Long-Term Storage Stability: Density of Jet A and Camelina Biodiesel Blends for UAV Micro-Turbojet Applications

This study evaluates the impact of long-term storage on aviation fuel blends composed of Jet A and camelina-derived biodiesel. The physicochemical properties of the pure biodiesel were assessed according to EN 14214 and ASTM D6751 standards, while the resulting Jet A–biodiesel blends were evaluated against ASTM D1655 aviation fuel specifications. Particular attention was given to the evolution of density during storage as an indicator of fuel stability. The results show that camelina methyl esters exhibit generally satisfactory physicochemical characteristics; however, the iodine value remains a critical limitation. The measured value of approximately 155 significantly exceeds the maximum limit of 120 established by European standards, reflecting the high degree of unsaturation of the feedstock. Long-term monitoring of the blends revealed a clear relationship between biodiesel concentration and the rate of fuel degradation. Increasing the biodiesel fraction led to more pronounced variations in density during storage, indicating reduced stability of the fuel system. Consequently, instability risks increase proportionally with the biodiesel-to-Jet A ratio, highlighting the need for appropriate storage strategies and technological optimization when considering higher concentrations of camelina-derived biodiesel in aviation fuel blends.