The aerodynamic design of micro air vehicles is challenging since previous studies have shown that the aerodynamic efficiency of airfoils and wings decreases substantially at low Reynolds-numbers. While many MAV approaches investigate biological designs, here a study is conducted on the aerodynamics of paper airplanes, which fly in the same Reynolds-number range as MAV, but have the advantage of simplicity compared to biological counterparts. Flow visualizations and force measurements in a water tunnel as well as large-eddy simulations are presented on one of the simplest paper airplane design: the dart. The results show that the high-sweep delta design of such an airplane provides high lift coefficients at low Reynolds-numbers. Furthermore, the centerfold of the airplane as a mean to improve the aerodynamic performance is identified.