft Propulsion (EAP). However, more is needed for implementation. The industry is leading EAP by developing a diverse community of novel vehicles from short-haul, small, urban-focused electric vertical takeoff and landing (eVTOL) to regional air mobility (RAM) and hybrid-electric, single-aisle transport category airplanes. There are a variety of novel EAP technologies for each of these novel vehicles. And the industry is not only looking at novel technology to advance the state of the art. Instead, the industry is looking to certify these novel aircraft through their regulatory authorities, such as the US Federal Aviation Administration (FAA), the European Union Aviation Safety Authority (EASA), Transport Canada Civil Aviation (TCCA), and Brazil’s Agência Nacional de Aviação Civil (National Civil Aviation Agency, ANAC), as well as other regulatory authorities. The NASA Electrified Powertrain Flight Demonstration (EPFD) project has partnered with two industry partners to advance integrated MW-class powertrain system technology demonstration that includes an assessment of their regulatory and standards gaps in their technology. The EPFD has conducted a generic regulatory gap analysis of hybrid electric engines that aligns with the industry partners’ efforts. The EPFD regulations and standards team is integrated into the industry standards community. The international industry standards community is wrestling with critical key challenges to certification. While some certification elements are proprietary, several technology elements cut across company propriety in aircraft engines (US 14 CFR Part 33 and EASA CS-E, regulations that only reflect reciprocating and turbine engines). The approach that several of these regulatory authorities have taken is to collaborate to address their challenges. The Certification Management Team (CMT) consists of the EASA, FAA, TCCA, and ANAC, and they have begun to address common questions, such as the Loss of Power Control (LOPC) for electric engines. They have reached out to the standards community to seek answers. The industry standards development organizations (SDO) have also looked ahead to address current regulations and standards gaps. The ASTM has built key committees in its ASTM F44 General Aviation Committee and F39 Aircraft Systems Committee. The SAE has established the E-40 Electric Propulsion and AE-10 High Voltage committees.

Standards↗
NASA NTRSDate not supplied

Effects of Motion Fidelity on Pilot Performance Using Mixed-Reality Visuals

This paper investigates the effects of simulator motion fidelity on pilot performance using mixed-reality visuals. In NASA’s Vertical Motion Simulator, eleven pilots flew a lift-plus-cruise electric vertical takeoff and landing vehicle in a vertiport approach and landing task with four different motion conditions: no motion, small hexapod motion, large hexapod motion, and full motion. The simulator motion condition statistically significantly affected: 1) the severity of cybersickness, 2) motion ratings, 3) final approach and take-off boundary crossing groundspeed, 4) longitudinal touchdown point, and 5) battery time remaining after landing. The findings suggest that motion systems are essential in simulators with virtual- or mixed-reality visuals when it is required to have pilot flying performance similar to that in real flight.

mixed reality↗
NASA NTRSDate not supplied

Effects of Motion Fidelity on Pilot Performance Using Mixed-Reality Visuals

This paper investigates the effects of simulator motion fidelity on pilot performance using mixed-reality visuals. In NASA’s Vertical Motion Simulator, eleven pilots flew a lift-plus-cruise electric vertical takeoff and landing vehicle in a vertiport approach and landing task under four different motion conditions: no motion, small hexapod motion, large hexapod motion, and full motion. The simulator motion condition statistically significantly affected: 1) the severity of cybersickness, 2) motion ratings, 3) final approach and take-off boundary crossing groundspeeds, 4) longitudinal touchdown point, and 5) battery time remaining after landing. These results suggest that the use of motion systems in simulators with virtual- or mixed-reality visuals is warranted.

simulation↗
NASA NTRSDate not supplied

Manufacturing and Scale-Up of Natural Fiber Composite eVTOL Propeller Skin and C-Channel

This presentation discusses the manufacturing and scale-up of natural fiber composites for aerospace applications, conducted within NASA’s Convergent Aeronautics Solutions portfolio to advance aircraft capabilities and efficiency. The effort focused on the development and demonstration of two proof-of concept articles, an electric vertical takeoff and landing (eVTOL) propeller skin and a C-channel subcomponent. Best practices and guidance on addressing key challenges with bio-based composite materials and manufacturing are provided.

Composites↗
NASA NTRS1990

Preliminary assessment of a supersonic STOVL flight research and demonstration aircraft

NASA Ames has conducted a conceptual design study of a supersonic short takeoff and vertical landing (STOVL) flight research and demonstration aircraft sized according to current technology levels. The aircraft would provide the capability for demonstrating advanced technologies required for STOVL and would be instrumented to provide temperature, pressure, and noise data for power-induced-effects research. The propulsion concept for the single-engine aircraft studied operates in mixed flow without thrust augmentation during power-lift flight. The study aircraft is full scale to facilitate STOVL propulsion-system component validation and power-induced aerodynamics research. Performance is sufficient to permit investigation and validation of vertical landing and hover, accelerating and decelerating transitions, short takeoff, reduced-weight vertical takeoff, and supersonic flight. Mission and maneuver capability is sufficient to demonstrate the operational utility of this class of aircraft. Aircraft mission and technology sensitivities were also examined.

Samuels, Jeffrey J.↗
NASA NTRS1991

Static internal performance of ventral and rear nozzle concepts for short-takeoff and vertical-landing aircraft

The internal performance of two exhaust system concepts applicable to single-engine short-take-off and vertical-landing tactical fighter configurations was investigated. These concepts involved blocking (or partially blocking) tailpipe flow to the rear (cruise) nozzle and diverting it through an opening to a ventral nozzle exit for vertical thrust. A set of variable angle vanes at the ventral nozzle exit were used to vary ventral nozzle thrust angle between 45 and 110 deg relative to the positive axial force direction. In the vertical flight mode the rear nozzle (or tailpipe flow to it) was completely blocked. In the transition flight mode flow in the tailpipe was split between the rear and ventral nozzles and the flow was vectored at both exits for aircraft control purposes through this flight regime. In the cruise flight mode the ventral nozzle was sealed and all flow exited through the rear nozzle.

Re, Richard J.↗
NASA NTRS1995

System identification methods for aircraft flight control development and validation

System-identification methods compose a mathematical model, or series of models, from measurements of inputs and outputs of dynamic systems. The extracted models allow the characterization of the response of the overall aircraft or component subsystem behavior, such as actuators and on-board signal processing algorithms. This paper discusses the use of frequency-domain system-identification methods for the development and integration of aircraft flight-control systems. The extraction and analysis of models of varying complexity from nonparametric frequency-responses to transfer-functions and high-order state-space representations is illustrated using the Comprehensive Identification from FrEquency Responses (CIFER) system-identification facility. Results are presented for test data of numerous flight and simulation programs at the Ames Research Center including rotorcraft, fixed-wing aircraft, advanced short takeoff and vertical landing (ASTOVL), vertical/short takeoff and landing (V/STOL), tiltrotor aircraft, and rotor experiments in the wind tunnel. Excellent system characterization and dynamic response prediction is achieved for this wide class of systems. Examples illustrate the role of system-identification technology in providing an integrated flow of dynamic response data around the entire life-cycle of aircraft development from initial specifications, through simulation and bench testing, and into flight-test optimization.

Tischler, Mark B.↗
NASA NTRS1998

Flight Research at Ames: Fifty-Seven Years of Development and Validation of Aeronautical Technology

This NASA special publication presents a general overview of the flight research that has been conducted at Ames Research Center over the last 57 years. Icing research, transonic model testing, aerodynamics, variable stability aircraft, boundary layer control, short takeoff and landing (STOL), vertical/ short takeoff and landing (V/STOL) and rotorcraft research are among the major topics of interest discussed. Flying qualities, stability and control, performance evaluations, gunsight tracking and guidance and control displays research are also presented. An epilogue is included which presents the significant contributions that came about as a result of research and development conducted at Ames.

Borchers, Paul F.↗
NASA NTRS1993

Overview of STOVL aircraft propulsion research offtakes and vertical lift systems

The overall Short Takeoff and Vertical Landing (STOVL) Aircraft Propulsion Research program includes key technologies involving offtake systems, vertical lift systems, hot gas ingestion, STOVL augmentors, and integrated flight propulsion controls. A part of the NASA Lewis work involving STOVL aircraft propulsion systems is presented with the emphasis on component-level experiments and analysis related to offtakes and vertical lift systems.

Biesiadny, Thomas J.↗
NASA NTRS1997

Moving-Base Simulation Evaluation of Control/Display Integration Issues for ASTOVL Aircraft

A moving-base simulation has been conducted on the Vertical Motion Simulator at Ames Research Center using a model of an advanced, short takeoff and vertical landing (STOVL) lift fan fighter aircraft. This experiment expanded on investigations during previous simulations with this STOVL configuration with the objective of evaluating (1) control law modifications over the low speed flight envelope, (2) integration of the throttle inceptor with flight control laws that provide direct thrust command for conventional flight, vertical and short takeoff, and flightpath or vertical velocity command for transition, hover, and vertical landing, (3) control mode blending for pitch, roll, yaw, and flightpath control during transition from wing-borne to jet-borne flight, and (4) effects of conformal versus nonconformal presentation of flightpath and pursuit guidance symbology on the out-the-window display for low speed STOVL operations. Assessments were made for takeoff, transition, hover, and landing, including precision hover and landing aboard an LPH-type amphibious assault ship in the presence of winds and rough seas. Results yielded Level 1 pilot ratings for the flightpath and vertical velocity command modes for a range of land-based and shipboard operation and were consistent with previous experience with earlier control laws and displays for this STOVL concept. Control mode blending was performed over speed ranges in accord with the pilot's tasks and with the change of the basic aircraft's characteristics between wing-borne and hover flight. Blending of yaw control from heading command in hover to sideslip command in wing-borne flight performed over a broad speed range helped reduce yaw transients during acceleration through the low speed regime. Although the pilots appreciated conformality of flightpath and guidance symbols with the external scene during the approach, increased sensitivity of the symbols for lateral path tracking elevated the pilots' control activity in the presence of turbulence. The pilots preferred the choice of scaling that was originally established during the display development and in-flight evaluations.

Franklin, James A.↗
NASA NTRS1980

Preliminary aerodynamic characteristics of several advanced VSTOL fighter/attack aircraft concepts

VSTOL attack aircraft to be developed in the mid- or late-1990's and research programs dealing with possible characteristics are discussed. Design studies of horizontal attitude takeoff and landing (HATOL) and vertical attitude takeoff and landing (VATOL) type aircraft were executed and wind tunnel models were built and tested. The configurations tested were a wing-canard HATOL concept with jet-diffuser ejectors as a vertical lift system and a variety of the same with nacelles which are closer together. Other proposals were a HATOL concept with wing-canard design and two vertical tails on twin afterbodies, and a VATOL concept which is tailless with an extended leading-edge wing to increase lift. Aerodynamic uncertainties were defined and wind tunnel tests were made. Special research concerning top-mounted air induction systems is also covered.

Nelms, W. P.↗
NASA NTRS1989

STOVL aircraft simulation for integrated flight and propulsion control research

The United States is in the initial stages of committing to a national program to develop a supersonic short takeoff and vertical landing (STOVL) aircraft. The goal of the propulsion community in this effort is to have the enabling propulsion technologies for this type aircraft in place to permit a low risk decision regarding the initiation of a research STOVL supersonic attack/fighter aircraft in the late mid-90's. This technology will effectively integrate, enhance, and extend the supersonic cruise, STOVL and fighter/attack programs to enable U.S. industry to develop a revolutionary supersonic short takeoff and vertical landing fighter/attack aircraft in the post-ATF period. A joint NASA Lewis and NASA Ames research program, with the objective of developing and validating technology for integrated-flight propulsion control design methodologies for short takeoff and vertical landing (STOVL) aircraft, was planned and is underway. This program, the NASA Supersonic STOVL Integrated Flight-Propulsion Controls Program, is a major element of the overall NASA-Lewis Supersonic STOVL Propulsion Technology Program. It uses an integrated approach to develop an integrated program to achieve integrated flight-propulsion control technology. Essential elements of the integrated controls research program are realtime simulations of the integrated aircraft and propulsion systems which will be used in integrated control concept development and evaluations. This paper describes pertinent parts of the research program leading up to the related realtime simulation development and remarks on the simulation structure to accommodate propulsion system hardware drop-in for real system evaluation.

Mihaloew, James R.↗
NASA NTRS1984

Calculation of vertical and ramp-assisted takeoffs for supersonic cruise fighters

A procedure that allows rapid preliminary evaluations of the vertical, short, and normal takeoff performance of supersonic cruise aircraft concepts was developed into a numerical computer program. The program is used to determine the effects on takeoff performance of various parameters, such as thrust-weight ratio, wing loading, thrust vector angle, and flap setting. Ramp-assisted takeoffs for overloaded configurations typical of a ground-attack mission are included. The effects of wind on the takeoff performance are also considered.

Liu, G. C.↗
NASA NTRS1997

Revised Simulation Model of the Control System, Displays, and Propulsion System for a ASTOVL Lift Fan Aircraft

This report describes revisions to a simulation model that was developed for use in piloted evaluations of takeoff, transition, hover, and landing characteristics of an advanced short takeoff and vertical landing lift fan fighter aircraft. These revisions have been made to the flight/propulsion control system, head-up display, and propulsion system to reflect recent flight and simulation experience with short takeoff and vertical landing operations. They include nonlinear inverse control laws in all axes (eliminating earlier versions with state rate feedback), throttle scaling laws for flightpath and thrust command, control selector commands apportioned based on relative effectiveness of the individual controls, lateral guidance algorithms that provide more flexibility for terminal area operations, and a simpler representation of the propulsion system. The model includes modes tailored to the phases of the aircraft's operation, with several response types which are coupled to the aircraft's aerodynamic and propulsion system effectors through a control selector tailored to the propulsion system. Head-up display modes for approach and hover are integrated with the corresponding control modes. Propulsion system components modeled include a remote lift fan and a lift-cruise engine. Their static performance and dynamic responses are represented by the model. A separate report describes the subsonic, power-off aerodynamics and jet induced aerodynamics in hover and forward flight, including ground effects.

Franklin, James A.↗
NASA NTRS1986

Aircraft automatic-flight-control system with inversion of the model in the feed-forward path using a Newton-Raphson technique for the inversion

A new automatic flight control system concept suitable for aircraft with highly nonlinear aerodynamic and propulsion characteristics and which must operate over a wide flight envelope was investigated. This exact model follower inverts a complete nonlinear model of the aircraft as part of the feed-forward path. The inversion is accomplished by a Newton-Raphson trim of the model at each digital computer cycle time of 0.05 seconds. The combination of the inverse model and the actual aircraft in the feed-forward path alloys the translational and rotational regulators in the feedback path to be easily designed by linear methods. An explanation of the model inversion procedure is presented. An extensive set of simulation data for essentially the full flight envelope for a vertical attitude takeoff and landing aircraft (VATOL) is presented. These data demonstrate the successful, smooth, and precise control that can be achieved with this concept. The trajectory includes conventional flight from 200 to 900 ft/sec with path accelerations and decelerations, altitude changes of over 6000 ft and 2g and 3g turns. Vertical attitude maneuvering as a tail sitter along all axes is demonstrated. A transition trajectory from 200 ft/sec in conventional flight to stationary hover in the vertical attitude includes satisfactory operation through lift-cure slope reversal as attitude goes from horizontal to vertical at constant altitude. A vertical attitude takeoff from stationary hover to conventional flight is also demonstrated.

Smith, G. A.↗