Experimental investigation of aerodynamic vectoring and power effects in UAVs

• Main Author: Foong, Herng Huei.
• Other Authors: Go Tiauw Hiong
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Aeronautical engineering::Aerodynamics
• Online Access: http://hdl.handle.net/10356/44977
• Institution: Nanyang Technological University

This project is an experimental investigation into two areas of research related to the aerodynamics and performance of small agile UAVs: aerodynamic vectoring and power effects. Aerodynamic vectoring involves the deflection of entire aerodynamic surfaces to improve control capabilities in small agile UAVs executing transition manoeuvres between hover and forward flight modes. A previous study using a computational aerodynamics model had shown that potential of aerodynamic vectoring. Wind tunnel testing was carried out on a conventionally configured aircraft model with a wing area of 0.06m2 and wind span of 0.51m. Experimental results obtained are in close agreement with the computational aerodynamics model. Power effects refer to the changes in the aerodynamic qualities of aircraft arising from thrust effects. In this project, the effects of propeller induced flow on the aerodynamics of UAVs are of particular interest. As such, effects arising directly from thrust and normal forces were removed during analysis so that the effects of propeller induced flow are isolated. Extensive wind tunnel testing at eight wind tunnel speeds ranging from 6.5m/s to 21.1m/s (Re ≈ 47000 – 152000) was carried out. During these tests, changes in lift, drag and pitching moments and flow separation angle were observed. Flow separation was delayed by up to 10 degrees; the maximum lift coefficient increased by up to 59%; drag coefficients increased in tests where the dynamic thrust was non-negative; pitching moment coefficients were observed to decrease to the extent that trim cannot be achieved. These effects are likely to be caused by increased dynamic pressures over the wings and elevators as well as changes in downwash angles.