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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 343 records · Page 19
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NASA NTRS2005

On a Slow Roll

Satellite navigation and surveillance products and services can cut costs, improve accuracy, expand coverage and enhance safety. But the global transformation of air traffic management (ATM) that satellites and ground augmentation systems have promised is being realized much more slowly than expected. "There are still a lot of nations that could benefit [from satellite navigation and surveillance] that haven't invested dime in new equipment." says Tim Katanik, manager of business development for navigation and landing systems Raytheon. But then things usually move slowly in this industry, he adds.

Hughes, David↗
NASA NTRS2005

The Implications of Handling Qualities in Civil Helicopter Accidents Involving Hover and Low Speed Flight

Because of increasing accident rates in Army helicopters in hover and low speed flight, a study was made in 1999 of accidents which could be attributed to inadequate stability augmentation. A study of civil helicopter accidents from 1993-2004 was then undertaken to pursue the issue of poor handling qualities in helicopters which, in almost all cases, had no stability augmentation. The vast majority of the mishaps studied occurred during daylight in visual meteorological condition, reducing the impact of degraded visual environments (DVE) on the results. Based on the Cooper-Harper Rating Scale, the handling qualities of many of the helicopters studied could be described as having from "very objectionable" to "major" deficiencies. These costly deficiencies have resulted in unnecessary loss of life, injury, and high dollar damage. Low cost and lightweight augmentation systems for helicopters have been developed in the past and are still being investigated. They offer the potential for significant reductions in the accident rate.

Dugan, Daniel C.↗
NASA NTRS2007

Generating high precision ionospheric ground-truth measurements

A method, apparatus and article of manufacture provide ionospheric ground-truth measurements for use in a wide-area augmentation system (WAAS). Ionospheric pseudorange/code and carrier phase data as primary observables is received by a WAAS receiver. A polynomial fit is performed on the phase data that is examined to identify any cycle slips in the phase data. The phase data is then leveled. Satellite and receiver biases are obtained and applied to the leveled phase data to obtain unbiased phase-leveled ionospheric measurements that are used in a WAAS system. In addition, one of several measurements may be selected and data is output that provides information on the quality of the measurements that are used to determine corrective messages as part of the WAAS system.

Komjathy, Attila↗
NASA NTRS2011

Commercially Hosted Government Payloads: Lessons from Recent Programs

In a commercially hosted operational mode, a scientific instrument or operational device is attached to a spacecraft but operates independently from the spacecraft s primary mission. Despite the expected benefits of this arrangement, there are few examples of hosted payload programs actually being executed by government organizations. The lack of hosted payload programs is largely driven by programmatic challenges, both real and perceived, rather than by technical challenges. Partly for these reasons, NASA has not sponsored a hosted payload program, in spite of the benefits and visible community interest in doing so. In the interest of increasing the use of hosted payloads across the space community, this paper seeks to alleviate concerns about hosted payloads by identifying these programmatic challenges and presenting ways in which they can be avoided or mitigated. Despite the challenges, several recent hosted payload programs have been successfully completed or are currently in progress. This paper presents an assessment of these programs, with a focus on acquisition, costs, schedules, risks, and other programmatic aspects. The hosted payloads included in this study are the Federal Aviation Administration's Wide Area Augmentation System (WAAS) payloads, United States Coast Guard's Automatic Identification System (AIS) demonstration payload, Department of Defense's IP Router In Space (IRIS) demonstration payload, the United States Air Force's Commercially Hosted Infrared Payload (CHIRP), and the Australian Defence Force's Ultra High Frequency (UHF) payload. General descriptions of each of these programs are presented along with issues that have been encountered and lessons learned from those experiences. A set of recommended approaches for future hosted payload programs is presented, with a focus on addressing risks or potential problem areas through smart and flexible contracting up front. This set of lessons and recommendations is broadly applicable to future hosted payload programs, whether they are technology demonstrations, communications systems, or operational sensors. Additionally, we present a basic cost model for commercial access to space for hosted payloads as a function of payload mass

Andraschko, Mark A.↗
NASA NTRS2014

Incorporating Handling Qualities Analysis into Rotorcraft Conceptual Design

This paper describes the initial development of a framework to incorporate handling qualities analyses into a rotorcraft conceptual design process. In particular, the paper describes how rotorcraft conceptual design level data can be used to generate flight dynamics models for handling qualities analyses. Also, methods are described that couple a basic stability augmentation system to the rotorcraft flight dynamics model to extend analysis to beyond that of the bare airframe. A methodology for calculating the handling qualities characteristics of the flight dynamics models and for comparing the results to ADS-33E criteria is described. Preliminary results from the application of the handling qualities analysis for variations in key rotorcraft design parameters of main rotor radius, blade chord, hub stiffness and flap moment of inertia are shown. Varying relationships, with counteracting trends for different handling qualities criteria and different flight speeds are exhibited, with the action of the control system playing a complex part in the outcomes. Overall, the paper demonstrates how a broad array of technical issues across flight dynamics stability and control, simulation and modeling, control law design and handling qualities testing and evaluation had to be confronted to implement even a moderately comprehensive handling qualities analysis of relatively low fidelity models. A key outstanding issue is to how to 'close the loop' with an overall design process, and options for the exploration of how to feedback handling qualities results to a conceptual design process are proposed for future work.

Analysis into Rotorcraft↗
NASA NTRS2015

Ionospheric Mapping Software Ensures Accuracy of Pilots GPS

IonoSTAGE and SuperTruth software are part of a suite created at the Jet Propulsion Laboratory to enable the Federal Aviation Administration's Wide Area Augmentation System, which provides pinpoint accuracy in aircraft GPS units. The system, used by more than 73,000 planes, facilitates landings under adverse conditions at small airports. In 2013, IonoSTAGE and SuperTruth found their first commercial license when NEC, based in Japan, with US headquarters in Irving, Texas, licensed the entire suite.

Source record↗
NASA NTRS2018

Propulsion System Options for a Potential Sample Return Lander (SRL) for Mars

A potential Mars Sample Return (MSR) campaign would be very unique challenge and has been the focus of technology development and planning efforts at JPL for several decades. The latest mission concept study focuses on a potential Sample Return Lander (SRL). The potential SRL examined several propulsion system approaches using monopropellant and bi-propellants for the terminal descent phase. A ranking was developed based on a mathematical optimization program. This paper focuses on the evaluations conducted for these system options. Historically, monopropellant and bi-propellant propulsion systems are usually considered for this application; this study took a fresh look at both conventional State of the Art (SOA) pressure fed monopropellant and bi-propellant propulsion system and augmenting the system using small Electrically Driven Pumps (EDP) for both these propulsion systems.

Preudhomme, Michael↗
NASA NTRS2021

The spatial distribution of ionospheric threats to WAAS integrity, 2000 – 2019: a systematic analysis

The United States’ Wide Area Augmentation System (WAAS) broadcasts data to facilitate aircraft navigation. This paper examines the spatial dependence of ionospheric disturbances that have threatened the accuracy and reliability of position estimates derived from these data over the period 2000 – 2019. We address two distinct aspects of this spatial dependence: (1) the geographic distribution of these threats, in particular, in relation to geomagnetic latitude, and (2) the geometric dependence of threats relative to the locations of the receiver sites that comprise the WAAS network. We analyze threat distributions in terms of the various means that WAAS employs to mitigate these threats, including the Extreme Storm Detector, the Moderate Storm Detector, local irregularity detectors, and the ionospheric threat model. Distinct distributions are presented for threats occurring in Solar Cycle 23 and those of Solar Cycle 24. To study the geometric dependence of threats on receiver locations, we use as a metric the distance separating a threat from the centroid of the nearest Ncentroid receivers. Large values of this metric identify threats at or beyond the edge of coverage. We conclude by discussing the implications of our results for WAAS operations.

Altshuler, Eric↗
NASA NTRSDate not supplied

Analyses of the Boeing 737-MAX Accidents: Formal Models and Psychological Perspectives

Two fatal accidents involving the B737MAX resulted from the flight crews’ inability to overcome the effects of the Maneuvering Characteristics Augmentation System (MCAS). MCAS was designed to mimic the control column feel pressure and pitching behavior of the B737NG, which was the certification basis for the B737MAX. We briefly describe the potential role of formally modeling different perspectives during system design, and how such modeling can reveal gaps and conflicts between perspectives. We also discuss some of the relevant human factors issues involved in these accidents and how the aircraft’s behavior may have affected the pilots’ psychological states. Implications for automation design are considered.

5737MAX↗
NASA NTRS1984

Leading edge flap system for aircraft control augmentation

Traditional roll control systems such as ailerons, elevons or spoilers are least effective at high angles of attack due to boundary layer separation over the wing. This invention uses independently deployed leading edge flaps on the upper surfaces of vortex stabilized wings to shift the center of lift outboard. A rolling moment is created that is used to control roll in flight at high angles of attack. The effectiveness of the rolling moment increases linearly with angle of attack. No adverse yaw effects are induced. In an alternate mode of operation, both leading edge flaps are deployed together at cruise speeds to create a very effective airbrake without appreciable modification in pitching moment. Little trim change is required.

Rao, D. M.↗
NASA NTRS1990

Rain-fade simulation and power augmentation for satellite communication systems

The design and implementation of an automated rain-fade simulation and power augmentation system is presented. The system experimentally simulates and measures the effects of radiofrequency power fade on a 20 GHz communication link using a multimode travelling wave tube amplifier for loss compensation. Precision, computer-controlled attenuators are used in the fade simulation. Test plans for analog and digital testing are discussed.

Shalkhauser, Kurt A.↗
NASA NTRS1972

Wind tunnel investigation of a large scale 35 deg swept wing jet transport model with an external blowing triple slotted flap

An investigation was conducted to determine the aerodynamic characteristics of a large-scale subsonic jet transport model with an externally jet-augmented flap system that would augment lift and provide direct-lift control. The model had a 35 deg swept wing of aspect ratio 7.82 and two side-by-side engines mounted on a single pylon under each wing close to the fuselage. The lift of the flap system was augmented by jet engine exhaust impingement on the triple-slotted flap surfaces. The rearmost flap provided direct lift control. Results were obtained for several combinations of flap deflections at gross thrust coefficients from 0 to 2.0. Three-component longitudinal data are presented with four engines operating. Limited longitudinal and lateral data are presented for asymmetric and symmetric thrust conditions with three engines operating. For the same overall flap deflection, lift coefficient and maximum lift coefficient were improved 13 and 7 percent compared to coefficients obtained with a double-slotted flap configuration. A maximum lift coefficient of 6.3 was obtained at a gross thrust coefficient of 2.0. At the same flap deflection lateral and directional trim moment requirements with an engine inoperative were reduced 55 and 33 percent, respectively, compared to those with the engines located farther outboard on the wing. Trim moment requirements in pitch were also reduced significantly. However, pitching-moment instability occurred and increased with gross thrust coefficient.

Aoyagi, K.↗
NASA NTRS2011

Man-Machine Integration Design and Analysis System (MIDAS) v5: Augmentations, Motivations, and Directions for Aeronautics Applications

As automation and advanced technologies are introduced into transport systems ranging from the Next Generation Air Transportation System termed NextGen, to the advanced surface transportation systems as exemplified by the Intelligent Transportations Systems, to future systems designed for space exploration, there is an increased need to validly predict how the future systems will be vulnerable to error given the demands imposed by the assistive technologies. One formalized approach to study the impact of assistive technologies on the human operator in a safe and non-obtrusive manner is through the use of human performance models (HPMs). HPMs play an integral role when complex human-system designs are proposed, developed, and tested. One HPM tool termed the Man-machine Integration Design and Analysis System (MIDAS) is a NASA Ames Research Center HPM software tool that has been applied to predict human-system performance in various domains since 1986. MIDAS is a dynamic, integrated HPM and simulation environment that facilitates the design, visualization, and computational evaluation of complex man-machine system concepts in simulated operational environments. The paper will discuss a range of aviation specific applications including an approach used to model human error for NASA s Aviation Safety Program, and what-if analyses to evaluate flight deck technologies for NextGen operations. This chapter will culminate by raising two challenges for the field of predictive HPMs for complex human-system designs that evaluate assistive technologies: that of (1) model transparency and (2) model validation.

Gore, Brian F.↗
NASA NTRS1987

Multimodal user input to supervisory control systems - Voice-augmented keyboard

The use of a voice-augmented keyboard input modality is evaluated in a supervisory control application. An implementation of voice recognition technology in supervisory control is proposed: voice is used to request display pages, while the keyboard is used to input system reconfiguration commands. Twenty participants controlled GT-MSOCC, a high-fidelity simulation of the operator interface to a NASA ground control system, via a workstation equipped with either a single keyboard or a voice-augmented keyboard. Experimental results showed that in all cases where significant performance differences occurred, performance with the voice-augmented keyboard modality was inferior to and had greater variance than the keyboard-only modality. These results suggest that current moderately priced voice recognition systems are an inappropriate human-computer interaction technology in supervisory control systems.

Mitchell, Christine M.↗
NASA NTRS1999

Development of a 12-Thrust Chamber Kerosene /Oxygen Primary Rocket Sub-System for an Early (1964) Air-Augmented Rocket Ground-Test System

Airbreathing/Rocket combined-cycle, and specifically rocket-based combined- cycle (RBCC), propulsion systems, typically employ an internal engine flow-path installed primary rocket subsystem. To achieve acceptably short mixing lengths in effecting the "air augmentation" process, a large rocket-exhaust/air interfacial mixing surface is needed. This leads, in some engine design concepts, to a "cluster" of small rocket units, suitably arrayed in the flowpath. To support an early (1964) subscale ground-test of a specific RBCC concept, such a 12-rocket cluster was developed by NASA's Marshall Space Flight Center (MSFC). The small primary rockets used in the cluster assembly were modified versions of an existing small kerosene/oxygen water-cooled rocket engine unit routinely tested at MSFC. Following individual thrust-chamber tests and overall subsystem qualification testing, the cluster assembly was installed at the U. S. Air Force's Arnold Engineering Development Center (AEDC) for RBCC systems testing. (The results of the special air-augmented rocket testing are not covered here.) While this project was eventually successfully completed, a number of hardware integration problems were met, leading to catastrophic thrust chamber failures. The principal "lessons learned" in conducting this early primary rocket subsystem experimental effort are documented here as a basic knowledge-base contribution for the benefit of today's RBCC research and development community.

Pryor, D.↗
NASA NTRS2002

Thrust Augmentation with Mixer/Ejector Systems

Older commercial aircraft often exceed FAA (Federal Aviation Administration) sideline noise regulations. The major problem is the jet noise associated with the high exhaust velocities of the low bypass ratio engines on such aircraft. Mixer/ejector exhaust systems can provide a simple means of reducing the jet noise on these aircraft by mixing cool ambient air with the high velocity engine gases before they are exhausted to ambient. This paper presents new information on thrust performance predictions, and thrust augmentation capabilities of mixer/ejectors. Results are presented from the recent development program of the patented Alternating Lobe Mixer Ejector Concept (ALMEC) suppressor system for the Gulfstream GII, GIIB and GIII aircraft. Mixer/ejector performance procedures are presented which include classical control volume analyses, compound compressible flow theory, lobed nozzle loss correlations and state of the art computational fluid dynamic predictions. The mixer/ejector thrust predictions are compared to subscale wind tunnel test model data and actual aircraft flight test measurements. The results demonstrate that a properly designed mixer/ejector noise suppressor can increase effective engine bypass ratio and generate large thrust gains at takeoff conditions with little or no thrust loss at cruise conditions. The cruise performance obtained for such noise suppressor systems is shown to be a strong function of installation effects on the aircraft.

Presz, Walter M., Jr.↗
NASA NTRS2014

Flight Testing of the Space Launch System (SLS) Adaptive Augmenting Control (AAC) Algorithm on an F/A-18

The Marshall Space Flight Center (MSFC) Flight Mechanics and Analysis Division developed an adaptive augmenting control (AAC) algorithm for launch vehicles that improves robustness and performance on an as-needed basis by adapting a classical control algorithm to unexpected environments or variations in vehicle dynamics. This was baselined as part of the Space Launch System (SLS) flight control system. The NASA Engineering and Safety Center (NESC) was asked to partner with the SLS Program and the Space Technology Mission Directorate (STMD) Game Changing Development Program (GCDP) to flight test the AAC algorithm on a manned aircraft that can achieve a high level of dynamic similarity to a launch vehicle and raise the technology readiness of the algorithm early in the program. This document reports the outcome of the NESC assessment.

Dennehy, Cornelius J.↗