Propulsion Technology Research Articles

Assessing the Impact of Hybrid Propulsion Systems on the Range and Efficiency of Aircraft

The demand for aviation continues to grow, posing issues in terms of fuel consumption, environmental effect, and operational efficiency. In addition, the COVID-19 pandemic has also highlighted the need for sustainable solutions in the aviation sector. To address these issues, hybrid electric propulsion systems have emerged as a potential option. Hybrid electric propulsion systems have the potential to improve airplane performance while reducing environmental impact. This article looks into the effects of hybrid electric propulsion technologies on optimal aircraft range. The study looks at aviation's environmental impact, several hybrid aircraft prototypes, and battery capacity and density challenges. Fuel usage increases in proportion to the weight of the aircraft. As a result, the range is shorter. In modern technology, along with to the added weight of batteries used as energy storage in hybrid propulsion systems, there are low battery densities and capacities. When the researches were reviewed, it was discovered that overcoming these limitations was easier for small aircraft and more difficult for large aircraft. As a consequence of the studies and research conducted, the development of light and reliable batteries with high energy density and capacity would expand the range of hybrid aircraft and allow them to be used more efficiently over long distances.

Digital twins for electric propulsion technologies

As the space industry is undergoing an evolution, the current approaches toward design, development, and qualification of Electric Propulsion (EP) systems largely based on empirical “trial-and-error” methodologies are falling short of addressing the emerging needs and keeping abreast of the rapid changes in market trends. Furthermore, with the proliferation of Artificial Intelligence (AI) within the space industry toward next-generation autonomous satellites and spacecrafts, the conventional EP monitoring and control strategies become inadequate and need to give way to approaches compatible with satellite-level autonomy requirements. A digital twin (DT) – a technology capable of providing an accurate dynamically adapting virtual representation of a physical asset – is a game-changing concept that catalyzes the transcendence of the EP industry past its pressing challenges today. In this paper, we aim to: (i) define the DT concept, highlighting how it surpasses traditional modelling, (ii) enumerate the DT’s breakthrough promises for the EP industry, and (iii) specify the challenges to realize practical and scalable EP DTs. Additionally, we report on the technical progress achieved and/or planned at Imperial Plasma Propulsion Laboratory to fill the foundational gaps in three building block elements of DTs, namely, (i) a cost-effective kinetic model to generate extensive high-fidelity databases for machine learning (ML), (ii) ML-enabled models for prediction and analysis of performance and operational behavior, and (iii) a DT architecture that integrates the numerical models in terms of a computing infrastructure and provides data pipelines and interfaces for the DT’s data exchanges with the real world, its dynamic updating, and uncertainty quantification.

Review of diver propulsion vehicle: A review

The ocean serves as a vital arena for resource exploitation, scientific inquiry, and strategic endeavors. Among the array of underwater propulsion technologies, diver propulsion vehicles (DPVs) stand out for their exceptional integration, concealability, and maneuverability. They hold a pivotal role in both marine scientific exploration and military operations beneath the waves, thus carrying significant research implications. However, the existing literature on DPVs remains limited, lacking comprehensive examinations of their design processes and parameters. This review systematically surveys and assesses the current landscape of DPV development and research. Three key facets—propeller design, performance assessment, and equipment engineering—are scrutinized and analyzed. By consolidating essential data from ongoing studies, this review offers valuable insights. Additionally, it forecasts potential directions and emerging focal points in the evolution of underwater propulsion for frogmen, drawing from current advancements. The objective is to furnish foundational data to support the design and study of frogman underwater propulsion systems, thereby advancing engineering applications in this domain.

Impact of automation and zero-emission propulsion on design of small inland cargo vessels

Abstract Small inland waterways offer considerable capacity for modal shift of cargo transport. Revitalization of smaller inland waterways, however, may require new vessel designs as most of the existing small vessels are outdated and incompatible with the present state of the technology development and the current commercial and regulatory requirements. This paper investigates the possibilities for modernization of small inland vessel designs and offers a systematic analysis of impact of “automation” and “zero-emission propulsion technology” on reference designs of standard European inland cargo vessels of CEMT classes I, II, III, and IV. The adopted level of automation enables the vessels to be remotely operated without human crew onboard, whereas the adopted zero-emission propulsion concept is based on electrification of the powertrain. The paper identifies the impacts of the modernization on general arrangement, cargo capacity, safety, structural design, etc. and indicates the vessel classes which could be the most promising candidates for the design of a future small autonomous inland ships.

Laser Propulsion Science and Technology

Laser propulsion is an advanced technology that holds promise for use in many aerospace propulsion applications [...]

Cathode-less RF plasma thruster design and optimisation for an atmosphere-breathing electric propulsion (ABEP) system

Atmosphere-breathing electric propulsion (ABEP) is a concept that ingests residual atmospheric gases as a source of propellant for an electric thruster, removing the need for onboard propellant storage. This would enable continuous low-thrust drag compensation, extending the lifetime of spacecraft in Very-Low Earth Orbit (VLEO); <250 km. VLEO is an appealing region for spacecraft operations, enabling new remote sensing missions with improved radiometric performance and spatial resolution, whilst reducing size, mass and power requirements, as well as mission cost. A preliminary design review and optimisation is therefore conducted for an ABEP system that uses the cathode-less radio frequency (RF) plasma thruster from Technology for Innovation & Propulsion (T4i) S.p.A. This removes the issue of thruster erosion by means of magnetic confinement and offers reduced susceptibility to varying atmospheric composition. A semi-empirical oxygen-nitrogen global source model (GSM) has been developed which considers the volume-averaged flux, momentum, and energy balance of the RF discharge. This includes a detailed chemistry model for the complex electron-molecular reactions and energy-loss channels of air plasma in the ionisation chamber. The GSM is coupled to an analytical model of flux balance for an air intake, verified by Direct Simulation Monte-Carlo (DSMC) simulation, to consider its design for maximum collection efficiency. This is then utilised in a robust multi-objective optimisation of the ABEP system, accounting also for spacecraft aerodynamics and power requirements.

Review Research Paper of Feasibility study on Anti-Gravity Effect for Advance Propulsion system and technologies

The concept of anti-gravity, often portrayed in science fiction as a means to counteract or negate the effects of gravitational force, has intrigued scientists and enthusiasts alike for decades. This paper explores the feasibility of achieving anti-gravity effects through various theoretical and experimental perspectives. Firstly, theoretical frameworks such as general relativity and quantum mechanics are reviewed to understand gravity and its potential manipulation. While these theories provide foundational insights, they also highlight the immense challenges involved in directly counteracting gravitational forces due to their fundamental nature. Next, experimental efforts and hypothetical technologies proposed in scientific literature are examined. Concepts such as negative mass, exotic matter, and gravitational shielding are discussed in terms of their theoretical underpinnings and practical limitations. Experimental evidence, including anomalies in gravitational measurements and speculative engineering proposals, are scrutinized to evaluate their relevance to achieving anti-gravity effects. Furthermore, the paper addresses the technological and ethical implications of developing anti-gravity technology. Considerations such as energy requirements, environmental impact, and societal readiness are explored to provide a holistic perspective on the feasibility and desirability of pursuing anti-gravity research. Ultimately, while the idea of anti-gravity remains a captivating subject of scientific inquiry and fiction, current understanding and technological capabilities suggest significant hurdles that must be overcome before practical anti-gravity effects can be realized. This paper concludes by outlining potential avenues for future research and highlighting the interdisciplinary nature of addressing such a complex phenomenon.

Research on Aircraft Engines and Advanced Power in Land, Sea and Air

This paper provides a comprehensive overview of advanced propulsion technologies in military applications across land, sea, and air domains. It examines the theoretical foundations of propulsion systems, tracing the evolution of aircraft engines from early piston designs to modern jet propulsion. The study explores current state-of-the-art technologies, including advanced turbofan engines, hybrid electric systems, and nuclear propulsion for naval vessels. Special attention is given to emerging fields such as unmanned aerial vehicle propulsion, hypersonic technologies, and stealth engine designs. The research also delves into futuristic concepts like magnetohydrodynamic propulsion and pulse detonation engines. Throughout the analysis, common themes of improved efficiency, enhanced power-to-weight ratios, and increased operational capabilities are highlighted. This paper aims to provide a holistic view of the current landscape and future trajectory of military propulsion technologies, underlining their critical role in shaping modern warfare capabilities.

Review of Solar Sail Propulsion Mechanisms and Missions for Space Travel

Since solar sailing employs the speed of sunlight to drive spacecraft, it is an efficient and environmentally friendly alternative to traditional propulsion technologies. The physics of photon compression, the significance of novel materials and systems that enhance sailing performance, and the appropriate testing of solar sailing systems are all covered in this research paper. The main solar sailing projects— LightSail, NEA Scout, and IKAROS—are examined in this paper, and their merits, demerits, and contributions to the field are discussed. Potential solar sailing technology for extended space travel are also covered, along with space sustainability. Consider how crucial it is for space exploration in the future. The goal of this research is to demonstrate the transformative potential of navigation and to spark further developments in the exciting field of space aerospace engineering by effectively integrating mission data and current research in the ever-changing landscape of space exploration. Since solar sailing employs the speed of sunlight to drive spacecraft, it is a practical and environmentally friendly alternative to traditional propulsion technologies. The physics of photon compression, the significance of novel materials and systems that enhance sailing performance, and the appropriate testing of solar sailing systems are all covered in this research paper. The main solar sailing projects—LightSail, NEA Scout, and IKAROS—are examined in this paper, and their merits, demerits, and contributions to the field are discussed. Potential solar sailing technology for extended space travel are also covered, along with space sustainability. Pay attention to how crucial it is for future space exploration. Through the efficient integration of mission data and current research, this project seeks to address the dynamic landscape of space exploration in the industry and encourage future advancements in the exciting field of space aeronautical engineering. Additionally, it aims to illustrate how navigation can have a transforming effect. Keywords: Space Exploration, Propulsion Technology, Interstellar Travel, Spacecraft Navigation, Attitude control, Trajectory optimization, Material Durability, Deep Space Missions, Interplanetary Travel, Solar Radiation Effect, Photon Pressure, Solar sail Deployment, Orbital Mechanics, Continues Thrust.

Net-Zero Greenhouse Gas Emission Electrified Aircraft Propulsion for Large Commercial Transport

Until recently, electrified aircraft propulsion (EAP) technology development has been driven by the dual objectives of reducing greenhouse gas (GHG) emissions and addressing the depletion of fossil fuels. However, the increasing severity of climate change, posing a significant threat to all life forms, has resulted in the global consensus of achieving net-zero GHG emissions by 2050. This major shift has alerted the aviation electrification industry to consider the following: What is the clear path forward for EAP technology development to support the net-zero GHG goals for large commercial transport aviation? The purpose of this paper is to answer this question. After identifying four types of GHG emissions that should be used as metrics to measure the effectiveness of each technology for GHG reduction, the paper presents three significant categories of GHG reduction efforts regarding the engine, evaluates the potential of EAP technologies within each category as well as combinations of technologies among the different categories using the identified metrics, and thus determines the path forward to support the net-zero GHG objective. Specifically, the paper underscores the need for the aviation electrification industry to adapt, adjust, and integrate its EAP technology development into the emerging new engine classes. These innovations and collaborations are crucial to accelerate net-zero GHG efforts effectively.

Thermodynamic and propulsive characterization of nitro-substituted quadricyclane

This investigation delves into the potential of Octa-nitro Quadricyclane (ONQC), a nitro-substituted quadricyclane, as a next-generation energetic material. Employing a robust B3LYP-gCP-D3/6-31G(d) computational approach, the study evaluates key material properties of ONQC, including strain energy (700.2 kJ/mol), enthalpy of formation (668.6 kJ/mol), and density (2.08 g/cm³). These enhanced properties result in predicted increases of 124 % in detonation pressure and 49.5 % in detonation velocity compared to TNT, significantly surpassing the performance of conventional high-energy density materials. Additionally, ONQC's suitability as an energetic additive in bipropellant formulations was evaluated with NASA's Chemical Equilibrium with Applications (CEA) software. The primary focus was on bipropellant formulations employing kerosene-based fuels (RP-1, JP-10, JP-5, etc.) and liquid oxygen (LOX) as the oxidizer. Incorporating ONQC into propellant formulations provides substantial improvements in specific impulse and reduces oxidizer requirements. This makes ONQC a promising candidate for advancing propulsion technology.

Reinforced Lyapunov controllers for low-thrust lunar transfers

Future missions to the Moon and beyond are likely to involve low-thrust propulsion technologies due to their propellant efficiency. However, these still present a difficult trajectory design problem, owing to the near continuous thrust, lack of control authority and chaotic dynamics. Lyapunov control laws can generate sub-optimal trajectories for such missions with minimal computational cost and are suitable for feasibility studies and as initial guesses for optimisation methods. In this work a Reinforced Lyapunov Controller is used to design optimal low-thrust transfers from geostationary transfer orbit towards lunar polar orbit. Within the reinforcement learning (RL) framework, a dual-actor network setup is used, one in each of the Earth- and Moon-centred inertial frames respectively. A key contribution of this paper is the demonstration of a forwards propagated trajectory, removing the need to define a patch point a priori. This is enabled by an adaptive patch distance and extensive initial geometry exploration during the RL training. Results for both time- and fuel-optimal transfers are presented, along with a Monte Carlo analysis of the robustness to disturbances for such transfers. Phasing is introduced where necessary to aid rendezvous with the Moon. The results demonstrate the potential for such techniques to provide a basis for the design and guidance of low-thrust lunar transfers.

Reversionary Control Modes for the Mitigation of Failures in a Partially Turboelectric Aircraft Propulsion System

Abstract In support of emission and fuel burn reduction goals, the aviation industry is actively pursuing the advancement of electrified aircraft propulsion (EAP) technology. This includes turboelectric and hybrid electric propulsion designs that combine gas turbine engine and electrical system hardware. Such architectures exhibit a high degree of coupling between subsystems. This drives the need for system-level control strategies to ensure the safe, coordinated, and efficient operation of all subsystems. The design and certification of any aircraft propulsion system requires that all potential subsystem failures are identified, and the hazards posed by these failures are appropriately mitigated. This requirement is particularly challenging for EAP systems due to their integrated nature. One approach to assist in EAP failure mitigation is the inclusion of automated reconfiguration capabilities within the propulsion control system. Such control modes, referred to as reversionary control modes, are designed to automatically detect failures and activate backup control modes upon failure detection. This paper covers the design and evaluation of reversionary control mode logic developed for a partially turboelectric propulsion concept. Test results from a real-time hardware-in-the-loop evaluation of the concept are also presented and discussed. The results show that the developed reversionary control logic can successfully detect and mitigate subsystem failures in a representative environment that includes actual electrical system hardware.

Impact assessment of future fleet compositions in vehicle emissions in urban areas: A methodological framework and a case study

This study explores the impact of emerging vehicle technologies on direct urban traffic emissions. It investigates emission reduction potential from shifts in fleet compositions and modal choices, especially considering climate change. To achieve this, three key research areas are explored for historical, current, and future scenarios (up to 2050): mode choice, emission factors for different vehicle categories, and diverse vehicle propulsion technologies. The estimation of the modal split is pivotal, developing a methodology utilizing Stated Preference survey data, discrete choice modeling, Monte Carlo simulations, and macroscopic traffic simulations. Future scenarios derive from the reference year’s modal split, and emission factors and fleet compositions are predetermined via an extensive literature review, aiding the assessment of their respective emissions. A subsequent sensitivity analysis identifies the impact of specific parameters on emissions, guiding future research focus. Study results underscore differences in greenhouse gas emissions and primary air pollutants between base and future scenarios.

Circulation-controlled wind-assisted ship propulsion: Technical innovations for future shipping industry decarbonization

Amidst mandatory policies aimed at energy savings and emission reductions in the shipping industry, wind-assisted ship propulsion technology has gained prominence for its immediate practicality in promoting environmental sustainability. Wing-sails possess favorable aerodynamic characteristics and adjustable capabilities, yet their efficiency is impeded by flow separation at high angles of attack. This study addressed the challenge of mitigating delayed separation and enhancing lift at large angles of attack for wing-sails through technical solutions involving trailing-edge circulation control and leading-edge boundary layer control. Three-dimensional steady-state flow fields of conventional and circulation-controlled wing-sails were accurately modeled using a Generalized k-ω (GEKO) model across angles of attack ranging from 0° to 30°. Under moderate jet strength conditions with a velocity ratio of 5, the stall angle of attack of the circulation-controlled wing-sail was delayed by approximately 6°. Furthermore, compared to a conventional wing-sail, the circulation-controlled variant exhibited a 111 % increase in maximum lift coefficient and a 120 % rise in maximum resultant force coefficient. The energy-saving and emission reduction benefits of implementing this innovative technology were quantified using the Energy Efficiency Design Index (EEDI) on a real very large crude carrier (VLCC). The circulation-controlled wing-sail demonstrated a 10.38 % reduction in EEDI under optimal operating conditions with medium jet strength, compared to an unassisted vessel. Moreover, this reduction was enhanced by 77.55 % compared to incorporating a conventional wing-sail. These discoveries signify an advancement in wind-assisted ship propulsion technology on an innovative frontier, promising greater energy utilization and reduced fuel consumption, thereby facilitating the achievement of stringent green ship standards.

The Magnet Engine

This research paper explores Michel K. Walden's Magnetite Engine and its transformative potential in engineering. The Magnetite Engine represents a significant advancement in propulsion technology, promising greater efficiency and performance than conventional combustion engines. Through a literature review and case studies, the paper assesses the engine's theoretical and practical aspects, focusing on its impact on automotive and aerospace industries. While it offers benefits like reduced emissions and improved energy efficiency, challenges such as scaling production and infrastructure integration remain. Future research directions are proposed to fully realize the Magnetite Engine's potential for sustainable engineering solutions.

Experimental investigation on the hydrodynamic performance of a bioinspired manta-ray underwater vehicle in various forward propulsion modes

Bionic propulsion technology is revolutionizing underwater exploration by enabling underwater vehicles to navigate the oceans more efficiently. This research developed a scaled-down (10:1) experimental prototype of bionic manta-ray underwater vehicle, which has two degrees of freedom (2-DOF) pectoral fins: flapping and rotating. The impact of four different pectoral fin motion patterns (sinusoidal flapping and rotating, flapping frequency asymmetric, flapping amplitude offset, and rotating amplitude limitation) on the forward propulsion performance was investigated experimentally in a static water tunnel using a force/torque sensor and power analyzer. The results revealed that introducing asymmetry into the fin's flapping motion (asymmetric frequency or amplitude) significantly improved both average thrust and propulsive efficiency (the average thrust can be increased by more than 30%). Flapping with amplitude offset can effectively adjust its pitching moment without sacrificing much thrust. While the rotating motion of the pectoral fins contributes minimally to thrust generation compared to flapping, it plays an important role in enhancing both longitudinal stability and propulsive efficiency. Understanding the hydrodynamic performance of these various forward propulsion modes provides valuable insights for optimizing control strategies of bionic manta-ray underwater vehicles.

Aircraft Electrification: Insights from a Cross-Sectional Thematic and Bibliometric Analysis

Electrifying aircraft, a crucial advancement in the aviation industry, aims to cut pollutive emissions and boost energy efficiency. Traditional aircraft depend on fossil fuels, which contribute significantly to greenhouse gas emissions and environmental pollution. Despite progress in electric propulsion and energy storage technologies, challenges such as low energy density and integration issues persist. This paper provides a comprehensive thematic and bibliometric analysis to map the research landscape in aircraft electrification, identifying key research themes, influential contributors, and emerging trends. This study applies natural language processing to unstructured bibliographic data and cross-sectional statistical methods to analyze publications, citations, and keyword distributions across various categories related to aircraft electrification. The findings reveal significant growth in research output, particularly in energy management and multidisciplinary design analysis. Collaborative networks highlight key international partnerships, with the United States and China being key research hubs, while citation metrics highlight the impact of leading researchers and institutions in these countries. This study provides valuable insights for researchers, policymakers, and industry stakeholders, guiding future research directions and collaborations.

Multi-objective design optimization and physics-based sensitivity analysis of field emission electric propulsion for CubeSat platforms

Field-emission electric propulsion is an electrostatic space electric propulsion technology that offers various advantageous features including efficient design, high specific impulse, and versatile thrust capabilities ranging from micro-Newton to milli-Newton levels. These characteristics make this type of propulsion a promising technology for small satellite platforms, enabling precise attitude control, orbit maintenance, and de-orbiting through ionization and acceleration of a liquid metal propellant. The growing demand for small propulsion systems in CubeSat platforms has spurred significant progress in modeling and characterizing field emission electric propulsion thrusters to enhance their overall performance. However, little study has been conducted to investigate the effect of geometric configurations on electric fields or expelled ion trajectories for design optimization. In this study, multi-objective design optimization is performed by incorporating electrostatic simulation coupled with an analytical performance model into evolutionary algorithms based on prediction from surrogate modeling, aiming to optimize the thruster emission design to maximize thruster performance. Physical insights into the key design factors influencing the performance of field emission electric propulsion have been gained by probing into the interaction between ion particles and electric field behavior within the thruster. It has been found that the length of the emitter tip has a significant effect on plume divergence, i.e., a longer emitter tip under the influence of electric field at higher emitter current tends to result in lower initial acceleration of emitted ions and subsequently wider spread or divergence of the ion beam. A shorter emitter tip, on the other hand, generates a sharper E-field gradient, resulting in a more focused and narrower ion beam. Additionally, sensitivity analysis has identified the mass flow rate and potential distributions as the most influential design factors on performance due to the active roles they play in the performance generation process.

Optimization of Plasma-Propelled Drone Performance Parameters

Recently, the world’s first plasma-propelled drone was successfully flown, demonstrating that plasma propulsion technology is suitable for drone flight. The research on plasma propulsion drones has sparked a surge of interest. This study utilized a proxy model and the NSGA-II multi-objective genetic algorithm to optimize the geometric parameters based on staggered thrusters that affect the performance of electroaerodynamics (EAD) thrusters used for solid-state plasma aircraft. This can help address key issues, such as the thrust density and the thrust-to-power ratio of solid-state plasma aircraft, promoting the widespread application of plasma propulsion drones. An appropriate sample set was established using Latin hypercube sampling, and the thrust and current data were collected using a customized experimental setup. The proxy model employed a genetically optimized Bayesian regularization backpropagation neural network, which was trained to predict the effects of variations in the geometric parameters of the electrode assembly on the performance parameters of the plasma aircraft. Based on this information, the maximum achievable value for a given performance parameter and its corresponding geometric parameters were determined, showing a significant increase compared to the sample data. Finally, the optimal parameter combination was determined by using the NSGA-II multi-objective genetic algorithm and the Analytic Hierarchy Process. These findings can serve as a basis for future researchers in the design of EAD thrusters, helping them produce plasma propulsion drones that better meet specific requirements.