M.Sc Thesis

M.Sc StudentLidor Alon
SubjectAlternative Energy Sources for Micro Unmanned Aerial
DepartmentDepartment of Aerospace Engineering
Supervisors PROF. Eran Sher
Full Thesis textFull thesis text - English Version


Recent years have seen an increased effort in research and development of remotely-controlled and autonomous micro aerial vehicles (MAV). While there are many different challenges in the development of MAVs, one of the severe limiting factors in terms of weight is the energy source/storage. Most of the MAVs developed to date are based on electrochemical batteries, with limited endurance (operational time) of less than 30 minutes. In the present study, several potential alternative energy storage systems are compared: carbon nano-tubes (CNT), fuel cells, shape memory alloys (SMA), synthetic muscles, flywheels, elastic elements, pneumatics, thermal systems, radioisotope thermoelectric generators, and phase change materials (PCM). The potential alternatives are compared to electrical batteries and hydrocarbon fuel storage for miniature internal combustion engines (ICE). The results are then applied to typical fixed wing and rotary wing MAV configurations with several mission profiles.

A novel PCM open cycle in which the environment is the warm reservoir is suggested and analyzed, revealing promising results in terms of specific power and thermodynamic efficiency. For a nitrogen based PCM open cycle with a 20W microturbine as the power generating device, a specific power of 45-140W/kg with an open-cycle thermodynamic efficiency of 22-54% is achieved. The specific energy of the system is 20-45W-h/kg, under different ambient conditions, with temperature ranging from -17.5°C to 45°C and pressure of 50kPa to 101.325kPa. We conclude that for the near future, a promising alternative energy storage method for MAVs is the phase-change materials. Other promising methods are micro fuel cells, and for the far future, carbon nano-tubes and synthetic muscles.