Wing-Embedded, Cross-Flow-Fan, Vertical Takeoff and Landing Air Vehicle
NAVAL POSTGRADUATE SCHOOL MONTEREY
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This research demonstrated that a vertical takeoff and landing aircraft capable of transitioning to conventional flight using cross-flow fans is possible. In particular, the design and manufacture of a wing-embedded cross-flow fan airfoil, and its implementation into an aircraft, was conducted. The design was developed based on the Gottingen 570 airfoil and generated lift coefficients of four--greater than the sum of the parts--due to the fundamental coupling between the wing and cross-flow fan. The wing was characterized with Ansys CFX solver over tip-speed ratios of zero hover to infinity glide, and predicted a hover angle of 36 deg with 56 of the lift coming from the airfoil. This meant that a full 90 deg rotation was not required to go from hover to forward flight additionally, even while hovering, more than half of the lift was generated by the airfoil. The airfoil was manufactured from pre-impregnated carbon fiber using a mold produced by 3D printing. Printer filament selection was based on glass transition temperature and printability. ABS filament was chosen due to its high temperature resistance and relative ease of 3D printing. The aircraft was configured with all the wing assemblies facing the same direction to favor faster forward flight. This differed from previous designs, which used symmetry to increase stability. Controlled untethered flight was successful.