A series of combustion experiments were performed employing a micro-jet engine under diverse conditions. These conditions encompassed a spectrum of Biofuel mixture ratios spanning from 10 to 50, alongside rotating speeds ranging between 80,000 and 100,000rpm. The primary objective was to clarify the combustion characteristics and exhaust gas components of Biofuel (fatty acid ethyl esters) derived from coconut oil. Comparing the combustion efficiency of jet fuel and Biofuel-blended fuel, the findings exhibited a marginal enhancement in efficiency when Biofuel mixtures comprised up to 50% Biofuel. This increase was ascribed to the increase in the oxygen content within the fatty acid ethyl ester constituents and the relatively low heating values of the ethyl esters compared with those of the jet fuel. On the other hand, the specific fuel consumption increases with higher Biofuel blending ratios. This is because, as the Biofuel blending ratio increases, the lower heating value decreases, necessitating more fuel for stable combustion. Gas analysis revealed various effects on greenhouse gas emissions. While CO emissions increased slightly, CO$_2$ and NO emissions decreased with an increase in the Biofuel blending ratio.

The partial load operational analysis of fully superconducting motors for the future electrified aircraft has been conducted based on the analytical equations. The authors modeled propulsion fan units and superconducting motor drive systems composed of fully superconducting motors and inverters. In the case of 6 propulsion fans and a pressure ratio of 1.45, a power density of 16.3kW/kg was obtained for a fully superconducting motor and 9.0 kW/kg for a motor drive system. Furthermore, it was demonstrated that the superconducting propulsion unit has the potential to achieve higher power density compared to the permanent magnet synchronous motor propulsion unit using conventional technology, provided that multiple design parameters are appropriately configured.

Numerical simulations of a lift-offset coaxial rotor with blade twist of 0, 4, and 8 degrees during high advance ratio forward flight are conducted. The coaxial rotor's performance, cyclic controls, blade airloads and hub loads were analyzed using the rFlow3D rotorcraft CFD code with lift-offsets up to 0.3 at high advance ratios (μ = 0.7, 0.3). The results show that as blade twist increases, the increased rotor normal force distribution in the front and rear of the rotor was flattened by the increased normal force near ψ = 90^º on the advancing side, and the effective drag coefficient decreases with a decrease in the collective pitch angle. The increase in blade twist is also effective in reducing vibration because it decreases both the blade airloads and the hub loads.

In the near future, manned and unmanned aircraft, for example helicopters and small drones, are expected to be operated simultaneously in the same airspace for monitoring purposes in immediate disaster response. However, most helicopters operate under visual flight rules (VFR) and their flight plans often do not contain sufficient information to allow ground operators to accurately predict their trajectory. Assuming VFR flights have to be segregated from small drones for safe operations, however, determination of operation volume is essential. This study investigates especially focusing on VFR operation volume for monitoring specific ground locations. As the VFR trajectories for such missions typically become circular, the operation volume would normally be designed as cylindrical ones based on conventional methodology. In this study, actual flight data for monitoring mission at a huge earthquake are analyzed to investigate their characteristics. As a result, a conical airspace is newly proposed for the VFR operation volume that is able to enhance the activity of unmanned aircraft in low altitude.