Today's unmanned aerial vehicles are being utilized by numerous groups around the world for various missions. Most of the smaller vehicles that have been developed use commercially-off-the-shelf parts, and little information about the performance characteristics of the propulsion systems is available in the archival literature. In light of this, the aim of the present research was to determine the performance of various smallscale propellers in the 4.0 to 6.0 inch diameter range driven by an electric motor. An experimental test stand was designed and constructed in which the propeller/electric motor was mounted in a wind tunnel for both static and dynamic testing. Both static and dynamic results from the present experiment were compared to those from previous studies. For static testing, the coefficient of thrust, the coefficient of propeller power, and the overall efficiency, defined as the ratio of the propeller output power to the electrical input power, were plotted versus the propeller rotational speed. For dynamic testing, the rotational speed of the propeller was held constant at regular intervals while the freestream airspeed was increased from zero to the windmill state. The coefficient of thrust, the coefficient of power, the propeller efficiency and the overall efficiency were plotted versus the advance ratio for various rotational speeds. The thrust and torque were found to increase with rotational speed, propeller pitch and diameter, and decrease with airspeed. Using the present data and data from the archival and non-archival sources, it was found that the coefficient of thrust increases with propeller diameter for square iv propellers where D = P. The coefficient of thrust for a family of propellers (same manufacturer and application) was found to have a good correlation from static conditions to the windmill state. While the propeller efficiency was well correlated for this family of propellers, the goodness of fit parameter was improved by modifying the propeller efficiency with D/P.
This paper examines a unique method of flight control for flapping wing micro air vehicles. Instead of employing rigid body joints and flaps for torsional agility, the technique implemented a compliant tail mechanism. The bio-inspired technique utilizes a flexible carbon fiber (CF) tail to mimic body posture changes of insects, specifically lateral abdomen deflections. This method of flight control was examined using Flytech's WowWee Dragonfly as an experimental platform. Trajectory analysis was done to generate a three dimensional flight path of the vehicle for examining flight characteristics. ANSYS FLUENT fluid dynamics software with GAMBIT and Solidworks CAD software were utilized to investigate aerodynamic torques and gravitational torques corresponding to active tail warping. The results provided evidences suggesting that the warping tail administered adequate control authority for basic maneuvering.
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