Methods and apparatus for unmanned long endurance flights are provided herein. In some embodiments, a lightweight solar wing for unmanned aircraft may include at least one airfoil profile, a top surface, a bottom surface, a leading edge, a trailing edge, wing tips, and at least one photovoltaic cell, wherein the surfaces and edges follow an arched bow shape across a span of the wing. In some embodiments, an unmanned solar-powered aircraft may include at least one lightweight solar wing as described above, at least one fuselage, and at least one propeller, wherein the fuselage is placed below the solar wing and contains an electric motor, battery, and electronics.