###### Abstract  
The article investigates the possibilities for the miscibility and practical use of different concentrations of biofuel rapeseed fatty acid methyl ester (FAME) with aviation kerosene Jet A-1 (or aviation kerosene PL-7 used in the Air Force of the Slovak Republic) in aircraft jet engines. The main objective of this research was the experimental verification of the technical possibilities of reliable operation of the experimental engine SJE-20 in a special laboratory of small jet engines using different concentrations of the mixture of aviation kerosene Jet A-1 and biofuel FAME and their influence on the selected operating parameters of the experimental engine. The motivation for this research is the desire to replace conventional aviation fuels with fuels that can be obtained from renewable sources. Investigation of the possibilities of powering the experimental SJE-20 engine with a mixture of traditional aviation kerosene Jet A-1 (PL-7) and rapeseed fatty acid methyl ester FAME was the subject of the internal project BIOFUEL (Biofuel for Aviation). b +
Footnote †: journal: Applied  
as a potential feedstock, an artificial cultivation system-photo-bioreactor would be the most effective in terms of the quantity of cultivated product but is confronted by the high operating cost. [PERSON] et al. [7] analyzed the possibilities of using babassu biofuels based on babassu culture in the aviation sector, concluding several critical factors, such as their high freezing point, make them unusable alone. However, they show good results when mixed with aviation kerosene. [PERSON] et al. [8] studied the uses of biofuels such as biokerosene and FAME in aeronautics, focusing on military aviation and pathways of alternative fuel production. Transesterification and hydro-treating were identified as two main processes for obtaining biofuels for aviation through two-level tests to determine alternative fuels' ability to replace fossil fuels. Multiple studies have provided research on alternative aviation fuels' performance and emissions characteristics. [PERSON] et al. [9] have provided an overview of the alternative aviation fuels in use over the last 30 years. According to their study, all the studied biofuels (biodiesel, bioethanol, bio-oil) and their blends have proven their ability to reduce gaseous and particulate matter emissions while improving gas turbine performance. Many authors have focused on the characteristics of blends of Jet A-1 fuel with various blends and additives [10; 11; 12; 13]. [PERSON] and [PERSON] [10] experimented on the miniature turbojet engine to determine the performance and emission characteristics of the Jet A-1 blend with 48% synthesized paraffinic kerosene. In comparison with neat Jet A-1, HEFA fuel showed a decrease in thrust and a reduction in fuel consumption caused by the higher heat of combustion and lower density of the HEFA fuel. [PERSON] et al. [11] studied the effects of Jet A-1 blends with butanol on the performance of gas turbine engines. The thrust, fuel combustion, turbine inlet temperature, exhaust gas temperature, and emissions characteristics were studied. The ratios of butanol ranged from 25% to 75%. It was determined that the operational thrust range of the engine was decreasing with the blends, and so were NOx and C.O. emissions. [PERSON] et al. [12] conducted an experiment on a micro gas turbine to determine the changes in combustion, emission, and performance characteristics when Jet A-1 fuel is blended with various additives. For their experiment, blends of Jet A-1 with biofuels from rapeseed and cona-sunflower oil were used with various ratios of ethanol and pentanol additives. All the blends showed higher static thrust with reduced fuel consumption and a reduction in NOx, CO, H.C., and other emissions compared to neat Jet A-1 fuel. [PERSON] et al. [13] studied the effects of Jet A-1 50% blends with biofuels to prove biofuels' potential. Reduction in static thrust and thrust-specific fuel consumption was observed, while thermal efficiency was increased.