Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Flight”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
NASA NTRS1960

V. The X-15 flight research program in relation to the development of advanced military aircraft

The design, construction, and development of advanced military aircraft undoubtedly will involve the utilization of many relatively new concepts in several deafferent, but related, areas. In many cases, these new concepts will require new flight techniques or involve development problems inherent in the use of relatively unproven methods, materials, structures, systems, and configurations. Moreover, flight verification will be required of aircraft aerodynamics and flight behavior because of the usual uncertainties associated with predicted data. Solutions to these problems obviously would require flight testing involving extensive time and effort before the aircraft could become operationally acceptable. Upon the inception of the X-15 research airplane project, many new and far-reaching techniques and principles were studied and applied in the aircraft design and are currently being demonstrated and investigated. Because similar concepts are likely to be used in advanced military aircraft, the X-15 flight program will provide significant information, over a broad flight environment, pertinent to the development of these vehicles. This paper discusses the research objectives of the X-15 flight program, some of the flight aerodynamic characteristics currently being obtained, some development problems encountered, and the experience obtained with the advanced systems investigated.

Military aircraft↗
NASA NTRS2005

Bone Markers, Calcium Metabolism, and Calcium Kinetics During Extended-Duration Space Flight on the Mir Space Station

Bone loss is a current limitation for long-term space exploration. Bone markers, calcitropic hormones, and calcium kinetics of crew members on space missions of 4-6 months were evaluated. Spaceflight-induced bone loss was associated with increased bone resorption and decreased calcium absorption. INTRODUCTION: Bone loss is a significant concern for the health of astronauts on long-duration missions. Defining the time course and mechanism of these changes will aid in developing means to counteract these losses during space flight and will have relevance for other clinical situations that impair weight-bearing activity. MATERIALS AND METHODS: We report here results from two studies conducted during the Shuttle-Mir Science Program. Study 1 was an evaluation of bone and calcium biochemical markers of 13 subjects before and after long-duration (4-6 months) space missions. In study 2, stable calcium isotopes were used to evaluate calcium metabolism in six subjects before, during, and after flight. Relationships between measures of bone turnover, biochemical markers, and calcium kinetics were examined. RESULTS: Pre- and postflight study results confirmed that, after landing, bone resorption was increased, as indicated by increases in urinary calcium (p < 0.05) and collagen cross-links (N-telopeptide, pyridinoline, and deoxypyridinoline were all increased >55% above preflight levels, p < 0.001). Parathyroid hormone and vitamin D metabolites were unchanged at landing. Biochemical markers of bone formation were unchanged at landing, but 2-3 weeks later, both bone-specific alkaline phosphatase and osteocalcin were significantly (p < 0.01) increased above preflight levels. In studies conducted during flight, bone resorption markers were also significantly higher than before flight. The calcium kinetic data also validated that bone resorption was increased during flight compared with preflight values (668 +/- 130 versus 427 +/- 153 mg/day; p < 0.001) and clearly documented that true intestinal calcium absorption was significantly lower during flight compared with preflight values (233 +/- 87 versus 460 +/- 47 mg/day; p < 0.01). Weightlessness had a detrimental effect on the balance in bone turnover such that the daily difference in calcium retention during flight compared with preflight values approached 300 mg/day (-234 +/- 102 versus 63 +/- 75 mg/day; p < 0.01). CONCLUSIONS: These bone marker and calcium kinetic studies indicated that the bone loss that occurs during space flight is a consequence of increased bone resorption and decreased intestinal calcium absorption.

Bone and Bones/metabolism/pathology↗
NASA NTRS2016

UAS Integration in the NAS Project: Flight Test 3 Data Analysis of JADEM-Autoresolver Detect and Avoid System

The Unmanned Aircraft Systems Integration in the National Airspace System project, or UAS Integration in the NAS, aims to reduce technical barriers related to safety and operational challenges associated with enabling routine UAS access to the NAS. The UAS Integration in the NAS Project conducted a flight test activity, referred to as Flight Test 3 (FT3), involving several Detect-and-Avoid (DAA) research prototype systems between June 15, 2015 and August 12, 2015 at the Armstrong Flight Research Center (AFRC). This report documents the flight testing and analysis results for the NASA Ames-developed JADEM-Autoresolver DAA system, referred to as 'Autoresolver' herein. Four flight test days (June 17, 18, 22, and July 22) were dedicated to Autoresolver testing. The objectives of this test were as follows: 1. Validate CPA prediction accuracy and detect-and-avoid (DAA, formerly known as self-separation) alerting logic in realistic flight conditions. 2. Validate DAA trajectory model including maneuvers. 3. Evaluate TCAS/DAA interoperability. 4. Inform final Minimum Operating Performance Standards (MOPS). Flight test scenarios were designed to collect data to directly address the objectives 1-3. Objective 4, inform final MOPS, was a general objective applicable to the UAS in the NAS project as a whole, of which flight test is a subset. This report presents analysis results completed in support of the UAS in the NAS project FT3 data review conducted on October 20, 2015. Due to time constraints and, to a lesser extent, TCAS data collection issues, objective 3 was not evaluated in this analysis.

flight test↗
NASA NTRS2017

Multi-Objective Flight Control for Drag Minimization and Load Alleviation of High-Aspect Ratio Flexible Wing Aircraft

As aircraft wings become much more flexible due to the use of light-weight composites material, adverse aerodynamics at off-design performance can result from changes in wing shapes due to aeroelastic deflections. Increased drag, hence increased fuel burn, is a potential consequence. Without means for aeroelastic compensation, the benefit of weight reduction from the use of light-weight material could be offset by less optimal aerodynamic performance at off-design flight conditions. Performance Adaptive Aeroelastic Wing (PAAW) technology can potentially address these technical challenges for future flexible wing transports. PAAW technology leverages multi-disciplinary solutions to maximize the aerodynamic performance payoff of future adaptive wing design, while addressing simultaneously operational constraints that can prevent the optimal aerodynamic performance from being realized. These operational constraints include reduced flutter margins, increased airframe responses to gust and maneuver loads, pilot handling qualities, and ride qualities. All of these constraints while seeking the optimal aerodynamic performance present themselves as a multi-objective flight control problem. The paper presents a multi-objective flight control approach based on a drag-cognizant optimal control method. A concept of virtual control, which was previously introduced, is implemented to address the pair-wise flap motion constraints imposed by the elastomer material. This method is shown to be able to satisfy the constraints. Real-time drag minimization control is considered to be an important consideration for PAAW technology. Drag minimization control has many technical challenges such as sensing and control. An initial outline of a real-time drag minimization control has already been developed and will be further investigated in the future. A simulation study of a multi-objective flight control for a flight path angle command with aeroelastic mode suppression and drag minimization demonstrates the effectiveness of the proposed solution. In-flight structural loads are also an important consideration. As wing flexibility increases, maneuver load and gust load responses can be significant and therefore can pose safety and flight control concerns. In this paper, we will extend the multi-objective flight control framework to include load alleviation control. The study will focus initially on maneuver load minimization control, and then subsequently will address gust load alleviation control in future work.

Aerolasticity↗
NASA NTRS2014

Benefits Analysis of Wind-Optimal Operations For Trans-Atlantic Flights

North Atlantic Tracks are trans-Atlantic routes across the busiest oceanic airspace in the world. This study analyzes and compares current flight-plan routes to wind-optimal routes for trans-Atlantic flights in terms of aircraft fuel burn, emissions and the associated climate impact. The historical flight track data recorded by EUROCONTROL's Central Flow Management Unit is merged with data from FAA's Enhanced Traffic Management System to provide an accurate flight movement database containing the highest available flight path resolution in both systems. The combined database is adopted for airspace simulation integrated with aircraft fuel burn and emissions models, contrail models, simplified climate response models, and a common climate metric to assess the climate impact of flight routes within the Organized Track System (OTS). The fuel burn and emissions for the tracks in the OTS are compared with the corresponding quantities for the wind-optimized routes to evaluate the potential environmental benefits of flying wind-optimal routes in North Atlantic Airspace. The potential fuel savings and reduction in emissions depend on existing inefficiencies in current flight plans, atmospheric conditions and location of the city-pairs. The potential benefits are scaled by comparing them with actual flight tests that have been conducted since 2010 between a few city-pairs in the transatlantic and trans-pacific region to improve fuel consumption and reduce the environmental impact of aviation.

air traffic optimization↗
NASA NTRS2021

A Simulation Study of Bin-and-Sort Policies in a Distributed System for Flights Scheduling

This is a report on the results of a simulation experiment conducted on an automated distributed system for scheduling flights in a shared airspace. The scheduling is carried out by computer systems owned by the private operators of the flights, which interface through a centralized independent server. The scheduling requires determining which of the group of flights at hand (whether owned by the same operator or different ones) are to have the advantage of being scheduled before the others. A chosen method of grouping and prioritizing flights must: have the ability to schedule a flight promptly, prevent scheduling conflicts between pairs of overlapping flight routes, and be computationally feasible. Scheduling flights one by one is the First Come First Served policy. Scheduling too many at a time is infeasible. The type of scheduling policy proposed herein, called bin-and-sort, is an attempt to reach a compromise between these two extremes. Bin-and-sort allows for each operator to choose its criteria for prioritizing its flights, and for the centralized component to use different arbitration criteria. A number of these criteria are used in the simulation presented herein. The results of each criterion choice are reported and analyzed.

flight scheduling↗
NASA NTRS2021

A Simulation Study of Bin-and-Sort Policies in a Distributed System for Flights Scheduling

This is a report on the results of a simulation experiment conducted on an automated distributed system for scheduling flights in a shared airspace. The scheduling is carried out by computer systems owned by the private operators of the flights, which interface through a centralized independent server. The scheduling requires determining which of the group of flights at hand (whether owned by the same operator or different ones) are to have the advantage of being scheduled before the others. A chosen method of grouping and prioritizing flights must: have the ability to schedule a flight promptly, prevent scheduling conflicts between pairs of overlapping flight routes, and be computationally feasible. Scheduling flights one by one is the First Come First Served policy. Scheduling too many at a time is infeasible. The type of scheduling policy proposed herein, called bin-and-sort, is an attempt to reach a compromise between these two extremes. Bin-and-sort allows for each operator to choose its criteria for prioritizing its flights, and for the centralized component to use different arbitration criteria. A number of these criteria are used in the simulation presented herein. The results of each criterion choice are reported and analyzed.

flight scheduling↗
NASA NTRSDate not supplied

System Identification for eVTOL Aircraft Using Simulated Flight Data

This paper describes a system identification method for electric vertical takeoff and landing (eVTOL) aircraft. The approach merges fixed-wing and rotary-wing modeling techniques with new strategies to develop a modeling method for eVTOL vehicles using flight test data. The eVTOL aircraft system identification approach is demonstrated through application to the NASA LA-8 tandem tilt-wing, distributed electric propulsion aircraft using a high-fidelity flight dynamics simulation. Orthogonal phase-optimized multisine inputs are applied to each control surface and propulsor at numerous flight conditions throughout the flight envelope to collect informative flight data. An aero-propulsive model is identified at each flight condition using the equation-error method in the frequency domain. The local model parameters are then blended to create a global model across the nominal flight envelope. Parameter estimation results are shown to provide a good fit to modeling data and have good prediction capability. The methodology is developed with a discussion of unique eVTOL vehicle aerodynamic characteristics and practical strategies intended to inform future flight-based system identification efforts for eVTOL aircraft.

system identification↗
DOE OSTI2024

Evaluation of the EarthSHAB Stratospheric Solar Hot Air Balloon Flight Prediction Model Using Balloon Trajectory Data

Abstract The heliotrope is a solar balloon design which is constructed out of painter’s plastic, and the exterior is coated in charcoal powder. Darkening the plastic gives the balloon a high solar absorptance, which allows it to ascend into the lower stratosphere and float for hours at a time. The balloons have previously been used to lift scientific instruments into the stratosphere to study chemical explosions, earthquakes, and stratospheric aerosols. They have also been proposed as a platform for planetary exploration. Flight predictions are crucial to preflight planning to reduce safety risks and meet flight objectives. However, there exists a wide range of possible flight paths due to varying environmental conditions and solar balloon configurations. EarthSHAB is one such software that was designed to support flight planning using the weather forecasts and balloon properties to predict the flight path of a solar balloon. We compare EarthSHAB-simulated flight paths to a set of observed flight paths for the 3.5-m diameter heliotrope design called the “Cloudskimmer.” Using the criteria that the modeled paths must fall within 5% of the observations to be considered successful, we found that EarthSHAB successfully predicted the Cloudskimmer ascent rate and average float altitude 10% and 90% of the time, respectively. We also found that the average difference in the observed and predicted landing locations was 97 km and landing times were 54 ± 38 min. Significant deviations between the observed and predicted ascent rates and excursions at float were found to be associated with heavy payloads and convective cloud development, respectively. Significance Statement Solar balloons are used to lift scientific instruments into the lower stratosphere for hours at a time to study chemical explosions, earthquakes, stratospheric aerosols, and more. The flight paths of solar balloons can be difficult to predict due to variability in their design and surrounding environment. We evaluate the accuracy of EarthSHAB, a software that predicts the altitude profile and horizontal trajectory of a solar balloon using inputs such as the weather, balloon size, and balloon mass. Our results suggest that for the balloon design used in this study, EarthSHAB is best suited for modeling the behavior of balloons with lightweight payloads that do not fly within or directly above clouds.

Lien, Jessica M. [Sandia National Laboratories, Al↗
NASA NTRS1975

Free-flight model investigation of a vertical-attitude VTOL fighter with twin vertical tails

Free-flight tests were conducted in the Langley full-scale tunnel to determine the stability and control characteristics of a vertical-attitude VTOL fighter having twin vertical tails and a pivoted fuselage forebody (nose-cockpit) arrangement. The flight tests included hovering flights and transition flights from hover to conventional forward flight. Static force tests were also made to aid in the analysis of the flight tests. The model exhibited satisfactory stability and control characteristics, and the transition from hovering flight to conventional forward flight was relatively smooth and straightforward.

Grafton, S. B.↗
NASA NTRS1977

Ion beam plume and efflux characterization flight experiment study

A flight experiment and flight experiment package for a shuttle-borne flight test of an 8-cm mercury ion thruster was designed to obtain charged particle and neutral particle material transport data that cannot be obtained in conventional ground based laboratory testing facilities. By the use of both ground and space testing of ion thrusters, the flight worthiness of these ion thrusters, for other spacecraft applications, may be demonstrated. The flight experiment definition for the ion thruster initially defined a broadly ranging series of flight experiments and flight test sensors. From this larger test series and sensor list, an initial flight test configuration was selected with measurements in charged particle material transport, condensible neutral material transport, thruster internal erosion, ion beam neutralization, and ion thrust beam/space plasma electrical equilibration. These measurement areas may all be examined for a seven day shuttle sortie mission and for available test time in the 50 - 100 hour period.

Sellen, J. M., Jr.↗
NASA NTRS1978

Flight simulation - A vital and expanding technology in aircraft development

Flight simulation, both ground and in-flight, is experiencing major technological improvement and growth. The increased capabilities are providing new opportunities for support of the aircraft development process. The development of faster digital computers, improved visual displays, better motion systems and increased interest in simulation fidelity has improved the ground simulator to the point where it accomplishes a major portion of the aircraft development before work on the flight article begins. The efficiency of the ground simulator as a forecaster for the flight testing phase is becoming well established. In-flight simulation is properly being used to bridge the gap between the ground simulator and the flight test article. Simulation provides the vital link between analysis, aerodynamic tests, and subsystem tests and the flight test article. This paper describes the latest advances in flight simulation and its increasing role in the aircraft development process.

Reynolds, P. A.↗
NASA NTRS1978

Digital Fly-By-Wire Flight Control Validation Experience

The experience gained in digital fly-by-wire technology through a flight test program being conducted by the NASA Dryden Flight Research Center in an F-8C aircraft is described. The system requirements are outlined, along with the requirements for flight qualification. The system is described, including the hardware components, the aircraft installation, and the system operation. The flight qualification experience is emphasized. The qualification process included the theoretical validation of the basic design, laboratory testing of the hardware and software elements, systems level testing, and flight testing. The most productive testing was performed on an iron bird aircraft, which used the actual electronic and hydraulic hardware and a simulation of the F-8 characteristics to provide the flight environment. The iron bird was used for sensor and system redundancy management testing, failure modes and effects testing, and stress testing in many cases with the pilot in the loop. The flight test program confirmed the quality of the validation process by achieving 50 flights without a known undetected failure and with no false alarms.

Szalai, K. J.↗
NASA NTRS1979

Flight test of a VTOL digital autoland system along complex trajectories

The objective of this research is the development and flight test of a digital multi-rate VTOL autoland system. This autoland system provided the NASA/Army Fly-by-Wire CH-47 helicopter with an automatic 4-D trajectory following and landing capability. Flight tests were conducted along complex trajectories with descending, turning, and decelerating segments. The flight software consists of a trajectory generator and guidance algorithm operating at two iterations per second and a set of sensor filters and an advanced controller operating at 10 iterations per second. This low iteration rate digital controller has a proportional-integral structure that provides an autotrim function. The control gains, scheduled as a function of flight condition, are updated every two seconds. All flight software, except input/output routines, are coded in FORTRAN using floating point arithmetic and are exercised in a ROLM 1664 flight computer. The flight software, the ground and flight hardware, the autoland system's position tracking performance, and the controller's velocity and heading tracking performance are presented.

Downing, D. R.↗
NASA NTRS1979

Spacelab flight operations

The paper covers the primary activities involved in Spacelab flight operations. These operations are characterized by a partnership between the operators of the Space Transportation System (STS) and the mission management organization which involves the activities of flight control personnel and the flight crew, and must exist as an integrated team to complete a Spacelab flight. An overview of this partnership is presented from the initial planning phase through the actual flight operation, noting the responsibilities and functions of the flight crew members and the makeup of the flight control team. A typical flight scenario describing the basic operation of the Spacelab and a description of the Mission Control Center and Payload Operations Control Center are given.

Harlan, C. S.↗
NASA NTRS1981

The effects of space flight on some rat liver enzymes regulating carbohydrate and lipid metabolism

The effects of space flight conditions on the activities of certain enzymes regulating carbohydrate and lipid metabolism in rat liver are investigated in an attempt to account for the losses in body weight observed during space flight despite preflight caloric consumption. Liver samples were analyzed for the activities of 32 cytosolic and microsomal enzymes as well as hepatic glycogen and individual fatty acid levels for ground control rats and rats flown on board the Cosmos 936 biosatellite under normal space flight conditions and in centrifuges which were sacrificed upon recovery or 25 days after recovery. Significant decreases in the activities of glycogen phosphorylase, alpha-glycerol phosphate acyl transferase, diglyceride acyl transferase, aconitase and 6-phosphogluconate dehydrogenase and an increase in palmitoyl CoA desaturase are found in the flight stationary relative to the flight contrifuged rats upon recovery, with all enzymes showing alterations returning to normal values 25 days postflight. The flight stationary group is also observed to be characterized by more than twice the amount of liver glycogen of the flight centrifuged group as well as a significant increase in the ratio of palmitic to palmitoleic acid. Results thus indicate metabolic changes which may be involved in the mechanism of weight loss during weightlessness, and demonstrate the equivalence of centrifugation during space flight to terrestrial gravity.

Abraham, S.↗
NASA NTRS1983

Flight management concepts development for fuel conservation

It is pointed out that increased airspace congestion will produce increased flight delay unless advanced flight management concepts are developed to compensate. It has been estimated that a 5 percent reduction in delay is approximately equivalent, in terms of direct operating costs, to a 5 percent reduction in drag. The present investigation regarding the development of the required flight management concepts is organized into three sections, related to background, current research, and future effort. In the background section, a summary is provided of past technical effort concerning flight management. The second section is concerned with on-going efforts to integrate flight management with ground-based flight planning, and with an advanced concepts simulator to test the new developments. In the third section, attention is given to research concerning airborne flight management integration with other flight functions.

Sorensen, J. A.↗
NASA NTRS1986

X-29A technology demonstrator flight test program overview

An overview of the X-29A functional flight program and concept evaluation program is presented, including some of the unique and different preparations for the first flight. Included are a discussion of the many organizational responsibilities and a description of the program management structure for the test team. Also discussed are preflight ground, flight functional envelope expansion, and flight research test objectives and qualitive results to date for both a limited-envelope flight control system and an expanded-envelope system. The aircraft, including the instrumentation system and measurements, is described. In addition, a discussion is included regarding the use of major support facilities, such as ground and flight simulators, the NASA Western Aeronautical Test Range and mission control center, and the Grumman automated telemetry station. An overview of the associated real-time and postflight batch data processing software approaches is presented. The use of hardware-in-the-loop simulation for independent verification and validation and mission planning and practice is discussed. Also included is a description of the flight-readiness review, the airworthiness and flight safety review, work scheduling, technical briefings, and preflight and postflight crew briefings. The configuration control process used on the X-29A program is described, and its relationship to both simulation and aircraft operations is discussed. An X-29A schedule overview is presented with an outline of a proposed follow-on program.

Sefic, W. J.↗