Aeronautical Research Research Articles

Biopsychosocial Health Considerations for Astronauts in Long-Duration Spaceflight: A Narrative Review.

Long-duration spaceflights beyond low-Earth orbit, including missions to the Moon and Mars, pose significant health risks. Although biomedical approaches commonly appear in the literature, considering psychological and social factors alongside physiologic health offers a more holistic approach to astronaut care. Integrating the biopsychosocial (BPS) framework into medical planning addresses complex spaceflight challenges and aids in developing mitigation strategies. This review examined health risks associated with long-duration spaceflight within a BPS framework. Sources included governmental space agencies, academic textbooks, and relevant publications from multiple databases. Considering the National Aeronautics and Space Administration's Human Research Program's 5 main hazards, a conceptual model was developed to highlight the multifactorial BPS effects of spaceflight. In space, astronauts face unique environments and biological adaptations, including fluid shift, plasma volume loss, bone density loss, and muscle atrophy. Noise and the absence of natural light disrupt circadian rhythms, causing sleep disturbances and fatigue, which affect physical and mental health. Studies on crews in isolated and confined extreme environments reveal psychosocial challenges, including impaired mood and cognition, interpersonal tension, and miscommunication. International collaboration in spaceflight introduces differences in communication, problem solving, and social customs due to diverse cultural backgrounds. Upcoming long-distance missions likely will amplify these challenges. This review emphasizes BPS health considerations in long-duration spaceflight. It highlights the interplay among psychological, social, and biological factors, advocating for multidisciplinary teams and a holistic approach to astronaut health and mission planning and the potential added value of BPS perspectives in considering countermeasures.

The analysis of Gurney flap applications for autonomous underwater gliders

ABSTRACT In this paper, the Gurney flap structure (GF) from aeronautical research was applied to underwater gliders for improving the lift-to-drag ratio. Firstly, the numerical simulation method was used to verify the lift enhancement principle of the GF structure and the feasibility of its application to autonomous underwater gliders (AUG). Secondly, the performance of different GF was simulated and analysed, and a variable GF structure was proposed with the requirements of the operating modes. The GF parameters were optimised by a genetic algorithm. The results show that the performance of GF in water is similar to that in air, so it is feasible to apply GF to AUG. When the height of GF is close to the turbulent boundary layer of the trailing edge of the wing, the lift-to-drag ratio is significantly improved, especially in the range of small angle of attack and the maximum increase is up to 30%.

Numerical reconstruction of atmospheric boundary layer seasonal turbulent wind field over a complex forest terrain

The wind characteristics of the atmospheric boundary layer (ABL) over complex forest terrains are inherently intricate, influenced by the interplay of rugged topography, seasonal climatic fluctuations, and periodic vegetation dynamics. These effects are especially evident in the near-ground wind field, which exhibits substantial seasonal variability. Conventional wind characterization methods, as outlined in current standards, often fail to accurately capture these seasonal variations, thereby complicating the reconstruction of the near-ground ABL turbulent wind field in complex forest terrains. Accordingly, we employ the narrow band synthetic random flow generation (NSRFG) technique within large eddy simulation (LES) to generate inflow turbulence representing the growing and baldness seasons in a complex forest terrain by adjusting parameter equations for seasonal adaptation and introducing new empirical equations for the turbulent spectrum. Subsequently, we verified the seasonal turbulent flow's statistical characteristics and flow structure to assess its feasibility and validity, ultimately establishing a ‘seasonal numerical wind field’ model. Finally, the seasonally modified LES-NSRFG method was applied to the numerical simulation of turbulent flow around the Commonwealth Advisory Aeronautical Research Council (CAARC) standard high-rise building model. A comprehensive comparison of wind effects was conducted for the CAARC model under varying incoming flow conditions. The results indicate that seasonal winds in a complex forest terrain significantly affect the building's vortex wake, increasing the irregularity and complexity of the structural wind pressure and base moment coefficients. Thus, the seasonal wind effect must be considered when designing wind-resistant engineering structures in forest regions moving forward.

Qualitative Data Coding of User Experience With an Urban Air Mobility Fleet Manager Interface

The NASA Aeronautics Research Mission Directorate created the High Density Vertiplex (HDV) project to integrate and evaluate a prototype Urban Air Mobility (UAM) ecosystem. Part of the HDV testing environment included a prototype operator user interface called the Fleet Manager Interface (FMI). In 2023, HDV conducted flight testing with the FMI during which a user experience (UX) study was performed to assess the quality of UX and elicit design recommendations. As a result, a large database of open-ended, qualitative responses was generated and then coded using a new qualitative data coding technique called Directive String Coding. The key themes that arose from the coded responses showed that the UX was pleasant, system notifications should be more salient, and information across multiple screens should be integrated into a central display. As the Fleet Manger operational role is still being defined, it is vital to increase our understanding of the tools and capabilities needed for such a role. The results from HDV work will eventually feed into standards for vertiport operations that will enable safe and scalable UAM operations in the United States.

Effect of self-excited oscillation of three-dimensional rectangular shock-induced thrust vector nozzle jet

The fluidic thrust vector nozzles including the shock-induced thrust vector nozzles stand out from traditional mechanical thrust vector nozzles used in aeronautics and astronautics due to their simplicity and potential for higher efficiency. However, a significant challenge in the transition from theoretical studies to practical applications is the phenomenon of self-excited oscillation of the nozzle jet, particularly in ramjet and scramjet engines. This oscillation can notably impact the jet control stability, which is critical for the operational reliability, accuracy, and safety of these engines. To investigate the effects of self-excited oscillation of the jet in the three-dimensional rectangular shock-induced thrust vector nozzles, a large eddy simulation approach has been utilized to examine various nozzle pressure ratios and secondary pressure ratios. The simulation data are in good agreement with the experimental data of National Aeronautics and Space Administration Langley Research Center, lending credibility to the simulation results. The research sheds light on the formation and evolution of self-excited oscillation. It does so by examining the interactions between shock waves and boundary layers, as well as bubble dynamics, offering a comprehensive view of the oscillation mechanism in a three-dimensional context. The results demonstrate that the self-excited oscillation of jet mainly belongs to low-frequency oscillation. With the increase in nozzle pressure ratio, the self-excited oscillation of the jet is suppressed because the shock system is pushed out of the shock-induced thrust vector nozzle exit. The variation of secondary pressure ratio only affects the amplitude of jet self-excited oscillation and does not transform the motion pattern.

Circularly polarized multi-layered ellipsoidal coaxial fed dielectric resonator antenna for wireless applications

This paper presents a circularly polarized multi-layered Ellipsoidal Dielectric Resonator Antenna (CP-EDRA) having a footprint of 0.2λ0× 0.4λ0 operating in the frequency band 11.24-14.05 GHz. The structure is fed using a 50 Ω coaxial probe. Three layers of ceramic material have been stacked together in the increasing order of their dielectric constants in order to enhance the impedance bandwidth. There is an angular offset given to the topmost ellipsoidal cylinder which in turn leads to circular polarization radiation from the antenna with an optimum realized gain of 7.2 dBic and axial-ratio bandwidth (ARBW) of 1.7 GHz (12.3-14 GHz). The radiation and total efficiency are in good coincidence with each other and above 95% throughout the operating bandwidth. The prototype of CP-EDRA is fabricated and tested for experimental validation. The measured results of the fabricated antenna are in good agreement with simulated ones. The presented work finds its applications in broadcasting satellites, aeronautical navigation space research, etc. The antenna has a simple design and working principle with better performance compared to those reported so far.

Laminar separation bubble formation and bursting on a finite wing

The transient processes of laminar separation bubble (LSB) formation and bursting on a rectangular NACA 0018 wing are studied experimentally. A two-dimensional airfoil model is used as a baseline for the assessment of finite wing effects. The models are subjected to ramp changes in free-stream velocity causing the flow to switch between a state where an LSB forms and a state without reattachment. Lift force and particle image velocimetry measurements are used to relate the flow development to the aerodynamic loading. The lift coefficient of the airfoil exhibits substantial hysteresis, and the duration of the lift transients range from $10$ to $22$ convective time scales for bubble formation and $22$ to $30$ convective time scales for bursting. In contrast, the transient lift coefficients of the wing change gradually, with less hysteresis. The wing tip causes greater three-dimensionality in the separation bubble, whose thickness increases near the midspan where bursting is initiated. During bubble formation, the region of separated flow contracts towards the midspan. The gradual change in lift of the wing is linked to slower spanwise expansion and contraction of the separated flow region relative to the airfoil. On both models, the wavenumbers and amplitudes of disturbances in the separated shear layer rapidly change when reattachment initiates or ceases. Applying the bursting criterion of Gaster (Tech. Rep. Reports and Memoranda 3595. Aeronautical Research Council, London, 1967) to the bubble on the wing shows that bursting of the bubble at a single spanwise location is insufficient to cause complete spanwise failure of reattachment, and that the relationship between bursting parameters depends on spanwise position.

Detached-eddy simulation of the vortex system on the high-lift common research model

A complex vortex system exists on the high-lift transport aircraft with components of the nacelle, pylon, high-lift devices, strakes, and brackets, and the investigation of the vortex system is helpful in profoundly understanding the aerodynamic characteristics of actual high-lift aircraft. To investigate the vortex system on the high-lift transport aircraft and evaluate the simulation capacity of detached-eddy simulation (DES) for the vortex system on the high-lift aircraft configuration, a high-resolution DES numerical investigation is carried out on a standard high-lift transport aircraft configuration, the National Aeronautics and Space Administration (NASA) high-lift common research model (CRM-HL). Reynolds-averaged Navier–Stokes simulation (RANS) is also performed to investigate the differences between DES and RANS in predicting time-averaged aerodynamic data on the CRM-HL. After experimental validation of time-averaged surface load and flow patterns, three vortex identification methods are adopted to extract the vortex structures of the flow field. It is found that the Rortex-based vortex identification method can more distinctly extract the fine vortex structures. The DES method can reliably predict the time-averaged surface load while capturing the complex vortex system on the CRM-HL under the concerned case of this work with high resolution.

Data-driven reduced-order modeling for nonlinear aerodynamics using an autoencoder neural network

The design of commercial air transportation vehicles heavily relies on understanding and modeling fluid flows, which pose computational challenges due to their complexity and high degrees of freedom. To overcome these challenges, we propose a novel approach based on machine learning (ML) to construct reduced-order models (ROMs) using an autoencoder neural network coupled with a discrete empirical interpolation method (DEIM). This methodology combines the interpolation of nonlinear functions identified based on selected interpolation points using DEIM with an ML-based clustering algorithm that provides accurate predictions by spanning a low-dimensional subspace at a significantly lower computational cost. In this study, we demonstrate the effectiveness of our approach by the calculation of transonic flows over the National Advisory Committee of Aeronautics 0012 airfoil and the National Aeronautics and Space Administration Common Research Model wing. All the results confirm that the ROM captures high-dimensional parameter variations efficiently and accurately in transonic regimes, in which the nonlinearities are induced by shock waves, demonstrating the feasibility of the ROM for nonlinear aerodynamics problems with varying flow conditions.

Design of a large-scale model for wind tunnel test of a multiadaptive flap concept

The design and application of morphing systems are ongoing issues compelling the aviation industry. The Clean Sky - program represents the most significant aeronautical research ever launched in Europe on advanced technologies for greening next-generation aircraft. The primary purpose of the program is to develop new concepts aimed at decreasing the effects of aviation on the environment, increasing reliability, and promoting eco-friendly mobility. These ambitions are pursued through research on enabling technologies fostering noise and gas emissions reduction, mainly by improving aircraft aerodynamic performances. Within the Clean Sky framework, a multimodal morphing flap device was designed based on tight industrial requirements and tailored for large civil aircraft applications. The flap is deployed in one unique setting, and its cross section is morphed differently in take-off and landing to get the necessary extra lift for the specific flight phase. Moreover, during the cruise, the tip of the flap is deflected for load control and induced drag reduction. Before manufacturing the first flap prototype, a high-speed (Ma = 0.3), large-scale test campaign (geometric scale factor 1:3) was deemed necessary to validate the performance improvements brought by this novel system at the aircraft level. On the other hand, the geometrical scaling of the flap prototype was considered impracticable due to the unscalability of the embedded mechanisms and actuators for shape transition. Therefore, a new architecture was conceived for the flap model to comply with the scaled dimensions requirements, withstand the relevant loads expected during the wind tunnel tests and emulate the shape transition capabilities of the true-scale flap. Simplified strategies were developed to effectively morph the model during wind tunnel tests while ensuring the robustness of each morphed configuration and maintaining adequate stiffness levels to prevent undesirable deviations from the intended aerodynamic shapes. Additionally, a simplified design was conceived for the flap-wing interface, allowing for quick adjustments of the flap setting and enabling load transmission paths like those arising between the full-scale flap and the wing. The design process followed for the definition of this challenging wind tunnel model has been addressed in this work, covering the definition of the conceptual layout, the numerical evaluation of the most severe loads expected during the test, and the verification of the structural layout by means of advanced finite element analyses.

CFD wind tunnel investigation for wind loads of steel television tower with grid structure

Television(TV) towers with grid structures serve as broadcasting frequency modulation or television transmission signals and provide sightseeing opportunities. Accurate wind load information is critical to the design of these towers to ensure their resistance to wind. Due to the scaling ratio of the test model, wind tunnel test can only determine the overall wind load, resulting in the loss of wind load information on specific rods. However, there is currently a lack of research on the wind loads of the specific rods of a core tube with a grid structure. This article focuses on this special topic. Computational fluid dynamics (CFD) technology, which was validated based on the Commonwealth Advisory Aeronautical Research Council (CAARC) model, was employed in simulation for a towering television tower with a grid structure. Wind load distributions of the grid structure and core tube were studied, including flow streamlines, velocity profiles and wind pressure distributions. The results indicate that the wind pressure distribution on the outer surface of the cross rods is similar at different heights. Net wind pressures of the rods in the flow separation zone are close to 0, which significantly reduces the across-wind load. Different wind direction angles significantly influence the wind load of the grid structure but slightly influence the core tube. The simulation results can provide a reference for wind load design of similar grid structures.

Think like a team: Shared mental models predict creativity and problem-solving in space analogs

As long-distance space exploration missions move beyond low Earth orbit, and crews become more Earth-independent, it is essential to identify predictors of team performance - properties of teams that can be monitored during space flight to anticipate performance decrements. The most robust team state predicting performance in the team effectiveness literature is shared mental models. Shared mental models are properties of a group reflecting how members organize knowledge and understanding about the purpose of the team, the nature of the work, and how members work together. In this study we developed a measure of shared mental models for use in ground-based analogs. It was administered in the National Aeronautics and Space Agency (NASA)'s Human Exploration Research Analog (HERA) Campaign 4, Campaign 5, and the Nazemnyy Eksperimental'nyy Kompleks (NEK) SIRIUS-19 mission. HERA included eight 4-member crews in isolation for 45 days; NEK SIRIUS-19 included a 6-member crew in isolation for 120 days. To track performance variations, we administered two team tasks: a creative thinking task and a problem-solving task. We found substantial positive correlations between shared mental models and both dimensions of team performance in HERA and in NEK. Though shared mental models are a strong predictor of team performance across mission stages, we found some nuanced shifts. First, mental model sharedness in HERA is associated with crews generating fewer ideas in the third quarter than in other quarters, but also generating more novel, original ideas. Second, in the NEK mission we observed a third quarter effect with problem-solving, and the nature of the effect was that the effect of the shared mental model was most important in all quarters except the third. These results suggest that mission timing but also mission duration are important factors that condition relations between team process variables like shared mental models and team performance indicators.

Parametric Analysis for Hybrid–Electric Regional Aircraft Conceptual Design and Development

This paper proposes a conceptual analysis of the limitations related to the development (and integration) of hybrid–electric propulsion on regional transport aircraft, with the aim to identify a feasibility space for this innovative aircraft concept. Hybrid–electric aircraft have attracted the interest of aeronautical research as these have the potential to reduce fuel consumption and, thus, the related greenhouse gas emissions. Nevertheless, considering the development of such an aircraft configuration while keeping the constraints deriving from technological and/or operating aspects loose could lead to the analysis of concepts that are unlikely to be realised. In this paper, specifically to outline the boundaries constraining the actual development of such aircraft, the influence on overall aircraft design and performance of the main technological, operating, and design factors characterising the development of such a configuration is analysed and discussed at a conceptual level. Specifically, the current achievable gravimetric battery energy density (BED) is identified as the main limiting factor for the development of regional hybrid–electric aircraft, and a sensitivity analysis shows the correlation of this important technological parameter with aircraft performance in terms of both fuel consumption and energy efficiency. In this context, minimum technological development thresholds are therefore identified to enable the effective development of this type of aircraft; namely, a minimum of BED = 500 Wh/kg at battery pack level is identified as necessary to provide tangible benefits. From an operating point of view, flight distance is the most limiting design requirement, and a proper assessment of the design range is necessary if a hybrid–electric aircraft is to be designed to achieve lower emissions than the state of the art; flight ranges equal to or lower than 600 nm are to be considered for this type of aircraft. As a bridging of both of the previous constraints, a change in the design paradigm with respect to established practices for state-of-the-art aircraft is necessary. More specifically, penalisations in maximum take-off weight and overall aircraft energy efficiency may be necessary if the aim is to reduce direct in-flight consumption by means of integration of hybrid–electric powertrains.

How much can electric aircraft contribute to reaching the Flightpath 2050 CO2 emissions goal? A system dynamics approach for european short haul flights

In 2012, the Advisory Council for Aeronautics Research in Europe (ACARE) introduced Flightpath 2050 defining the emission reduction targets for the aviation industry in the EU. The purpose of this study is to assess the impact of narrow body electric aircraft for short haul flights on reaching the Flightpath 2050 CO2 emissions goal using different policy scenarios within the EU. We develop a system dynamics model of the air transport system (ATS), consisting of the interaction between three major segments, namely air travel demand, airline industry and aircraft manufacturers. The model is run for the time period from 1991 to 2050, where electric aircraft are introduced in the year 2035. We simulate the behavior of the ATS under different policy scenarios, e.g., introduction of jet fuel tax, electricity subsidy, seat tax or fleet restriction policy, to test their influence on electric aircraft adoption rates. The results of the analysis suggest that most of the individual policies when implemented are not enough to reach the Flightpath 2050 CO2 emissions goal. Furthermore, a strong set of policy combination was required to reach the goal. Specifically, the combination of an electricity subsidy with kerosene tax demonstrates a higher electric aircraft adoption rate than that of other combinations. On the other hand, sensitivity analysis shows that combinations with electricity subsidy display higher volatility in the CO2 emissions interval. The main reason for this sensitivity is due to the uncertainty in cost pertaining to electric aircraft development parameters.

Quiet Spacecraft Cabin Ventilation Fan Development: Motivation and Context

It is important to control acoustical noise aboard crewed space vehicles and space habitats to provide a satisfactory environment for voice communications, alarm audibility, and restful sleep, and to minimize the risk for hearing loss and annoyance. As with most noise control efforts, it is best to control the noise at the source, and for spaceflight vehicles these are typically the fans associated with the Environmental Control and Life Support system. These include cabin ventilation fans and intermodule ventilation fans, among others. Throughout the history of crewed spaceflight, there have been issues with noise from ventilation fans, going back to Apollo. And, with the spaceflight vehicles and habitats currently being developed, there are again concerns with noise from ventilation fans. To address this problem, NASA is working to leverage the technology developed in its Aeronautics Research Mission Directorate, specifically at the Glenn Research Center, to design highly efficient and quiet fans for reducing community noise levels from civilian aircraft. This paper will discuss the need for transfer of this technology to spaceflight use, and will discuss the potential benefits, which are significant and will be crucial for the successful development and operations of future spaceflight vehicles, space suits, and habitats.

Maintaining Warp Speed: Policy Requirements for a Just-in-Time, Capability-Based, Scalable Medical Countermeasure Research and Development Enterprise.

Maintaining Warp Speed: Policy Requirements for a Just-in-Time, Capability-Based, Scalable Medical Countermeasure Research and Development Enterprise.

Predictive Algorithm for Team Mental Model Convergence

Is everyone on your team on the same page about the task? This is a question team leaders want to know. Herein, we take an approach that can help managers move the team in the right direction of team mental models (TMMs), individually held cognitive representations of task components that when similar and/or accurate can promote task success. We begin by defining the new concept of mental model shifts (MMSs) as the directional shift in each team member’s mental model, leading to an increase or decrease in convergence toward a shared or quality referent mental model. Next, we propose an algorithm that applies the concepts of Markov chains and vector geometry on communication patterns to predict future patterns and TMM convergence (i.e., sharedness and quality) levels. We base the model on a dataset of teams conducting the National Aeronautics and Space Administration (NASA) human exploration research analog (HERA) missions from which we draw communication attributes of MMS, process topic, and message purpose. We show that tasks can be modeled as vectors using the frequency of attribute patterns. Our initial experiments show that an accuracy of up to 86.21% can be achieved in predicting future communication patterns with data from real-world tasks. Furthermore, we validate the estimation of TMM sharedness, showing that the model results are comparable to sharedness ratings provided by subject matter experts with an average accuracy of 71.29%. Research and practical implications are discussed.

Autonomous material composite morphing wing

Aeronautics research has continually sought to achieve the adaptability and morphing performance of avian wings, but in practice, wings of all scales continue to use the same hinged control-surface embodiment. Recent research into compliant and bio-inspired mechanisms for morphing wings and control surfaces has indicated promising results, though often these are mechanically complex, or limited in the number of degrees-of-freedom (DOF) they can control. Seeking to improve on these limitations, we apply a new paradigm denoted Autonomous Material Composites to the design of avian-scale morphing wings. With this methodology, we reduce the need for complex actuation and mechanisms, and allow for three-dimensional placement of stretchable fiber optic strain gauges (Optical Lace) throughout the metamaterial structure. This structure centers around elastomeric conformal lattices, and by applying functionally-graded warping and thickening to this lattice, we allow for local tailoring of the compliance properties to fit the desired morphing. As a result, the wing achieves high-deformation morphing in three DOF: twist, camber, and extension/compression, with these morphed shapes effectively modifying the aerodynamic performance of the wing, as demonstrated in low-Reynolds wind tunnel testing. Our sensors also successfully demonstrate differentiable trends across all degrees of morphing, enabling the future state estimation and control of this wing.

An improved inflow turbulence generator for large eddy simulation evaluation of wind effects on tall buildings

Accurate inflow turbulence wind profile is a key premise of large eddy simulation (LES) methodology for super tall buildings. This paper presents an improved method for narrow band synthesis random flow generation to produce a more accurate inflow turbulence of LES based on superposition of harmonics. The proposed method considers time correlation by adopting time parameters, and an accurate expression of wind speed spectrum energy by a modified spectrum integral equation is used. These improvements could generate a more accurate turbulence intensity for the atmospheric boundary layer. A simple numerical example is applied to verify the spectrum characteristic, time correlation and spatial correlation of atmospheric numerical boundary layer. Meanwhile, the effects of the introduced parameters are investigated and the method is applied to the LES of the Commonwealth Advisory Aeronautical Research Council building (CAARC). The improved method could increase the accuracy of simulated turbulence intensity. Compared with the results of CAARC model obtained from the wind tunnel test, the improved method in this study decreases the errors of root-mean-square (rms) of the based bending moment from 5.3% to 4.1% in the along-wind direction and from 5.6% to 1.3% in the cross-wind direction.

Overview of NASA’s Solar Irradiance Science Team #2 (SIST‐2) Program

AbstractThe Solar Irradiance Science Team (SIST) #2 (SIST‐2) program is a competitively solicited National Aeronautics and Space Administration (NASA) Earth Science Division science research program providing 3‐year awards beginning in July 2018 to quantify and understand the solar irradiance variability and implications for Earth's climate and atmospheric composition. The purpose for the SIST‐2 program is limited to the accurate specification of the incoming solar irradiance into the Earth system considering the 44‐year satellite data record as well as proxies to which the satellite record can be tied. The SIST‐2 program funded eight research grants to study the variability of the total solar irradiance and solar spectral irradiance and to develop improved space‐based data sets, solar proxies, and variability models of the solar irradiance. The SIST‐2 projects are briefly introduced.