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This comprehensive review examines the role of sustainable aviation fuels (SAFs) in promoting a more environmentally responsible aviation industry. This study explores various types of biofuels, including hydroprocessed esters and fatty acids (HEFAs), Fischer–Tropsch (FT) fuels, alcohol-to-jet (ATJ) fuels, and oil derived from algae. Technological advancements in production and processing have enabled SAF to offer significant reductions in greenhouse gas emissions and other pollutants, contributing to a cleaner environment and better air quality. The review addresses the environmental, economic, and technical benefits of SAF, as well as the challenges associated with their adoption. Lifecycle analyses are used to assess the net environmental benefits of SAF, with a focus on feedstock sustainability, energy efficiency, and potential impacts on biodiversity and land use. Challenges such as economic viability, scalability, and regulatory compliance are discussed, with emphasis on the need for supportive policies and international collaboration to ensure the long-term sustainability of SAF. This study also explores current applications of SAF in commercial airlines and military settings, highlighting successful case studies and regional differences driven by policy frameworks and government incentives. By promoting technological innovation and addressing regulatory and economic barriers, SAF has the potential to play a crucial role in the aviation industry's transition toward sustainability. [ABSTRACT FROM AUTHOR]

Planned maintenance is required by licensed maintenance organizations to detect and prevent performance degradation in aircraft engines. In the literature, engine performance is evaluated with parameters that show engine performance. Fuel flow parameter is one of the important parameters that shows engine performance. In the models developed earlier, no engine performance evaluation was made with the fuel flow parameter at all stages from the take-off to the landing of the aircraft. In this study, fuel flow parameter is estimated with over 99.9% accuracy by using artificial neural network in MATLAB® software. In order to detect the engine performance deterioration of the aircraft, the fuel flow values obtained from the artificial neural network and confidence intervals with 99% confidence level were established. Each value taken from the fuel flow sensor is evaluated by the model in all flight phases. In the model, engine performance is considered normal if the fuel flow value is within the confidence interval, and abnormal (anomaly) if it is outside the confidence interval. An accuracy of over 99.9% was achieved and results of this study showed that fuel flow rate of the engine of interest was within the confidence interval (no performance deterioration). [ABSTRACT FROM AUTHOR]

Analyzing the research directions of leading aviation companies, it is evident that biocomponents will soon become a very important addition to the fuel used in turbine aircraft engines. Similarly, intensive efforts are underway to implement this type of solution in the armed forces. Here, the situation is more complex. All military fuels are intended for long-term storage, and bio-additives significantly alter the properties of fuels during this specific storage process. These changes invariably result in the deterioration of fuel quality parameters. The article presents an analysis and conclusions related to biocomponents as additives to F-35 fuel (NATO code-the military equivalent of Jet A-1 fuel). F-35 aviation fuel mixtures with the addition of biocomponents (HVO-Hydrorefined Vegetable Oil) at concentrations of 0–20% (V/V) were independently composed and stored for extended periods (0–6 months). The disadvantages and potential problems of this solution are discussed. The research has demonstrated that using biocomponents in the mixtures significantly alters the course of the distillation curve and increases the fuel’s electrical conductivity. Another adverse effect observed was a significant deterioration in the fuel’s low-temperature properties. The research indicates that using a bio-additive like HVO in F-35 fuel will require addressing many challenges. At the level of laboratory tests, it is to determine the limit value of the share of a biocomponent in a mixture at which the normative values are not yet violated and to confirm or rule out whether the mixtures are suitable for long-term storage. [ABSTRACT FROM AUTHOR]

• Without any design change, drop-in sustainable aviation fuel (SAF100) can be tailored to promote energy savings of at most 0.33 %. Such fuel would have an energy density of 34.3 GJ/m3 which is just inside the ± 2σ experience interval of conventional jet fuel; 34.0–35.6 GL/m3. • By eliminating the minimum aromatics content imposed on SAF100, optimized fuel could afford at most 0.40% energy savings for a fuel with an energy density of 34.2 GJ/m3, or 0.33% energy savings for a fuel with an energy density of 35.7 GJ/m3. • By raising the minimum energy density requirement (or design point reference fuel) by 4% and increasing the lower heating value of the design point reference fuel by 1%, both of which are attainable for optimized, 100% SAF without aromatics (Jet-X), supersonic aircraft can be made at most 2.3% more energy efficient. • The composition and property characteristics of optimized SAF100 and Jet-X are discussed at length in this article. Whether the feedstock for sustainable aviation fuel (SAF) originates from agriculture or from waste streams, life cycle CO 2 emissions per unit enthalpy are lower for SAF than they are for petroleum distillates primarily because of differences on the front end such as fostered growth of crops or decreased demand for resources or acreage to manage wastes. This work, however, is concerned with what happens on the consumption side. Sustainable aviation fuel is required by ASTM D4054 / D7566 to meet a higher thermal stability standard than petroleum distillate fuels and this characteristic can be leveraged to improve energy efficiency in new engine or aircraft designs where a commitment has been made to burning fuel that meets a specification beyond that of conventional JetA. Beyond thermal stability, non-drop-in SAF (Jet-X) developers have the opportunity to further increase the value of their product by infusing higher-than-conventional-JetA energy density (enthalpy per unit volume, ED) into their SAF. Finally, fuel specific energy (enthalpy per unit mass, LHV) has a direct impact on aircraft efficiency which we have determined to be 0.43% per MJ/kg increase in LHV depending on the mission and aircraft model, and this is applicable to both drop-in and non-drop-in applications. While higher energy density fuels may be leveraged in a new aircraft design to decrease drag and weight, aircraft development potential with reduced tank volumes is typically constrained by other factors such as wing packaging, passenger volume requirements and overall center of gravity and flight control law restrictions. [ABSTRACT FROM AUTHOR]

• Combustion systems and aviation adaptability in piston engines are analyzed. • The key technologies related to in-cylinder combustion research are summarized. • Combustion characteristics and aviation adaptability of fuels are examined. • Future development directions of combustion technology are analyzed and predicted. The in-cylinder combustion process is a focus on research on heavy fuel aviation piston engine (HF-APE), which is quite significant because of its strong correction with engine's power and economic performance, as well as the level of emissions. This study reviews the representative combustion types of HF-APE in recent years, and comprehensively analyzes their aviation adaptability from various aspects. A review was conducted from the perspective of visualization measurement, combustion analysis, and high-altitude simulation technologies, all of which are the crucial methods to study the HF-APE combustion process. A comparative study was investigated on the combustion characteristics and aviation adaptability under different fuels. To meet the requirements of airworthiness regulations and the development of general aviation for more energy saving and environmental protection, further summarizing the progress as well as predicting the trends of HF-APE combustion technologies, are expected to be promoted due to their valuable scientific significance and engineering applications. [ABSTRACT FROM AUTHOR]

• Demonstrates payload range capability of a modern aircraft retrofitted with Ammonia. • Ammonia enables smaller and compact turbofan cores with engine weight reduction. • Ammonia exists as subcooled liquid under the assessed engine operating points. • Fuel conditioning is a major design driver for Ammonia operated turbofan engines. • Impacts of Ammonia as a Hydrogen carrier for civil aviation on engine and aircraft. The 2050 net zero targets for aviation to decarbonize the industry means that solutions need to be delivered that can help achieve those targets. Transitioning to zero carbon aviation fuel is an effective solution to achieve those targets. This research article aims to highlight the potential design and performance implications of using Ammonia as a zero-carbon fuel for civil aviation through a retrofit case study conducted for an Airbus A350-1000 equivalent aircraft. The impacts on both turbofan design and aircraft payload-range capability are presented. A feasibility study of using Ammonia as a Hydrogen carrier for civil aviation is also presented. The turbofan design impacts, and payload range capability are assessed using Cranfield University's in-house gas turbine performance tool TURBOMATCH and NASA FLOPS respectively. A 3-point turbofan cycle design strategy is utilized for redesigning turbofan engine cycles using Ammonia as a fuel. Ammonia fuel conditioning assessment is made using REFPROP to investigate its impact on turbofan design. Utilizing pure Ammonia as an aircraft fuel can provide significant turbofan redesign opportunities. Fuel conditioning assessment revealed that for a 430 kN thrust class engine, 2.1 MW of thermal power is required to condition Ammonia fuel at take-off. As a result, various strategies to condition the fuel and its significant impact on turbofan design are presented indicating fuel conditioning as a major design driver for Ammonia fuelled turbofan engines in the future. Although upon initial preliminary assessment, Ammonia utilized as a Hydrogen carrier showcased potential by providing additional mission range capability when compared to a pure Ammonia burning aircraft, the significant thermal energy required to crack (decompose) Ammonia into Hydrogen highlighted the challenges at aircraft mission level and Hydrogen turbofan design implications. It is found that energy requirement (power) to crack Ammonia into Hydrogen are significant which is approximately an order of magnitude higher than Ammonia fuel conditioning itself. [ABSTRACT FROM AUTHOR]