This paper presents the design details and flight tests validation of printed circuit board fabricated micro gliders. The purpose of the micro glider is to be launched from a super pressure balloon at high altitude, glide to the target position to collect data and upload data to the staying balloon. The mission demand requires the micro glider to finish precise landing with small size and low fabrication cost. To complete this concept, we designed a PCB fabricated aircraft with limited sensors including GPS and IMU. The first part of the article describes the aerodynamic design methods. The second part introduced the control and guidance system design by controlling the roll angle and flight path angle to complete the precise landing. In the simulation results presented in the third part, launch with no wind condition shows desirable precise landing ability. As a contrast, wind direction and magnitude have significant effects on the guidance ability and accuracy. In the last part, two real flight tests conducted in Inner Mongolia of China are described to compare the flight performance with the current aerodynamics and control system design. Returned data indicated the micro gliders could successfully fly at high altitude. The control algorithm can compute the command roll angle only with GPS and IMU, but some design details still need to be improved to achieve precise landing ability.
This paper presents an aeroelastic analysis for the high altitude propeller designed for the stratospheric airship KFG-series. Aerodynamic analysis is carried out in Fluent by using sliding mesh method and a loosely coupled method is employed to solve the aeroelastic response. The real composite propeller structure is modeled in Ansys Acp module and Mechanical APDL enable the data exchange between CFD and CSD solver. Spring-based smoothing method is adopted for updating the mesh deformation. Firstly a comparison between experimental and numerical results is employed for validating the accuracy of the numerical model. Then in fluid-structure analysis, aeroelastic response of the blade tip leading edge shows a limit cycle oscillation and the blade averaged deformation shows a very small deflection due to the dynamic stiffness effect. In the final, equivalent stress of the blade material and a comparative study of the aerodynamic performance for rigid and deformed propeller at the design condition are presented and it is found that there is a lower thrust performance for the deformed propeller due to the small pitch variation.
Based on the characteristics of the configuration and flight of the micro gliding air vehicle (MGAV), an analysis and optimization for general gliding path of different mission demands is carried out. Firstly, an overall design method and parameters are summarized. Secondly, the equilibrium glide launching parameters are determined based on the general aircraft re-entry equation. The real launching parameter are also developed by considering the real launching facility. Furthermore, the un-controlled maximum-range-towards path characteristics for the real and equilibrium glide are compared and analyzed. The range in equilibrium glide is 5 km larger than real glide. Then, two potential flight demand are explained and the Gauss pseudo-spectral method is adopted to solve the maximum endurance and the maximum endurance and range with the process constraint and final constraint. The first target is 8 minutes longer than the original glide path but the range is 20 km less compared to the maximum range. The second target could keep the maximum range and at the meantime, the endurance could be increased 2 minutes. Finally, the control variables are substituted into the dynamic equations to validate the results. The result shows that the Gauss pseudo-spectral method is an effective and feasible way to solve the optimum gliding path.
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