The inboard-winglet concept was examined for its flow characteristics by testing for pressure coefficients over the wing and winglet surface in the Virginia Tech Stability Wind Tunnel over a range of freestream velocity and angle of attack. The results were analytically applied to calculate aircraft performance of a roadable aircraft, Pegasus II, which used the inboard-winglet concept in its design. The results proved that this concept has the potential to increase a wing lift coefficient at the right combination of thrust setting and freestream velocity better than a conventional wing-propeller arrangement. The lift coefficient inside the winglet channel was approximated as 2D in behavior. It is also shown that the winglets produce thrust at a positive-lift wing configuration. In the Pegasus II, the vertical stabilizers act like inboard winglets and produce a thrust component from its resultant force, giving 5.2% improvement in its effective aspect ratio and resulting in an induced-drag decrease. With an application of the new wing concept, the Pegasus II performance is comparable to other general aviation aircraft. / Master of Science

The topic of the thesis is a conceptual design of a roadable aircraft. The comparison of existing concepts is made, as well as description of proposed solution, aircraft mass analysis, basic aerostatic calculations, flight and gust envelope calculation and a design of truss construction of the fuselage. The CS-VLA, alternatively ELSA-K, has been used as a certification base. The compliance to this certification specification is one of the goals of this thesis.