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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Determination of an angle of attack sensor correction for a general aviation airplane at large angles of attack as determined from wind tunnel and flight tests

A comprehensive investigation into the flow correction for an angle of attack sensor mounted ahead of the wing tip of a general aviation research airplane has been conducted at the Langley Research Center. This correction has been determined in wind tunnels using a full-scale model up to angles of attack of 45 deg and a 1/5-scale model up to 80 deg angle of attack. The flow correction has also been obtained in flight by using a standard technique at low angles of attack and in spinning flight at larger angles of attack, by using both a simple approximate technique and a parameter estimation technique. The results show the correction is significant, reaching 10 deg at a measured angle of attack of about 90 deg. The flow correction was sensitive to the angle of sideslip at measured angles of attack greater than 60 deg and was not influenced by wing leading-edge modifications or aileron deflections.

Moul, T. M.↗
DOE OSTI2023

Hybrid Cyber-attack Detection in Photovoltaic Farms

Here, to address the cyber-physical security in PV farms, a hybrid cyber-attack detection is proposed in this manuscript. To secure PV farms, the proposed method integrates model-based and data-driven methods by fusing the detection score at the device and system levels. First, a model-based cyber-attack detection method is developed for each PV inverter. A residual between the estimation of the Kalman filter and measurement is calculated. By leveraging the calculated residual from all inverters, a squared Mahalanobis distance is developed for device detection score generation. At the system level, a convolutional neural network (CNN) is proposed to detect cyber-attack using the waveform data at the point of common coupling (PCC) in PV farms. To improve the CNN detection accuracy, a set of well-designed features are extracted from the raw waveform data. Finally, a weighted detection score fusion method is proposed to combine device and system detection scores by using their complementary strength. The feasibility and robustness of the proposed method are validated by testing cases and a comparative experiment.

14 SOLAR ENERGY↗
NASA NTRS1979

Wind-tunnel investigation of the flow correction for a model-mounted angle of attack sensor at angles of attack from -10 deg to 110 deg

A preliminary wind tunnel investigation was undertaken to determine the flow correction for a vane angle of attack sensor over an angle of attack range from -10 deg to 110 deg. The sensor was mounted ahead of the wing on a 1/5 scale model of a general aviation airplane. It was shown that the flow correction was substantial, reaching about 15 deg at an angle of attack of 90 deg. The flow correction was found to increase as the sensor was moved closer to the wing or closer to the fuselage. The experimentally determined slope of the flow correction versus the measured angle of attack below the stall angle of attack agreed closely with the slope of flight data from a similar full scale airplane.

Moul, T. M.↗
NASA NTRS1952

Propeller induced angles of attack and section angles of attack for the NACA 10-(3)(066)-03, 10-(3)(049)-03, 10-(3)(090)-03, 10-(5)(066)-03, and 10-(0)(066)-03 propellers

This paper presents the results of an induced angle-of-attack calculation using a method applicable to a propeller with arbitrary circulation distribution. Tables of induced angles of attack and section angles of attack and curves of wake-survey results are presented for the NACA 10-(3)(066)-03, 10-(3)(049)-03, 10-(3)(090)-03, 10-(5)(066)-03, and 10-(0)(066)-03 propellers. A brief description of the method of calculating propeller induced angles of attack is given.

Igoe, William, B↗
NASA NTRS1972

Space shuttle: Verification of transition reentry corridor at high angles of attack and determination of transition aerodynamic characteristics and subsonic aerodynamic characteristics at low angles of attack for the Boeing H-32 booster

Experimental aerodynamic investigations were made in a transonic wind tunnel on a 1/150-scale model of the Boeing H-32 space shuttle booster configuration. The purpose of the test was: (1) to verify the transonic reentry corridor at high angles of attack; (2) to determine the transonic aerodynamic characteristics; and (3) to determine the subsonic aerodynamic characteristics at low angles of attack. Test variables included configuration buildup, horizontal stabilizer settings of 0 and -20 deg, elevator deflections of 0 and -30 deg, and wing spoiler settings of 60 deg.

Houser, J.↗
NASA NTRS1972

Space shuttle: High angle of attack transition and low angle of attack launch phase aerodynamic stability and control of GD/C B-18E-2, B-18E-3 delta wing booster, and launch configuration of MSC-040A orbiter and twin pressure fed boosters

The test was a conventional stability and control test except for two aspects. One was the very high angles of attack at which the delta wing configurations were tested (up to 60 degrees) at Mach numbers of 3 and 4.96. The other was the installation of the orbiter and twin boosters in a manner that caused the support system to induce normal forces and side forces on the aft portion of the boosters at all Mach numbers; i.e., the support and the booster bodies were close together, side by side.

Debevoise, J. M.↗
NASA NTRS1983

The effect of asymmetric attack on trim angle of attack

Ballistic range tests were conducted to determine the effect of an asymmetrically ablated heat shield on the trim angle of attack of an entry vehicle. The tests, which were in support of Project Galileo, were conducted in atmospheric air at Mach numbers from 0.7 to 2.0. For the results for the configuration that was tested, the deduced trim angle varied between 13 deg and 21 deg.

Kruse, R. L.↗
DOE OSTI2024

Human fatalities resulting from wild pig attacks worldwide – 2000-2019

Although reported to be rare, human fatalities resulting from wild pig (Sus scrofa) attacks do occur. Toward a better understanding of patterns in fatal wild pig attacks, we synthesized worldwide reports of wild pig attacks on humans between 2000 and 2019. We documented 163 separate reports of fatal wild pig attacks that resulted in 172 human deaths. On average, 8.6 human deaths occurred annually due to wild pig attacks during those 2 decades. The majority of fatal attacks resulted in a single human death; however, there were 6 cases in which an individual fatal attack resulted in 2–4 human deaths. These fatal wild pig attacks occurred in 29 countries, mostly within the wild pig’s native global range. Fatal attacks primarily occurred under non-hunting circumstances and involved seemingly unprovoked wild pigs. Under hunting circumstances, fatal attacks primarily involved provoked or wounded wild pigs. Fatal attacks typically involved a solitary wild pig, with 12% involving multiple pigs. Solitary pigs involved in fatal attacks were typically large boars that in most attacks exhibited defensive behaviors, although we discovered 7 attacks during which the pig’s behaviors appeared to be predatory. Three fatal attacks were initially investigated as homicides. Overall, victims of fatal wild pig attacks were between 3 and 85 years old and were traveling on foot when the attack occurred. The majority of victims of fatal attacks were adult (20–59 years old), male, traveling on foot, and working in isolation. Among all fatal attacks, 50% identified the cause of death, which included exsanguination/hemorrhagic shock, severe injury, heart attack, craniocerebral injury, severe injury/disembowelment/intestinal prolapse, and toxemia/septicemia. Fatal wild pig attacks occurred primarily in rural areas, with fatal attacks 390% more likely to occur in rural areas with large populations and at least 45% forested and agricultural cover. The greater the rural human population size within a country is, the greater the number of fatal wild pig attacks.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Model-Based Detection of Coordinated Attacks (DCA) in Distribution Systems

The fast-paced growth in digitization of smart grid components enhances system observability and remote-control capabilities through efficient communication. However, enhanced connectivity results in heightened system vulnerability towards cybersecurity risks in the cyber-physical power system. Coordinated cyber-attacks (CCA), when undetected, lead to system-wide impact in terms of large disturbances or widespread outages. Detecting CCA in the cyber layer is critical to thwart cyber-attacks in real-time before the attack impacts the physical system. The challenge of locating CCA stems from the complex grid dynamics, making it difficult to distinguish between normal operational variations and cyber-attack impact. CCA often employs multiple attack vectors targeting geographically distributed components, further complicating CCA identification. Existing research in intrusion detection is primarily focused on the transmission network and limited to detecting individual attacks. In this paper, a novel proactive DCA strategy is proposed for early detection of CCA by establishing correlations among distinct attack events through model-based reinforcement learning that utilizes abductive reasoning to conclude the attacker goal. The solution includes understanding the system model, learning the system dynamics, and correlating individual cyber-attacks to extract the attacker’s objective. The developed learning algorithm identifies the most probable attack path to reach the attacker’s objective by predicting the next attack steps. A DNP3-based cyber-physical co-simulation testbed is developed to test the proposed algorithm using the IEEE 13-node test feeder.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2024

A Framework for Evaluating the Implementation Cost of Attacks on Large Language Models

Large Language Models (LLMs) have been increasingly proposed as a method to enhance productivity in tasks that involve language and code. However, these models are large, complex, and their capabilities are not easily understood and controlled, meaning that their adoption opens many possibilities for new cyberattacks and misuse. Numerous attacks on LLMs have been reported and summarized in literature reviews, but we found existing reviews lacking in understanding the implementation cost of the attacks - i.e., how much effort would an attacker need in terms of coding, expertise, and resources to adopt attacks presented in the literature. Therefore, we divide existing attacks on LLMs into a taxonomy, and define a cost evaluation framework to determine the cost of the attack. An attack’s cost can be 1) estimated from reading the publication about the attack or 2) determined by implementing the attack from that publication. We provide an example evaluation of a couple jailbreaking frameworks based on experiments, and then apply the more lightweight cost estimate to a representative selection of attacks across the taxonomy we define. We discuss the relative difficulty of the attacks and also highlight defenses that have attempted to mitigate these attacks and assess their effectiveness.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1992

Correlation of forebody pressures and aircraft yawing moments on the X-29A aircraft at high angles of attack

In-flight pressure distributions at four fuselage stations on the forebody of the X-29A aircraft have been reported at angles of attack from 15 to 66 deg and at Mach numbers from 0.22 to 0.60. At angles of attack of 20 deg and higher, vortices shed from the nose strake caused suction peaks in the pressure distributions that generally increased in magnitude with angle of attack. Above 30 deg-angle of attack, the forebody pressure distributions became asymmetrical at the most forward station, while they remained nearly symmetrical until 50 to 55 deg-angle of attack for the aft stations. Between 59 to 66 deg-angle of attack, the asymmetry of the pressure distributions changed direction. Yawing moments for the forebody alone were obtained by integrating the forebody pressure distributions. At 45 deg-angle of attack, the aircraft yaws to the right and at 50 deg and higher, the aircraft yaws to the left. The forebody yawing moments correlated well with the aircraft left yawing moment at an angle of attack of 50 deg or higher. At a 45 deg-angle of attack, the forebody yawing moments did not correlate well with the aircraft yawing moment, but it is suggested that this was due to asymmetric pressures on the cockpit region of the fuselage which was not instrumented. The forebody was also shown to provide a positive component of directional stability of the aircraft at angles of attack of 25 deg or higher. A Mach number effect was noted at angles of attack of 30 deg or higher at the station where the nose strake was present. At this station, the suction peaks in the pressure distributions at the highest Mach number were reduced and much more symmetrical as compared to the lower Mach number pressure distributions.

Fisher, David F.↗
NASA NTRS1992

Correlation of Forebody Pressures and Aircraft Yawing Moments on the X-29A Aircraft at High Angles of Attack

In-flight pressure distributions at four fuselage stations on the forebody of the X-29A aircraft have been reported at angles of attack from 15 to 66° and at Mach numbers from 0.22 to 0.60. At angles of attack of 20° and higher, vortices shed from the nose strake caused suction peaks in the pressure distributions that generally increased in magnitude with angle of attack. Above 30° -angle of attack, the fore body pressure distributions became asymmetrical at the most forward station, while they remained nearly symmetrical until 50- to 55°-angle of attack for the aft stations. Between 59- to 66°-angle of attack, the asymmetry of the pressure distributions changed direction. Yawing moments for the forebody alone were obtained by integrating the forebody pressure distributions. At 45°-angle of attack, the aircraft yaws to the right and at 50° and higher, the aircraft yaws to the left. The fore body yawing moments correlated well with the aircraft left yawing moment at an angle of attack of 50° or higher. At a 45°-angle of attack, the forebody yawing moments did not correlate well with the aircraft yawing moment, but it is suggested that this was due to asymmetric pressures on the cockpit region of the fuselage which was not instrumented. The forebody was also shown to provide a positive component of directional stability of the aircraft at angles of attack of 25° or higher. A Mach number effect was noted at angles of attack of 30° or higher at the station where the nose strake was present. At this station, the suction peaks in the pressure distributions at the highest Mach number were reduced and much more symmetrical as compared to the lower Mach number pressure distributions.

Flight Testing↗
DOE OSTI2026

Cyote-attack Chain Estimator

Attack Chain Estimator (ACE) Application Overview The Attack Chain Estimator (ACE) Application is a sophisticated tool designed for the ingestion, classification, sequencing, and enrichment of cybersecurity threat reports. This application leverages advanced machine learning models and extensive historical data to provide comprehensive insights into cyber threats, specifically targeting Industrial Control Systems (ICS). Purpose The primary functions of the ACE Application include: Ingestion of Cybersecurity Threat Reporting: Capable of ingesting text-based threat reports in markdown or text file format. Supports ingestion of structured data from other sources in STIX/JSON format. Classification of Report’s Text-Based Events: Utilizes a DeBERTa classifier, specifically trained on cybersecurity data, to map the events to MITRE ATT&CK for ICS Tactics and Techniques. Classification is performed using multiple Jupyter notebooks and machine learning workflows hosted as FastAPI microservices: regex_data deberta_base_35_train_hft_classifier_mlflow.ipynb hft_regex_classifier_mlflow.ipynb param_train_hft_classifier_mlflow.ipynb regex_tactic_tech.ipynb Ordering of Tactics, Techniques, and Observable Events: Sequences the identified tactics, techniques, and events to form a coherent attack chain. Enrichment with Historical Attack Chain Details: Enhances the attack chain with details from historical attacks using a Markov model developed from CyOTE Precursor Analysis Report data. The Markov model is available as a FastAPI endpoint for seamless integration. Enrichment with Adversary Emulation Capabilities Data: Integrates adversary emulation capabilities data using MITRE Caldera for OT adversary abilities UUIDs. Export of Output Files: Provides options to export the enriched attack chain in JSON or CSV formats. Routing of Output to Other Applications: Facilitates routing of output to various platforms and applications, including: Threat Intelligence Platforms COREII Scout for Threat Intelligence Analysis COREII Modeling and Simulation for Adversary Emulation Technical Description The ACE Application is an advanced cybersecurity tool designed to provide detailed threat analysis and sequence generation. It is built on a robust architecture that integrates natural language processing, machine learning, and historical data modeling. Key Components: Data Ingestion Module: Handles the input of threat reports and data from various formats, ensuring flexibility in data sources. Classification Engine: Employs DeBERTa-based classifiers hosted as FastAPI microservices to analyze and classify threat report events in accordance with the MITRE ATT&CK framework for ICS. Sequence Generator: Orders the classified events into a logical attack chain, providing clear insight into the sequence of tactics and techniques used in the threat. Enrichment Engine: Integrates historical data and adversary emulation capabilities to enhance the attack chain with valuable context and additional details. The historical data enrichment is powered by a Markov model, which is available as a FastAPI endpoint. Export and Routing Module: Facilitates the export of the enriched attack chain in multiple formats and routes the output to designated applications for further analysis or emulation.

Paul, Tony [Idaho National Laboratory (INL), Idaho↗
NASA NTRS1954

Longitudinal Aerodynamic Characteristics to Large Angles of Attack of a Cruciform Missile Configuration at a Mach Number of 2

The lift, pitching-moment, and drag characteristics of a missile configuration having a body of fineness ratio 9.33 and a cruciform triangular wing and tail of aspect ratio 4 were measured at a Mach number of 1.99 and a Reynolds number of 6.0 million, based on the body length. The tests were performed through an angle-of-attack range of -5 deg to 28 deg to investigate the effects on the aerodynamic characteristics of roll angle, wing-tail interdigitation, wing deflection, and interference among the components (body, wing, and tail). Theoretical lift and moment characteristics of the configuration and its components were calculated by the use of existing theoretical methods which have been modified for application to high angles of attack, and these characteristics are compared with experiment. The lift and drag characteristics of all combinations of the body, wing, and tail were independent of roll angle throughout the angle-of-attack range. The pitching-moment characteristics of the body-wing and body-wing-tail combinations, however, were influenced significantly by the roll angle at large angles of attack (greater than 10 deg). A roll from 0 deg (one pair of wing panels horizontal) to 45 deg caused a forward shift in the center of pressure which was of the same magnitude for both of these combinations, indicating that this shift originated from body-wing interference effects. A favorable lift-interference effect (lift of the combination greater than the sum of the lifts of the components) and a rearward shift in the center of pressure from a position corresponding to that for the components occurred at small angles of attack when the body was combined with either the exposed wing or tail surfaces. These lift and center-of-pressure interference effects were gradually reduced to zero as the angle of attack was increased to large values. The effect of wing-tail interference, which influenced primarily the pitching-moment characteristics, is dependent on the distance between the wing trailing vortex wake and the tail surfaces and thus was a function of angle of attack, angle of roll, and wing-tail interdigitation. Although the configuration at zero roll with the wing and tail in line exhibited the least center-of-pressure travel, the configuration with the wing and tail interdigitated had the least change in wing-tail interference over the angle-of-attack range. The lift effectiveness of the variable-incidence wing was reduced by more than 70 percent as a result of an increase in the combined angle of attack and wing incidence from 0 deg to 40 deg. The wing-tail interference (effective downwash at the tail) due to wing deflection was nearly zero as a result of a region of negative vorticity shed from the inboard portion of the wing. The lift characteristics of the configuration and its components were satisfactorily predicted by the calculated results, but the pitching moments at large angles of attack were not because of the influence of factors for which no adequate theory is available, such as the variation of the crossflow drag coefficient along the body and the effect of the wing downwash field on the afterbody loading.

Spahr, J. R.↗
NASA NTRS1954

Longitudinal Aerodynamic Characteristics to Large Angles of Attack of a Cruciform Missile Configuration at a Mach Number of 2

The lift, pitching-moment, and drag characteristics of a missile configuration having a body of fineness ratio 9.33 and a cruciform triangular wing and tail of aspect ratio 4 were measured at a Mach number of 1.99 and a Reynolds number of 6.0 million, based on the body length. The tests were performed through an angle-of-attack range of -5 deg to 28 deg to investigate the effects on the aerodynamic characteristics of roll angle, wing-tail interdigitation, wing deflection, and interference among the components (body, wing, and tail). Theoretical lift and moment characteristics of the configuration and its components were calculated by the use of existing theoretical methods which have been modified for application to high angles of attack, and these characteristics are compared with experiment. The lift and drag characteristics of all combinations of the body, wing, and tail were independent of roll angle throughout the angle-of-attack range. The pitching-moment characteristics of the body-wing and body-wing- tail combinations, however, were influenced significantly by the roll angle at large angles of attack (greater than 10 deg). A roll from 0 deg (one pair of wing panels horizontal) to 45 deg caused a forward shift in the center of pressure which was of the same magnitude for both of these combinations, indicating that this shift originated from body-wing interference effects. A favorable lift - interference effect (lift of the combination greater than the sum of the lifts of the components) and a rearward shift in the center of pressure from a position corresponding to that for the components occurred at small angles of attack when the body was combined with either the exposed wing or tail surfaces. These lift and center-of-pressure interference effects were gradually reduced to zero as the angle of attack was increased to large values. The effect of wing-tail interference, which influenced primarily the pitching-moment characteristics, is dependent on the distance between the wing trailing vortex wake and the tail surfaces and thus was a function of angle of attack, angle of roll, and wing- tail interdigitation. Although the configuration at zero roll with the wing and tail in line exhibited the least center-of-pressure travel, the configuration with the wing and tail interdigitated had the least change in wing- tail interference over the angle - of-attack range. The lift effectiveness of the variable-incidence wing was reduced by more than 70 percent as a result of an increase in the combined angle of attack and wing incidence from 0 deg to 40 deg center dot The wing- tail interference (effective downwash at the tail) due to wing deflection was nearly zero as a result of a region of negative vorticity shed from the inboard portion of the wing. The lift characteristics of the configuration and its components were satisfactorily predicted by the calculated results, but the pitching moments at large angles of attack were not because of the influence of factors for which no adequate theory is available, such as the variation of the cross flow drag coefficient along the body and the effect of the wing downwash field on the after body loading.

Spahr, J Richard↗
NASA NTRS1961

A Simulator Study of the Effectiveness of a Pilot's Indicator which Combined Angle of Attack and Rate of Change of Total Pressure as Applied to the Take-Off Rotation and Climbout of a Supersonic Transport

A simulator study has been made to determine the effectiveness of a single instrument presentation as an aid to the pilot in controlling both rotation and climbout path in take-off. The instrument was basically an angle-of-attack indicator, biased with a total-pressure-rate input as a means of suppressing the phugoid oscillation. Linearized six-degree-of-freedom equations of motion were utilized in simulating a hypothetical supersonic transport as the test vehicle. Each of several experienced pilots performed a number of simulated take-offs, using conventional flight instruments and either an angle-of-attack instrument or the combined angle-of-attack and total-pressure-rate instrument. The pilots were able to rotate the airplane, with satisfactory precision, to the 15 deg. angle of attack required for lift-off when using either an angle-of-attack instrument or the instrument which combined total-pressure-rate with angle of attack. At least 4 to 6 second-S appeared to be required for rotation to prevent overshoot, particularly with the latter instrument. The flight paths resulting from take-offs with simulated engine failures were relatively smooth and repeatable within a reasonably narrow band when the combined angle-of-attack and total-pressure-rate instrument presentation was used. Some of the flight paths resulting from take-offs with the same engine-failure conditions were very oscillatory when conventional instruments and an angle-of-attack instrument were used. The pilots considered the combined angle-of-attack and total- pressure-rate instrument a very effective aid. Even though they could, with sufficient practice, perform satisfactory climbouts after simulated engine failure by monitoring the conventional instruments and making correction based on their readings, it was much easier to maintain a smooth flight path with the single combined angle-of-attack and total-pressure-rate instrument.

Hall, Albert W.↗
NASA NTRS1959

Low-Subsonic Static Stability and Damping Derivatives at Angles of Attack From 0 deg to 90 deg for a Model with a Low-Aspect-Ratio Unswept Wing and Two Different Fuselage Forebodies

An investigation has been made in the Langley free-flight tunnel at low-subsonic speed to determine the static stability, control effectiveness, and damping in roll and yaw of a model with a low-aspect-ratio unswept wing and two different fuselage forebodies at angles of attack from 0 deg to 90 deg. Results were obtained with a fuselage configuration having a long pointed nose and a shorter rounded nose. Although the wing stalled at an angle of attack of about 12 deg, maximum lift did not occur until an angle of attack of about 40 deg or 50 deg was obtained. The static longitudinal stability of the model having a short rounded nose was greater than that of the model having a longer pointed nose over the entire angle-of-attack range. The pointed-nose model had large out-of-trim yawing moments above an angle of attack of about 40 deg. Shortening and rounding the nose of the model delayed these out-of-trim yawing moments to slightly higher angles of attack. Both models were directionally unstable above an angle of attack of about 20 deg, but both had positive effective dihedral over virtually the entire angle-of-attack range. At the higher angles of attack the pointed-nose model had generally better damping in roll than that of the rounded-nose model. Both models had very high damping in yaw at an angle of attack of about 50 deg or 60 deg.

Boisseau, Peter C.↗